1 ## Copyright (C) 1996-2020 The Squid Software Foundation and contributors
3 ## Squid software is distributed under GPLv2+ license and includes
4 ## contributions from numerous individuals and organizations.
5 ## Please see the COPYING and CONTRIBUTORS files for details.
10 ----------------------------
12 This is the documentation for the Squid configuration file.
13 This documentation can also be found online at:
14 http://www.squid-cache.org/Doc/config/
16 You may wish to look at the Squid home page and wiki for the
17 FAQ and other documentation:
18 http://www.squid-cache.org/
19 http://wiki.squid-cache.org/SquidFaq
20 http://wiki.squid-cache.org/ConfigExamples
22 This documentation shows what the defaults for various directives
23 happen to be. If you don't need to change the default, you should
24 leave the line out of your squid.conf in most cases.
26 In some cases "none" refers to no default setting at all,
27 while in other cases it refers to the value of the option
28 - the comments for that keyword indicate if this is the case.
33 Configuration options can be included using the "include" directive.
34 Include takes a list of files to include. Quoting and wildcards are
39 include /path/to/included/file/squid.acl.config
41 Includes can be nested up to a hard-coded depth of 16 levels.
42 This arbitrary restriction is to prevent recursive include references
43 from causing Squid entering an infinite loop whilst trying to load
46 Values with byte units
48 Squid accepts size units on some size related directives. All
49 such directives are documented with a default value displaying
52 Units accepted by Squid are:
54 KB - Kilobyte (1024 bytes)
58 Values with spaces, quotes, and other special characters
60 Squid supports directive parameters with spaces, quotes, and other
61 special characters. Surround such parameters with "double quotes". Use
62 the configuration_includes_quoted_values directive to enable or
65 Squid supports reading configuration option parameters from external
66 files using the syntax:
67 parameters("/path/filename")
69 acl whitelist dstdomain parameters("/etc/squid/whitelist.txt")
71 Conditional configuration
73 If-statements can be used to make configuration directives
77 ... regular configuration directives ...
79 ... regular configuration directives ...]
82 The else part is optional. The keywords "if", "else", and "endif"
83 must be typed on their own lines, as if they were regular
84 configuration directives.
86 NOTE: An else-if condition is not supported.
88 These individual conditions types are supported:
91 Always evaluates to true.
93 Always evaluates to false.
95 Equality comparison of two integer numbers.
100 The following SMP-related preprocessor macros can be used.
102 ${process_name} expands to the current Squid process "name"
103 (e.g., squid1, squid2, or cache1).
105 ${process_number} expands to the current Squid process
106 identifier, which is an integer number (e.g., 1, 2, 3) unique
107 across all Squid processes of the current service instance.
109 ${service_name} expands into the current Squid service instance
110 name identifier which is provided by -n on the command line.
114 Logformat macros can be used in many places outside of the logformat
115 directive. In theory, all of the logformat codes can be used as %macros,
116 where they are supported. In practice, a %macro expands as a dash (-) when
117 the transaction does not yet have enough information and a value is needed.
119 There is no definitive list of what tokens are available at the various
120 stages of the transaction.
122 And some information may already be available to Squid but not yet
123 committed where the macro expansion code can access it (report
124 such instances!). The macro will be expanded into a single dash
125 ('-') in such cases. Not all macros have been tested.
129 # options still not yet ported from 2.7 to 3.x
130 NAME: broken_vary_encoding
133 This option is not yet supported by Squid-3.
139 This option is not yet supported by Squid-3.
145 This option is not yet supported by Squid-3.
148 NAME: external_refresh_check
151 This option is not yet supported by Squid-3.
154 NAME: location_rewrite_program location_rewrite_access location_rewrite_children location_rewrite_concurrency
157 This option is not yet supported by Squid-3.
160 NAME: refresh_stale_hit
163 This option is not yet supported by Squid-3.
166 # Options removed in 4.x
167 NAME: cache_peer_domain cache_host_domain
170 Replace with dstdomain ACLs and cache_peer_access.
176 Remove this line. The behaviour enabled by this is no longer needed.
179 NAME: sslproxy_cafile
182 Remove this line. Use tls_outgoing_options cafile= instead.
185 NAME: sslproxy_capath
188 Remove this line. Use tls_outgoing_options capath= instead.
191 NAME: sslproxy_cipher
194 Remove this line. Use tls_outgoing_options cipher= instead.
197 NAME: sslproxy_client_certificate
200 Remove this line. Use tls_outgoing_options cert= instead.
203 NAME: sslproxy_client_key
206 Remove this line. Use tls_outgoing_options key= instead.
212 Remove this line. Use tls_outgoing_options flags= instead.
215 NAME: sslproxy_options
218 Remove this line. Use tls_outgoing_options options= instead.
221 NAME: sslproxy_version
224 Remove this line. Use tls_outgoing_options options= instead.
227 # Options removed in 3.5
228 NAME: hierarchy_stoplist
231 Remove this line. Use always_direct or cache_peer_access ACLs instead if you need to prevent cache_peer use.
234 # Options removed in 3.4
238 Remove this line. Use acls with access_log directives to control access logging
244 Remove this line. Use acls with icap_log directives to control icap logging
247 # Options Removed in 3.3
248 NAME: ignore_ims_on_miss
251 Remove this line. The HTTP/1.1 feature is now configured by 'cache_miss_revalidate'.
254 # Options Removed in 3.2
255 NAME: balance_on_multiple_ip
258 Remove this line. Squid performs a 'Happy Eyeballs' algorithm, this multiple-IP algorithm is not longer relevant.
261 NAME: chunked_request_body_max_size
264 Remove this line. Squid is now HTTP/1.1 compliant.
267 NAME: dns_v4_fallback
270 Remove this line. Squid performs a 'Happy Eyeballs' algorithm, the 'fallback' algorithm is no longer relevant.
273 NAME: emulate_httpd_log
276 Replace this with an access_log directive using the format 'common' or 'combined'.
282 Use a regular access.log with ACL limiting it to MISS events.
288 Remove this line. Configure FTP page display using the CSS controls in errorpages.css instead.
291 NAME: ignore_expect_100
294 Remove this line. The HTTP/1.1 feature is now fully supported by default.
300 Remove this option from your config. To log FQDN use %>A in the log format.
303 NAME: log_ip_on_direct
306 Remove this option from your config. To log server or peer names use %<A in the log format.
309 NAME: maximum_single_addr_tries
312 Replaced by connect_retries. The behaviour has changed, please read the documentation before altering.
315 NAME: referer_log referrer_log
318 Replace this with an access_log directive using the format 'referrer'.
324 Remove this line. The feature is supported by default in storage types where update is implemented.
327 NAME: url_rewrite_concurrency
330 Remove this line. Set the 'concurrency=' option of url_rewrite_children instead.
336 Replace this with an access_log directive using the format 'useragent'.
339 # Options Removed in 3.1
343 Remove this line. DNS is no longer tested on startup.
346 NAME: extension_methods
349 Remove this line. All valid methods for HTTP are accepted by default.
352 # 2.7 Options Removed/Replaced in 3.2
357 # 2.7 Options Removed/Replaced in 3.1
365 Remove this line. HTTP/1.1 is supported by default.
368 NAME: upgrade_http0.9
371 Remove this line. ICY/1.0 streaming protocol is supported by default.
374 NAME: zph_local zph_mode zph_option zph_parent zph_sibling
377 Alter these entries. Use the qos_flows directive instead.
380 # Options Removed in 3.0
384 Since squid-3.0 replace with request_header_access or reply_header_access
385 depending on whether you wish to match client requests or server replies.
388 NAME: httpd_accel_no_pmtu_disc
391 Since squid-3.0 use the 'disable-pmtu-discovery' flag on http_port instead.
394 NAME: wais_relay_host
397 Replace this line with 'cache_peer' configuration.
400 NAME: wais_relay_port
403 Replace this line with 'cache_peer' configuration.
408 -----------------------------------------------------------------------------
415 DEFAULT_DOC: SMP support disabled.
417 Number of main Squid processes or "workers" to fork and maintain.
418 0: "no daemon" mode, like running "squid -N ..."
419 1: "no SMP" mode, start one main Squid process daemon (default)
420 N: start N main Squid process daemons (i.e., SMP mode)
422 In SMP mode, each worker does nearly all what a single Squid daemon
423 does (e.g., listen on http_port and forward HTTP requests).
426 NAME: cpu_affinity_map
428 LOC: Config.cpuAffinityMap
430 DEFAULT_DOC: Let operating system decide.
432 Usage: cpu_affinity_map process_numbers=P1,P2,... cores=C1,C2,...
434 Sets 1:1 mapping between Squid processes and CPU cores. For example,
436 cpu_affinity_map process_numbers=1,2,3,4 cores=1,3,5,7
438 affects processes 1 through 4 only and places them on the first
439 four even cores, starting with core #1.
441 CPU cores are numbered starting from 1. Requires support for
442 sched_getaffinity(2) and sched_setaffinity(2) system calls.
444 Multiple cpu_affinity_map options are merged.
449 NAME: shared_memory_locking
452 LOC: Config.shmLocking
455 Whether to ensure that all required shared memory is available by
456 "locking" that shared memory into RAM when Squid starts. The
457 alternative is faster startup time followed by slightly slower
458 performance and, if not enough RAM is actually available during
459 runtime, mysterious crashes.
461 SMP Squid uses many shared memory segments. These segments are
462 brought into Squid memory space using an mmap(2) system call. During
463 Squid startup, the mmap() call often succeeds regardless of whether
464 the system has enough RAM. In general, Squid cannot tell whether the
465 kernel applies this "optimistic" memory allocation policy (but
466 popular modern kernels usually use it).
468 Later, if Squid attempts to actually access the mapped memory
469 regions beyond what the kernel is willing to allocate, the
470 "optimistic" kernel simply kills Squid kid with a SIGBUS signal.
471 Some of the memory limits enforced by the kernel are currently
472 poorly understood: We do not know how to detect and check them. This
473 option ensures that the mapped memory will be available.
475 This option may have a positive performance side-effect: Locking
476 memory at start avoids runtime paging I/O. Paging slows Squid down.
478 Locking memory may require a large enough RLIMIT_MEMLOCK OS limit,
479 CAP_IPC_LOCK capability, or equivalent.
482 NAME: hopeless_kid_revival_delay
485 LOC: Config.hopelessKidRevivalDelay
488 Normally, when a kid process dies, Squid immediately restarts the
489 kid. A kid experiencing frequent deaths is marked as "hopeless" for
490 the duration specified by this directive. Hopeless kids are not
491 automatically restarted.
493 Currently, zero values are not supported because they result in
494 misconfigured SMP Squid instances running forever, endlessly
495 restarting each dying kid. To effectively disable hopeless kids
496 revival, set the delay to a huge value (e.g., 1 year).
498 Reconfiguration also clears all hopeless kids designations, allowing
499 for manual revival of hopeless kids.
503 OPTIONS FOR AUTHENTICATION
504 -----------------------------------------------------------------------------
510 LOC: Auth::TheConfig.schemes
513 This is used to define parameters for the various authentication
514 schemes supported by Squid.
516 format: auth_param scheme parameter [setting]
518 The order in which authentication schemes are presented to the client is
519 dependent on the order the scheme first appears in config file. IE
520 has a bug (it's not RFC 2617 compliant) in that it will use the basic
521 scheme if basic is the first entry presented, even if more secure
522 schemes are presented. For now use the order in the recommended
523 settings section below. If other browsers have difficulties (don't
524 recognize the schemes offered even if you are using basic) either
525 put basic first, or disable the other schemes (by commenting out their
528 Once an authentication scheme is fully configured, it can only be
529 shutdown by shutting squid down and restarting. Changes can be made on
530 the fly and activated with a reconfigure. I.E. You can change to a
531 different helper, but not unconfigure the helper completely.
533 Please note that while this directive defines how Squid processes
534 authentication it does not automatically activate authentication.
535 To use authentication you must in addition make use of ACLs based
536 on login name in http_access (proxy_auth, proxy_auth_regex or
537 external with %LOGIN used in the format tag). The browser will be
538 challenged for authentication on the first such acl encountered
539 in http_access processing and will also be re-challenged for new
540 login credentials if the request is being denied by a proxy_auth
543 WARNING: authentication can't be used in a transparently intercepting
544 proxy as the client then thinks it is talking to an origin server and
545 not the proxy. This is a limitation of bending the TCP/IP protocol to
546 transparently intercepting port 80, not a limitation in Squid.
547 Ports flagged 'transparent', 'intercept', or 'tproxy' have
548 authentication disabled.
550 === Parameters common to all schemes. ===
553 Specifies the command for the external authenticator.
555 By default, each authentication scheme is not used unless a
556 program is specified.
558 See http://wiki.squid-cache.org/Features/AddonHelpers for
559 more details on helper operations and creating your own.
562 Specifies a string to be append to request line format for
563 the authentication helper. "Quoted" format values may contain
564 spaces and logformat %macros. In theory, any logformat %macro
565 can be used. In practice, a %macro expands as a dash (-) if
566 the helper request is sent before the required macro
567 information is available to Squid.
569 By default, Squid uses request formats provided in
570 scheme-specific examples below (search for %credentials).
572 The expanded key_extras value is added to the Squid credentials
573 cache and, hence, will affect authentication. It can be used to
574 autenticate different users with identical user names (e.g.,
575 when user authentication depends on http_port).
577 Avoid adding frequently changing information to key_extras. For
578 example, if you add user source IP, and it changes frequently
579 in your environment, then max_user_ip ACL is going to treat
580 every user+IP combination as a unique "user", breaking the ACL
581 and wasting a lot of memory on those user records. It will also
582 force users to authenticate from scratch whenever their IP
586 Specifies the protection scope (aka realm name) which is to be
587 reported to the client for the authentication scheme. It is
588 commonly part of the text the user will see when prompted for
589 their username and password.
591 For Basic the default is "Squid proxy-caching web server".
592 For Digest there is no default, this parameter is mandatory.
593 For NTLM and Negotiate this parameter is ignored.
595 "children" numberofchildren [startup=N] [idle=N] [concurrency=N]
596 [queue-size=N] [on-persistent-overload=action]
597 [reservation-timeout=seconds]
599 The maximum number of authenticator processes to spawn. If
600 you start too few Squid will have to wait for them to process
601 a backlog of credential verifications, slowing it down. When
602 password verifications are done via a (slow) network you are
603 likely to need lots of authenticator processes.
605 The startup= and idle= options permit some skew in the exact
606 amount run. A minimum of startup=N will begin during startup
607 and reconfigure. Squid will start more in groups of up to
608 idle=N in an attempt to meet traffic needs and to keep idle=N
609 free above those traffic needs up to the maximum.
611 The concurrency= option sets the number of concurrent requests
612 the helper can process. The default of 0 is used for helpers
613 who only supports one request at a time. Setting this to a
614 number greater than 0 changes the protocol used to include a
615 channel ID field first on the request/response line, allowing
616 multiple requests to be sent to the same helper in parallel
617 without waiting for the response.
619 Concurrency must not be set unless it's known the helper
620 supports the input format with channel-ID fields.
622 The queue-size option sets the maximum number of queued
623 requests. A request is queued when no existing child can
624 accept it due to concurrency limit and no new child can be
625 started due to numberofchildren limit. The default maximum is
626 2*numberofchildren. Squid is allowed to temporarily exceed the
627 configured maximum, marking the affected helper as
628 "overloaded". If the helper overload lasts more than 3
629 minutes, the action prescribed by the on-persistent-overload
632 The on-persistent-overload=action option specifies Squid
633 reaction to a new helper request arriving when the helper
634 has been overloaded for more that 3 minutes already. The number
635 of queued requests determines whether the helper is overloaded
636 (see the queue-size option).
638 Two actions are supported:
640 die Squid worker quits. This is the default behavior.
642 ERR Squid treats the helper request as if it was
643 immediately submitted, and the helper immediately
644 replied with an ERR response. This action has no effect
645 on the already queued and in-progress helper requests.
647 NOTE: NTLM and Negotiate schemes do not support concurrency
648 in the Squid code module even though some helpers can.
650 The reservation-timeout=seconds option allows NTLM and Negotiate
651 helpers to forget about clients that abandon their in-progress
652 connection authentication without closing the connection. The
653 timeout is measured since the last helper response received by
654 Squid for the client. Fractional seconds are not supported.
656 After the timeout, the helper will be used for other clients if
657 there are no unreserved helpers available. In the latter case,
658 the old client attempt to resume authentication will not be
659 forwarded to the helper (and the client should open a new HTTP
660 connection and retry authentication from scratch).
662 By default, reservations do not expire and clients that keep
663 their connections open without completing authentication may
664 exhaust all NTLM and Negotiate helpers.
667 If you experience problems with PUT/POST requests when using
668 the NTLM or Negotiate schemes then you can try setting this
669 to off. This will cause Squid to forcibly close the connection
670 on the initial request where the browser asks which schemes
671 are supported by the proxy.
673 For Basic and Digest this parameter is ignored.
676 Useful for sending credentials to authentication backends that
677 expect UTF-8 encoding (e.g., LDAP).
679 When this option is enabled, Squid uses HTTP Accept-Language
680 request header to guess the received credentials encoding
681 (ISO-Latin-1, CP1251, or UTF-8) and then converts the first
682 two encodings into UTF-8.
684 When this option is disabled and by default, Squid sends
685 credentials in their original (i.e. received) encoding.
687 This parameter is only honored for Basic and Digest schemes.
688 For Basic, the entire username:password credentials are
689 checked and, if necessary, re-encoded. For Digest -- just the
690 username component. For NTLM and Negotiate schemes, this
691 parameter is ignored.
693 IF HAVE_AUTH_MODULE_BASIC
694 === Basic authentication parameters ===
696 "credentialsttl" timetolive
697 Specifies how long squid assumes an externally validated
698 username:password pair is valid for - in other words how
699 often the helper program is called for that user. Set this
700 low to force revalidation with short lived passwords.
702 NOTE: setting this high does not impact your susceptibility
703 to replay attacks unless you are using an one-time password
704 system (such as SecureID). If you are using such a system,
705 you will be vulnerable to replay attacks unless you also
706 use the max_user_ip ACL in an http_access rule.
708 "casesensitive" on|off
709 Specifies if usernames are case sensitive. Most user databases
710 are case insensitive allowing the same username to be spelled
711 using both lower and upper case letters, but some are case
712 sensitive. This makes a big difference for user_max_ip ACL
713 processing and similar.
716 IF HAVE_AUTH_MODULE_DIGEST
717 === Digest authentication parameters ===
719 "nonce_garbage_interval" timeinterval
720 Specifies the interval that nonces that have been issued
721 to client_agent's are checked for validity.
723 "nonce_max_duration" timeinterval
724 Specifies the maximum length of time a given nonce will be
727 "nonce_max_count" number
728 Specifies the maximum number of times a given nonce can be
731 "nonce_strictness" on|off
732 Determines if squid requires strict increment-by-1 behavior
733 for nonce counts, or just incrementing (off - for use when
734 user agents generate nonce counts that occasionally miss 1
735 (ie, 1,2,4,6)). Default off.
737 "check_nonce_count" on|off
738 This directive if set to off can disable the nonce count check
739 completely to work around buggy digest qop implementations in
740 certain mainstream browser versions. Default on to check the
741 nonce count to protect from authentication replay attacks.
743 "post_workaround" on|off
744 This is a workaround to certain buggy browsers who send an
745 incorrect request digest in POST requests when reusing the
746 same nonce as acquired earlier on a GET request.
750 === Example Configuration ===
752 This configuration displays the recommended authentication scheme
753 order from most to least secure with recommended minimum configuration
754 settings for each scheme:
756 #auth_param negotiate program <uncomment and complete this line to activate>
757 #auth_param negotiate children 20 startup=0 idle=1
759 #auth_param digest program <uncomment and complete this line to activate>
760 #auth_param digest children 20 startup=0 idle=1
761 #auth_param digest realm Squid proxy-caching web server
762 #auth_param digest nonce_garbage_interval 5 minutes
763 #auth_param digest nonce_max_duration 30 minutes
764 #auth_param digest nonce_max_count 50
766 #auth_param ntlm program <uncomment and complete this line to activate>
767 #auth_param ntlm children 20 startup=0 idle=1
769 #auth_param basic program <uncomment and complete this line>
770 #auth_param basic children 5 startup=5 idle=1
771 #auth_param basic credentialsttl 2 hours
774 NAME: authenticate_cache_garbage_interval
778 LOC: Auth::TheConfig.garbageCollectInterval
780 The time period between garbage collection across the username cache.
781 This is a trade-off between memory utilization (long intervals - say
782 2 days) and CPU (short intervals - say 1 minute). Only change if you
786 NAME: authenticate_ttl
790 LOC: Auth::TheConfig.credentialsTtl
792 The time a user & their credentials stay in the logged in
793 user cache since their last request. When the garbage
794 interval passes, all user credentials that have passed their
795 TTL are removed from memory.
798 NAME: authenticate_ip_ttl
801 LOC: Auth::TheConfig.ipTtl
804 If you use proxy authentication and the 'max_user_ip' ACL,
805 this directive controls how long Squid remembers the IP
806 addresses associated with each user. Use a small value
807 (e.g., 60 seconds) if your users might change addresses
808 quickly, as is the case with dialup. You might be safe
809 using a larger value (e.g., 2 hours) in a corporate LAN
810 environment with relatively static address assignments.
815 -----------------------------------------------------------------------------
818 NAME: external_acl_type
819 TYPE: externalAclHelper
820 LOC: Config.externalAclHelperList
823 This option defines external acl classes using a helper program
824 to look up the status
826 external_acl_type name [options] FORMAT /path/to/helper [helper arguments]
830 ttl=n TTL in seconds for cached results (defaults to 3600
834 TTL for cached negative lookups (default same
837 grace=n Percentage remaining of TTL where a refresh of a
838 cached entry should be initiated without needing to
839 wait for a new reply. (default is for no grace period)
841 cache=n The maximum number of entries in the result cache. The
842 default limit is 262144 entries. Each cache entry usually
843 consumes at least 256 bytes. Squid currently does not remove
844 expired cache entries until the limit is reached, so a proxy
845 will sooner or later reach the limit. The expanded FORMAT
846 value is used as the cache key, so if the details in FORMAT
847 are highly variable, a larger cache may be needed to produce
848 reduction in helper load.
851 Maximum number of acl helper processes spawned to service
852 external acl lookups of this type. (default 5)
855 Minimum number of acl helper processes to spawn during
856 startup and reconfigure to service external acl lookups
857 of this type. (default 0)
860 Number of acl helper processes to keep ahead of traffic
861 loads. Squid will spawn this many at once whenever load
862 rises above the capabilities of existing processes.
863 Up to the value of children-max. (default 1)
865 concurrency=n concurrency level per process. Only used with helpers
866 capable of processing more than one query at a time.
868 queue-size=N The queue-size option sets the maximum number of
869 queued requests. A request is queued when no existing
870 helper can accept it due to concurrency limit and no
871 new helper can be started due to children-max limit.
872 If the queued requests exceed queue size, the acl is
873 ignored. The default value is set to 2*children-max.
875 protocol=2.5 Compatibility mode for Squid-2.5 external acl helpers.
877 ipv4 / ipv6 IP protocol used to communicate with this helper.
878 The default is to auto-detect IPv6 and use it when available.
881 FORMAT is a series of %macro codes. See logformat directive for a full list
882 of the accepted codes. Although note that at the time of any external ACL
883 being tested data may not be available and thus some %macro expand to '-'.
885 In addition to the logformat codes; when processing external ACLs these
886 additional macros are made available:
888 %ACL The name of the ACL being tested.
890 %DATA The ACL arguments specified in the referencing config
891 'acl ... external' line, separated by spaces (an
892 "argument string"). see acl external.
894 If there are no ACL arguments %DATA expands to '-'.
896 If you do not specify a DATA macro inside FORMAT,
897 Squid automatically appends %DATA to your FORMAT.
898 Note that Squid-3.x may expand %DATA to whitespace
899 or nothing in this case.
901 By default, Squid applies URL-encoding to each ACL
902 argument inside the argument string. If an explicit
903 encoding modifier is used (e.g., %#DATA), then Squid
904 encodes the whole argument string as a single token
905 (e.g., with %#DATA, spaces between arguments become
908 If SSL is enabled, the following formating codes become available:
910 %USER_CERT SSL User certificate in PEM format
911 %USER_CERTCHAIN SSL User certificate chain in PEM format
912 %USER_CERT_xx SSL User certificate subject attribute xx
913 %USER_CA_CERT_xx SSL User certificate issuer attribute xx
916 NOTE: all other format codes accepted by older Squid versions
920 General request syntax:
922 [channel-ID] FORMAT-values
925 FORMAT-values consists of transaction details expanded with
926 whitespace separation per the config file FORMAT specification
927 using the FORMAT macros listed above.
929 Request values sent to the helper are URL escaped to protect
930 each value in requests against whitespaces.
932 If using protocol=2.5 then the request sent to the helper is not
933 URL escaped to protect against whitespace.
935 NOTE: protocol=3.0 is deprecated as no longer necessary.
937 When using the concurrency= option the protocol is changed by
938 introducing a query channel tag in front of the request/response.
939 The query channel tag is a number between 0 and concurrency-1.
940 This value must be echoed back unchanged to Squid as the first part
941 of the response relating to its request.
944 The helper receives lines expanded per the above format specification
945 and for each input line returns 1 line starting with OK/ERR/BH result
946 code and optionally followed by additional keywords with more details.
949 General result syntax:
951 [channel-ID] result keyword=value ...
953 Result consists of one of the codes:
956 the ACL test produced a match.
959 the ACL test does not produce a match.
962 An internal error occurred in the helper, preventing
963 a result being identified.
965 The meaning of 'a match' is determined by your squid.conf
966 access control configuration. See the Squid wiki for details.
970 user= The users name (login)
972 password= The users password (for login= cache_peer option)
974 message= Message describing the reason for this response.
975 Available as %o in error pages.
976 Useful on (ERR and BH results).
978 tag= Apply a tag to a request. Only sets a tag once,
979 does not alter existing tags.
981 log= String to be logged in access.log. Available as
982 %ea in logformat specifications.
984 clt_conn_tag= Associates a TAG with the client TCP connection.
985 Please see url_rewrite_program related documentation
988 Any keywords may be sent on any response whether OK, ERR or BH.
990 All response keyword values need to be a single token with URL
991 escaping, or enclosed in double quotes (") and escaped using \ on
992 any double quotes or \ characters within the value. The wrapping
993 double quotes are removed before the value is interpreted by Squid.
994 \r and \n are also replace by CR and LF.
996 Some example key values:
1000 user="J. \"Bob\" Smith"
1007 DEFAULT: ssl::certHasExpired ssl_error X509_V_ERR_CERT_HAS_EXPIRED
1008 DEFAULT: ssl::certNotYetValid ssl_error X509_V_ERR_CERT_NOT_YET_VALID
1009 DEFAULT: ssl::certDomainMismatch ssl_error SQUID_X509_V_ERR_DOMAIN_MISMATCH
1010 DEFAULT: ssl::certUntrusted ssl_error X509_V_ERR_INVALID_CA X509_V_ERR_SELF_SIGNED_CERT_IN_CHAIN X509_V_ERR_UNABLE_TO_VERIFY_LEAF_SIGNATURE X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY X509_V_ERR_CERT_UNTRUSTED
1011 DEFAULT: ssl::certSelfSigned ssl_error X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT
1013 DEFAULT: all src all
1014 DEFAULT: manager url_regex -i ^cache_object:// +i ^https?://[^/]+/squid-internal-mgr/
1015 DEFAULT: localhost src 127.0.0.1/32 ::1
1016 DEFAULT: to_localhost dst 127.0.0.0/8 0.0.0.0/32 ::1/128 ::/128
1017 DEFAULT: CONNECT method CONNECT
1018 DEFAULT_DOC: ACLs all, manager, localhost, to_localhost, and CONNECT are predefined.
1020 Defining an Access List
1022 Every access list definition must begin with an aclname and acltype,
1023 followed by either type-specific arguments or a quoted filename that
1026 acl aclname acltype argument ...
1027 acl aclname acltype "file" ...
1029 When using "file", the file should contain one item per line.
1034 Some acl types supports options which changes their default behaviour:
1036 -i,+i By default, regular expressions are CASE-SENSITIVE. To make them
1037 case-insensitive, use the -i option. To return case-sensitive
1038 use the +i option between patterns, or make a new ACL line
1041 -n Disable lookups and address type conversions. If lookup or
1042 conversion is required because the parameter type (IP or
1043 domain name) does not match the message address type (domain
1044 name or IP), then the ACL would immediately declare a mismatch
1045 without any warnings or lookups.
1048 Perform a list membership test, interpreting values as
1049 comma-separated token lists and matching against individual
1050 tokens instead of whole values.
1051 The optional "delimiters" parameter specifies one or more
1052 alternative non-alphanumeric delimiter characters.
1053 non-alphanumeric delimiter characters.
1055 -- Used to stop processing all options, in the case the first acl
1056 value has '-' character as first character (for example the '-'
1057 is a valid domain name)
1059 Some acl types require suspending the current request in order
1060 to access some external data source.
1061 Those which do are marked with the tag [slow], those which
1062 don't are marked as [fast].
1063 See http://wiki.squid-cache.org/SquidFaq/SquidAcl
1064 for further information
1066 ***** ACL TYPES AVAILABLE *****
1068 acl aclname src ip-address/mask ... # clients IP address [fast]
1069 acl aclname src addr1-addr2/mask ... # range of addresses [fast]
1070 acl aclname dst [-n] ip-address/mask ... # URL host's IP address [slow]
1071 acl aclname localip ip-address/mask ... # IP address the client connected to [fast]
1074 acl aclname arp mac-address ...
1075 acl aclname eui64 eui64-address ...
1077 # MAC (EUI-48) and EUI-64 addresses use xx:xx:xx:xx:xx:xx notation.
1079 # The 'arp' ACL code is not portable to all operating systems.
1080 # It works on Linux, Solaris, Windows, FreeBSD, and some other
1083 # The eui_lookup directive is required to be 'on' (the default)
1084 # and Squid built with --enable-eui for MAC/EUI addresses to be
1085 # available for this ACL.
1087 # Squid can only determine the MAC/EUI address for IPv4
1088 # clients that are on the same subnet. If the client is on a
1089 # different subnet, then Squid cannot find out its address.
1091 # IPv6 protocol does not contain ARP. MAC/EUI is either
1092 # encoded directly in the IPv6 address or not available.
1094 acl aclname clientside_mark mark[/mask] ...
1095 # matches CONNMARK of an accepted connection [fast]
1096 # DEPRECATED. Use the 'client_connection_mark' instead.
1098 acl aclname client_connection_mark mark[/mask] ...
1099 # matches CONNMARK of an accepted connection [fast]
1101 # mark and mask are unsigned integers (hex, octal, or decimal).
1102 # If multiple marks are given, then the ACL matches if at least
1105 # Uses netfilter-conntrack library.
1106 # Requires building Squid with --enable-linux-netfilter.
1108 # The client, various intermediaries, and Squid itself may set
1109 # CONNMARK at various times. The last CONNMARK set wins. This ACL
1110 # checks the mark present on an accepted connection or set by
1111 # Squid afterwards, depending on the ACL check timing. This ACL
1112 # effectively ignores any mark set by other agents after Squid has
1113 # accepted the connection.
1115 acl aclname srcdomain .foo.com ...
1116 # reverse lookup, from client IP [slow]
1117 acl aclname dstdomain [-n] .foo.com ...
1118 # Destination server from URL [fast]
1119 acl aclname srcdom_regex [-i] \.foo\.com ...
1120 # regex matching client name [slow]
1121 acl aclname dstdom_regex [-n] [-i] \.foo\.com ...
1122 # regex matching server [fast]
1124 # For dstdomain and dstdom_regex a reverse lookup is tried if a IP
1125 # based URL is used and no match is found. The name "none" is used
1126 # if the reverse lookup fails.
1128 acl aclname src_as number ...
1129 acl aclname dst_as number ...
1131 # Except for access control, AS numbers can be used for
1132 # routing of requests to specific caches. Here's an
1133 # example for routing all requests for AS#1241 and only
1134 # those to mycache.mydomain.net:
1135 # acl asexample dst_as 1241
1136 # cache_peer_access mycache.mydomain.net allow asexample
1137 # cache_peer_access mycache_mydomain.net deny all
1139 acl aclname peername myPeer ...
1140 acl aclname peername_regex [-i] regex-pattern ...
1142 # match against a named cache_peer entry
1143 # set unique name= on cache_peer lines for reliable use.
1145 acl aclname time [day-abbrevs] [h1:m1-h2:m2]
1155 # h1:m1 must be less than h2:m2
1157 acl aclname url_regex [-i] ^http:// ...
1158 # regex matching on whole URL [fast]
1159 acl aclname urllogin [-i] [^a-zA-Z0-9] ...
1160 # regex matching on URL login field
1161 acl aclname urlpath_regex [-i] \.gif$ ...
1162 # regex matching on URL path [fast]
1164 acl aclname port 80 70 21 0-1024... # destination TCP port [fast]
1166 acl aclname localport 3128 ... # TCP port the client connected to [fast]
1167 # NP: for interception mode this is usually '80'
1169 acl aclname myportname 3128 ... # *_port name [fast]
1171 acl aclname proto HTTP FTP ... # request protocol [fast]
1173 acl aclname method GET POST ... # HTTP request method [fast]
1175 acl aclname http_status 200 301 500- 400-403 ...
1176 # status code in reply [fast]
1178 acl aclname browser [-i] regexp ...
1179 # pattern match on User-Agent header (see also req_header below) [fast]
1181 acl aclname referer_regex [-i] regexp ...
1182 # pattern match on Referer header [fast]
1183 # Referer is highly unreliable, so use with care
1185 acl aclname ident [-i] username ...
1186 acl aclname ident_regex [-i] pattern ...
1187 # string match on ident output [slow]
1188 # use REQUIRED to accept any non-null ident.
1190 acl aclname proxy_auth [-i] username ...
1191 acl aclname proxy_auth_regex [-i] pattern ...
1192 # perform http authentication challenge to the client and match against
1193 # supplied credentials [slow]
1195 # takes a list of allowed usernames.
1196 # use REQUIRED to accept any valid username.
1198 # Will use proxy authentication in forward-proxy scenarios, and plain
1199 # http authenticaiton in reverse-proxy scenarios
1201 # NOTE: when a Proxy-Authentication header is sent but it is not
1202 # needed during ACL checking the username is NOT logged
1205 # NOTE: proxy_auth requires a EXTERNAL authentication program
1206 # to check username/password combinations (see
1207 # auth_param directive).
1209 # NOTE: proxy_auth can't be used in a transparent/intercepting proxy
1210 # as the browser needs to be configured for using a proxy in order
1211 # to respond to proxy authentication.
1213 acl aclname snmp_community string ...
1214 # A community string to limit access to your SNMP Agent [fast]
1217 # acl snmppublic snmp_community public
1219 acl aclname maxconn number
1220 # This will be matched when the client's IP address has
1221 # more than <number> TCP connections established. [fast]
1222 # NOTE: This only measures direct TCP links so X-Forwarded-For
1223 # indirect clients are not counted.
1225 acl aclname max_user_ip [-s] number
1226 # This will be matched when the user attempts to log in from more
1227 # than <number> different ip addresses. The authenticate_ip_ttl
1228 # parameter controls the timeout on the ip entries. [fast]
1229 # If -s is specified the limit is strict, denying browsing
1230 # from any further IP addresses until the ttl has expired. Without
1231 # -s Squid will just annoy the user by "randomly" denying requests.
1232 # (the counter is reset each time the limit is reached and a
1233 # request is denied)
1234 # NOTE: in acceleration mode or where there is mesh of child proxies,
1235 # clients may appear to come from multiple addresses if they are
1236 # going through proxy farms, so a limit of 1 may cause user problems.
1238 acl aclname random probability
1239 # Pseudo-randomly match requests. Based on the probability given.
1240 # Probability may be written as a decimal (0.333), fraction (1/3)
1241 # or ratio of matches:non-matches (3:5).
1243 acl aclname req_mime_type [-i] mime-type ...
1244 # regex match against the mime type of the request generated
1245 # by the client. Can be used to detect file upload or some
1246 # types HTTP tunneling requests [fast]
1247 # NOTE: This does NOT match the reply. You cannot use this
1248 # to match the returned file type.
1250 acl aclname req_header header-name [-i] any\.regex\.here
1251 # regex match against any of the known request headers. May be
1252 # thought of as a superset of "browser", "referer" and "mime-type"
1255 acl aclname rep_mime_type [-i] mime-type ...
1256 # regex match against the mime type of the reply received by
1257 # squid. Can be used to detect file download or some
1258 # types HTTP tunneling requests. [fast]
1259 # NOTE: This has no effect in http_access rules. It only has
1260 # effect in rules that affect the reply data stream such as
1261 # http_reply_access.
1263 acl aclname rep_header header-name [-i] any\.regex\.here
1264 # regex match against any of the known reply headers. May be
1265 # thought of as a superset of "browser", "referer" and "mime-type"
1268 acl aclname external class_name [arguments...]
1269 # external ACL lookup via a helper class defined by the
1270 # external_acl_type directive [slow]
1272 acl aclname user_cert attribute values...
1273 # match against attributes in a user SSL certificate
1274 # attribute is one of DN/C/O/CN/L/ST or a numerical OID [fast]
1276 acl aclname ca_cert attribute values...
1277 # match against attributes a users issuing CA SSL certificate
1278 # attribute is one of DN/C/O/CN/L/ST or a numerical OID [fast]
1280 acl aclname ext_user [-i] username ...
1281 acl aclname ext_user_regex [-i] pattern ...
1282 # string match on username returned by external acl helper [slow]
1283 # use REQUIRED to accept any non-null user name.
1285 acl aclname tag tagvalue ...
1286 # string match on tag returned by external acl helper [fast]
1287 # DEPRECATED. Only the first tag will match with this ACL.
1288 # Use the 'note' ACL instead for handling multiple tag values.
1290 acl aclname hier_code codename ...
1291 # string match against squid hierarchy code(s); [fast]
1292 # e.g., DIRECT, PARENT_HIT, NONE, etc.
1294 # NOTE: This has no effect in http_access rules. It only has
1295 # effect in rules that affect the reply data stream such as
1296 # http_reply_access.
1298 acl aclname note [-m[=delimiters]] name [value ...]
1299 # match transaction annotation [fast]
1300 # Without values, matches any annotation with a given name.
1301 # With value(s), matches any annotation with a given name that
1302 # also has one of the given values.
1303 # If the -m flag is used, then the value of the named
1304 # annotation is interpreted as a list of tokens, and the ACL
1305 # matches individual name=token pairs rather than whole
1306 # name=value pairs. See "ACL Options" above for more info.
1307 # Annotation sources include note and adaptation_meta directives
1308 # as well as helper and eCAP responses.
1310 acl aclname annotate_transaction [-m[=delimiters]] key=value ...
1311 acl aclname annotate_transaction [-m[=delimiters]] key+=value ...
1312 # Always matches. [fast]
1313 # Used for its side effect: This ACL immediately adds a
1314 # key=value annotation to the current master transaction.
1315 # The added annotation can then be tested using note ACL and
1316 # logged (or sent to helpers) using %note format code.
1318 # Annotations can be specified using replacement and addition
1319 # formats. The key=value form replaces old same-key annotation
1320 # value(s). The key+=value form appends a new value to the old
1321 # same-key annotation. Both forms create a new key=value
1322 # annotation if no same-key annotation exists already. If
1323 # -m flag is used, then the value is interpreted as a list
1324 # and the annotation will contain key=token pair(s) instead of the
1325 # whole key=value pair.
1327 # This ACL is especially useful for recording complex multi-step
1328 # ACL-driven decisions. For example, the following configuration
1329 # avoids logging transactions accepted after aclX matched:
1331 # # First, mark transactions accepted after aclX matched
1332 # acl markSpecial annotate_transaction special=true
1333 # http_access allow acl001
1335 # http_access deny acl100
1336 # http_access allow aclX markSpecial
1338 # # Second, do not log marked transactions:
1339 # acl markedSpecial note special true
1340 # access_log ... deny markedSpecial
1342 # # Note that the following would not have worked because aclX
1343 # # alone does not determine whether the transaction was allowed:
1344 # access_log ... deny aclX # Wrong!
1346 # Warning: This ACL annotates the transaction even when negated
1347 # and even if subsequent ACLs fail to match. For example, the
1348 # following three rules will have exactly the same effect as far
1349 # as annotations set by the "mark" ACL are concerned:
1351 # some_directive acl1 ... mark # rule matches if mark is reached
1352 # some_directive acl1 ... !mark # rule never matches
1353 # some_directive acl1 ... mark !all # rule never matches
1355 acl aclname annotate_client [-m[=delimiters]] key=value ...
1356 acl aclname annotate_client [-m[=delimiters]] key+=value ...
1358 # Always matches. [fast]
1359 # Used for its side effect: This ACL immediately adds a
1360 # key=value annotation to the current client-to-Squid
1361 # connection. Connection annotations are propagated to the current
1362 # and all future master transactions on the annotated connection.
1363 # See the annotate_transaction ACL for details.
1365 # For example, the following configuration avoids rewriting URLs
1366 # of transactions bumped by SslBump:
1368 # # First, mark bumped connections:
1369 # acl markBumped annotate_client bumped=true
1370 # ssl_bump peek acl1
1371 # ssl_bump stare acl2
1372 # ssl_bump bump acl3 markBumped
1373 # ssl_bump splice all
1375 # # Second, do not send marked transactions to the redirector:
1376 # acl markedBumped note bumped true
1377 # url_rewrite_access deny markedBumped
1379 # # Note that the following would not have worked because acl3 alone
1380 # # does not determine whether the connection is going to be bumped:
1381 # url_rewrite_access deny acl3 # Wrong!
1383 acl aclname adaptation_service service ...
1384 # Matches the name of any icap_service, ecap_service,
1385 # adaptation_service_set, or adaptation_service_chain that Squid
1386 # has used (or attempted to use) for the master transaction.
1387 # This ACL must be defined after the corresponding adaptation
1388 # service is named in squid.conf. This ACL is usable with
1389 # adaptation_meta because it starts matching immediately after
1390 # the service has been selected for adaptation.
1392 acl aclname transaction_initiator initiator ...
1393 # Matches transaction's initiator [fast]
1395 # Supported initiators are:
1396 # esi: matches transactions fetching ESI resources
1397 # certificate-fetching: matches transactions fetching
1398 # a missing intermediate TLS certificate
1399 # cache-digest: matches transactions fetching Cache Digests
1401 # htcp: matches HTCP requests from peers
1402 # icp: matches ICP requests to peers
1403 # icmp: matches ICMP RTT database (NetDB) requests to peers
1404 # asn: matches asns db requests
1405 # internal: matches any of the above
1406 # client: matches transactions containing an HTTP or FTP
1407 # client request received at a Squid *_port
1408 # all: matches any transaction, including internal transactions
1409 # without a configurable initiator and hopefully rare
1410 # transactions without a known-to-Squid initiator
1412 # Multiple initiators are ORed.
1414 acl aclname has component
1415 # matches a transaction "component" [fast]
1417 # Supported transaction components are:
1418 # request: transaction has a request header (at least)
1419 # response: transaction has a response header (at least)
1420 # ALE: transaction has an internally-generated Access Log Entry
1421 # structure; bugs notwithstanding, all transaction have it
1423 # For example, the following configuration helps when dealing with HTTP
1424 # clients that close connections without sending a request header:
1426 # acl hasRequest has request
1427 # acl logMe note important_transaction
1428 # # avoid "logMe ACL is used in context without an HTTP request" warnings
1429 # access_log ... logformat=detailed hasRequest logMe
1430 # # log request-less transactions, instead of ignoring them
1431 # access_log ... logformat=brief !hasRequest
1433 # Multiple components are not supported for one "acl" rule, but
1434 # can be specified (and are ORed) using multiple same-name rules:
1436 # # OK, this strange logging daemon needs request or response,
1437 # # but can work without either a request or a response:
1438 # acl hasWhatMyLoggingDaemonNeeds has request
1439 # acl hasWhatMyLoggingDaemonNeeds has response
1441 acl aclname at_step step
1442 # match against the current request processing step [fast]
1444 # GeneratingCONNECT: Generating HTTP CONNECT request headers
1446 # The following ssl_bump processing steps are recognized:
1447 # SslBump1: After getting TCP-level and HTTP CONNECT info.
1448 # SslBump2: After getting SSL Client Hello info.
1449 # SslBump3: After getting SSL Server Hello info.
1453 acl aclname ssl_error errorname
1454 # match against SSL certificate validation error [fast]
1456 # For valid error names see in @DEFAULT_ERROR_DIR@/templates/error-details.txt
1459 # The following can be used as shortcuts for certificate properties:
1460 # [ssl::]certHasExpired: the "not after" field is in the past
1461 # [ssl::]certNotYetValid: the "not before" field is in the future
1462 # [ssl::]certUntrusted: The certificate issuer is not to be trusted.
1463 # [ssl::]certSelfSigned: The certificate is self signed.
1464 # [ssl::]certDomainMismatch: The certificate CN domain does not
1465 # match the name the name of the host we are connecting to.
1467 # The ssl::certHasExpired, ssl::certNotYetValid, ssl::certDomainMismatch,
1468 # ssl::certUntrusted, and ssl::certSelfSigned can also be used as
1469 # predefined ACLs, just like the 'all' ACL.
1471 # NOTE: The ssl_error ACL is only supported with sslproxy_cert_error,
1472 # sslproxy_cert_sign, and sslproxy_cert_adapt options.
1474 acl aclname server_cert_fingerprint [-sha1] fingerprint
1475 # match against server SSL certificate fingerprint [fast]
1477 # The fingerprint is the digest of the DER encoded version
1478 # of the whole certificate. The user should use the form: XX:XX:...
1479 # Optional argument specifies the digest algorithm to use.
1480 # The SHA1 digest algorithm is the default and is currently
1481 # the only algorithm supported (-sha1).
1483 acl aclname ssl::server_name [option] .foo.com ...
1484 # matches server name obtained from various sources [fast]
1486 # The ACL computes server name(s) using such information sources as
1487 # CONNECT request URI, TLS client SNI, and TLS server certificate
1488 # subject (CN and SubjectAltName). The computed server name(s) usually
1489 # change with each SslBump step, as more info becomes available:
1490 # * SNI is used as the server name instead of the request URI,
1491 # * subject name(s) from the server certificate (CN and
1492 # SubjectAltName) are used as the server names instead of SNI.
1494 # When the ACL computes multiple server names, matching any single
1495 # computed name is sufficient for the ACL to match.
1497 # The "none" name can be used to match transactions where the ACL
1498 # could not compute the server name using any information source
1499 # that was both available and allowed to be used by the ACL options at
1500 # the ACL evaluation time.
1502 # Unlike dstdomain, this ACL does not perform DNS lookups.
1504 # An ACL option below may be used to restrict what information
1505 # sources are used to extract the server names from:
1507 # --client-requested
1508 # The server name is SNI regardless of what the server says.
1510 # The server name(s) are the certificate subject name(s), regardless
1511 # of what the client has requested. If the server certificate is
1512 # unavailable, then the name is "none".
1514 # The server name is either SNI (if SNI matches at least one of the
1515 # certificate subject names) or "none" (otherwise). When the server
1516 # certificate is unavailable, the consensus server name is SNI.
1518 # Combining multiple options in one ACL is a fatal configuration
1521 # For all options: If no SNI is available, then the CONNECT request
1522 # target (a.k.a. URI) is used instead of SNI (for an intercepted
1523 # connection, this target is the destination IP address).
1525 acl aclname ssl::server_name_regex [-i] \.foo\.com ...
1526 # regex matches server name obtained from various sources [fast]
1528 acl aclname connections_encrypted
1529 # matches transactions with all HTTP messages received over TLS
1530 # transport connections. [fast]
1532 # The master transaction deals with HTTP messages received from
1533 # various sources. All sources used by the master transaction in the
1534 # past are considered by the ACL. The following rules define whether
1535 # a given message source taints the entire master transaction,
1536 # resulting in ACL mismatches:
1538 # * The HTTP client transport connection is not TLS.
1539 # * An adaptation service connection-encryption flag is off.
1540 # * The peer or origin server transport connection is not TLS.
1542 # Caching currently does not affect these rules. This cache ignorance
1543 # implies that only the current HTTP client transport and REQMOD
1544 # services status determine whether this ACL matches a from-cache
1545 # transaction. The source of the cached response does not have any
1546 # effect on future transaction that use the cached response without
1547 # revalidation. This may change.
1549 # DNS, ICP, and HTCP exchanges during the master transaction do not
1550 # affect these rules.
1552 acl aclname any-of acl1 acl2 ...
1553 # match any one of the acls [fast or slow]
1554 # The first matching ACL stops further ACL evaluation.
1556 # ACLs from multiple any-of lines with the same name are ORed.
1557 # For example, A = (a1 or a2) or (a3 or a4) can be written as
1558 # acl A any-of a1 a2
1559 # acl A any-of a3 a4
1561 # This group ACL is fast if all evaluated ACLs in the group are fast
1562 # and slow otherwise.
1564 acl aclname all-of acl1 acl2 ...
1565 # match all of the acls [fast or slow]
1566 # The first mismatching ACL stops further ACL evaluation.
1568 # ACLs from multiple all-of lines with the same name are ORed.
1569 # For example, B = (b1 and b2) or (b3 and b4) can be written as
1570 # acl B all-of b1 b2
1571 # acl B all-of b3 b4
1573 # This group ACL is fast if all evaluated ACLs in the group are fast
1574 # and slow otherwise.
1577 acl macaddress arp 09:00:2b:23:45:67
1578 acl myexample dst_as 1241
1579 acl password proxy_auth REQUIRED
1580 acl fileupload req_mime_type -i ^multipart/form-data$
1581 acl javascript rep_mime_type -i ^application/x-javascript$
1585 # Recommended minimum configuration:
1588 # Example rule allowing access from your local networks.
1589 # Adapt to list your (internal) IP networks from where browsing
1591 acl localnet src 0.0.0.1-0.255.255.255 # RFC 1122 "this" network (LAN)
1592 acl localnet src 10.0.0.0/8 # RFC 1918 local private network (LAN)
1593 acl localnet src 100.64.0.0/10 # RFC 6598 shared address space (CGN)
1594 acl localnet src 169.254.0.0/16 # RFC 3927 link-local (directly plugged) machines
1595 acl localnet src 172.16.0.0/12 # RFC 1918 local private network (LAN)
1596 acl localnet src 192.168.0.0/16 # RFC 1918 local private network (LAN)
1597 acl localnet src fc00::/7 # RFC 4193 local private network range
1598 acl localnet src fe80::/10 # RFC 4291 link-local (directly plugged) machines
1600 acl SSL_ports port 443
1601 acl Safe_ports port 80 # http
1602 acl Safe_ports port 21 # ftp
1603 acl Safe_ports port 443 # https
1604 acl Safe_ports port 70 # gopher
1605 acl Safe_ports port 210 # wais
1606 acl Safe_ports port 1025-65535 # unregistered ports
1607 acl Safe_ports port 280 # http-mgmt
1608 acl Safe_ports port 488 # gss-http
1609 acl Safe_ports port 591 # filemaker
1610 acl Safe_ports port 777 # multiling http
1614 NAME: proxy_protocol_access
1616 LOC: Config.accessList.proxyProtocol
1618 DEFAULT_DOC: all TCP connections to ports with require-proxy-header will be denied
1620 Determine which client proxies can be trusted to provide correct
1621 information regarding real client IP address using PROXY protocol.
1623 Requests may pass through a chain of several other proxies
1624 before reaching us. The original source details may by sent in:
1625 * HTTP message Forwarded header, or
1626 * HTTP message X-Forwarded-For header, or
1627 * PROXY protocol connection header.
1629 This directive is solely for validating new PROXY protocol
1630 connections received from a port flagged with require-proxy-header.
1631 It is checked only once after TCP connection setup.
1633 A deny match results in TCP connection closure.
1635 An allow match is required for Squid to permit the corresponding
1636 TCP connection, before Squid even looks for HTTP request headers.
1637 If there is an allow match, Squid starts using PROXY header information
1638 to determine the source address of the connection for all future ACL
1639 checks, logging, etc.
1641 SECURITY CONSIDERATIONS:
1643 Any host from which we accept client IP details can place
1644 incorrect information in the relevant header, and Squid
1645 will use the incorrect information as if it were the
1646 source address of the request. This may enable remote
1647 hosts to bypass any access control restrictions that are
1648 based on the client's source addresses.
1650 This clause only supports fast acl types.
1651 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
1654 NAME: follow_x_forwarded_for
1656 IFDEF: FOLLOW_X_FORWARDED_FOR
1657 LOC: Config.accessList.followXFF
1658 DEFAULT_IF_NONE: deny all
1659 DEFAULT_DOC: X-Forwarded-For header will be ignored.
1661 Determine which client proxies can be trusted to provide correct
1662 information regarding real client IP address.
1664 Requests may pass through a chain of several other proxies
1665 before reaching us. The original source details may by sent in:
1666 * HTTP message Forwarded header, or
1667 * HTTP message X-Forwarded-For header, or
1668 * PROXY protocol connection header.
1670 PROXY protocol connections are controlled by the proxy_protocol_access
1671 directive which is checked before this.
1673 If a request reaches us from a source that is allowed by this
1674 directive, then we trust the information it provides regarding
1675 the IP of the client it received from (if any).
1677 For the purpose of ACLs used in this directive the src ACL type always
1678 matches the address we are testing and srcdomain matches its rDNS.
1680 On each HTTP request Squid checks for X-Forwarded-For header fields.
1681 If found the header values are iterated in reverse order and an allow
1682 match is required for Squid to continue on to the next value.
1683 The verification ends when a value receives a deny match, cannot be
1684 tested, or there are no more values to test.
1685 NOTE: Squid does not yet follow the Forwarded HTTP header.
1687 The end result of this process is an IP address that we will
1688 refer to as the indirect client address. This address may
1689 be treated as the client address for access control, ICAP, delay
1690 pools and logging, depending on the acl_uses_indirect_client,
1691 icap_uses_indirect_client, delay_pool_uses_indirect_client,
1692 log_uses_indirect_client and tproxy_uses_indirect_client options.
1694 This clause only supports fast acl types.
1695 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
1697 SECURITY CONSIDERATIONS:
1699 Any host from which we accept client IP details can place
1700 incorrect information in the relevant header, and Squid
1701 will use the incorrect information as if it were the
1702 source address of the request. This may enable remote
1703 hosts to bypass any access control restrictions that are
1704 based on the client's source addresses.
1708 acl localhost src 127.0.0.1
1709 acl my_other_proxy srcdomain .proxy.example.com
1710 follow_x_forwarded_for allow localhost
1711 follow_x_forwarded_for allow my_other_proxy
1714 NAME: acl_uses_indirect_client
1717 IFDEF: FOLLOW_X_FORWARDED_FOR
1719 LOC: Config.onoff.acl_uses_indirect_client
1721 Controls whether the indirect client address
1722 (see follow_x_forwarded_for) is used instead of the
1723 direct client address in acl matching.
1725 NOTE: maxconn ACL considers direct TCP links and indirect
1726 clients will always have zero. So no match.
1729 NAME: delay_pool_uses_indirect_client
1732 IFDEF: FOLLOW_X_FORWARDED_FOR&&USE_DELAY_POOLS
1734 LOC: Config.onoff.delay_pool_uses_indirect_client
1736 Controls whether the indirect client address
1737 (see follow_x_forwarded_for) is used instead of the
1738 direct client address in delay pools.
1741 NAME: log_uses_indirect_client
1744 IFDEF: FOLLOW_X_FORWARDED_FOR
1746 LOC: Config.onoff.log_uses_indirect_client
1748 Controls whether the indirect client address
1749 (see follow_x_forwarded_for) is used instead of the
1750 direct client address in the access log.
1753 NAME: tproxy_uses_indirect_client
1756 IFDEF: FOLLOW_X_FORWARDED_FOR&&LINUX_NETFILTER
1758 LOC: Config.onoff.tproxy_uses_indirect_client
1760 Controls whether the indirect client address
1761 (see follow_x_forwarded_for) is used instead of the
1762 direct client address when spoofing the outgoing client.
1764 This has no effect on requests arriving in non-tproxy
1767 SECURITY WARNING: Usage of this option is dangerous
1768 and should not be used trivially. Correct configuration
1769 of follow_x_forwarded_for with a limited set of trusted
1770 sources is required to prevent abuse of your proxy.
1773 NAME: spoof_client_ip
1775 LOC: Config.accessList.spoof_client_ip
1777 DEFAULT_DOC: Allow spoofing on all TPROXY traffic.
1779 Control client IP address spoofing of TPROXY traffic based on
1780 defined access lists.
1782 spoof_client_ip allow|deny [!]aclname ...
1784 If there are no "spoof_client_ip" lines present, the default
1785 is to "allow" spoofing of any suitable request.
1787 Note that the cache_peer "no-tproxy" option overrides this ACL.
1789 This clause supports fast acl types.
1790 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
1795 LOC: Config.accessList.http
1796 DEFAULT_IF_NONE: deny all
1797 DEFAULT_DOC: Deny, unless rules exist in squid.conf.
1799 Allowing or Denying access based on defined access lists
1801 To allow or deny a message received on an HTTP, HTTPS, or FTP port:
1802 http_access allow|deny [!]aclname ...
1804 NOTE on default values:
1806 If there are no "access" lines present, the default is to deny
1809 If none of the "access" lines cause a match, the default is the
1810 opposite of the last line in the list. If the last line was
1811 deny, the default is allow. Conversely, if the last line
1812 is allow, the default will be deny. For these reasons, it is a
1813 good idea to have an "deny all" entry at the end of your access
1814 lists to avoid potential confusion.
1816 This clause supports both fast and slow acl types.
1817 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
1822 # Recommended minimum Access Permission configuration:
1824 # Deny requests to certain unsafe ports
1825 http_access deny !Safe_ports
1827 # Deny CONNECT to other than secure SSL ports
1828 http_access deny CONNECT !SSL_ports
1830 # Only allow cachemgr access from localhost
1831 http_access allow localhost manager
1832 http_access deny manager
1834 # We strongly recommend the following be uncommented to protect innocent
1835 # web applications running on the proxy server who think the only
1836 # one who can access services on "localhost" is a local user
1837 #http_access deny to_localhost
1840 # INSERT YOUR OWN RULE(S) HERE TO ALLOW ACCESS FROM YOUR CLIENTS
1843 # Example rule allowing access from your local networks.
1844 # Adapt localnet in the ACL section to list your (internal) IP networks
1845 # from where browsing should be allowed
1846 http_access allow localnet
1847 http_access allow localhost
1849 # And finally deny all other access to this proxy
1850 http_access deny all
1854 NAME: adapted_http_access http_access2
1856 LOC: Config.accessList.adapted_http
1858 DEFAULT_DOC: Allow, unless rules exist in squid.conf.
1860 Allowing or Denying access based on defined access lists
1862 Essentially identical to http_access, but runs after redirectors
1863 and ICAP/eCAP adaptation. Allowing access control based on their
1866 If not set then only http_access is used.
1869 NAME: http_reply_access
1871 LOC: Config.accessList.reply
1873 DEFAULT_DOC: Allow, unless rules exist in squid.conf.
1875 Allow replies to client requests. This is complementary to http_access.
1877 http_reply_access allow|deny [!] aclname ...
1879 NOTE: if there are no access lines present, the default is to allow
1882 If none of the access lines cause a match the opposite of the
1883 last line will apply. Thus it is good practice to end the rules
1884 with an "allow all" or "deny all" entry.
1886 This clause supports both fast and slow acl types.
1887 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
1892 LOC: Config.accessList.icp
1894 DEFAULT_DOC: Deny, unless rules exist in squid.conf.
1896 Allowing or Denying access to the ICP port based on defined
1899 icp_access allow|deny [!]aclname ...
1901 NOTE: The default if no icp_access lines are present is to
1902 deny all traffic. This default may cause problems with peers
1905 This clause only supports fast acl types.
1906 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
1908 # Allow ICP queries from local networks only
1909 #icp_access allow localnet
1910 #icp_access deny all
1916 LOC: Config.accessList.htcp
1918 DEFAULT_DOC: Deny, unless rules exist in squid.conf.
1920 Allowing or Denying access to the HTCP port based on defined
1923 htcp_access allow|deny [!]aclname ...
1925 See also htcp_clr_access for details on access control for
1926 cache purge (CLR) HTCP messages.
1928 NOTE: The default if no htcp_access lines are present is to
1929 deny all traffic. This default may cause problems with peers
1930 using the htcp option.
1932 This clause only supports fast acl types.
1933 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
1935 # Allow HTCP queries from local networks only
1936 #htcp_access allow localnet
1937 #htcp_access deny all
1940 NAME: htcp_clr_access
1943 LOC: Config.accessList.htcp_clr
1945 DEFAULT_DOC: Deny, unless rules exist in squid.conf.
1947 Allowing or Denying access to purge content using HTCP based
1948 on defined access lists.
1949 See htcp_access for details on general HTCP access control.
1951 htcp_clr_access allow|deny [!]aclname ...
1953 This clause only supports fast acl types.
1954 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
1956 # Allow HTCP CLR requests from trusted peers
1957 acl htcp_clr_peer src 192.0.2.2 2001:DB8::2
1958 htcp_clr_access allow htcp_clr_peer
1959 htcp_clr_access deny all
1964 LOC: Config.accessList.miss
1966 DEFAULT_DOC: Allow, unless rules exist in squid.conf.
1968 Determines whether network access is permitted when satisfying a request.
1971 to force your neighbors to use you as a sibling instead of
1974 acl localclients src 192.0.2.0/24 2001:DB8::a:0/64
1975 miss_access deny !localclients
1976 miss_access allow all
1978 This means only your local clients are allowed to fetch relayed/MISS
1979 replies from the network and all other clients can only fetch cached
1982 The default for this setting allows all clients who passed the
1983 http_access rules to relay via this proxy.
1985 This clause only supports fast acl types.
1986 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
1989 NAME: ident_lookup_access
1993 DEFAULT_DOC: Unless rules exist in squid.conf, IDENT is not fetched.
1994 LOC: Ident::TheConfig.identLookup
1996 A list of ACL elements which, if matched, cause an ident
1997 (RFC 931) lookup to be performed for this request. For
1998 example, you might choose to always perform ident lookups
1999 for your main multi-user Unix boxes, but not for your Macs
2000 and PCs. By default, ident lookups are not performed for
2003 To enable ident lookups for specific client addresses, you
2004 can follow this example:
2006 acl ident_aware_hosts src 198.168.1.0/24
2007 ident_lookup_access allow ident_aware_hosts
2008 ident_lookup_access deny all
2010 Only src type ACL checks are fully supported. A srcdomain
2011 ACL might work at times, but it will not always provide
2014 This clause only supports fast acl types.
2015 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
2018 NAME: reply_body_max_size
2019 COMMENT: size [acl acl...]
2022 DEFAULT_DOC: No limit is applied.
2023 LOC: Config.ReplyBodySize
2025 This option specifies the maximum size of a reply body. It can be
2026 used to prevent users from downloading very large files, such as
2027 MP3's and movies. When the reply headers are received, the
2028 reply_body_max_size lines are processed, and the first line where
2029 all (if any) listed ACLs are true is used as the maximum body size
2032 This size is checked twice. First when we get the reply headers,
2033 we check the content-length value. If the content length value exists
2034 and is larger than the allowed size, the request is denied and the
2035 user receives an error message that says "the request or reply
2036 is too large." If there is no content-length, and the reply
2037 size exceeds this limit, the client's connection is just closed
2038 and they will receive a partial reply.
2040 WARNING: downstream caches probably can not detect a partial reply
2041 if there is no content-length header, so they will cache
2042 partial responses and give them out as hits. You should NOT
2043 use this option if you have downstream caches.
2045 WARNING: A maximum size smaller than the size of squid's error messages
2046 will cause an infinite loop and crash squid. Ensure that the smallest
2047 non-zero value you use is greater that the maximum header size plus
2048 the size of your largest error page.
2050 If you set this parameter none (the default), there will be
2053 Configuration Format is:
2054 reply_body_max_size SIZE UNITS [acl ...]
2056 reply_body_max_size 10 MB
2060 NAME: on_unsupported_protocol
2061 TYPE: on_unsupported_protocol
2062 LOC: Config.accessList.on_unsupported_protocol
2064 DEFAULT_DOC: Respond with an error message to unidentifiable traffic
2066 Determines Squid behavior when encountering strange requests at the
2067 beginning of an accepted TCP connection or the beginning of a bumped
2068 CONNECT tunnel. Controlling Squid reaction to unexpected traffic is
2069 especially useful in interception environments where Squid is likely
2070 to see connections for unsupported protocols that Squid should either
2071 terminate or tunnel at TCP level.
2073 on_unsupported_protocol <action> [!]acl ...
2075 The first matching action wins. Only fast ACLs are supported.
2077 Supported actions are:
2079 tunnel: Establish a TCP connection with the intended server and
2080 blindly shovel TCP packets between the client and server.
2082 respond: Respond with an error message, using the transfer protocol
2083 for the Squid port that received the request (e.g., HTTP
2084 for connections intercepted at the http_port). This is the
2087 Squid expects the following traffic patterns:
2089 http_port: a plain HTTP request
2090 https_port: SSL/TLS handshake followed by an [encrypted] HTTP request
2091 ftp_port: a plain FTP command (no on_unsupported_protocol support yet!)
2092 CONNECT tunnel on http_port: same as https_port
2093 CONNECT tunnel on https_port: same as https_port
2095 Currently, this directive has effect on intercepted connections and
2096 bumped tunnels only. Other cases are not supported because Squid
2097 cannot know the intended destination of other traffic.
2100 # define what Squid errors indicate receiving non-HTTP traffic:
2101 acl foreignProtocol squid_error ERR_PROTOCOL_UNKNOWN ERR_TOO_BIG
2102 # define what Squid errors indicate receiving nothing:
2103 acl serverTalksFirstProtocol squid_error ERR_REQUEST_START_TIMEOUT
2104 # tunnel everything that does not look like HTTP:
2105 on_unsupported_protocol tunnel foreignProtocol
2106 # tunnel if we think the client waits for the server to talk first:
2107 on_unsupported_protocol tunnel serverTalksFirstProtocol
2108 # in all other error cases, just send an HTTP "error page" response:
2109 on_unsupported_protocol respond all
2111 See also: squid_error ACL
2117 LOC: Auth::TheConfig.schemeAccess
2119 DEFAULT_DOC: use all auth_param schemes in their configuration order
2121 Use this directive to customize authentication schemes presence and
2122 order in Squid's Unauthorized and Authentication Required responses.
2124 auth_schemes scheme1,scheme2,... [!]aclname ...
2126 where schemeN is the name of one of the authentication schemes
2127 configured using auth_param directives. At least one scheme name is
2128 required. Multiple scheme names are separated by commas. Either
2129 avoid whitespace or quote the entire schemes list.
2131 A special "ALL" scheme name expands to all auth_param-configured
2132 schemes in their configuration order. This directive cannot be used
2133 to configure Squid to offer no authentication schemes at all.
2135 The first matching auth_schemes rule determines the schemes order
2136 for the current Authentication Required transaction. Note that the
2137 future response is not yet available during auth_schemes evaluation.
2139 If this directive is not used or none of its rules match, then Squid
2140 responds with all configured authentication schemes in the order of
2141 auth_param directives in the configuration file.
2143 This directive does not determine when authentication is used or
2144 how each authentication scheme authenticates clients.
2146 The following example sends basic and negotiate authentication
2147 schemes, in that order, when requesting authentication of HTTP
2148 requests matching the isIE ACL (not shown) while sending all
2149 auth_param schemes in their configuration order to other clients:
2151 auth_schemes basic,negotiate isIE
2152 auth_schemes ALL all # explicit default
2154 This directive supports fast ACLs only.
2156 See also: auth_param.
2161 -----------------------------------------------------------------------------
2164 NAME: http_port ascii_port
2169 Usage: port [mode] [options]
2170 hostname:port [mode] [options]
2171 1.2.3.4:port [mode] [options]
2173 The socket addresses where Squid will listen for HTTP client
2174 requests. You may specify multiple socket addresses.
2175 There are three forms: port alone, hostname with port, and
2176 IP address with port. If you specify a hostname or IP
2177 address, Squid binds the socket to that specific
2178 address. Most likely, you do not need to bind to a specific
2179 address, so you can use the port number alone.
2181 If you are running Squid in accelerator mode, you
2182 probably want to listen on port 80 also, or instead.
2184 The -a command line option may be used to specify additional
2185 port(s) where Squid listens for proxy request. Such ports will
2186 be plain proxy ports with no options.
2188 You may specify multiple socket addresses on multiple lines.
2192 intercept Support for IP-Layer NAT interception delivering
2193 traffic to this Squid port.
2194 NP: disables authentication on the port.
2196 tproxy Support Linux TPROXY (or BSD divert-to) with spoofing
2197 of outgoing connections using the client IP address.
2198 NP: disables authentication on the port.
2200 accel Accelerator / reverse proxy mode
2202 ssl-bump For each CONNECT request allowed by ssl_bump ACLs,
2203 establish secure connection with the client and with
2204 the server, decrypt HTTPS messages as they pass through
2205 Squid, and treat them as unencrypted HTTP messages,
2206 becoming the man-in-the-middle.
2208 The ssl_bump option is required to fully enable
2209 bumping of CONNECT requests.
2211 Omitting the mode flag causes default forward proxy mode to be used.
2214 Accelerator Mode Options:
2216 defaultsite=domainname
2217 What to use for the Host: header if it is not present
2218 in a request. Determines what site (not origin server)
2219 accelerators should consider the default.
2221 no-vhost Disable using HTTP/1.1 Host header for virtual domain support.
2223 protocol= Protocol to reconstruct accelerated and intercepted
2224 requests with. Defaults to HTTP/1.1 for http_port and
2225 HTTPS/1.1 for https_port.
2226 When an unsupported value is configured Squid will
2227 produce a FATAL error.
2228 Values: HTTP or HTTP/1.1, HTTPS or HTTPS/1.1
2230 vport Virtual host port support. Using the http_port number
2231 instead of the port passed on Host: headers.
2233 vport=NN Virtual host port support. Using the specified port
2234 number instead of the port passed on Host: headers.
2237 Act as if this Squid is the origin server.
2238 This currently means generate new Date: and Expires:
2239 headers on HIT instead of adding Age:.
2241 ignore-cc Ignore request Cache-Control headers.
2243 WARNING: This option violates HTTP specifications if
2244 used in non-accelerator setups.
2246 allow-direct Allow direct forwarding in accelerator mode. Normally
2247 accelerated requests are denied direct forwarding as if
2248 never_direct was used.
2250 WARNING: this option opens accelerator mode to security
2251 vulnerabilities usually only affecting in interception
2252 mode. Make sure to protect forwarding with suitable
2253 http_access rules when using this.
2256 SSL Bump Mode Options:
2257 In addition to these options ssl-bump requires TLS/SSL options.
2259 generate-host-certificates[=<on|off>]
2260 Dynamically create SSL server certificates for the
2261 destination hosts of bumped CONNECT requests.When
2262 enabled, the cert and key options are used to sign
2263 generated certificates. Otherwise generated
2264 certificate will be selfsigned.
2265 If there is a CA certificate lifetime of the generated
2266 certificate equals lifetime of the CA certificate. If
2267 generated certificate is selfsigned lifetime is three
2269 This option is enabled by default when ssl-bump is used.
2270 See the ssl-bump option above for more information.
2272 dynamic_cert_mem_cache_size=SIZE
2273 Approximate total RAM size spent on cached generated
2274 certificates. If set to zero, caching is disabled. The
2275 default value is 4MB.
2279 tls-cert= Path to file containing an X.509 certificate (PEM format)
2280 to be used in the TLS handshake ServerHello.
2282 If this certificate is constrained by KeyUsage TLS
2283 feature it must allow HTTP server usage, along with
2284 any additional restrictions imposed by your choice
2285 of options= settings.
2287 When OpenSSL is used this file may also contain a
2288 chain of intermediate CA certificates to send in the
2291 When GnuTLS is used this option (and any paired
2292 tls-key= option) may be repeated to load multiple
2293 certificates for different domains.
2295 Also, when generate-host-certificates=on is configured
2296 the first tls-cert= option must be a CA certificate
2297 capable of signing the automatically generated
2300 tls-key= Path to a file containing private key file (PEM format)
2301 for the previous tls-cert= option.
2303 If tls-key= is not specified tls-cert= is assumed to
2304 reference a PEM file containing both the certificate
2307 cipher= Colon separated list of supported ciphers.
2308 NOTE: some ciphers such as EDH ciphers depend on
2309 additional settings. If those settings are
2310 omitted the ciphers may be silently ignored
2311 by the OpenSSL library.
2313 options= Various SSL implementation options. The most important
2316 NO_SSLv3 Disallow the use of SSLv3
2318 NO_TLSv1 Disallow the use of TLSv1.0
2320 NO_TLSv1_1 Disallow the use of TLSv1.1
2322 NO_TLSv1_2 Disallow the use of TLSv1.2
2325 Always create a new key when using
2326 temporary/ephemeral DH key exchanges
2329 Enable ephemeral ECDH key exchange.
2330 The adopted curve should be specified
2331 using the tls-dh option.
2334 Disable use of RFC5077 session tickets.
2335 Some servers may have problems
2336 understanding the TLS extension due
2337 to ambiguous specification in RFC4507.
2339 ALL Enable various bug workarounds
2340 suggested as "harmless" by OpenSSL
2341 Be warned that this reduces SSL/TLS
2342 strength to some attacks.
2344 See the OpenSSL SSL_CTX_set_options documentation for a
2347 clientca= File containing the list of CAs to use when
2348 requesting a client certificate.
2350 tls-cafile= PEM file containing CA certificates to use when verifying
2351 client certificates. If not configured clientca will be
2352 used. May be repeated to load multiple files.
2354 capath= Directory containing additional CA certificates
2355 and CRL lists to use when verifying client certificates.
2356 Requires OpenSSL or LibreSSL.
2358 crlfile= File of additional CRL lists to use when verifying
2359 the client certificate, in addition to CRLs stored in
2360 the capath. Implies VERIFY_CRL flag below.
2363 File containing DH parameters for temporary/ephemeral DH key
2364 exchanges, optionally prefixed by a curve for ephemeral ECDH
2366 See OpenSSL documentation for details on how to create the
2367 DH parameter file. Supported curves for ECDH can be listed
2368 using the "openssl ecparam -list_curves" command.
2369 WARNING: EDH and EECDH ciphers will be silently disabled if
2370 this option is not set.
2372 sslflags= Various flags modifying the use of SSL:
2374 Don't request client certificates
2375 immediately, but wait until acl processing
2376 requires a certificate (not yet implemented).
2378 Don't allow for session reuse. Each connection
2379 will result in a new SSL session.
2381 Verify CRL lists when accepting client
2384 Verify CRL lists for all certificates in the
2385 client certificate chain.
2387 tls-default-ca[=off]
2388 Whether to use the system Trusted CAs. Default is OFF.
2390 tls-no-npn Do not use the TLS NPN extension to advertise HTTP/1.1.
2392 sslcontext= SSL session ID context identifier.
2396 connection-auth[=on|off]
2397 use connection-auth=off to tell Squid to prevent
2398 forwarding Microsoft connection oriented authentication
2399 (NTLM, Negotiate and Kerberos)
2401 disable-pmtu-discovery=
2402 Control Path-MTU discovery usage:
2403 off lets OS decide on what to do (default).
2404 transparent disable PMTU discovery when transparent
2406 always disable always PMTU discovery.
2408 In many setups of transparently intercepting proxies
2409 Path-MTU discovery can not work on traffic towards the
2410 clients. This is the case when the intercepting device
2411 does not fully track connections and fails to forward
2412 ICMP must fragment messages to the cache server. If you
2413 have such setup and experience that certain clients
2414 sporadically hang or never complete requests set
2415 disable-pmtu-discovery option to 'transparent'.
2417 name= Specifies a internal name for the port. Defaults to
2418 the port specification (port or addr:port)
2420 tcpkeepalive[=idle,interval,timeout]
2421 Enable TCP keepalive probes of idle connections.
2422 In seconds; idle is the initial time before TCP starts
2423 probing the connection, interval how often to probe, and
2424 timeout the time before giving up.
2426 require-proxy-header
2427 Require PROXY protocol version 1 or 2 connections.
2428 The proxy_protocol_access is required to whitelist
2429 downstream proxies which can be trusted.
2432 Ask TCP stack to maintain a dedicated listening queue
2433 for each worker accepting requests at this port.
2434 Requires TCP stack that supports the SO_REUSEPORT socket
2437 SECURITY WARNING: Enabling worker-specific queues
2438 allows any process running as Squid's effective user to
2439 easily accept requests destined to this port.
2441 If you run Squid on a dual-homed machine with an internal
2442 and an external interface we recommend you to specify the
2443 internal address:port in http_port. This way Squid will only be
2444 visible on the internal address.
2448 # Squid normally listens to port 3128
2449 http_port @DEFAULT_HTTP_PORT@
2454 IFDEF: USE_GNUTLS||USE_OPENSSL
2459 Usage: [ip:]port [mode] tls-cert=certificate.pem [options]
2461 The socket address where Squid will listen for client requests made
2462 over TLS or SSL connections. Commonly referred to as HTTPS.
2464 This is most useful for situations where you are running squid in
2465 accelerator mode and you want to do the TLS work at the accelerator
2468 You may specify multiple socket addresses on multiple lines,
2469 each with their own certificate and/or options.
2471 The tls-cert= option is mandatory on HTTPS ports.
2473 See http_port for a list of modes and options.
2481 Enables Native FTP proxy by specifying the socket address where Squid
2482 listens for FTP client requests. See http_port directive for various
2483 ways to specify the listening address and mode.
2485 Usage: ftp_port address [mode] [options]
2487 WARNING: This is a new, experimental, complex feature that has seen
2488 limited production exposure. Some Squid modules (e.g., caching) do not
2489 currently work with native FTP proxying, and many features have not
2490 even been tested for compatibility. Test well before deploying!
2492 Native FTP proxying differs substantially from proxying HTTP requests
2493 with ftp:// URIs because Squid works as an FTP server and receives
2494 actual FTP commands (rather than HTTP requests with FTP URLs).
2496 Native FTP commands accepted at ftp_port are internally converted or
2497 wrapped into HTTP-like messages. The same happens to Native FTP
2498 responses received from FTP origin servers. Those HTTP-like messages
2499 are shoveled through regular access control and adaptation layers
2500 between the FTP client and the FTP origin server. This allows Squid to
2501 examine, adapt, block, and log FTP exchanges. Squid reuses most HTTP
2502 mechanisms when shoveling wrapped FTP messages. For example,
2503 http_access and adaptation_access directives are used.
2507 intercept Same as http_port intercept. The FTP origin address is
2508 determined based on the intended destination of the
2509 intercepted connection.
2511 tproxy Support Linux TPROXY for spoofing outgoing
2512 connections using the client IP address.
2513 NP: disables authentication and maybe IPv6 on the port.
2515 By default (i.e., without an explicit mode option), Squid extracts the
2516 FTP origin address from the login@origin parameter of the FTP USER
2517 command. Many popular FTP clients support such native FTP proxying.
2521 name=token Specifies an internal name for the port. Defaults to
2522 the port address. Usable with myportname ACL.
2525 Enables tracking of FTP directories by injecting extra
2526 PWD commands and adjusting Request-URI (in wrapping
2527 HTTP requests) to reflect the current FTP server
2528 directory. Tracking is disabled by default.
2530 protocol=FTP Protocol to reconstruct accelerated and intercepted
2531 requests with. Defaults to FTP. No other accepted
2532 values have been tested with. An unsupported value
2533 results in a FATAL error. Accepted values are FTP,
2534 HTTP (or HTTP/1.1), and HTTPS (or HTTPS/1.1).
2536 Other http_port modes and options that are not specific to HTTP and
2537 HTTPS may also work.
2540 NAME: tcp_outgoing_tos tcp_outgoing_ds tcp_outgoing_dscp
2543 LOC: Ip::Qos::TheConfig.tosToServer
2545 Allows you to select a TOS/Diffserv value for packets outgoing
2546 on the server side, based on an ACL.
2548 tcp_outgoing_tos ds-field [!]aclname ...
2550 Example where normal_service_net uses the TOS value 0x00
2551 and good_service_net uses 0x20
2553 acl normal_service_net src 10.0.0.0/24
2554 acl good_service_net src 10.0.1.0/24
2555 tcp_outgoing_tos 0x00 normal_service_net
2556 tcp_outgoing_tos 0x20 good_service_net
2558 TOS/DSCP values really only have local significance - so you should
2559 know what you're specifying. For more information, see RFC2474,
2560 RFC2475, and RFC3260.
2562 The TOS/DSCP byte must be exactly that - a octet value 0 - 255, or
2563 "default" to use whatever default your host has.
2564 Note that only multiples of 4 are usable as the two rightmost bits have
2565 been redefined for use by ECN (RFC 3168 section 23.1).
2566 The squid parser will enforce this by masking away the ECN bits.
2568 Processing proceeds in the order specified, and stops at first fully
2571 Only fast ACLs are supported.
2574 NAME: clientside_tos
2577 LOC: Ip::Qos::TheConfig.tosToClient
2579 Allows you to select a TOS/DSCP value for packets being transmitted
2580 on the client-side, based on an ACL.
2582 clientside_tos ds-field [!]aclname ...
2584 Example where normal_service_net uses the TOS value 0x00
2585 and good_service_net uses 0x20
2587 acl normal_service_net src 10.0.0.0/24
2588 acl good_service_net src 10.0.1.0/24
2589 clientside_tos 0x00 normal_service_net
2590 clientside_tos 0x20 good_service_net
2592 Note: This feature is incompatible with qos_flows. Any TOS values set here
2593 will be overwritten by TOS values in qos_flows.
2595 The TOS/DSCP byte must be exactly that - a octet value 0 - 255, or
2596 "default" to use whatever default your host has.
2597 Note that only multiples of 4 are usable as the two rightmost bits have
2598 been redefined for use by ECN (RFC 3168 section 23.1).
2599 The squid parser will enforce this by masking away the ECN bits.
2601 This clause only supports fast acl types.
2602 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
2605 NAME: tcp_outgoing_mark
2607 IFDEF: SO_MARK&&USE_LIBCAP
2609 LOC: Ip::Qos::TheConfig.nfmarkToServer
2611 Allows you to apply a Netfilter mark value to outgoing packets
2612 on the server side, based on an ACL.
2614 tcp_outgoing_mark mark-value [!]aclname ...
2616 Example where normal_service_net uses the mark value 0x00
2617 and good_service_net uses 0x20
2619 acl normal_service_net src 10.0.0.0/24
2620 acl good_service_net src 10.0.1.0/24
2621 tcp_outgoing_mark 0x00 normal_service_net
2622 tcp_outgoing_mark 0x20 good_service_net
2624 Only fast ACLs are supported.
2627 NAME: mark_client_packet clientside_mark
2629 IFDEF: SO_MARK&&USE_LIBCAP
2631 LOC: Ip::Qos::TheConfig.nfmarkToClient
2633 Allows you to apply a Netfilter MARK value to packets being transmitted
2634 on the client-side, based on an ACL.
2636 mark_client_packet mark-value [!]aclname ...
2638 Example where normal_service_net uses the MARK value 0x00
2639 and good_service_net uses 0x20
2641 acl normal_service_net src 10.0.0.0/24
2642 acl good_service_net src 10.0.1.0/24
2643 mark_client_packet 0x00 normal_service_net
2644 mark_client_packet 0x20 good_service_net
2646 Note: This feature is incompatible with qos_flows. Any mark values set here
2647 will be overwritten by mark values in qos_flows.
2649 This clause only supports fast acl types.
2650 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
2653 NAME: mark_client_connection
2655 IFDEF: SO_MARK&&USE_LIBCAP
2657 LOC: Ip::Qos::TheConfig.nfConnmarkToClient
2659 Allows you to apply a Netfilter CONNMARK value to a connection
2660 on the client-side, based on an ACL.
2662 mark_client_connection mark-value[/mask] [!]aclname ...
2664 The mark-value and mask are unsigned integers (hex, octal, or decimal).
2665 The mask may be used to preserve marking previously set by other agents
2668 A matching rule replaces the CONNMARK value. If a mask is also
2669 specified, then the masked bits of the original value are zeroed, and
2670 the configured mark-value is ORed with that adjusted value.
2671 For example, applying a mark-value 0xAB/0xF to 0x5F CONNMARK, results
2672 in a 0xFB marking (rather than a 0xAB or 0x5B).
2674 This directive semantics is similar to iptables --set-mark rather than
2675 --set-xmark functionality.
2677 The directive does not interfere with qos_flows (which uses packet MARKs,
2680 Example where squid marks intercepted FTP connections:
2682 acl proto_ftp proto FTP
2683 mark_client_connection 0x200/0xff00 proto_ftp
2685 This clause only supports fast acl types.
2686 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
2693 LOC: Ip::Qos::TheConfig
2695 Allows you to select a TOS/DSCP value to mark outgoing
2696 connections to the client, based on where the reply was sourced.
2697 For platforms using netfilter, allows you to set a netfilter mark
2698 value instead of, or in addition to, a TOS value.
2700 By default this functionality is disabled. To enable it with the default
2701 settings simply use "qos_flows mark" or "qos_flows tos". Default
2702 settings will result in the netfilter mark or TOS value being copied
2703 from the upstream connection to the client. Note that it is the connection
2704 CONNMARK value not the packet MARK value that is copied.
2706 It is not currently possible to copy the mark or TOS value from the
2707 client to the upstream connection request.
2709 TOS values really only have local significance - so you should
2710 know what you're specifying. For more information, see RFC2474,
2711 RFC2475, and RFC3260.
2713 The TOS/DSCP byte must be exactly that - a octet value 0 - 255.
2714 Note that only multiples of 4 are usable as the two rightmost bits have
2715 been redefined for use by ECN (RFC 3168 section 23.1).
2716 The squid parser will enforce this by masking away the ECN bits.
2718 Mark values can be any unsigned 32-bit integer value.
2720 This setting is configured by setting the following values:
2722 tos|mark Whether to set TOS or netfilter mark values
2724 local-hit=0xFF Value to mark local cache hits.
2726 sibling-hit=0xFF Value to mark hits from sibling peers.
2728 parent-hit=0xFF Value to mark hits from parent peers.
2730 miss=0xFF[/mask] Value to mark cache misses. Takes precedence
2731 over the preserve-miss feature (see below), unless
2732 mask is specified, in which case only the bits
2733 specified in the mask are written.
2735 The TOS variant of the following features are only possible on Linux
2736 and require your kernel to be patched with the TOS preserving ZPH
2737 patch, available from http://zph.bratcheda.org
2738 No patch is needed to preserve the netfilter mark, which will work
2739 with all variants of netfilter.
2741 disable-preserve-miss
2742 This option disables the preservation of the TOS or netfilter
2743 mark. By default, the existing TOS or netfilter mark value of
2744 the response coming from the remote server will be retained
2745 and masked with miss-mark.
2746 NOTE: in the case of a netfilter mark, the mark must be set on
2747 the connection (using the CONNMARK target) not on the packet
2751 Allows you to mask certain bits in the TOS or mark value
2752 received from the remote server, before copying the value to
2753 the TOS sent towards clients.
2754 Default for tos: 0xFF (TOS from server is not changed).
2755 Default for mark: 0xFFFFFFFF (mark from server is not changed).
2757 All of these features require the --enable-zph-qos compilation flag
2758 (enabled by default). Netfilter marking also requires the
2759 libnetfilter_conntrack libraries (--with-netfilter-conntrack) and
2760 libcap 2.09+ (--with-libcap).
2764 NAME: tcp_outgoing_address
2767 DEFAULT_DOC: Address selection is performed by the operating system.
2768 LOC: Config.accessList.outgoing_address
2770 Allows you to map requests to different outgoing IP addresses
2771 based on the username or source address of the user making
2774 tcp_outgoing_address ipaddr [[!]aclname] ...
2777 Forwarding clients with dedicated IPs for certain subnets.
2779 acl normal_service_net src 10.0.0.0/24
2780 acl good_service_net src 10.0.2.0/24
2782 tcp_outgoing_address 2001:db8::c001 good_service_net
2783 tcp_outgoing_address 10.1.0.2 good_service_net
2785 tcp_outgoing_address 2001:db8::beef normal_service_net
2786 tcp_outgoing_address 10.1.0.1 normal_service_net
2788 tcp_outgoing_address 2001:db8::1
2789 tcp_outgoing_address 10.1.0.3
2791 Processing proceeds in the order specified, and stops at first fully
2794 Squid will add an implicit IP version test to each line.
2795 Requests going to IPv4 websites will use the outgoing 10.1.0.* addresses.
2796 Requests going to IPv6 websites will use the outgoing 2001:db8:* addresses.
2799 NOTE: The use of this directive using client dependent ACLs is
2800 incompatible with the use of server side persistent connections. To
2801 ensure correct results it is best to set server_persistent_connections
2802 to off when using this directive in such configurations.
2804 NOTE: The use of this directive to set a local IP on outgoing TCP links
2805 is incompatible with using TPROXY to set client IP out outbound TCP links.
2806 When needing to contact peers use the no-tproxy cache_peer option and the
2807 client_dst_passthru directive re-enable normal forwarding such as this.
2809 This clause only supports fast acl types.
2810 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
2813 NAME: host_verify_strict
2816 LOC: Config.onoff.hostStrictVerify
2818 Regardless of this option setting, when dealing with intercepted
2819 traffic, Squid always verifies that the destination IP address matches
2820 the Host header domain or IP (called 'authority form URL').
2822 This enforcement is performed to satisfy a MUST-level requirement in
2823 RFC 2616 section 14.23: "The Host field value MUST represent the naming
2824 authority of the origin server or gateway given by the original URL".
2827 Squid always responds with an HTTP 409 (Conflict) error
2828 page and logs a security warning if there is no match.
2830 Squid verifies that the destination IP address matches
2831 the Host header for forward-proxy and reverse-proxy traffic
2832 as well. For those traffic types, Squid also enables the
2833 following checks, comparing the corresponding Host header
2834 and Request-URI components:
2836 * The host names (domain or IP) must be identical,
2837 but valueless or missing Host header disables all checks.
2838 For the two host names to match, both must be either IP
2841 * Port numbers must be identical, but if a port is missing
2842 the scheme-default port is assumed.
2845 When set to OFF (the default):
2846 Squid allows suspicious requests to continue but logs a
2847 security warning and blocks caching of the response.
2849 * Forward-proxy traffic is not checked at all.
2851 * Reverse-proxy traffic is not checked at all.
2853 * Intercepted traffic which passes verification is handled
2854 according to client_dst_passthru.
2856 * Intercepted requests which fail verification are sent
2857 to the client original destination instead of DIRECT.
2858 This overrides 'client_dst_passthru off'.
2860 For now suspicious intercepted CONNECT requests are always
2861 responded to with an HTTP 409 (Conflict) error page.
2866 As described in CVE-2009-0801 when the Host: header alone is used
2867 to determine the destination of a request it becomes trivial for
2868 malicious scripts on remote websites to bypass browser same-origin
2869 security policy and sandboxing protections.
2871 The cause of this is that such applets are allowed to perform their
2872 own HTTP stack, in which case the same-origin policy of the browser
2873 sandbox only verifies that the applet tries to contact the same IP
2874 as from where it was loaded at the IP level. The Host: header may
2875 be different from the connected IP and approved origin.
2879 NAME: client_dst_passthru
2882 LOC: Config.onoff.client_dst_passthru
2884 With NAT or TPROXY intercepted traffic Squid may pass the request
2885 directly to the original client destination IP or seek a faster
2886 source using the HTTP Host header.
2888 Using Host to locate alternative servers can provide faster
2889 connectivity with a range of failure recovery options.
2890 But can also lead to connectivity trouble when the client and
2891 server are attempting stateful interactions unaware of the proxy.
2893 This option (on by default) prevents alternative DNS entries being
2894 located to send intercepted traffic DIRECT to an origin server.
2895 The clients original destination IP and port will be used instead.
2897 Regardless of this option setting, when dealing with intercepted
2898 traffic Squid will verify the Host: header and any traffic which
2899 fails Host verification will be treated as if this option were ON.
2901 see host_verify_strict for details on the verification process.
2906 -----------------------------------------------------------------------------
2909 NAME: tls_outgoing_options
2910 IFDEF: USE_GNUTLS||USE_OPENSSL
2911 TYPE: securePeerOptions
2912 DEFAULT: min-version=1.0
2913 LOC: Security::ProxyOutgoingConfig
2915 disable Do not support https:// URLs.
2917 cert=/path/to/client/certificate
2918 A client X.509 certificate to use when connecting.
2920 key=/path/to/client/private_key
2921 The private key corresponding to the cert= above.
2923 If key= is not specified cert= is assumed to
2924 reference a PEM file containing both the certificate
2927 cipher=... The list of valid TLS ciphers to use.
2930 The minimum TLS protocol version to permit.
2931 To control SSLv3 use the options= parameter.
2932 Supported Values: 1.0 (default), 1.1, 1.2, 1.3
2934 options=... Specify various TLS/SSL implementation options.
2936 OpenSSL options most important are:
2938 NO_SSLv3 Disallow the use of SSLv3
2941 Always create a new key when using
2942 temporary/ephemeral DH key exchanges
2945 Disable use of RFC5077 session tickets.
2946 Some servers may have problems
2947 understanding the TLS extension due
2948 to ambiguous specification in RFC4507.
2950 ALL Enable various bug workarounds
2951 suggested as "harmless" by OpenSSL
2952 Be warned that this reduces SSL/TLS
2953 strength to some attacks.
2955 See the OpenSSL SSL_CTX_set_options documentation
2956 for a more complete list.
2958 GnuTLS options most important are:
2961 Disable use of RFC5077 session tickets.
2962 Some servers may have problems
2963 understanding the TLS extension due
2964 to ambiguous specification in RFC4507.
2966 See the GnuTLS Priority Strings documentation
2967 for a more complete list.
2968 http://www.gnutls.org/manual/gnutls.html#Priority-Strings
2971 cafile= PEM file containing CA certificates to use when verifying
2972 the peer certificate. May be repeated to load multiple files.
2974 capath= A directory containing additional CA certificates to
2975 use when verifying the peer certificate.
2976 Requires OpenSSL or LibreSSL.
2978 crlfile=... A certificate revocation list file to use when
2979 verifying the peer certificate.
2981 flags=... Specify various flags modifying the TLS implementation:
2984 Accept certificates even if they fail to
2987 Don't verify the peer certificate
2988 matches the server name
2991 Whether to use the system Trusted CAs. Default is ON.
2993 domain= The peer name as advertised in its certificate.
2994 Used for verifying the correctness of the received peer
2995 certificate. If not specified the peer hostname will be
3001 -----------------------------------------------------------------------------
3004 NAME: ssl_unclean_shutdown
3008 LOC: Config.SSL.unclean_shutdown
3010 Some browsers (especially MSIE) bugs out on SSL shutdown
3017 LOC: Config.SSL.ssl_engine
3020 The OpenSSL engine to use. You will need to set this if you
3021 would like to use hardware SSL acceleration for example.
3024 NAME: sslproxy_session_ttl
3027 LOC: Config.SSL.session_ttl
3030 Sets the timeout value for SSL sessions
3033 NAME: sslproxy_session_cache_size
3036 LOC: Config.SSL.sessionCacheSize
3039 Sets the cache size to use for ssl session
3042 NAME: sslproxy_foreign_intermediate_certs
3045 LOC: Config.ssl_client.foreignIntermediateCertsPath
3048 Many origin servers fail to send their full server certificate
3049 chain for verification, assuming the client already has or can
3050 easily locate any missing intermediate certificates.
3052 Squid uses the certificates from the specified file to fill in
3053 these missing chains when trying to validate origin server
3056 The file is expected to contain zero or more PEM-encoded
3057 intermediate certificates. These certificates are not treated
3058 as trusted root certificates, and any self-signed certificate in
3059 this file will be ignored.
3062 NAME: sslproxy_cert_sign_hash
3065 LOC: Config.SSL.certSignHash
3068 Sets the hashing algorithm to use when signing generated certificates.
3069 Valid algorithm names depend on the OpenSSL library used. The following
3070 names are usually available: sha1, sha256, sha512, and md5. Please see
3071 your OpenSSL library manual for the available hashes. By default, Squids
3072 that support this option use sha256 hashes.
3074 Squid does not forcefully purge cached certificates that were generated
3075 with an algorithm other than the currently configured one. They remain
3076 in the cache, subject to the regular cache eviction policy, and become
3077 useful if the algorithm changes again.
3082 TYPE: sslproxy_ssl_bump
3083 LOC: Config.accessList.ssl_bump
3084 DEFAULT_DOC: Become a TCP tunnel without decrypting proxied traffic.
3087 This option is consulted when a CONNECT request is received on
3088 an http_port (or a new connection is intercepted at an
3089 https_port), provided that port was configured with an ssl-bump
3090 flag. The subsequent data on the connection is either treated as
3091 HTTPS and decrypted OR tunneled at TCP level without decryption,
3092 depending on the first matching bumping "action".
3094 ssl_bump <action> [!]acl ...
3096 The following bumping actions are currently supported:
3099 Become a TCP tunnel without decrypting proxied traffic.
3100 This is the default action.
3103 When used on step SslBump1, establishes a secure connection
3104 with the client first, then connect to the server.
3105 When used on step SslBump2 or SslBump3, establishes a secure
3106 connection with the server and, using a mimicked server
3107 certificate, with the client.
3110 Receive client (step SslBump1) or server (step SslBump2)
3111 certificate while preserving the possibility of splicing the
3112 connection. Peeking at the server certificate (during step 2)
3113 usually precludes bumping of the connection at step 3.
3116 Receive client (step SslBump1) or server (step SslBump2)
3117 certificate while preserving the possibility of bumping the
3118 connection. Staring at the server certificate (during step 2)
3119 usually precludes splicing of the connection at step 3.
3122 Close client and server connections.
3124 Backward compatibility actions available at step SslBump1:
3127 Bump the connection. Establish a secure connection with the
3128 client first, then connect to the server. This old mode does
3129 not allow Squid to mimic server SSL certificate and does not
3130 work with intercepted SSL connections.
3133 Bump the connection. Establish a secure connection with the
3134 server first, then establish a secure connection with the
3135 client, using a mimicked server certificate. Works with both
3136 CONNECT requests and intercepted SSL connections, but does
3137 not allow to make decisions based on SSL handshake info.
3140 Decide whether to bump or splice the connection based on
3141 client-to-squid and server-to-squid SSL hello messages.
3145 Same as the "splice" action.
3147 All ssl_bump rules are evaluated at each of the supported bumping
3148 steps. Rules with actions that are impossible at the current step are
3149 ignored. The first matching ssl_bump action wins and is applied at the
3150 end of the current step. If no rules match, the splice action is used.
3151 See the at_step ACL for a list of the supported SslBump steps.
3153 This clause supports both fast and slow acl types.
3154 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
3156 See also: http_port ssl-bump, https_port ssl-bump, and acl at_step.
3159 # Example: Bump all TLS connections except those originating from
3160 # localhost or those going to example.com.
3162 acl broken_sites ssl::server_name .example.com
3163 ssl_bump splice localhost
3164 ssl_bump splice broken_sites
3168 NAME: sslproxy_cert_error
3171 DEFAULT_DOC: Server certificate errors terminate the transaction.
3172 LOC: Config.ssl_client.cert_error
3175 Use this ACL to bypass server certificate validation errors.
3177 For example, the following lines will bypass all validation errors
3178 when talking to servers for example.com. All other
3179 validation errors will result in ERR_SECURE_CONNECT_FAIL error.
3181 acl BrokenButTrustedServers dstdomain example.com
3182 sslproxy_cert_error allow BrokenButTrustedServers
3183 sslproxy_cert_error deny all
3185 This clause only supports fast acl types.
3186 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
3187 Using slow acl types may result in server crashes
3189 Without this option, all server certificate validation errors
3190 terminate the transaction to protect Squid and the client.
3192 SQUID_X509_V_ERR_INFINITE_VALIDATION error cannot be bypassed
3193 but should not happen unless your OpenSSL library is buggy.
3196 Bypassing validation errors is dangerous because an
3197 error usually implies that the server cannot be trusted
3198 and the connection may be insecure.
3200 See also: sslproxy_flags and DONT_VERIFY_PEER.
3203 NAME: sslproxy_cert_sign
3206 POSTSCRIPTUM: signUntrusted ssl::certUntrusted
3207 POSTSCRIPTUM: signSelf ssl::certSelfSigned
3208 POSTSCRIPTUM: signTrusted all
3209 TYPE: sslproxy_cert_sign
3210 LOC: Config.ssl_client.cert_sign
3213 sslproxy_cert_sign <signing algorithm> acl ...
3215 The following certificate signing algorithms are supported:
3218 Sign using the configured CA certificate which is usually
3219 placed in and trusted by end-user browsers. This is the
3220 default for trusted origin server certificates.
3223 Sign to guarantee an X509_V_ERR_CERT_UNTRUSTED browser error.
3224 This is the default for untrusted origin server certificates
3225 that are not self-signed (see ssl::certUntrusted).
3228 Sign using a self-signed certificate with the right CN to
3229 generate a X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT error in the
3230 browser. This is the default for self-signed origin server
3231 certificates (see ssl::certSelfSigned).
3233 This clause only supports fast acl types.
3235 When sslproxy_cert_sign acl(s) match, Squid uses the corresponding
3236 signing algorithm to generate the certificate and ignores all
3237 subsequent sslproxy_cert_sign options (the first match wins). If no
3238 acl(s) match, the default signing algorithm is determined by errors
3239 detected when obtaining and validating the origin server certificate.
3241 WARNING: SQUID_X509_V_ERR_DOMAIN_MISMATCH and ssl:certDomainMismatch can
3242 be used with sslproxy_cert_adapt, but if and only if Squid is bumping a
3243 CONNECT request that carries a domain name. In all other cases (CONNECT
3244 to an IP address or an intercepted SSL connection), Squid cannot detect
3245 the domain mismatch at certificate generation time when
3246 bump-server-first is used.
3249 NAME: sslproxy_cert_adapt
3252 TYPE: sslproxy_cert_adapt
3253 LOC: Config.ssl_client.cert_adapt
3256 sslproxy_cert_adapt <adaptation algorithm> acl ...
3258 The following certificate adaptation algorithms are supported:
3261 Sets the "Not After" property to the "Not After" property of
3262 the CA certificate used to sign generated certificates.
3265 Sets the "Not Before" property to the "Not Before" property of
3266 the CA certificate used to sign generated certificates.
3268 setCommonName or setCommonName{CN}
3269 Sets Subject.CN property to the host name specified as a
3270 CN parameter or, if no explicit CN parameter was specified,
3271 extracted from the CONNECT request. It is a misconfiguration
3272 to use setCommonName without an explicit parameter for
3273 intercepted or tproxied SSL connections.
3275 This clause only supports fast acl types.
3277 Squid first groups sslproxy_cert_adapt options by adaptation algorithm.
3278 Within a group, when sslproxy_cert_adapt acl(s) match, Squid uses the
3279 corresponding adaptation algorithm to generate the certificate and
3280 ignores all subsequent sslproxy_cert_adapt options in that algorithm's
3281 group (i.e., the first match wins within each algorithm group). If no
3282 acl(s) match, the default mimicking action takes place.
3284 WARNING: SQUID_X509_V_ERR_DOMAIN_MISMATCH and ssl:certDomainMismatch can
3285 be used with sslproxy_cert_adapt, but if and only if Squid is bumping a
3286 CONNECT request that carries a domain name. In all other cases (CONNECT
3287 to an IP address or an intercepted SSL connection), Squid cannot detect
3288 the domain mismatch at certificate generation time when
3289 bump-server-first is used.
3292 NAME: sslpassword_program
3295 LOC: Config.Program.ssl_password
3298 Specify a program used for entering SSL key passphrases
3299 when using encrypted SSL certificate keys. If not specified
3300 keys must either be unencrypted, or Squid started with the -N
3301 option to allow it to query interactively for the passphrase.
3303 The key file name is given as argument to the program allowing
3304 selection of the right password if you have multiple encrypted
3309 OPTIONS RELATING TO EXTERNAL SSL_CRTD
3310 -----------------------------------------------------------------------------
3313 NAME: sslcrtd_program
3316 DEFAULT: @DEFAULT_SSL_CRTD@ -s @DEFAULT_SSL_DB_DIR@ -M 4MB
3317 LOC: Ssl::TheConfig.ssl_crtd
3319 Specify the location and options of the executable for certificate
3322 @DEFAULT_SSL_CRTD@ program can use a disk cache to improve response
3323 times on repeated requests. To enable caching, specify -s and -M
3324 parameters. If those parameters are not given, the program generates
3325 a new certificate on every request.
3327 For more information use:
3328 @DEFAULT_SSL_CRTD@ -h
3331 NAME: sslcrtd_children
3332 TYPE: HelperChildConfig
3334 DEFAULT: 32 startup=5 idle=1
3335 LOC: Ssl::TheConfig.ssl_crtdChildren
3337 Specifies the maximum number of certificate generation processes that
3338 Squid may spawn (numberofchildren) and several related options. Using
3339 too few of these helper processes (a.k.a. "helpers") creates request
3340 queues. Using too many helpers wastes your system resources. Squid
3341 does not support spawning more than 32 helpers.
3343 Usage: numberofchildren [option]...
3345 The startup= and idle= options allow some measure of skew in your
3350 Sets the minimum number of processes to spawn when Squid
3351 starts or reconfigures. When set to zero the first request will
3352 cause spawning of the first child process to handle it.
3354 Starting too few children temporary slows Squid under load while it
3355 tries to spawn enough additional processes to cope with traffic.
3359 Sets a minimum of how many processes Squid is to try and keep available
3360 at all times. When traffic begins to rise above what the existing
3361 processes can handle this many more will be spawned up to the maximum
3362 configured. A minimum setting of 1 is required.
3366 Sets the maximum number of queued requests. A request is queued when
3367 no existing child is idle and no new child can be started due to
3368 numberofchildren limit. If the queued requests exceed queue size for
3369 more than 3 minutes squid aborts its operation. The default value is
3370 set to 2*numberofchildren.
3372 You must have at least one ssl_crtd process.
3375 NAME: sslcrtvalidator_program
3379 LOC: Ssl::TheConfig.ssl_crt_validator
3381 Specify the location and options of the executable for ssl_crt_validator
3384 Usage: sslcrtvalidator_program [ttl=n] [cache=n] path ...
3387 ttl=n TTL in seconds for cached results. The default is 60 secs
3388 cache=n limit the result cache size. The default value is 2048
3391 NAME: sslcrtvalidator_children
3392 TYPE: HelperChildConfig
3394 DEFAULT: 32 startup=5 idle=1 concurrency=1
3395 LOC: Ssl::TheConfig.ssl_crt_validator_Children
3397 Specifies the maximum number of certificate validation processes that
3398 Squid may spawn (numberofchildren) and several related options. Using
3399 too few of these helper processes (a.k.a. "helpers") creates request
3400 queues. Using too many helpers wastes your system resources. Squid
3401 does not support spawning more than 32 helpers.
3403 Usage: numberofchildren [option]...
3405 The startup= and idle= options allow some measure of skew in your
3410 Sets the minimum number of processes to spawn when Squid
3411 starts or reconfigures. When set to zero the first request will
3412 cause spawning of the first child process to handle it.
3414 Starting too few children temporary slows Squid under load while it
3415 tries to spawn enough additional processes to cope with traffic.
3419 Sets a minimum of how many processes Squid is to try and keep available
3420 at all times. When traffic begins to rise above what the existing
3421 processes can handle this many more will be spawned up to the maximum
3422 configured. A minimum setting of 1 is required.
3426 The number of requests each certificate validator helper can handle in
3427 parallel. A value of 0 indicates the certficate validator does not
3428 support concurrency. Defaults to 1.
3430 When this directive is set to a value >= 1 then the protocol
3431 used to communicate with the helper is modified to include
3432 a request ID in front of the request/response. The request
3433 ID from the request must be echoed back with the response
3438 Sets the maximum number of queued requests. A request is queued when
3439 no existing child can accept it due to concurrency limit and no new
3440 child can be started due to numberofchildren limit. If the queued
3441 requests exceed queue size for more than 3 minutes squid aborts its
3442 operation. The default value is set to 2*numberofchildren.
3444 You must have at least one ssl_crt_validator process.
3448 OPTIONS WHICH AFFECT THE NEIGHBOR SELECTION ALGORITHM
3449 -----------------------------------------------------------------------------
3457 To specify other caches in a hierarchy, use the format:
3459 cache_peer hostname type http-port icp-port [options]
3464 # hostname type port port options
3465 # -------------------- -------- ----- ----- -----------
3466 cache_peer parent.foo.net parent 3128 3130 default
3467 cache_peer sib1.foo.net sibling 3128 3130 proxy-only
3468 cache_peer sib2.foo.net sibling 3128 3130 proxy-only
3469 cache_peer example.com parent 80 0 default
3470 cache_peer cdn.example.com sibling 3128 0
3472 type: either 'parent', 'sibling', or 'multicast'.
3474 proxy-port: The port number where the peer accept HTTP requests.
3475 For other Squid proxies this is usually 3128
3476 For web servers this is usually 80
3478 icp-port: Used for querying neighbor caches about objects.
3479 Set to 0 if the peer does not support ICP or HTCP.
3480 See ICP and HTCP options below for additional details.
3483 ==== ICP OPTIONS ====
3485 You MUST also set icp_port and icp_access explicitly when using these options.
3486 The defaults will prevent peer traffic using ICP.
3489 no-query Disable ICP queries to this neighbor.
3492 Indicates the named peer is a member of a multicast group.
3493 ICP queries will not be sent directly to the peer, but ICP
3494 replies will be accepted from it.
3496 closest-only Indicates that, for ICP_OP_MISS replies, we'll only forward
3497 CLOSEST_PARENT_MISSes and never FIRST_PARENT_MISSes.
3500 To only send ICP queries to this neighbor infrequently.
3501 This is used to keep the neighbor round trip time updated
3502 and is usually used in conjunction with weighted-round-robin.
3505 ==== HTCP OPTIONS ====
3507 You MUST also set htcp_port and htcp_access explicitly when using these options.
3508 The defaults will prevent peer traffic using HTCP.
3511 htcp Send HTCP, instead of ICP, queries to the neighbor.
3512 You probably also want to set the "icp-port" to 4827
3513 instead of 3130. This directive accepts a comma separated
3514 list of options described below.
3516 htcp=oldsquid Send HTCP to old Squid versions (2.5 or earlier).
3518 htcp=no-clr Send HTCP to the neighbor but without
3519 sending any CLR requests. This cannot be used with
3522 htcp=only-clr Send HTCP to the neighbor but ONLY CLR requests.
3523 This cannot be used with no-clr.
3526 Send HTCP to the neighbor including CLRs but only when
3527 they do not result from PURGE requests.
3530 Forward any HTCP CLR requests this proxy receives to the peer.
3533 ==== PEER SELECTION METHODS ====
3535 The default peer selection method is ICP, with the first responding peer
3536 being used as source. These options can be used for better load balancing.
3539 default This is a parent cache which can be used as a "last-resort"
3540 if a peer cannot be located by any of the peer-selection methods.
3541 If specified more than once, only the first is used.
3543 round-robin Load-Balance parents which should be used in a round-robin
3544 fashion in the absence of any ICP queries.
3545 weight=N can be used to add bias.
3547 weighted-round-robin
3548 Load-Balance parents which should be used in a round-robin
3549 fashion with the frequency of each parent being based on the
3550 round trip time. Closer parents are used more often.
3551 Usually used for background-ping parents.
3552 weight=N can be used to add bias.
3554 carp Load-Balance parents which should be used as a CARP array.
3555 The requests will be distributed among the parents based on the
3556 CARP load balancing hash function based on their weight.
3558 userhash Load-balance parents based on the client proxy_auth or ident username.
3560 sourcehash Load-balance parents based on the client source IP.
3563 To be used only for cache peers of type "multicast".
3564 ALL members of this multicast group have "sibling"
3565 relationship with it, not "parent". This is to a multicast
3566 group when the requested object would be fetched only from
3567 a "parent" cache, anyway. It's useful, e.g., when
3568 configuring a pool of redundant Squid proxies, being
3569 members of the same multicast group.
3572 ==== PEER SELECTION OPTIONS ====
3574 weight=N use to affect the selection of a peer during any weighted
3575 peer-selection mechanisms.
3576 The weight must be an integer; default is 1,
3577 larger weights are favored more.
3578 This option does not affect parent selection if a peering
3579 protocol is not in use.
3581 basetime=N Specify a base amount to be subtracted from round trip
3583 It is subtracted before division by weight in calculating
3584 which parent to fectch from. If the rtt is less than the
3585 base time the rtt is set to a minimal value.
3587 ttl=N Specify a TTL to use when sending multicast ICP queries
3589 Only useful when sending to a multicast group.
3590 Because we don't accept ICP replies from random
3591 hosts, you must configure other group members as
3592 peers with the 'multicast-responder' option.
3594 no-delay To prevent access to this neighbor from influencing the
3597 digest-url=URL Tell Squid to fetch the cache digest (if digests are
3598 enabled) for this host from the specified URL rather
3599 than the Squid default location.
3602 ==== CARP OPTIONS ====
3604 carp-key=key-specification
3605 use a different key than the full URL to hash against the peer.
3606 the key-specification is a comma-separated list of the keywords
3607 scheme, host, port, path, params
3608 Order is not important.
3610 ==== ACCELERATOR / REVERSE-PROXY OPTIONS ====
3612 originserver Causes this parent to be contacted as an origin server.
3613 Meant to be used in accelerator setups when the peer
3617 Set the Host header of requests forwarded to this peer.
3618 Useful in accelerator setups where the server (peer)
3619 expects a certain domain name but clients may request
3620 others. ie example.com or www.example.com
3622 no-digest Disable request of cache digests.
3625 Disables requesting ICMP RTT database (NetDB).
3628 ==== AUTHENTICATION OPTIONS ====
3631 If this is a personal/workgroup proxy and your parent
3632 requires proxy authentication.
3634 Note: The string can include URL escapes (i.e. %20 for
3635 spaces). This also means % must be written as %%.
3638 Send login details received from client to this peer.
3639 Both Proxy- and WWW-Authorization headers are passed
3640 without alteration to the peer.
3641 Authentication is not required by Squid for this to work.
3643 Note: This will pass any form of authentication but
3644 only Basic auth will work through a proxy unless the
3645 connection-auth options are also used.
3647 login=PASS Send login details received from client to this peer.
3648 Authentication is not required by this option.
3650 If there are no client-provided authentication headers
3651 to pass on, but username and password are available
3652 from an external ACL user= and password= result tags
3653 they may be sent instead.
3655 Note: To combine this with proxy_auth both proxies must
3656 share the same user database as HTTP only allows for
3657 a single login (one for proxy, one for origin server).
3658 Also be warned this will expose your users proxy
3659 password to the peer. USE WITH CAUTION
3662 Send the username to the upstream cache, but with a
3663 fixed password. This is meant to be used when the peer
3664 is in another administrative domain, but it is still
3665 needed to identify each user.
3666 The star can optionally be followed by some extra
3667 information which is added to the username. This can
3668 be used to identify this proxy to the peer, similar to
3669 the login=username:password option above.
3672 If this is a personal/workgroup proxy and your parent
3673 requires a secure proxy authentication.
3674 The first principal from the default keytab or defined by
3675 the environment variable KRB5_KTNAME will be used.
3677 WARNING: The connection may transmit requests from multiple
3678 clients. Negotiate often assumes end-to-end authentication
3679 and a single-client. Which is not strictly true here.
3681 login=NEGOTIATE:principal_name
3682 If this is a personal/workgroup proxy and your parent
3683 requires a secure proxy authentication.
3684 The principal principal_name from the default keytab or
3685 defined by the environment variable KRB5_KTNAME will be
3688 WARNING: The connection may transmit requests from multiple
3689 clients. Negotiate often assumes end-to-end authentication
3690 and a single-client. Which is not strictly true here.
3692 connection-auth=on|off
3693 Tell Squid that this peer does or not support Microsoft
3694 connection oriented authentication, and any such
3695 challenges received from there should be ignored.
3696 Default is auto to automatically determine the status
3700 Do not use a keytab to authenticate to a peer when
3701 login=NEGOTIATE is specified. Let the GSSAPI
3702 implementation determine which already existing
3703 credentials cache to use instead.
3706 ==== SSL / HTTPS / TLS OPTIONS ====
3708 tls Encrypt connections to this peer with TLS.
3710 sslcert=/path/to/ssl/certificate
3711 A client X.509 certificate to use when connecting to
3714 sslkey=/path/to/ssl/key
3715 The private key corresponding to sslcert above.
3717 If sslkey= is not specified sslcert= is assumed to
3718 reference a PEM file containing both the certificate
3721 sslcipher=... The list of valid SSL ciphers to use when connecting
3725 The minimum TLS protocol version to permit. To control
3726 SSLv3 use the tls-options= parameter.
3727 Supported Values: 1.0 (default), 1.1, 1.2
3729 tls-options=... Specify various TLS implementation options.
3731 OpenSSL options most important are:
3733 NO_SSLv3 Disallow the use of SSLv3
3736 Always create a new key when using
3737 temporary/ephemeral DH key exchanges
3740 Disable use of RFC5077 session tickets.
3741 Some servers may have problems
3742 understanding the TLS extension due
3743 to ambiguous specification in RFC4507.
3745 ALL Enable various bug workarounds
3746 suggested as "harmless" by OpenSSL
3747 Be warned that this reduces SSL/TLS
3748 strength to some attacks.
3750 See the OpenSSL SSL_CTX_set_options documentation for a
3753 GnuTLS options most important are:
3756 Disable use of RFC5077 session tickets.
3757 Some servers may have problems
3758 understanding the TLS extension due
3759 to ambiguous specification in RFC4507.
3761 See the GnuTLS Priority Strings documentation
3762 for a more complete list.
3763 http://www.gnutls.org/manual/gnutls.html#Priority-Strings
3765 tls-cafile= PEM file containing CA certificates to use when verifying
3766 the peer certificate. May be repeated to load multiple files.
3768 sslcapath=... A directory containing additional CA certificates to
3769 use when verifying the peer certificate.
3770 Requires OpenSSL or LibreSSL.
3772 sslcrlfile=... A certificate revocation list file to use when
3773 verifying the peer certificate.
3775 sslflags=... Specify various flags modifying the SSL implementation:
3778 Accept certificates even if they fail to
3782 Don't verify the peer certificate
3783 matches the server name
3785 ssldomain= The peer name as advertised in it's certificate.
3786 Used for verifying the correctness of the received peer
3787 certificate. If not specified the peer hostname will be
3790 front-end-https[=off|on|auto]
3791 Enable the "Front-End-Https: On" header needed when
3792 using Squid as a SSL frontend in front of Microsoft OWA.
3793 See MS KB document Q307347 for details on this header.
3794 If set to auto the header will only be added if the
3795 request is forwarded as a https:// URL.
3797 tls-default-ca[=off]
3798 Whether to use the system Trusted CAs. Default is ON.
3800 tls-no-npn Do not use the TLS NPN extension to advertise HTTP/1.1.
3802 ==== GENERAL OPTIONS ====
3805 A peer-specific connect timeout.
3806 Also see the peer_connect_timeout directive.
3808 connect-fail-limit=N
3809 How many times connecting to a peer must fail before
3810 it is marked as down. Standby connection failures
3811 count towards this limit. Default is 10.
3813 allow-miss Disable Squid's use of only-if-cached when forwarding
3814 requests to siblings. This is primarily useful when
3815 icp_hit_stale is used by the sibling. Excessive use
3816 of this option may result in forwarding loops. One way
3817 to prevent peering loops when using this option, is to
3818 deny cache peer usage on requests from a peer:
3820 cache_peer_access peerName deny fromPeer
3822 max-conn=N Limit the number of concurrent connections the Squid
3823 may open to this peer, including already opened idle
3824 and standby connections. There is no peer-specific
3825 connection limit by default.
3827 A peer exceeding the limit is not used for new
3828 requests unless a standby connection is available.
3830 max-conn currently works poorly with idle persistent
3831 connections: When a peer reaches its max-conn limit,
3832 and there are idle persistent connections to the peer,
3833 the peer may not be selected because the limiting code
3834 does not know whether Squid can reuse those idle
3837 standby=N Maintain a pool of N "hot standby" connections to an
3838 UP peer, available for requests when no idle
3839 persistent connection is available (or safe) to use.
3840 By default and with zero N, no such pool is maintained.
3841 N must not exceed the max-conn limit (if any).
3843 At start or after reconfiguration, Squid opens new TCP
3844 standby connections until there are N connections
3845 available and then replenishes the standby pool as
3846 opened connections are used up for requests. A used
3847 connection never goes back to the standby pool, but
3848 may go to the regular idle persistent connection pool
3849 shared by all peers and origin servers.
3851 Squid never opens multiple new standby connections
3852 concurrently. This one-at-a-time approach minimizes
3853 flooding-like effect on peers. Furthermore, just a few
3854 standby connections should be sufficient in most cases
3855 to supply most new requests with a ready-to-use
3858 Standby connections obey server_idle_pconn_timeout.
3859 For the feature to work as intended, the peer must be
3860 configured to accept and keep them open longer than
3861 the idle timeout at the connecting Squid, to minimize
3862 race conditions typical to idle used persistent
3863 connections. Default request_timeout and
3864 server_idle_pconn_timeout values ensure such a
3867 name=xxx Unique name for the peer.
3868 Required if you have multiple peers on the same host
3869 but different ports.
3870 This name can be used in cache_peer_access and similar
3871 directives to identify the peer.
3872 Can be used by outgoing access controls through the
3875 no-tproxy Do not use the client-spoof TPROXY support when forwarding
3876 requests to this peer. Use normal address selection instead.
3877 This overrides the spoof_client_ip ACL.
3879 proxy-only objects fetched from the peer will not be stored locally.
3883 NAME: cache_peer_access
3886 DEFAULT_DOC: No peer usage restrictions.
3889 Restricts usage of cache_peer proxies.
3892 cache_peer_access peer-name allow|deny [!]aclname ...
3894 For the required peer-name parameter, use either the value of the
3895 cache_peer name=value parameter or, if name=value is missing, the
3896 cache_peer hostname parameter.
3898 This directive narrows down the selection of peering candidates, but
3899 does not determine the order in which the selected candidates are
3900 contacted. That order is determined by the peer selection algorithms
3901 (see PEER SELECTION sections in the cache_peer documentation).
3903 If a deny rule matches, the corresponding peer will not be contacted
3904 for the current transaction -- Squid will not send ICP queries and
3905 will not forward HTTP requests to that peer. An allow match leaves
3906 the corresponding peer in the selection. The first match for a given
3907 peer wins for that peer.
3909 The relative order of cache_peer_access directives for the same peer
3910 matters. The relative order of any two cache_peer_access directives
3911 for different peers does not matter. To ease interpretation, it is a
3912 good idea to group cache_peer_access directives for the same peer
3915 A single cache_peer_access directive may be evaluated multiple times
3916 for a given transaction because individual peer selection algorithms
3917 may check it independently from each other. These redundant checks
3918 may be optimized away in future Squid versions.
3920 This clause only supports fast acl types.
3921 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
3925 NAME: neighbor_type_domain
3926 TYPE: hostdomaintype
3928 DEFAULT_DOC: The peer type from cache_peer directive is used for all requests to that peer.
3931 Modify the cache_peer neighbor type when passing requests
3932 about specific domains to the peer.
3935 neighbor_type_domain neighbor parent|sibling domain domain ...
3938 cache_peer foo.example.com parent 3128 3130
3939 neighbor_type_domain foo.example.com sibling .au .de
3941 The above configuration treats all requests to foo.example.com as a
3942 parent proxy unless the request is for a .au or .de ccTLD domain name.
3945 NAME: dead_peer_timeout
3949 LOC: Config.Timeout.deadPeer
3951 This controls how long Squid waits to declare a peer cache
3952 as "dead." If there are no ICP replies received in this
3953 amount of time, Squid will declare the peer dead and not
3954 expect to receive any further ICP replies. However, it
3955 continues to send ICP queries, and will mark the peer as
3956 alive upon receipt of the first subsequent ICP reply.
3958 This timeout also affects when Squid expects to receive ICP
3959 replies from peers. If more than 'dead_peer' seconds have
3960 passed since the last ICP reply was received, Squid will not
3961 expect to receive an ICP reply on the next query. Thus, if
3962 your time between requests is greater than this timeout, you
3963 will see a lot of requests sent DIRECT to origin servers
3964 instead of to your parents.
3967 NAME: forward_max_tries
3970 LOC: Config.forward_max_tries
3972 Limits the number of attempts to forward the request.
3974 For the purpose of this limit, Squid counts all high-level request
3975 forwarding attempts, including any same-destination retries after
3976 certain persistent connection failures and any attempts to use a
3977 different peer. However, low-level connection reopening attempts
3978 (enabled using connect_retries) are not counted.
3980 See also: forward_timeout and connect_retries.
3984 MEMORY CACHE OPTIONS
3985 -----------------------------------------------------------------------------
3992 LOC: Config.memMaxSize
3994 NOTE: THIS PARAMETER DOES NOT SPECIFY THE MAXIMUM PROCESS SIZE.
3995 IT ONLY PLACES A LIMIT ON HOW MUCH ADDITIONAL MEMORY SQUID WILL
3996 USE AS A MEMORY CACHE OF OBJECTS. SQUID USES MEMORY FOR OTHER
3997 THINGS AS WELL. SEE THE SQUID FAQ SECTION 8 FOR DETAILS.
3999 'cache_mem' specifies the ideal amount of memory to be used
4001 * In-Transit objects
4003 * Negative-Cached objects
4005 Data for these objects are stored in 4 KB blocks. This
4006 parameter specifies the ideal upper limit on the total size of
4007 4 KB blocks allocated. In-Transit objects take the highest
4010 In-transit objects have priority over the others. When
4011 additional space is needed for incoming data, negative-cached
4012 and hot objects will be released. In other words, the
4013 negative-cached and hot objects will fill up any unused space
4014 not needed for in-transit objects.
4016 If circumstances require, this limit will be exceeded.
4017 Specifically, if your incoming request rate requires more than
4018 'cache_mem' of memory to hold in-transit objects, Squid will
4019 exceed this limit to satisfy the new requests. When the load
4020 decreases, blocks will be freed until the high-water mark is
4021 reached. Thereafter, blocks will be used to store hot
4024 If shared memory caching is enabled, Squid does not use the shared
4025 cache space for in-transit objects, but they still consume as much
4026 local memory as they need. For more details about the shared memory
4027 cache, see memory_cache_shared.
4030 NAME: maximum_object_size_in_memory
4034 LOC: Config.Store.maxInMemObjSize
4036 Objects greater than this size will not be attempted to kept in
4037 the memory cache. This should be set high enough to keep objects
4038 accessed frequently in memory to improve performance whilst low
4039 enough to keep larger objects from hoarding cache_mem.
4042 NAME: memory_cache_shared
4045 LOC: Config.memShared
4047 DEFAULT_DOC: "on" where supported if doing memory caching with multiple SMP workers.
4049 Controls whether the memory cache is shared among SMP workers.
4051 The shared memory cache is meant to occupy cache_mem bytes and replace
4052 the non-shared memory cache, although some entities may still be
4053 cached locally by workers for now (e.g., internal and in-transit
4054 objects may be served from a local memory cache even if shared memory
4055 caching is enabled).
4057 By default, the memory cache is shared if and only if all of the
4058 following conditions are satisfied: Squid runs in SMP mode with
4059 multiple workers, cache_mem is positive, and Squid environment
4060 supports required IPC primitives (e.g., POSIX shared memory segments
4061 and GCC-style atomic operations).
4063 To avoid blocking locks, shared memory uses opportunistic algorithms
4064 that do not guarantee that every cachable entity that could have been
4065 shared among SMP workers will actually be shared.
4068 NAME: memory_cache_mode
4072 DEFAULT_DOC: Keep the most recently fetched objects in memory
4074 Controls which objects to keep in the memory cache (cache_mem)
4076 always Keep most recently fetched objects in memory (default)
4078 disk Only disk cache hits are kept in memory, which means
4079 an object must first be cached on disk and then hit
4080 a second time before cached in memory.
4082 network Only objects fetched from network is kept in memory
4085 NAME: memory_replacement_policy
4087 LOC: Config.memPolicy
4090 The memory replacement policy parameter determines which
4091 objects are purged from memory when memory space is needed.
4093 See cache_replacement_policy for details on algorithms.
4098 -----------------------------------------------------------------------------
4101 NAME: cache_replacement_policy
4103 LOC: Config.replPolicy
4106 The cache replacement policy parameter determines which
4107 objects are evicted (replaced) when disk space is needed.
4109 lru : Squid's original list based LRU policy
4110 heap GDSF : Greedy-Dual Size Frequency
4111 heap LFUDA: Least Frequently Used with Dynamic Aging
4112 heap LRU : LRU policy implemented using a heap
4114 Applies to any cache_dir lines listed below this directive.
4116 The LRU policies keeps recently referenced objects.
4118 The heap GDSF policy optimizes object hit rate by keeping smaller
4119 popular objects in cache so it has a better chance of getting a
4120 hit. It achieves a lower byte hit rate than LFUDA though since
4121 it evicts larger (possibly popular) objects.
4123 The heap LFUDA policy keeps popular objects in cache regardless of
4124 their size and thus optimizes byte hit rate at the expense of
4125 hit rate since one large, popular object will prevent many
4126 smaller, slightly less popular objects from being cached.
4128 Both policies utilize a dynamic aging mechanism that prevents
4129 cache pollution that can otherwise occur with frequency-based
4130 replacement policies.
4132 NOTE: if using the LFUDA replacement policy you should increase
4133 the value of maximum_object_size above its default of 4 MB to
4134 to maximize the potential byte hit rate improvement of LFUDA.
4136 For more information about the GDSF and LFUDA cache replacement
4137 policies see http://www.hpl.hp.com/techreports/1999/HPL-1999-69.html
4138 and http://fog.hpl.external.hp.com/techreports/98/HPL-98-173.html.
4141 NAME: minimum_object_size
4145 DEFAULT_DOC: no limit
4146 LOC: Config.Store.minObjectSize
4148 Objects smaller than this size will NOT be saved on disk. The
4149 value is specified in bytes, and the default is 0 KB, which
4150 means all responses can be stored.
4153 NAME: maximum_object_size
4157 LOC: Config.Store.maxObjectSize
4159 Set the default value for max-size parameter on any cache_dir.
4160 The value is specified in bytes, and the default is 4 MB.
4162 If you wish to get a high BYTES hit ratio, you should probably
4163 increase this (one 32 MB object hit counts for 3200 10KB
4166 If you wish to increase hit ratio more than you want to
4167 save bandwidth you should leave this low.
4169 NOTE: if using the LFUDA replacement policy you should increase
4170 this value to maximize the byte hit rate improvement of LFUDA!
4171 See cache_replacement_policy for a discussion of this policy.
4177 DEFAULT_DOC: No disk cache. Store cache ojects only in memory.
4178 LOC: Config.cacheSwap
4181 cache_dir Type Directory-Name Fs-specific-data [options]
4183 You can specify multiple cache_dir lines to spread the
4184 cache among different disk partitions.
4186 Type specifies the kind of storage system to use. Only "ufs"
4187 is built by default. To enable any of the other storage systems
4188 see the --enable-storeio configure option.
4190 'Directory' is a top-level directory where cache swap
4191 files will be stored. If you want to use an entire disk
4192 for caching, this can be the mount-point directory.
4193 The directory must exist and be writable by the Squid
4194 process. Squid will NOT create this directory for you.
4196 In SMP configurations, cache_dir must not precede the workers option
4197 and should use configuration macros or conditionals to give each
4198 worker interested in disk caching a dedicated cache directory.
4201 ==== The ufs store type ====
4203 "ufs" is the old well-known Squid storage format that has always
4207 cache_dir ufs Directory-Name Mbytes L1 L2 [options]
4209 'Mbytes' is the amount of disk space (MB) to use under this
4210 directory. The default is 100 MB. Change this to suit your
4211 configuration. Do NOT put the size of your disk drive here.
4212 Instead, if you want Squid to use the entire disk drive,
4213 subtract 20% and use that value.
4215 'L1' is the number of first-level subdirectories which
4216 will be created under the 'Directory'. The default is 16.
4218 'L2' is the number of second-level subdirectories which
4219 will be created under each first-level directory. The default
4223 ==== The aufs store type ====
4225 "aufs" uses the same storage format as "ufs", utilizing
4226 POSIX-threads to avoid blocking the main Squid process on
4227 disk-I/O. This was formerly known in Squid as async-io.
4230 cache_dir aufs Directory-Name Mbytes L1 L2 [options]
4232 see argument descriptions under ufs above
4235 ==== The diskd store type ====
4237 "diskd" uses the same storage format as "ufs", utilizing a
4238 separate process to avoid blocking the main Squid process on
4242 cache_dir diskd Directory-Name Mbytes L1 L2 [options] [Q1=n] [Q2=n]
4244 see argument descriptions under ufs above
4246 Q1 specifies the number of unacknowledged I/O requests when Squid
4247 stops opening new files. If this many messages are in the queues,
4248 Squid won't open new files. Default is 64
4250 Q2 specifies the number of unacknowledged messages when Squid
4251 starts blocking. If this many messages are in the queues,
4252 Squid blocks until it receives some replies. Default is 72
4254 When Q1 < Q2 (the default), the cache directory is optimized
4255 for lower response time at the expense of a decrease in hit
4256 ratio. If Q1 > Q2, the cache directory is optimized for
4257 higher hit ratio at the expense of an increase in response
4261 ==== The rock store type ====
4264 cache_dir rock Directory-Name Mbytes [options]
4266 The Rock Store type is a database-style storage. All cached
4267 entries are stored in a "database" file, using fixed-size slots.
4268 A single entry occupies one or more slots.
4270 If possible, Squid using Rock Store creates a dedicated kid
4271 process called "disker" to avoid blocking Squid worker(s) on disk
4272 I/O. One disker kid is created for each rock cache_dir. Diskers
4273 are created only when Squid, running in daemon mode, has support
4274 for the IpcIo disk I/O module.
4276 swap-timeout=msec: Squid will not start writing a miss to or
4277 reading a hit from disk if it estimates that the swap operation
4278 will take more than the specified number of milliseconds. By
4279 default and when set to zero, disables the disk I/O time limit
4280 enforcement. Ignored when using blocking I/O module because
4281 blocking synchronous I/O does not allow Squid to estimate the
4282 expected swap wait time.
4284 max-swap-rate=swaps/sec: Artificially limits disk access using
4285 the specified I/O rate limit. Swap out requests that
4286 would cause the average I/O rate to exceed the limit are
4287 delayed. Individual swap in requests (i.e., hits or reads) are
4288 not delayed, but they do contribute to measured swap rate and
4289 since they are placed in the same FIFO queue as swap out
4290 requests, they may wait longer if max-swap-rate is smaller.
4291 This is necessary on file systems that buffer "too
4292 many" writes and then start blocking Squid and other processes
4293 while committing those writes to disk. Usually used together
4294 with swap-timeout to avoid excessive delays and queue overflows
4295 when disk demand exceeds available disk "bandwidth". By default
4296 and when set to zero, disables the disk I/O rate limit
4297 enforcement. Currently supported by IpcIo module only.
4299 slot-size=bytes: The size of a database "record" used for
4300 storing cached responses. A cached response occupies at least
4301 one slot and all database I/O is done using individual slots so
4302 increasing this parameter leads to more disk space waste while
4303 decreasing it leads to more disk I/O overheads. Should be a
4304 multiple of your operating system I/O page size. Defaults to
4305 16KBytes. A housekeeping header is stored with each slot and
4306 smaller slot-sizes will be rejected. The header is smaller than
4310 ==== COMMON OPTIONS ====
4312 no-store no new objects should be stored to this cache_dir.
4314 min-size=n the minimum object size in bytes this cache_dir
4315 will accept. It's used to restrict a cache_dir
4316 to only store large objects (e.g. AUFS) while
4317 other stores are optimized for smaller objects
4321 max-size=n the maximum object size in bytes this cache_dir
4323 The value in maximum_object_size directive sets
4324 the default unless more specific details are
4325 available (ie a small store capacity).
4327 Note: To make optimal use of the max-size limits you should order
4328 the cache_dir lines with the smallest max-size value first.
4332 # Uncomment and adjust the following to add a disk cache directory.
4333 #cache_dir ufs @DEFAULT_SWAP_DIR@ 100 16 256
4337 NAME: store_dir_select_algorithm
4339 LOC: Config.store_dir_select_algorithm
4342 How Squid selects which cache_dir to use when the response
4343 object will fit into more than one.
4345 Regardless of which algorithm is used the cache_dir min-size
4346 and max-size parameters are obeyed. As such they can affect
4347 the selection algorithm by limiting the set of considered
4354 This algorithm is suited to caches with similar cache_dir
4355 sizes and disk speeds.
4357 The disk with the least I/O pending is selected.
4358 When there are multiple disks with the same I/O load ranking
4359 the cache_dir with most available capacity is selected.
4361 When a mix of cache_dir sizes are configured the faster disks
4362 have a naturally lower I/O loading and larger disks have more
4363 capacity. So space used to store objects and data throughput
4364 may be very unbalanced towards larger disks.
4369 This algorithm is suited to caches with unequal cache_dir
4372 Each cache_dir is selected in a rotation. The next suitable
4375 Available cache_dir capacity is only considered in relation
4376 to whether the object will fit and meets the min-size and
4377 max-size parameters.
4379 Disk I/O loading is only considered to prevent overload on slow
4380 disks. This algorithm does not spread objects by size, so any
4381 I/O loading per-disk may appear very unbalanced and volatile.
4383 If several cache_dirs use similar min-size, max-size, or other
4384 limits to to reject certain responses, then do not group such
4385 cache_dir lines together, to avoid round-robin selection bias
4386 towards the first cache_dir after the group. Instead, interleave
4387 cache_dir lines from different groups. For example:
4389 store_dir_select_algorithm round-robin
4390 cache_dir rock /hdd1 ... min-size=100000
4391 cache_dir rock /ssd1 ... max-size=99999
4392 cache_dir rock /hdd2 ... min-size=100000
4393 cache_dir rock /ssd2 ... max-size=99999
4394 cache_dir rock /hdd3 ... min-size=100000
4395 cache_dir rock /ssd3 ... max-size=99999
4398 NAME: max_open_disk_fds
4400 LOC: Config.max_open_disk_fds
4402 DEFAULT_DOC: no limit
4404 To avoid having disk as the I/O bottleneck Squid can optionally
4405 bypass the on-disk cache if more than this amount of disk file
4406 descriptors are open.
4408 A value of 0 indicates no limit.
4411 NAME: cache_swap_low
4412 COMMENT: (percent, 0-100)
4415 LOC: Config.Swap.lowWaterMark
4417 The low-water mark for AUFS/UFS/diskd cache object eviction by
4418 the cache_replacement_policy algorithm.
4420 Removal begins when the swap (disk) usage of a cache_dir is
4421 above this low-water mark and attempts to maintain utilization
4422 near the low-water mark.
4424 As swap utilization increases towards the high-water mark set
4425 by cache_swap_high object eviction becomes more agressive.
4427 The value difference in percentages between low- and high-water
4428 marks represent an eviction rate of 300 objects per second and
4429 the rate continues to scale in agressiveness by multiples of
4430 this above the high-water mark.
4432 Defaults are 90% and 95%. If you have a large cache, 5% could be
4433 hundreds of MB. If this is the case you may wish to set these
4434 numbers closer together.
4436 See also cache_swap_high and cache_replacement_policy
4439 NAME: cache_swap_high
4440 COMMENT: (percent, 0-100)
4443 LOC: Config.Swap.highWaterMark
4445 The high-water mark for AUFS/UFS/diskd cache object eviction by
4446 the cache_replacement_policy algorithm.
4448 Removal begins when the swap (disk) usage of a cache_dir is
4449 above the low-water mark set by cache_swap_low and attempts to
4450 maintain utilization near the low-water mark.
4452 As swap utilization increases towards this high-water mark object
4453 eviction becomes more agressive.
4455 The value difference in percentages between low- and high-water
4456 marks represent an eviction rate of 300 objects per second and
4457 the rate continues to scale in agressiveness by multiples of
4458 this above the high-water mark.
4460 Defaults are 90% and 95%. If you have a large cache, 5% could be
4461 hundreds of MB. If this is the case you may wish to set these
4462 numbers closer together.
4464 See also cache_swap_low and cache_replacement_policy
4469 -----------------------------------------------------------------------------
4476 DEFAULT_DOC: The format definitions squid, common, combined, referrer, useragent are built in.
4480 logformat <name> <format specification>
4482 Defines an access log format.
4484 The <format specification> is a string with embedded % format codes
4486 % format codes all follow the same basic structure where all
4487 components but the formatcode are optional and usually unnecessary,
4488 especially when dealing with common codes.
4490 % [encoding] [-] [[0]width] [{arg}] formatcode [{arg}]
4492 encoding escapes or otherwise protects "special" characters:
4494 " Quoted string encoding where quote(") and
4495 backslash(\) characters are \-escaped while
4496 CR, LF, and TAB characters are encoded as \r,
4497 \n, and \t two-character sequences.
4499 [ Custom Squid encoding where percent(%), square
4500 brackets([]), backslash(\) and characters with
4501 codes outside of [32,126] range are %-encoded.
4502 SP is not encoded. Used by log_mime_hdrs.
4504 # URL encoding (a.k.a. percent-encoding) where
4505 all URL unsafe and control characters (per RFC
4506 1738) are %-encoded.
4508 / Shell-like encoding where quote(") and
4509 backslash(\) characters are \-escaped while CR
4510 and LF characters are encoded as \r and \n
4511 two-character sequences. Values containing SP
4512 character(s) are surrounded by quotes(").
4514 ' Raw/as-is encoding with no escaping/quoting.
4516 Default encoding: When no explicit encoding is
4517 specified, each %code determines its own encoding.
4518 Most %codes use raw/as-is encoding, but some codes use
4519 a so called "pass-through URL encoding" where all URL
4520 unsafe and control characters (per RFC 1738) are
4521 %-encoded, but the percent character(%) is left as is.
4525 width minimum and/or maximum field width:
4526 [width_min][.width_max]
4527 When minimum starts with 0, the field is zero-padded.
4528 String values exceeding maximum width are truncated.
4530 {arg} argument such as header name etc. This field may be
4531 placed before or after the token, but not both at once.
4535 % a literal % character
4536 sn Unique sequence number per log line entry
4537 err_code The ID of an error response served by Squid or
4538 a similar internal error identifier.
4539 err_detail Additional err_code-dependent error information.
4540 note The annotation specified by the argument. Also
4541 logs the adaptation meta headers set by the
4542 adaptation_meta configuration parameter.
4543 If no argument given all annotations logged.
4544 The argument may include a separator to use with
4547 By default, multiple note values are separated with ","
4548 and multiple notes are separated with "\r\n".
4549 When logging named notes with %{name}note, the
4550 explicitly configured separator is used between note
4551 values. When logging all notes with %note, the
4552 explicitly configured separator is used between
4553 individual notes. There is currently no way to
4554 specify both value and notes separators when logging
4555 all notes with %note.
4556 master_xaction The master transaction identifier is an unsigned
4557 integer. These IDs are guaranteed to monotonically
4558 increase within a single worker process lifetime, with
4559 higher values corresponding to transactions that were
4560 accepted or initiated later. Due to current implementation
4561 deficiencies, some IDs are skipped (i.e. never logged).
4562 Concurrent workers and restarted workers use similar,
4563 overlapping sequences of master transaction IDs.
4565 Connection related format codes:
4567 >a Client source IP address
4569 >p Client source port
4570 >eui Client source EUI (MAC address, EUI-48 or EUI-64 identifier)
4571 >la Local IP address the client connected to
4572 >lp Local port number the client connected to
4573 >qos Client connection TOS/DSCP value set by Squid
4574 >nfmark Client connection netfilter packet MARK set by Squid
4576 transport::>connection_id Identifies a transport connection
4577 accepted by Squid (e.g., a connection carrying the
4578 logged HTTP request). Currently, Squid only supports
4579 TCP transport connections.
4581 The logged identifier is an unsigned integer. These
4582 IDs are guaranteed to monotonically increase within a
4583 single worker process lifetime, with higher values
4584 corresponding to connections that were accepted later.
4585 Many IDs are skipped (i.e. never logged). Concurrent
4586 workers and restarted workers use similar, partially
4587 overlapping sequences of IDs.
4589 la Local listening IP address the client connection was connected to.
4590 lp Local listening port number the client connection was connected to.
4592 <a Server IP address of the last server or peer connection
4593 <A Server FQDN or peer name
4594 <p Server port number of the last server or peer connection
4595 <la Local IP address of the last server or peer connection
4596 <lp Local port number of the last server or peer connection
4597 <qos Server connection TOS/DSCP value set by Squid
4598 <nfmark Server connection netfilter packet MARK set by Squid
4600 >handshake Raw client handshake
4601 Initial client bytes received by Squid on a newly
4602 accepted TCP connection or inside a just established
4603 CONNECT tunnel. Squid stops accumulating handshake
4604 bytes as soon as the handshake parser succeeds or
4605 fails (determining whether the client is using the
4608 For HTTP clients, the handshake is the request line.
4609 For TLS clients, the handshake consists of all TLS
4610 records up to and including the TLS record that
4611 contains the last byte of the first ClientHello
4612 message. For clients using an unsupported protocol,
4613 this field contains the bytes received by Squid at the
4614 time of the handshake parsing failure.
4616 See the on_unsupported_protocol directive for more
4617 information on Squid handshake traffic expectations.
4619 Current support is limited to these contexts:
4620 - http_port connections, but only when the
4621 on_unsupported_protocol directive is in use.
4622 - https_port connections (and CONNECT tunnels) that
4623 are subject to the ssl_bump peek or stare action.
4625 To protect binary handshake data, this field is always
4626 base64-encoded (RFC 4648 Section 4). If logformat
4627 field encoding is configured, that encoding is applied
4628 on top of base64. Otherwise, the computed base64 value
4631 Time related format codes:
4633 ts Seconds since epoch
4634 tu subsecond time (milliseconds)
4635 tl Local time. Optional strftime format argument
4636 default %d/%b/%Y:%H:%M:%S %z
4637 tg GMT time. Optional strftime format argument
4638 default %d/%b/%Y:%H:%M:%S %z
4639 tr Response time (milliseconds)
4640 dt Total time spent making DNS lookups (milliseconds)
4641 tS Approximate master transaction start time in
4642 <full seconds since epoch>.<fractional seconds> format.
4643 Currently, Squid considers the master transaction
4644 started when a complete HTTP request header initiating
4645 the transaction is received from the client. This is
4646 the same value that Squid uses to calculate transaction
4647 response time when logging %tr to access.log. Currently,
4648 Squid uses millisecond resolution for %tS values,
4649 similar to the default access.log "current time" field
4652 Access Control related format codes:
4654 et Tag returned by external acl
4655 ea Log string returned by external acl
4656 un User name (any available)
4657 ul User name from authentication
4658 ue User name from external acl helper
4659 ui User name from ident
4660 un A user name. Expands to the first available name
4661 from the following list of information sources:
4662 - authenticated user name, like %ul
4663 - user name supplied by an external ACL, like %ue
4664 - SSL client name, like %us
4665 - ident user name, like %ui
4666 credentials Client credentials. The exact meaning depends on
4667 the authentication scheme: For Basic authentication,
4668 it is the password; for Digest, the realm sent by the
4669 client; for NTLM and Negotiate, the client challenge
4670 or client credentials prefixed with "YR " or "KK ".
4672 HTTP related format codes:
4676 [http::]rm Request method (GET/POST etc)
4677 [http::]>rm Request method from client
4678 [http::]<rm Request method sent to server or peer
4680 [http::]ru Request URL received (or computed) and sanitized
4682 Logs request URI received from the client, a
4683 request adaptation service, or a request
4684 redirector (whichever was applied last).
4686 Computed URLs are URIs of internally generated
4687 requests and various "error:..." URIs.
4689 Honors strip_query_terms and uri_whitespace.
4691 This field is not encoded by default. Encoding
4692 this field using variants of %-encoding will
4693 clash with uri_whitespace modifications that
4694 also use %-encoding.
4696 [http::]>ru Request URL received from the client (or computed)
4698 Computed URLs are URIs of internally generated
4699 requests and various "error:..." URIs.
4701 Unlike %ru, this request URI is not affected
4702 by request adaptation, URL rewriting services,
4703 and strip_query_terms.
4705 Honors uri_whitespace.
4707 This field is using pass-through URL encoding
4708 by default. Encoding this field using other
4709 variants of %-encoding will clash with
4710 uri_whitespace modifications that also use
4713 [http::]<ru Request URL sent to server or peer
4714 [http::]>rs Request URL scheme from client
4715 [http::]<rs Request URL scheme sent to server or peer
4716 [http::]>rd Request URL domain from client
4717 [http::]<rd Request URL domain sent to server or peer
4718 [http::]>rP Request URL port from client
4719 [http::]<rP Request URL port sent to server or peer
4720 [http::]rp Request URL path excluding hostname
4721 [http::]>rp Request URL path excluding hostname from client
4722 [http::]<rp Request URL path excluding hostname sent to server or peer
4723 [http::]rv Request protocol version
4724 [http::]>rv Request protocol version from client
4725 [http::]<rv Request protocol version sent to server or peer
4727 [http::]>h Original received request header.
4728 Usually differs from the request header sent by
4729 Squid, although most fields are often preserved.
4730 Accepts optional header field name/value filter
4731 argument using name[:[separator]element] format.
4732 [http::]>ha Received request header after adaptation and
4733 redirection (pre-cache REQMOD vectoring point).
4734 Usually differs from the request header sent by
4735 Squid, although most fields are often preserved.
4736 Optional header name argument as for >h
4740 [http::]<Hs HTTP status code received from the next hop
4741 [http::]>Hs HTTP status code sent to the client
4743 [http::]<h Reply header. Optional header name argument
4746 [http::]mt MIME content type
4751 [http::]st Total size of request + reply traffic with client
4752 [http::]>st Total size of request received from client.
4753 Excluding chunked encoding bytes.
4754 [http::]<st Total size of reply sent to client (after adaptation)
4756 [http::]>sh Size of request headers received from client
4757 [http::]<sh Size of reply headers sent to client (after adaptation)
4759 [http::]<sH Reply high offset sent
4760 [http::]<sS Upstream object size
4762 [http::]<bs Number of HTTP-equivalent message body bytes
4763 received from the next hop, excluding chunked
4764 transfer encoding and control messages.
4765 Generated FTP/Gopher listings are treated as
4770 [http::]<pt Peer response time in milliseconds. The timer starts
4771 when the last request byte is sent to the next hop
4772 and stops when the last response byte is received.
4773 [http::]<tt Total time in milliseconds. The timer
4774 starts with the first connect request (or write I/O)
4775 sent to the first selected peer. The timer stops
4776 with the last I/O with the last peer.
4778 Squid handling related format codes:
4780 Ss Squid request status (TCP_MISS etc)
4781 Sh Squid hierarchy status (DEFAULT_PARENT etc)
4783 SSL-related format codes:
4785 ssl::bump_mode SslBump decision for the transaction:
4787 For CONNECT requests that initiated bumping of
4788 a connection and for any request received on
4789 an already bumped connection, Squid logs the
4790 corresponding SslBump mode ("splice", "bump",
4791 "peek", "stare", "terminate", "server-first"
4792 or "client-first"). See the ssl_bump option
4793 for more information about these modes.
4795 A "none" token is logged for requests that
4796 triggered "ssl_bump" ACL evaluation matching
4799 In all other cases, a single dash ("-") is
4802 ssl::>sni SSL client SNI sent to Squid.
4805 The Subject field of the received client
4806 SSL certificate or a dash ('-') if Squid has
4807 received an invalid/malformed certificate or
4808 no certificate at all. Consider encoding the
4809 logged value because Subject often has spaces.
4812 The Issuer field of the received client
4813 SSL certificate or a dash ('-') if Squid has
4814 received an invalid/malformed certificate or
4815 no certificate at all. Consider encoding the
4816 logged value because Issuer often has spaces.
4819 The Subject field of the received server
4820 TLS certificate or a dash ('-') if this is
4821 not available. Consider encoding the logged
4822 value because Subject often has spaces.
4825 The Issuer field of the received server
4826 TLS certificate or a dash ('-') if this is
4827 not available. Consider encoding the logged
4828 value because Issuer often has spaces.
4831 The received server x509 certificate in PEM
4832 format, including BEGIN and END lines (or a
4833 dash ('-') if the certificate is unavailable).
4835 WARNING: Large certificates will exceed the
4836 current 8KB access.log record limit, resulting
4837 in truncated records. Such truncation usually
4838 happens in the middle of a record field. The
4839 limit applies to all access logging modules.
4841 The logged certificate may have failed
4842 validation and may not be trusted by Squid.
4843 This field does not include any intermediate
4844 certificates that may have been received from
4845 the server or fetched during certificate
4848 Currently, Squid only collects server
4849 certificates during step3 of SslBump
4850 processing; connections that were not subject
4851 to ssl_bump rules or that did not match a peek
4852 or stare rule at step2 will not have the
4853 server certificate information.
4855 This field is using pass-through URL encoding
4859 The list of certificate validation errors
4860 detected by Squid (including OpenSSL and
4861 certificate validation helper components). The
4862 errors are listed in the discovery order. By
4863 default, the error codes are separated by ':'.
4864 Accepts an optional separator argument.
4866 %ssl::>negotiated_version The negotiated TLS version of the
4869 %ssl::<negotiated_version The negotiated TLS version of the
4870 last server or peer connection.
4872 %ssl::>received_hello_version The TLS version of the Hello
4873 message received from TLS client.
4875 %ssl::<received_hello_version The TLS version of the Hello
4876 message received from TLS server.
4878 %ssl::>received_supported_version The maximum TLS version
4879 supported by the TLS client.
4881 %ssl::<received_supported_version The maximum TLS version
4882 supported by the TLS server.
4884 %ssl::>negotiated_cipher The negotiated cipher of the
4887 %ssl::<negotiated_cipher The negotiated cipher of the
4888 last server or peer connection.
4890 If ICAP is enabled, the following code becomes available (as
4891 well as ICAP log codes documented with the icap_log option):
4893 icap::tt Total ICAP processing time for the HTTP
4894 transaction. The timer ticks when ICAP
4895 ACLs are checked and when ICAP
4896 transaction is in progress.
4898 If adaptation is enabled the following codes become available:
4900 adapt::<last_h The header of the last ICAP response or
4901 meta-information from the last eCAP
4902 transaction related to the HTTP transaction.
4903 Like <h, accepts an optional header name
4906 adapt::sum_trs Summed adaptation transaction response
4907 times recorded as a comma-separated list in
4908 the order of transaction start time. Each time
4909 value is recorded as an integer number,
4910 representing response time of one or more
4911 adaptation (ICAP or eCAP) transaction in
4912 milliseconds. When a failed transaction is
4913 being retried or repeated, its time is not
4914 logged individually but added to the
4915 replacement (next) transaction. See also:
4918 adapt::all_trs All adaptation transaction response times.
4919 Same as adaptation_strs but response times of
4920 individual transactions are never added
4921 together. Instead, all transaction response
4922 times are recorded individually.
4924 You can prefix adapt::*_trs format codes with adaptation
4925 service name in curly braces to record response time(s) specific
4926 to that service. For example: %{my_service}adapt::sum_trs
4928 Format codes related to the PROXY protocol:
4930 proxy_protocol::>h PROXY protocol header, including optional TLVs.
4932 Supports the same field and element reporting/extraction logic
4933 as %http::>h. For configuration and reporting purposes, Squid
4934 maps each PROXY TLV to an HTTP header field: the TLV type
4935 (configured as a decimal integer) is the field name, and the
4936 TLV value is the field value. All TLVs of "LOCAL" connections
4937 (in PROXY protocol terminology) are currently skipped/ignored.
4939 Squid also maps the following standard PROXY protocol header
4940 blocks to pseudo HTTP headers (their names use PROXY
4941 terminology and start with a colon, following HTTP tradition
4942 for pseudo headers): :command, :version, :src_addr, :dst_addr,
4943 :src_port, and :dst_port.
4945 Without optional parameters, this logformat code logs
4946 pseudo headers and TLVs.
4948 This format code uses pass-through URL encoding by default.
4951 # relay custom PROXY TLV #224 to adaptation services
4952 adaptation_meta Client-Foo "%proxy_protocol::>h{224}"
4956 The default formats available (which do not need re-defining) are:
4958 logformat squid %ts.%03tu %6tr %>a %Ss/%03>Hs %<st %rm %ru %[un %Sh/%<a %mt
4959 logformat common %>a %[ui %[un [%tl] "%rm %ru HTTP/%rv" %>Hs %<st %Ss:%Sh
4960 logformat combined %>a %[ui %[un [%tl] "%rm %ru HTTP/%rv" %>Hs %<st "%{Referer}>h" "%{User-Agent}>h" %Ss:%Sh
4961 logformat referrer %ts.%03tu %>a %{Referer}>h %ru
4962 logformat useragent %>a [%tl] "%{User-Agent}>h"
4964 NOTE: When the log_mime_hdrs directive is set to ON.
4965 The squid, common and combined formats have a safely encoded copy
4966 of the mime headers appended to each line within a pair of brackets.
4968 NOTE: The common and combined formats are not quite true to the Apache definition.
4969 The logs from Squid contain an extra status and hierarchy code appended.
4973 NAME: access_log cache_access_log
4975 LOC: Config.Log.accesslogs
4976 DEFAULT_IF_NONE: daemon:@DEFAULT_ACCESS_LOG@ squid
4978 Configures whether and how Squid logs HTTP and ICP transactions.
4979 If access logging is enabled, a single line is logged for every
4980 matching HTTP or ICP request. The recommended directive formats are:
4982 access_log <module>:<place> [option ...] [acl acl ...]
4983 access_log none [acl acl ...]
4985 The following directive format is accepted but may be deprecated:
4986 access_log <module>:<place> [<logformat name> [acl acl ...]]
4988 In most cases, the first ACL name must not contain the '=' character
4989 and should not be equal to an existing logformat name. You can always
4990 start with an 'all' ACL to work around those restrictions.
4992 Will log to the specified module:place using the specified format (which
4993 must be defined in a logformat directive) those entries which match
4994 ALL the acl's specified (which must be defined in acl clauses).
4995 If no acl is specified, all requests will be logged to this destination.
4997 ===== Available options for the recommended directive format =====
4999 logformat=name Names log line format (either built-in or
5000 defined by a logformat directive). Defaults
5003 buffer-size=64KB Defines approximate buffering limit for log
5004 records (see buffered_logs). Squid should not
5005 keep more than the specified size and, hence,
5006 should flush records before the buffer becomes
5007 full to avoid overflows under normal
5008 conditions (the exact flushing algorithm is
5009 module-dependent though). The on-error option
5010 controls overflow handling.
5012 on-error=die|drop Defines action on unrecoverable errors. The
5013 'drop' action ignores (i.e., does not log)
5014 affected log records. The default 'die' action
5015 kills the affected worker. The drop action
5016 support has not been tested for modules other
5019 rotate=N Specifies the number of log file rotations to
5020 make when you run 'squid -k rotate'. The default
5021 is to obey the logfile_rotate directive. Setting
5022 rotate=0 will disable the file name rotation,
5023 but the log files are still closed and re-opened.
5024 This will enable you to rename the logfiles
5025 yourself just before sending the rotate signal.
5026 Only supported by the stdio module.
5028 ===== Modules Currently available =====
5030 none Do not log any requests matching these ACL.
5031 Do not specify Place or logformat name.
5033 stdio Write each log line to disk immediately at the completion of
5035 Place: the filename and path to be written.
5037 daemon Very similar to stdio. But instead of writing to disk the log
5038 line is passed to a daemon helper for asychronous handling instead.
5039 Place: varies depending on the daemon.
5041 log_file_daemon Place: the file name and path to be written.
5043 syslog To log each request via syslog facility.
5044 Place: The syslog facility and priority level for these entries.
5045 Place Format: facility.priority
5047 where facility could be any of:
5048 authpriv, daemon, local0 ... local7 or user.
5050 And priority could be any of:
5051 err, warning, notice, info, debug.
5053 udp To send each log line as text data to a UDP receiver.
5054 Place: The destination host name or IP and port.
5055 Place Format: //host:port
5057 tcp To send each log line as text data to a TCP receiver.
5058 Lines may be accumulated before sending (see buffered_logs).
5059 Place: The destination host name or IP and port.
5060 Place Format: //host:port
5063 access_log daemon:@DEFAULT_ACCESS_LOG@ squid
5069 LOC: Config.Log.icaplogs
5072 ICAP log files record ICAP transaction summaries, one line per
5075 The icap_log option format is:
5076 icap_log <filepath> [<logformat name> [acl acl ...]]
5077 icap_log none [acl acl ...]]
5079 Please see access_log option documentation for details. The two
5080 kinds of logs share the overall configuration approach and many
5083 ICAP processing of a single HTTP message or transaction may
5084 require multiple ICAP transactions. In such cases, multiple
5085 ICAP transaction log lines will correspond to a single access
5088 ICAP log supports many access.log logformat %codes. In ICAP context,
5089 HTTP message-related %codes are applied to the HTTP message embedded
5090 in an ICAP message. Logformat "%http::>..." codes are used for HTTP
5091 messages embedded in ICAP requests while "%http::<..." codes are used
5092 for HTTP messages embedded in ICAP responses. For example:
5094 http::>h To-be-adapted HTTP message headers sent by Squid to
5095 the ICAP service. For REQMOD transactions, these are
5096 HTTP request headers. For RESPMOD, these are HTTP
5097 response headers, but Squid currently cannot log them
5098 (i.e., %http::>h will expand to "-" for RESPMOD).
5100 http::<h Adapted HTTP message headers sent by the ICAP
5101 service to Squid (i.e., HTTP request headers in regular
5102 REQMOD; HTTP response headers in RESPMOD and during
5103 request satisfaction in REQMOD).
5105 ICAP OPTIONS transactions do not embed HTTP messages.
5107 Several logformat codes below deal with ICAP message bodies. An ICAP
5108 message body, if any, typically includes a complete HTTP message
5109 (required HTTP headers plus optional HTTP message body). When
5110 computing HTTP message body size for these logformat codes, Squid
5111 either includes or excludes chunked encoding overheads; see
5112 code-specific documentation for details.
5114 For Secure ICAP services, all size-related information is currently
5115 computed before/after TLS encryption/decryption, as if TLS was not
5118 The following format codes are also available for ICAP logs:
5120 icap::<A ICAP server IP address. Similar to <A.
5122 icap::<service_name ICAP service name from the icap_service
5123 option in Squid configuration file.
5125 icap::ru ICAP Request-URI. Similar to ru.
5127 icap::rm ICAP request method (REQMOD, RESPMOD, or
5128 OPTIONS). Similar to existing rm.
5130 icap::>st The total size of the ICAP request sent to the ICAP
5131 server (ICAP headers + ICAP body), including chunking
5134 icap::<st The total size of the ICAP response received from the
5135 ICAP server (ICAP headers + ICAP body), including
5136 chunking metadata (if any).
5138 icap::<bs The size of the ICAP response body received from the
5139 ICAP server, excluding chunking metadata (if any).
5141 icap::tr Transaction response time (in
5142 milliseconds). The timer starts when
5143 the ICAP transaction is created and
5144 stops when the transaction is completed.
5147 icap::tio Transaction I/O time (in milliseconds). The
5148 timer starts when the first ICAP request
5149 byte is scheduled for sending. The timers
5150 stops when the last byte of the ICAP response
5153 icap::to Transaction outcome: ICAP_ERR* for all
5154 transaction errors, ICAP_OPT for OPTION
5155 transactions, ICAP_ECHO for 204
5156 responses, ICAP_MOD for message
5157 modification, and ICAP_SAT for request
5158 satisfaction. Similar to Ss.
5160 icap::Hs ICAP response status code. Similar to Hs.
5162 icap::>h ICAP request header(s). Similar to >h.
5164 icap::<h ICAP response header(s). Similar to <h.
5166 The default ICAP log format, which can be used without an explicit
5167 definition, is called icap_squid:
5169 logformat icap_squid %ts.%03tu %6icap::tr %>A %icap::to/%03icap::Hs %icap::<st %icap::rm %icap::ru %un -/%icap::<A -
5171 See also: logformat and %adapt::<last_h
5174 NAME: logfile_daemon
5176 DEFAULT: @DEFAULT_LOGFILED@
5177 LOC: Log::TheConfig.logfile_daemon
5179 Specify the path to the logfile-writing daemon. This daemon is
5180 used to write the access and store logs, if configured.
5182 Squid sends a number of commands to the log daemon:
5183 L<data>\n - logfile data
5188 r<n>\n - set rotate count to <n>
5189 b<n>\n - 1 = buffer output, 0 = don't buffer output
5191 No responses is expected.
5194 NAME: stats_collection
5196 LOC: Config.accessList.stats_collection
5198 DEFAULT_DOC: Allow logging for all transactions.
5199 COMMENT: allow|deny acl acl...
5201 This options allows you to control which requests gets accounted
5202 in performance counters.
5204 This clause only supports fast acl types.
5205 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
5208 NAME: cache_store_log
5211 LOC: Config.Log.store
5213 Logs the activities of the storage manager. Shows which
5214 objects are ejected from the cache, and which objects are
5215 saved and for how long.
5216 There are not really utilities to analyze this data, so you can safely
5217 disable it (the default).
5219 Store log uses modular logging outputs. See access_log for the list
5220 of modules supported.
5223 cache_store_log stdio:@DEFAULT_STORE_LOG@
5224 cache_store_log daemon:@DEFAULT_STORE_LOG@
5227 NAME: cache_swap_state cache_swap_log
5229 LOC: Config.Log.swap
5231 DEFAULT_DOC: Store the journal inside its cache_dir
5233 Location for the cache "swap.state" file. This index file holds
5234 the metadata of objects saved on disk. It is used to rebuild
5235 the cache during startup. Normally this file resides in each
5236 'cache_dir' directory, but you may specify an alternate
5237 pathname here. Note you must give a full filename, not just
5238 a directory. Since this is the index for the whole object
5239 list you CANNOT periodically rotate it!
5241 If %s can be used in the file name it will be replaced with a
5242 a representation of the cache_dir name where each / is replaced
5243 with '.'. This is needed to allow adding/removing cache_dir
5244 lines when cache_swap_log is being used.
5246 If have more than one 'cache_dir', and %s is not used in the name
5247 these swap logs will have names such as:
5253 The numbered extension (which is added automatically)
5254 corresponds to the order of the 'cache_dir' lines in this
5255 configuration file. If you change the order of the 'cache_dir'
5256 lines in this file, these index files will NOT correspond to
5257 the correct 'cache_dir' entry (unless you manually rename
5258 them). We recommend you do NOT use this option. It is
5259 better to keep these index files in each 'cache_dir' directory.
5262 NAME: logfile_rotate
5265 LOC: Config.Log.rotateNumber
5267 Specifies the default number of logfile rotations to make when you
5268 type 'squid -k rotate'. The default is 10, which will rotate
5269 with extensions 0 through 9. Setting logfile_rotate to 0 will
5270 disable the file name rotation, but the logfiles are still closed
5271 and re-opened. This will enable you to rename the logfiles
5272 yourself just before sending the rotate signal.
5274 Note, from Squid-3.1 this option is only a default for cache.log,
5275 that log can be rotated separately by using debug_options.
5277 Note, from Squid-4 this option is only a default for access.log
5278 recorded by stdio: module. Those logs can be rotated separately by
5279 using the rotate=N option on their access_log directive.
5281 Note, the 'squid -k rotate' command normally sends a USR1
5282 signal to the running squid process. In certain situations
5283 (e.g. on Linux with Async I/O), USR1 is used for other
5284 purposes, so -k rotate uses another signal. It is best to get
5285 in the habit of using 'squid -k rotate' instead of 'kill -USR1
5292 DEFAULT: @DEFAULT_MIME_TABLE@
5293 LOC: Config.mimeTablePathname
5295 Path to Squid's icon configuration file.
5297 You shouldn't need to change this, but the default file contains
5298 examples and formatting information if you do.
5304 LOC: Config.onoff.log_mime_hdrs
5307 The Cache can record both the request and the response MIME
5308 headers for each HTTP transaction. The headers are encoded
5309 safely and will appear as two bracketed fields at the end of
5310 the access log (for either the native or httpd-emulated log
5311 formats). To enable this logging set log_mime_hdrs to 'on'.
5316 DEFAULT: @DEFAULT_PID_FILE@
5317 LOC: Config.pidFilename
5319 A filename to write the process-id to. To disable, enter "none".
5322 NAME: client_netmask
5324 LOC: Config.Addrs.client_netmask
5326 DEFAULT_DOC: Log full client IP address
5328 A netmask for client addresses in logfiles and cachemgr output.
5329 Change this to protect the privacy of your cache clients.
5330 A netmask of 255.255.255.0 will log all IP's in that range with
5331 the last digit set to '0'.
5334 NAME: strip_query_terms
5336 LOC: Config.onoff.strip_query_terms
5339 By default, Squid strips query terms from requested URLs before
5340 logging. This protects your user's privacy and reduces log size.
5342 When investigating HIT/MISS or other caching behaviour you
5343 will need to disable this to see the full URL used by Squid.
5350 LOC: Config.onoff.buffered_logs
5352 Whether to write/send access_log records ASAP or accumulate them and
5353 then write/send them in larger chunks. Buffering may improve
5354 performance because it decreases the number of I/Os. However,
5355 buffering increases the delay before log records become available to
5356 the final recipient (e.g., a disk file or logging daemon) and,
5357 hence, increases the risk of log records loss.
5359 Note that even when buffered_logs are off, Squid may have to buffer
5360 records if it cannot write/send them immediately due to pending I/Os
5361 (e.g., the I/O writing the previous log record) or connectivity loss.
5363 Currently honored by 'daemon' and 'tcp' access_log modules only.
5366 NAME: netdb_filename
5368 DEFAULT: stdio:@DEFAULT_NETDB_FILE@
5369 LOC: Config.netdbFilename
5372 Where Squid stores it's netdb journal.
5373 When enabled this journal preserves netdb state between restarts.
5375 To disable, enter "none".
5379 OPTIONS FOR TROUBLESHOOTING
5380 -----------------------------------------------------------------------------
5385 DEFAULT_IF_NONE: @DEFAULT_CACHE_LOG@
5386 LOC: Debug::cache_log
5388 Squid administrative logging file.
5390 This is where general information about Squid behavior goes. You can
5391 increase the amount of data logged to this file and how often it is
5392 rotated with "debug_options"
5398 DEFAULT_DOC: Log all critical and important messages.
5399 LOC: Debug::debugOptions
5401 Logging options are set as section,level where each source file
5402 is assigned a unique section. Lower levels result in less
5403 output, Full debugging (level 9) can result in a very large
5404 log file, so be careful.
5406 The magic word "ALL" sets debugging levels for all sections.
5407 The default is to run with "ALL,1" to record important warnings.
5409 The rotate=N option can be used to keep more or less of these logs
5410 than would otherwise be kept by logfile_rotate.
5411 For most uses a single log should be enough to monitor current
5412 events affecting Squid.
5417 LOC: Config.coredump_dir
5418 DEFAULT_IF_NONE: none
5419 DEFAULT_DOC: Use the directory from where Squid was started.
5421 By default Squid leaves core files in the directory from where
5422 it was started. If you set 'coredump_dir' to a directory
5423 that exists, Squid will chdir() to that directory at startup
5424 and coredump files will be left there.
5428 # Leave coredumps in the first cache dir
5429 coredump_dir @DEFAULT_SWAP_DIR@
5435 OPTIONS FOR FTP GATEWAYING
5436 -----------------------------------------------------------------------------
5442 LOC: Config.Ftp.anon_user
5444 If you want the anonymous login password to be more informative
5445 (and enable the use of picky FTP servers), set this to something
5446 reasonable for your domain, like wwwuser@somewhere.net
5448 The reason why this is domainless by default is the
5449 request can be made on the behalf of a user in any domain,
5450 depending on how the cache is used.
5451 Some FTP server also validate the email address is valid
5452 (for example perl.com).
5458 LOC: Config.Ftp.passive
5460 If your firewall does not allow Squid to use passive
5461 connections, turn off this option.
5463 Use of ftp_epsv_all option requires this to be ON.
5469 LOC: Config.Ftp.epsv_all
5471 FTP Protocol extensions permit the use of a special "EPSV ALL" command.
5473 NATs may be able to put the connection on a "fast path" through the
5474 translator, as the EPRT command will never be used and therefore,
5475 translation of the data portion of the segments will never be needed.
5477 When a client only expects to do two-way FTP transfers this may be
5479 If squid finds that it must do a three-way FTP transfer after issuing
5480 an EPSV ALL command, the FTP session will fail.
5482 If you have any doubts about this option do not use it.
5483 Squid will nicely attempt all other connection methods.
5485 Requires ftp_passive to be ON (default) for any effect.
5491 LOC: Config.accessList.ftp_epsv
5493 FTP Protocol extensions permit the use of a special "EPSV" command.
5495 NATs may be able to put the connection on a "fast path" through the
5496 translator using EPSV, as the EPRT command will never be used
5497 and therefore, translation of the data portion of the segments
5498 will never be needed.
5500 EPSV is often required to interoperate with FTP servers on IPv6
5501 networks. On the other hand, it may break some IPv4 servers.
5503 By default, EPSV may try EPSV with any FTP server. To fine tune
5504 that decision, you may restrict EPSV to certain clients or servers
5507 ftp_epsv allow|deny al1 acl2 ...
5509 WARNING: Disabling EPSV may cause problems with external NAT and IPv6.
5511 Only fast ACLs are supported.
5512 Requires ftp_passive to be ON (default) for any effect.
5518 LOC: Config.Ftp.eprt
5520 FTP Protocol extensions permit the use of a special "EPRT" command.
5522 This extension provides a protocol neutral alternative to the
5523 IPv4-only PORT command. When supported it enables active FTP data
5524 channels over IPv6 and efficient NAT handling.
5526 Turning this OFF will prevent EPRT being attempted and will skip
5527 straight to using PORT for IPv4 servers.
5529 Some devices are known to not handle this extension correctly and
5530 may result in crashes. Devices which suport EPRT enough to fail
5531 cleanly will result in Squid attempting PORT anyway. This directive
5532 should only be disabled when EPRT results in device failures.
5534 WARNING: Doing so will convert Squid back to the old behavior with all
5535 the related problems with external NAT devices/layers and IPv4-only FTP.
5538 NAME: ftp_sanitycheck
5541 LOC: Config.Ftp.sanitycheck
5543 For security and data integrity reasons Squid by default performs
5544 sanity checks of the addresses of FTP data connections ensure the
5545 data connection is to the requested server. If you need to allow
5546 FTP connections to servers using another IP address for the data
5547 connection turn this off.
5550 NAME: ftp_telnet_protocol
5553 LOC: Config.Ftp.telnet
5555 The FTP protocol is officially defined to use the telnet protocol
5556 as transport channel for the control connection. However, many
5557 implementations are broken and does not respect this aspect of
5560 If you have trouble accessing files with ASCII code 255 in the
5561 path or similar problems involving this ASCII code you can
5562 try setting this directive to off. If that helps, report to the
5563 operator of the FTP server in question that their FTP server
5564 is broken and does not follow the FTP standard.
5568 OPTIONS FOR EXTERNAL SUPPORT PROGRAMS
5569 -----------------------------------------------------------------------------
5574 DEFAULT: @DEFAULT_DISKD@
5575 LOC: Config.Program.diskd
5577 Specify the location of the diskd executable.
5578 Note this is only useful if you have compiled in
5579 diskd as one of the store io modules.
5582 NAME: unlinkd_program
5585 DEFAULT: @DEFAULT_UNLINKD@
5586 LOC: Config.Program.unlinkd
5588 Specify the location of the executable for file deletion process.
5591 NAME: pinger_program
5594 DEFAULT: @DEFAULT_PINGER@
5597 Specify the location of the executable for the pinger process.
5606 Control whether the pinger is active at run-time.
5607 Enables turning ICMP pinger on and off with a simple
5608 squid -k reconfigure.
5613 OPTIONS FOR URL REWRITING
5614 -----------------------------------------------------------------------------
5617 NAME: url_rewrite_program redirect_program
5619 LOC: Config.Program.redirect
5622 Specify the location of the executable URL rewriter to use.
5623 Since they can perform almost any function there isn't one included.
5625 For each requested URL, the rewriter will receive on line with the format
5627 [channel-ID <SP>] URL [<SP> extras]<NL>
5629 See url_rewrite_extras on how to send "extras" with optional values to
5631 After processing the request the helper must reply using the following format:
5633 [channel-ID <SP>] result [<SP> kv-pairs]
5635 The result code can be:
5637 OK status=30N url="..."
5638 Redirect the URL to the one supplied in 'url='.
5639 'status=' is optional and contains the status code to send
5640 the client in Squids HTTP response. It must be one of the
5641 HTTP redirect status codes: 301, 302, 303, 307, 308.
5642 When no status is given Squid will use 302.
5644 OK rewrite-url="..."
5645 Rewrite the URL to the one supplied in 'rewrite-url='.
5646 The new URL is fetched directly by Squid and returned to
5647 the client as the response to its request.
5650 When neither of url= and rewrite-url= are sent Squid does
5654 Do not change the URL.
5657 An internal error occurred in the helper, preventing
5658 a result being identified. The 'message=' key name is
5659 reserved for delivering a log message.
5662 In addition to the above kv-pairs Squid also understands the following
5663 optional kv-pairs received from URL rewriters:
5665 Associates a TAG with the client TCP connection.
5666 The TAG is treated as a regular annotation but persists across
5667 future requests on the client connection rather than just the
5668 current request. A helper may update the TAG during subsequent
5669 requests be returning a new kv-pair.
5671 When using the concurrency= option the protocol is changed by
5672 introducing a query channel tag in front of the request/response.
5673 The query channel tag is a number between 0 and concurrency-1.
5674 This value must be echoed back unchanged to Squid as the first part
5675 of the response relating to its request.
5677 WARNING: URL re-writing ability should be avoided whenever possible.
5678 Use the URL redirect form of response instead.
5680 Re-write creates a difference in the state held by the client
5681 and server. Possibly causing confusion when the server response
5682 contains snippets of its view state. Embeded URLs, response
5683 and content Location headers, etc. are not re-written by this
5686 By default, a URL rewriter is not used.
5689 NAME: url_rewrite_children redirect_children
5690 TYPE: HelperChildConfig
5691 DEFAULT: 20 startup=0 idle=1 concurrency=0
5692 LOC: Config.redirectChildren
5694 Specifies the maximum number of redirector processes that Squid may
5695 spawn (numberofchildren) and several related options. Using too few of
5696 these helper processes (a.k.a. "helpers") creates request queues.
5697 Using too many helpers wastes your system resources.
5699 Usage: numberofchildren [option]...
5701 The startup= and idle= options allow some measure of skew in your
5706 Sets a minimum of how many processes are to be spawned when Squid
5707 starts or reconfigures. When set to zero the first request will
5708 cause spawning of the first child process to handle it.
5710 Starting too few will cause an initial slowdown in traffic as Squid
5711 attempts to simultaneously spawn enough processes to cope.
5715 Sets a minimum of how many processes Squid is to try and keep available
5716 at all times. When traffic begins to rise above what the existing
5717 processes can handle this many more will be spawned up to the maximum
5718 configured. A minimum setting of 1 is required.
5722 The number of requests each redirector helper can handle in
5723 parallel. Defaults to 0 which indicates the redirector
5724 is a old-style single threaded redirector.
5726 When this directive is set to a value >= 1 then the protocol
5727 used to communicate with the helper is modified to include
5728 an ID in front of the request/response. The ID from the request
5729 must be echoed back with the response to that request.
5733 Sets the maximum number of queued requests. A request is queued when
5734 no existing child can accept it due to concurrency limit and no new
5735 child can be started due to numberofchildren limit. The default
5736 maximum is zero if url_rewrite_bypass is enabled and
5737 2*numberofchildren otherwise. If the queued requests exceed queue size
5738 and redirector_bypass configuration option is set, then redirector is
5739 bypassed. Otherwise, Squid is allowed to temporarily exceed the
5740 configured maximum, marking the affected helper as "overloaded". If
5741 the helper overload lasts more than 3 minutes, the action prescribed
5742 by the on-persistent-overload option applies.
5744 on-persistent-overload=action
5746 Specifies Squid reaction to a new helper request arriving when the helper
5747 has been overloaded for more that 3 minutes already. The number of queued
5748 requests determines whether the helper is overloaded (see the queue-size
5751 Two actions are supported:
5753 die Squid worker quits. This is the default behavior.
5755 ERR Squid treats the helper request as if it was
5756 immediately submitted, and the helper immediately
5757 replied with an ERR response. This action has no effect
5758 on the already queued and in-progress helper requests.
5761 NAME: url_rewrite_host_header redirect_rewrites_host_header
5764 LOC: Config.onoff.redir_rewrites_host
5766 To preserve same-origin security policies in browsers and
5767 prevent Host: header forgery by redirectors Squid rewrites
5768 any Host: header in redirected requests.
5770 If you are running an accelerator this may not be a wanted
5771 effect of a redirector. This directive enables you disable
5772 Host: alteration in reverse-proxy traffic.
5774 WARNING: Entries are cached on the result of the URL rewriting
5775 process, so be careful if you have domain-virtual hosts.
5777 WARNING: Squid and other software verifies the URL and Host
5778 are matching, so be careful not to relay through other proxies
5779 or inspecting firewalls with this disabled.
5782 NAME: url_rewrite_access redirector_access
5785 DEFAULT_DOC: Allow, unless rules exist in squid.conf.
5786 LOC: Config.accessList.redirector
5788 If defined, this access list specifies which requests are
5789 sent to the redirector processes.
5791 This clause supports both fast and slow acl types.
5792 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
5795 NAME: url_rewrite_bypass redirector_bypass
5797 LOC: Config.onoff.redirector_bypass
5800 When this is 'on', a request will not go through the
5801 redirector if all the helpers are busy. If this is 'off' and the
5802 redirector queue grows too large, the action is prescribed by the
5803 on-persistent-overload option. You should only enable this if the
5804 redirectors are not critical to your caching system. If you use
5805 redirectors for access control, and you enable this option,
5806 users may have access to pages they should not
5807 be allowed to request.
5809 Enabling this option sets the default url_rewrite_children queue-size
5813 NAME: url_rewrite_extras
5814 TYPE: TokenOrQuotedString
5815 LOC: Config.redirector_extras
5816 DEFAULT: "%>a/%>A %un %>rm myip=%la myport=%lp"
5818 Specifies a string to be append to request line format for the
5819 rewriter helper. "Quoted" format values may contain spaces and
5820 logformat %macros. In theory, any logformat %macro can be used.
5821 In practice, a %macro expands as a dash (-) if the helper request is
5822 sent before the required macro information is available to Squid.
5825 NAME: url_rewrite_timeout
5826 TYPE: UrlHelperTimeout
5827 LOC: Config.onUrlRewriteTimeout
5829 DEFAULT_DOC: Squid waits for the helper response forever
5831 Squid times active requests to redirector. The timeout value and Squid
5832 reaction to a timed out request are configurable using the following
5835 url_rewrite_timeout timeout time-units on_timeout=<action> [response=<quoted-response>]
5837 supported timeout actions:
5838 fail Squid return a ERR_GATEWAY_FAILURE error page
5840 bypass Do not re-write the URL
5842 retry Send the lookup to the helper again
5844 use_configured_response
5845 Use the <quoted-response> as helper response
5849 OPTIONS FOR STORE ID
5850 -----------------------------------------------------------------------------
5853 NAME: store_id_program storeurl_rewrite_program
5855 LOC: Config.Program.store_id
5858 Specify the location of the executable StoreID helper to use.
5859 Since they can perform almost any function there isn't one included.
5861 For each requested URL, the helper will receive one line with the format
5863 [channel-ID <SP>] URL [<SP> extras]<NL>
5866 After processing the request the helper must reply using the following format:
5868 [channel-ID <SP>] result [<SP> kv-pairs]
5870 The result code can be:
5873 Use the StoreID supplied in 'store-id='.
5876 The default is to use HTTP request URL as the store ID.
5879 An internal error occurred in the helper, preventing
5880 a result being identified.
5882 In addition to the above kv-pairs Squid also understands the following
5883 optional kv-pairs received from URL rewriters:
5885 Associates a TAG with the client TCP connection.
5886 Please see url_rewrite_program related documentation for this
5889 Helper programs should be prepared to receive and possibly ignore
5890 additional whitespace-separated tokens on each input line.
5892 When using the concurrency= option the protocol is changed by
5893 introducing a query channel tag in front of the request/response.
5894 The query channel tag is a number between 0 and concurrency-1.
5895 This value must be echoed back unchanged to Squid as the first part
5896 of the response relating to its request.
5898 NOTE: when using StoreID refresh_pattern will apply to the StoreID
5899 returned from the helper and not the URL.
5901 WARNING: Wrong StoreID value returned by a careless helper may result
5902 in the wrong cached response returned to the user.
5904 By default, a StoreID helper is not used.
5907 NAME: store_id_extras
5908 TYPE: TokenOrQuotedString
5909 LOC: Config.storeId_extras
5910 DEFAULT: "%>a/%>A %un %>rm myip=%la myport=%lp"
5912 Specifies a string to be append to request line format for the
5913 StoreId helper. "Quoted" format values may contain spaces and
5914 logformat %macros. In theory, any logformat %macro can be used.
5915 In practice, a %macro expands as a dash (-) if the helper request is
5916 sent before the required macro information is available to Squid.
5919 NAME: store_id_children storeurl_rewrite_children
5920 TYPE: HelperChildConfig
5921 DEFAULT: 20 startup=0 idle=1 concurrency=0
5922 LOC: Config.storeIdChildren
5924 Specifies the maximum number of StoreID helper processes that Squid
5925 may spawn (numberofchildren) and several related options. Using
5926 too few of these helper processes (a.k.a. "helpers") creates request
5927 queues. Using too many helpers wastes your system resources.
5929 Usage: numberofchildren [option]...
5931 The startup= and idle= options allow some measure of skew in your
5936 Sets a minimum of how many processes are to be spawned when Squid
5937 starts or reconfigures. When set to zero the first request will
5938 cause spawning of the first child process to handle it.
5940 Starting too few will cause an initial slowdown in traffic as Squid
5941 attempts to simultaneously spawn enough processes to cope.
5945 Sets a minimum of how many processes Squid is to try and keep available
5946 at all times. When traffic begins to rise above what the existing
5947 processes can handle this many more will be spawned up to the maximum
5948 configured. A minimum setting of 1 is required.
5952 The number of requests each storeID helper can handle in
5953 parallel. Defaults to 0 which indicates the helper
5954 is a old-style single threaded program.
5956 When this directive is set to a value >= 1 then the protocol
5957 used to communicate with the helper is modified to include
5958 an ID in front of the request/response. The ID from the request
5959 must be echoed back with the response to that request.
5963 Sets the maximum number of queued requests to N. A request is queued
5964 when no existing child can accept it due to concurrency limit and no
5965 new child can be started due to numberofchildren limit. The default
5966 maximum is 2*numberofchildren. If the queued requests exceed queue
5967 size and redirector_bypass configuration option is set, then
5968 redirector is bypassed. Otherwise, Squid is allowed to temporarily
5969 exceed the configured maximum, marking the affected helper as
5970 "overloaded". If the helper overload lasts more than 3 minutes, the
5971 action prescribed by the on-persistent-overload option applies.
5973 on-persistent-overload=action
5975 Specifies Squid reaction to a new helper request arriving when the helper
5976 has been overloaded for more that 3 minutes already. The number of queued
5977 requests determines whether the helper is overloaded (see the queue-size
5980 Two actions are supported:
5982 die Squid worker quits. This is the default behavior.
5984 ERR Squid treats the helper request as if it was
5985 immediately submitted, and the helper immediately
5986 replied with an ERR response. This action has no effect
5987 on the already queued and in-progress helper requests.
5990 NAME: store_id_access storeurl_rewrite_access
5993 DEFAULT_DOC: Allow, unless rules exist in squid.conf.
5994 LOC: Config.accessList.store_id
5996 If defined, this access list specifies which requests are
5997 sent to the StoreID processes. By default all requests
6000 This clause supports both fast and slow acl types.
6001 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
6004 NAME: store_id_bypass storeurl_rewrite_bypass
6006 LOC: Config.onoff.store_id_bypass
6009 When this is 'on', a request will not go through the
6010 helper if all helpers are busy. If this is 'off' and the helper
6011 queue grows too large, the action is prescribed by the
6012 on-persistent-overload option. You should only enable this if the
6013 helpers are not critical to your caching system. If you use
6014 helpers for critical caching components, and you enable this
6015 option, users may not get objects from cache.
6016 This options sets default queue-size option of the store_id_children
6021 OPTIONS FOR TUNING THE CACHE
6022 -----------------------------------------------------------------------------
6025 NAME: cache no_cache
6028 DEFAULT_DOC: By default, this directive is unused and has no effect.
6029 LOC: Config.accessList.noCache
6031 Requests denied by this directive will not be served from the cache
6032 and their responses will not be stored in the cache. This directive
6033 has no effect on other transactions and on already cached responses.
6035 This clause supports both fast and slow acl types.
6036 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
6038 This and the two other similar caching directives listed below are
6039 checked at different transaction processing stages, have different
6040 access to response information, affect different cache operations,
6041 and differ in slow ACLs support:
6043 * cache: Checked before Squid makes a hit/miss determination.
6044 No access to reply information!
6045 Denies both serving a hit and storing a miss.
6046 Supports both fast and slow ACLs.
6047 * send_hit: Checked after a hit was detected.
6048 Has access to reply (hit) information.
6049 Denies serving a hit only.
6050 Supports fast ACLs only.
6051 * store_miss: Checked before storing a cachable miss.
6052 Has access to reply (miss) information.
6053 Denies storing a miss only.
6054 Supports fast ACLs only.
6056 If you are not sure which of the three directives to use, apply the
6057 following decision logic:
6059 * If your ACL(s) are of slow type _and_ need response info, redesign.
6060 Squid does not support that particular combination at this time.
6062 * If your directive ACL(s) are of slow type, use "cache"; and/or
6063 * if your directive ACL(s) need no response info, use "cache".
6065 * If you do not want the response cached, use store_miss; and/or
6066 * if you do not want a hit on a cached response, use send_hit.
6072 DEFAULT_DOC: By default, this directive is unused and has no effect.
6073 LOC: Config.accessList.sendHit
6075 Responses denied by this directive will not be served from the cache
6076 (but may still be cached, see store_miss). This directive has no
6077 effect on the responses it allows and on the cached objects.
6079 Please see the "cache" directive for a summary of differences among
6080 store_miss, send_hit, and cache directives.
6082 Unlike the "cache" directive, send_hit only supports fast acl
6083 types. See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
6087 # apply custom Store ID mapping to some URLs
6088 acl MapMe dstdomain .c.example.com
6089 store_id_program ...
6090 store_id_access allow MapMe
6092 # but prevent caching of special responses
6093 # such as 302 redirects that cause StoreID loops
6094 acl Ordinary http_status 200-299
6095 store_miss deny MapMe !Ordinary
6097 # and do not serve any previously stored special responses
6098 # from the cache (in case they were already cached before
6099 # the above store_miss rule was in effect).
6100 send_hit deny MapMe !Ordinary
6106 DEFAULT_DOC: By default, this directive is unused and has no effect.
6107 LOC: Config.accessList.storeMiss
6109 Responses denied by this directive will not be cached (but may still
6110 be served from the cache, see send_hit). This directive has no
6111 effect on the responses it allows and on the already cached responses.
6113 Please see the "cache" directive for a summary of differences among
6114 store_miss, send_hit, and cache directives. See the
6115 send_hit directive for a usage example.
6117 Unlike the "cache" directive, store_miss only supports fast acl
6118 types. See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
6124 LOC: Config.maxStale
6127 This option puts an upper limit on how stale content Squid
6128 will serve from the cache if cache validation fails.
6129 Can be overriden by the refresh_pattern max-stale option.
6132 NAME: refresh_pattern
6133 TYPE: refreshpattern
6137 usage: refresh_pattern [-i] regex min percent max [options]
6139 By default, regular expressions are CASE-SENSITIVE. To make
6140 them case-insensitive, use the -i option.
6142 'Min' is the time (in minutes) an object without an explicit
6143 expiry time should be considered fresh. The recommended
6144 value is 0, any higher values may cause dynamic applications
6145 to be erroneously cached unless the application designer
6146 has taken the appropriate actions.
6148 'Percent' is a percentage of the objects age (time since last
6149 modification age) an object without explicit expiry time
6150 will be considered fresh.
6152 'Max' is an upper limit on how long objects without an explicit
6153 expiry time will be considered fresh. The value is also used
6154 to form Cache-Control: max-age header for a request sent from
6155 Squid to origin/parent.
6157 options: override-expire
6167 override-expire enforces min age even if the server
6168 sent an explicit expiry time (e.g., with the
6169 Expires: header or Cache-Control: max-age). Doing this
6170 VIOLATES the HTTP standard. Enabling this feature
6171 could make you liable for problems which it causes.
6173 Note: override-expire does not enforce staleness - it only extends
6174 freshness / min. If the server returns a Expires time which
6175 is longer than your max time, Squid will still consider
6176 the object fresh for that period of time.
6178 override-lastmod enforces min age even on objects
6179 that were modified recently.
6181 reload-into-ims changes a client no-cache or ``reload''
6182 request for a cached entry into a conditional request using
6183 If-Modified-Since and/or If-None-Match headers, provided the
6184 cached entry has a Last-Modified and/or a strong ETag header.
6185 Doing this VIOLATES the HTTP standard. Enabling this feature
6186 could make you liable for problems which it causes.
6188 ignore-reload ignores a client no-cache or ``reload''
6189 header. Doing this VIOLATES the HTTP standard. Enabling
6190 this feature could make you liable for problems which
6193 ignore-no-store ignores any ``Cache-control: no-store''
6194 headers received from a server. Doing this VIOLATES
6195 the HTTP standard. Enabling this feature could make you
6196 liable for problems which it causes.
6198 ignore-private ignores any ``Cache-control: private''
6199 headers received from a server. Doing this VIOLATES
6200 the HTTP standard. Enabling this feature could make you
6201 liable for problems which it causes.
6203 refresh-ims causes squid to contact the origin server
6204 when a client issues an If-Modified-Since request. This
6205 ensures that the client will receive an updated version
6206 if one is available.
6208 store-stale stores responses even if they don't have explicit
6209 freshness or a validator (i.e., Last-Modified or an ETag)
6210 present, or if they're already stale. By default, Squid will
6211 not cache such responses because they usually can't be
6212 reused. Note that such responses will be stale by default.
6214 max-stale=NN provide a maximum staleness factor. Squid won't
6215 serve objects more stale than this even if it failed to
6216 validate the object. Default: use the max_stale global limit.
6218 Basically a cached object is:
6220 FRESH if expire > now, else STALE
6222 FRESH if lm-factor < percent, else STALE
6226 The refresh_pattern lines are checked in the order listed here.
6227 The first entry which matches is used. If none of the entries
6228 match the default will be used.
6230 Note, you must uncomment all the default lines if you want
6231 to change one. The default setting is only active if none is
6237 # Add any of your own refresh_pattern entries above these.
6239 refresh_pattern ^ftp: 1440 20% 10080
6240 refresh_pattern ^gopher: 1440 0% 1440
6241 refresh_pattern -i (/cgi-bin/|\?) 0 0% 0
6242 refresh_pattern . 0 20% 4320
6246 NAME: quick_abort_min
6250 LOC: Config.quickAbort.min
6253 NAME: quick_abort_max
6257 LOC: Config.quickAbort.max
6260 NAME: quick_abort_pct
6264 LOC: Config.quickAbort.pct
6266 The cache by default continues downloading aborted requests
6267 which are almost completed (less than 16 KB remaining). This
6268 may be undesirable on slow (e.g. SLIP) links and/or very busy
6269 caches. Impatient users may tie up file descriptors and
6270 bandwidth by repeatedly requesting and immediately aborting
6273 When the user aborts a request, Squid will check the
6274 quick_abort values to the amount of data transferred until
6277 If the transfer has less than 'quick_abort_min' KB remaining,
6278 it will finish the retrieval.
6280 If the transfer has more than 'quick_abort_max' KB remaining,
6281 it will abort the retrieval.
6283 If more than 'quick_abort_pct' of the transfer has completed,
6284 it will finish the retrieval.
6286 If you do not want any retrieval to continue after the client
6287 has aborted, set both 'quick_abort_min' and 'quick_abort_max'
6290 If you want retrievals to always continue if they are being
6291 cached set 'quick_abort_min' to '-1 KB'.
6294 NAME: read_ahead_gap
6295 COMMENT: buffer-size
6297 LOC: Config.readAheadGap
6300 The amount of data the cache will buffer ahead of what has been
6301 sent to the client when retrieving an object from another server.
6305 IFDEF: USE_HTTP_VIOLATIONS
6308 LOC: Config.negativeTtl
6311 Set the Default Time-to-Live (TTL) for failed requests.
6312 Certain types of failures (such as "connection refused" and
6313 "404 Not Found") are able to be negatively-cached for a short time.
6314 Modern web servers should provide Expires: header, however if they
6315 do not this can provide a minimum TTL.
6316 The default is not to cache errors with unknown expiry details.
6318 Note that this is different from negative caching of DNS lookups.
6320 WARNING: Doing this VIOLATES the HTTP standard. Enabling
6321 this feature could make you liable for problems which it
6325 NAME: positive_dns_ttl
6328 LOC: Config.positiveDnsTtl
6331 Upper limit on how long Squid will cache positive DNS responses.
6332 Default is 6 hours (360 minutes). This directive must be set
6333 larger than negative_dns_ttl.
6336 NAME: negative_dns_ttl
6339 LOC: Config.negativeDnsTtl
6342 Time-to-Live (TTL) for negative caching of failed DNS lookups.
6343 This also sets the lower cache limit on positive lookups.
6344 Minimum value is 1 second, and it is not recommendable to go
6345 much below 10 seconds.
6348 NAME: range_offset_limit
6349 COMMENT: size [acl acl...]
6351 LOC: Config.rangeOffsetLimit
6354 usage: (size) [units] [[!]aclname]
6356 Sets an upper limit on how far (number of bytes) into the file
6357 a Range request may be to cause Squid to prefetch the whole file.
6358 If beyond this limit, Squid forwards the Range request as it is and
6359 the result is NOT cached.
6361 This is to stop a far ahead range request (lets say start at 17MB)
6362 from making Squid fetch the whole object up to that point before
6363 sending anything to the client.
6365 Multiple range_offset_limit lines may be specified, and they will
6366 be searched from top to bottom on each request until a match is found.
6367 The first match found will be used. If no line matches a request, the
6368 default limit of 0 bytes will be used.
6370 'size' is the limit specified as a number of units.
6372 'units' specifies whether to use bytes, KB, MB, etc.
6373 If no units are specified bytes are assumed.
6375 A size of 0 causes Squid to never fetch more than the
6376 client requested. (default)
6378 A size of 'none' causes Squid to always fetch the object from the
6379 beginning so it may cache the result. (2.0 style)
6381 'aclname' is the name of a defined ACL.
6383 NP: Using 'none' as the byte value here will override any quick_abort settings
6384 that may otherwise apply to the range request. The range request will
6385 be fully fetched from start to finish regardless of the client
6386 actions. This affects bandwidth usage.
6389 NAME: minimum_expiry_time
6392 LOC: Config.minimum_expiry_time
6395 The minimum caching time according to (Expires - Date)
6396 headers Squid honors if the object can't be revalidated.
6397 The default is 60 seconds.
6399 In reverse proxy environments it might be desirable to honor
6400 shorter object lifetimes. It is most likely better to make
6401 your server return a meaningful Last-Modified header however.
6403 In ESI environments where page fragments often have short
6404 lifetimes, this will often be best set to 0.
6407 NAME: store_avg_object_size
6411 LOC: Config.Store.avgObjectSize
6413 Average object size, used to estimate number of objects your
6414 cache can hold. The default is 13 KB.
6416 This is used to pre-seed the cache index memory allocation to
6417 reduce expensive reallocate operations while handling clients
6418 traffic. Too-large values may result in memory allocation during
6419 peak traffic, too-small values will result in wasted memory.
6421 Check the cache manager 'info' report metrics for the real
6422 object sizes seen by your Squid before tuning this.
6425 NAME: store_objects_per_bucket
6428 LOC: Config.Store.objectsPerBucket
6430 Target number of objects per bucket in the store hash table.
6431 Lowering this value increases the total number of buckets and
6432 also the storage maintenance rate. The default is 20.
6437 -----------------------------------------------------------------------------
6440 NAME: request_header_max_size
6444 LOC: Config.maxRequestHeaderSize
6446 This specifies the maximum size for HTTP headers in a request.
6447 Request headers are usually relatively small (about 512 bytes).
6448 Placing a limit on the request header size will catch certain
6449 bugs (for example with persistent connections) and possibly
6450 buffer-overflow or denial-of-service attacks.
6453 NAME: reply_header_max_size
6457 LOC: Config.maxReplyHeaderSize
6459 This specifies the maximum size for HTTP headers in a reply.
6460 Reply headers are usually relatively small (about 512 bytes).
6461 Placing a limit on the reply header size will catch certain
6462 bugs (for example with persistent connections) and possibly
6463 buffer-overflow or denial-of-service attacks.
6466 NAME: request_body_max_size
6470 DEFAULT_DOC: No limit.
6471 LOC: Config.maxRequestBodySize
6473 This specifies the maximum size for an HTTP request body.
6474 In other words, the maximum size of a PUT/POST request.
6475 A user who attempts to send a request with a body larger
6476 than this limit receives an "Invalid Request" error message.
6477 If you set this parameter to a zero (the default), there will
6478 be no limit imposed.
6480 See also client_request_buffer_max_size for an alternative
6481 limitation on client uploads which can be configured.
6484 NAME: client_request_buffer_max_size
6488 LOC: Config.maxRequestBufferSize
6490 This specifies the maximum buffer size of a client request.
6491 It prevents squid eating too much memory when somebody uploads
6496 IFDEF: USE_HTTP_VIOLATIONS
6499 DEFAULT_DOC: Obey RFC 2616.
6500 LOC: Config.accessList.brokenPosts
6502 A list of ACL elements which, if matched, causes Squid to send
6503 an extra CRLF pair after the body of a PUT/POST request.
6505 Some HTTP servers has broken implementations of PUT/POST,
6506 and rely on an extra CRLF pair sent by some WWW clients.
6508 Quote from RFC2616 section 4.1 on this matter:
6510 Note: certain buggy HTTP/1.0 client implementations generate an
6511 extra CRLF's after a POST request. To restate what is explicitly
6512 forbidden by the BNF, an HTTP/1.1 client must not preface or follow
6513 a request with an extra CRLF.
6515 This clause only supports fast acl types.
6516 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
6519 acl buggy_server url_regex ^http://....
6520 broken_posts allow buggy_server
6523 NAME: adaptation_uses_indirect_client icap_uses_indirect_client
6526 IFDEF: FOLLOW_X_FORWARDED_FOR&&USE_ADAPTATION
6528 LOC: Adaptation::Config::use_indirect_client
6530 Controls whether the indirect client IP address (instead of the direct
6531 client IP address) is passed to adaptation services.
6533 See also: follow_x_forwarded_for adaptation_send_client_ip
6537 IFDEF: USE_HTTP_VIOLATIONS
6541 LOC: Config.onoff.via
6543 If set (default), Squid will include a Via header in requests and
6544 replies as required by RFC2616.
6547 NAME: vary_ignore_expire
6550 LOC: Config.onoff.vary_ignore_expire
6553 Many HTTP servers supporting Vary gives such objects
6554 immediate expiry time with no cache-control header
6555 when requested by a HTTP/1.0 client. This option
6556 enables Squid to ignore such expiry times until
6557 HTTP/1.1 is fully implemented.
6559 WARNING: If turned on this may eventually cause some
6560 varying objects not intended for caching to get cached.
6563 NAME: request_entities
6565 LOC: Config.onoff.request_entities
6568 Squid defaults to deny GET and HEAD requests with request entities,
6569 as the meaning of such requests are undefined in the HTTP standard
6570 even if not explicitly forbidden.
6572 Set this directive to on if you have clients which insists
6573 on sending request entities in GET or HEAD requests. But be warned
6574 that there is server software (both proxies and web servers) which
6575 can fail to properly process this kind of request which may make you
6576 vulnerable to cache pollution attacks if enabled.
6579 NAME: request_header_access
6580 IFDEF: USE_HTTP_VIOLATIONS
6581 TYPE: http_header_access
6582 LOC: Config.request_header_access
6584 DEFAULT_DOC: No limits.
6586 Usage: request_header_access header_name allow|deny [!]aclname ...
6588 WARNING: Doing this VIOLATES the HTTP standard. Enabling
6589 this feature could make you liable for problems which it
6592 This option replaces the old 'anonymize_headers' and the
6593 older 'http_anonymizer' option with something that is much
6594 more configurable. A list of ACLs for each header name allows
6595 removal of specific header fields under specific conditions.
6597 This option only applies to outgoing HTTP request headers (i.e.,
6598 headers sent by Squid to the next HTTP hop such as a cache peer
6599 or an origin server). The option has no effect during cache hit
6600 detection. The equivalent adaptation vectoring point in ICAP
6601 terminology is post-cache REQMOD.
6603 The option is applied to individual outgoing request header
6604 fields. For each request header field F, Squid uses the first
6605 qualifying sets of request_header_access rules:
6607 1. Rules with header_name equal to F's name.
6608 2. Rules with header_name 'Other', provided F's name is not
6609 on the hard-coded list of commonly used HTTP header names.
6610 3. Rules with header_name 'All'.
6612 Within that qualifying rule set, rule ACLs are checked as usual.
6613 If ACLs of an "allow" rule match, the header field is allowed to
6614 go through as is. If ACLs of a "deny" rule match, the header is
6615 removed and request_header_replace is then checked to identify
6616 if the removed header has a replacement. If no rules within the
6617 set have matching ACLs, the header field is left as is.
6619 For example, to achieve the same behavior as the old
6620 'http_anonymizer standard' option, you should use:
6622 request_header_access From deny all
6623 request_header_access Referer deny all
6624 request_header_access User-Agent deny all
6626 Or, to reproduce the old 'http_anonymizer paranoid' feature
6629 request_header_access Authorization allow all
6630 request_header_access Proxy-Authorization allow all
6631 request_header_access Cache-Control allow all
6632 request_header_access Content-Length allow all
6633 request_header_access Content-Type allow all
6634 request_header_access Date allow all
6635 request_header_access Host allow all
6636 request_header_access If-Modified-Since allow all
6637 request_header_access Pragma allow all
6638 request_header_access Accept allow all
6639 request_header_access Accept-Charset allow all
6640 request_header_access Accept-Encoding allow all
6641 request_header_access Accept-Language allow all
6642 request_header_access Connection allow all
6643 request_header_access All deny all
6645 HTTP reply headers are controlled with the reply_header_access directive.
6647 By default, all headers are allowed (no anonymizing is performed).
6650 NAME: reply_header_access
6651 IFDEF: USE_HTTP_VIOLATIONS
6652 TYPE: http_header_access
6653 LOC: Config.reply_header_access
6655 DEFAULT_DOC: No limits.
6657 Usage: reply_header_access header_name allow|deny [!]aclname ...
6659 WARNING: Doing this VIOLATES the HTTP standard. Enabling
6660 this feature could make you liable for problems which it
6663 This option only applies to reply headers, i.e., from the
6664 server to the client.
6666 This is the same as request_header_access, but in the other
6667 direction. Please see request_header_access for detailed
6670 For example, to achieve the same behavior as the old
6671 'http_anonymizer standard' option, you should use:
6673 reply_header_access Server deny all
6674 reply_header_access WWW-Authenticate deny all
6675 reply_header_access Link deny all
6677 Or, to reproduce the old 'http_anonymizer paranoid' feature
6680 reply_header_access Allow allow all
6681 reply_header_access WWW-Authenticate allow all
6682 reply_header_access Proxy-Authenticate allow all
6683 reply_header_access Cache-Control allow all
6684 reply_header_access Content-Encoding allow all
6685 reply_header_access Content-Length allow all
6686 reply_header_access Content-Type allow all
6687 reply_header_access Date allow all
6688 reply_header_access Expires allow all
6689 reply_header_access Last-Modified allow all
6690 reply_header_access Location allow all
6691 reply_header_access Pragma allow all
6692 reply_header_access Content-Language allow all
6693 reply_header_access Retry-After allow all
6694 reply_header_access Title allow all
6695 reply_header_access Content-Disposition allow all
6696 reply_header_access Connection allow all
6697 reply_header_access All deny all
6699 HTTP request headers are controlled with the request_header_access directive.
6701 By default, all headers are allowed (no anonymizing is
6705 NAME: request_header_replace header_replace
6706 IFDEF: USE_HTTP_VIOLATIONS
6707 TYPE: http_header_replace
6708 LOC: Config.request_header_access
6711 Usage: request_header_replace header_name message
6712 Example: request_header_replace User-Agent Nutscrape/1.0 (CP/M; 8-bit)
6714 This option allows you to change the contents of headers
6715 denied with request_header_access above, by replacing them
6716 with some fixed string.
6718 This only applies to request headers, not reply headers.
6720 By default, headers are removed if denied.
6723 NAME: reply_header_replace
6724 IFDEF: USE_HTTP_VIOLATIONS
6725 TYPE: http_header_replace
6726 LOC: Config.reply_header_access
6729 Usage: reply_header_replace header_name message
6730 Example: reply_header_replace Server Foo/1.0
6732 This option allows you to change the contents of headers
6733 denied with reply_header_access above, by replacing them
6734 with some fixed string.
6736 This only applies to reply headers, not request headers.
6738 By default, headers are removed if denied.
6741 NAME: request_header_add
6742 TYPE: HeaderWithAclList
6743 LOC: Config.request_header_add
6746 Usage: request_header_add field-name field-value [ acl ... ]
6747 Example: request_header_add X-Client-CA "CA=%ssl::>cert_issuer" all
6749 This option adds header fields to outgoing HTTP requests (i.e.,
6750 request headers sent by Squid to the next HTTP hop such as a
6751 cache peer or an origin server). The option has no effect during
6752 cache hit detection. The equivalent adaptation vectoring point
6753 in ICAP terminology is post-cache REQMOD.
6755 Field-name is a token specifying an HTTP header name. If a
6756 standard HTTP header name is used, Squid does not check whether
6757 the new header conflicts with any existing headers or violates
6758 HTTP rules. If the request to be modified already contains a
6759 field with the same name, the old field is preserved but the
6760 header field values are not merged.
6762 Field-value is either a token or a quoted string. If quoted
6763 string format is used, then the surrounding quotes are removed
6764 while escape sequences and %macros are processed.
6766 One or more Squid ACLs may be specified to restrict header
6767 injection to matching requests. As always in squid.conf, all
6768 ACLs in the ACL list must be satisfied for the insertion to
6769 happen. The request_header_add supports fast ACLs only.
6771 See also: reply_header_add.
6774 NAME: reply_header_add
6775 TYPE: HeaderWithAclList
6776 LOC: Config.reply_header_add
6779 Usage: reply_header_add field-name field-value [ acl ... ]
6780 Example: reply_header_add X-Client-CA "CA=%ssl::>cert_issuer" all
6782 This option adds header fields to outgoing HTTP responses (i.e., response
6783 headers delivered by Squid to the client). This option has no effect on
6784 cache hit detection. The equivalent adaptation vectoring point in
6785 ICAP terminology is post-cache RESPMOD. This option does not apply to
6786 successful CONNECT replies.
6788 Field-name is a token specifying an HTTP header name. If a
6789 standard HTTP header name is used, Squid does not check whether
6790 the new header conflicts with any existing headers or violates
6791 HTTP rules. If the response to be modified already contains a
6792 field with the same name, the old field is preserved but the
6793 header field values are not merged.
6795 Field-value is either a token or a quoted string. If quoted
6796 string format is used, then the surrounding quotes are removed
6797 while escape sequences and %macros are processed.
6799 One or more Squid ACLs may be specified to restrict header
6800 injection to matching responses. As always in squid.conf, all
6801 ACLs in the ACL list must be satisfied for the insertion to
6802 happen. The reply_header_add option supports fast ACLs only.
6804 See also: request_header_add.
6812 This option used to log custom information about the master
6813 transaction. For example, an admin may configure Squid to log
6814 which "user group" the transaction belongs to, where "user group"
6815 will be determined based on a set of ACLs and not [just]
6816 authentication information.
6817 Values of key/value pairs can be logged using %{key}note macros:
6819 note key value acl ...
6820 logformat myFormat ... %{key}note ...
6822 This clause only supports fast acl types.
6823 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
6826 NAME: relaxed_header_parser
6827 COMMENT: on|off|warn
6829 LOC: Config.onoff.relaxed_header_parser
6832 In the default "on" setting Squid accepts certain forms
6833 of non-compliant HTTP messages where it is unambiguous
6834 what the sending application intended even if the message
6835 is not correctly formatted. The messages is then normalized
6836 to the correct form when forwarded by Squid.
6838 If set to "warn" then a warning will be emitted in cache.log
6839 each time such HTTP error is encountered.
6841 If set to "off" then such HTTP errors will cause the request
6842 or response to be rejected.
6845 NAME: collapsed_forwarding
6848 LOC: Config.onoff.collapsed_forwarding
6851 This option controls whether Squid is allowed to merge multiple
6852 potentially cachable requests for the same URI before Squid knows
6853 whether the response is going to be cachable.
6855 When enabled, instead of forwarding each concurrent request for
6856 the same URL, Squid just sends the first of them. The other, so
6857 called "collapsed" requests, wait for the response to the first
6858 request and, if it happens to be cachable, use that response.
6859 Here, "concurrent requests" means "received after the first
6860 request headers were parsed and before the corresponding response
6861 headers were parsed".
6863 This feature is disabled by default: enabling collapsed
6864 forwarding needlessly delays forwarding requests that look
6865 cachable (when they are collapsed) but then need to be forwarded
6866 individually anyway because they end up being for uncachable
6867 content. However, in some cases, such as acceleration of highly
6868 cachable content with periodic or grouped expiration times, the
6869 gains from collapsing [large volumes of simultaneous refresh
6870 requests] outweigh losses from such delays.
6872 Squid collapses two kinds of requests: regular client requests
6873 received on one of the listening ports and internal "cache
6874 revalidation" requests which are triggered by those regular
6875 requests hitting a stale cached object. Revalidation collapsing
6876 is currently disabled for Squid instances containing SMP-aware
6877 disk or memory caches and for Vary-controlled cached objects.
6880 NAME: collapsed_forwarding_access
6883 DEFAULT_DOC: Requests may be collapsed if collapsed_forwarding is on.
6884 LOC: Config.accessList.collapsedForwardingAccess
6886 Use this directive to restrict collapsed forwarding to a subset of
6887 eligible requests. The directive is checked for regular HTTP
6888 requests, internal revalidation requests, and HTCP/ICP requests.
6890 collapsed_forwarding_access allow|deny [!]aclname ...
6892 This directive cannot force collapsing. It has no effect on
6893 collapsing unless collapsed_forwarding is 'on', and all other
6894 collapsing preconditions are satisfied.
6896 * A denied request will not collapse, and future transactions will
6897 not collapse on it (even if they are allowed to collapse).
6899 * An allowed request may collapse, or future transactions may
6900 collapse on it (provided they are allowed to collapse).
6902 This directive is evaluated before receiving HTTP response headers
6903 and without access to Squid-to-peer connection (if any).
6905 Only fast ACLs are supported.
6907 See also: collapsed_forwarding.
6910 NAME: shared_transient_entries_limit collapsed_forwarding_shared_entries_limit
6911 COMMENT: (number of entries)
6913 LOC: Config.shared_transient_entries_limit
6916 This directive limits the size of a table used for sharing current
6917 transaction information among SMP workers. A table entry stores meta
6918 information about a single cache entry being delivered to Squid
6919 client(s) by one or more SMP workers. A single table entry consumes
6920 less than 128 shared memory bytes.
6922 The limit should be significantly larger than the number of
6923 concurrent non-collapsed cachable responses leaving Squid. For a
6924 cache that handles less than 5000 concurrent requests, the default
6925 setting of 16384 should be plenty.
6927 Using excessively large values wastes shared memory. Limiting the
6928 table size too much results in hash collisions, leading to lower hit
6929 ratio and missed SMP request collapsing opportunities: Transactions
6930 left without a table entry cannot cache their responses and are
6931 invisible to other concurrent requests for the same resource.
6933 A zero limit is allowed but unsupported. A positive small limit
6934 lowers hit ratio, but zero limit disables a lot of essential
6935 synchronization among SMP workers, leading to HTTP violations (e.g.,
6936 stale hit responses). It also disables shared collapsed forwarding:
6937 A worker becomes unable to collapse its requests on transactions in
6938 other workers, resulting in more trips to the origin server and more
6944 -----------------------------------------------------------------------------
6947 NAME: forward_timeout
6950 LOC: Config.Timeout.forward
6953 This parameter specifies how long Squid should at most attempt in
6954 finding a forwarding path for the request before giving up.
6957 NAME: connect_timeout
6960 LOC: Config.Timeout.connect
6963 This parameter specifies how long to wait for the TCP connect to
6964 the requested server or peer to complete before Squid should
6965 attempt to find another path where to forward the request.
6968 NAME: peer_connect_timeout
6971 LOC: Config.Timeout.peer_connect
6974 This parameter specifies how long to wait for a pending TCP
6975 connection to a peer cache. The default is 30 seconds. You
6976 may also set different timeout values for individual neighbors
6977 with the 'connect-timeout' option on a 'cache_peer' line.
6983 LOC: Config.Timeout.read
6986 Applied on peer server connections.
6988 After each successful read(), the timeout will be extended by this
6989 amount. If no data is read again after this amount of time,
6990 the request is aborted and logged with ERR_READ_TIMEOUT.
6992 The default is 15 minutes.
6998 LOC: Config.Timeout.write
7001 This timeout is tracked for all connections that have data
7002 available for writing and are waiting for the socket to become
7003 ready. After each successful write, the timeout is extended by
7004 the configured amount. If Squid has data to write but the
7005 connection is not ready for the configured duration, the
7006 transaction associated with the connection is terminated. The
7007 default is 15 minutes.
7010 NAME: request_timeout
7012 LOC: Config.Timeout.request
7015 How long to wait for complete HTTP request headers after initial
7016 connection establishment.
7019 NAME: request_start_timeout
7021 LOC: Config.Timeout.request_start_timeout
7024 How long to wait for the first request byte after initial
7025 connection establishment.
7028 NAME: client_idle_pconn_timeout persistent_request_timeout
7030 LOC: Config.Timeout.clientIdlePconn
7033 How long to wait for the next HTTP request on a persistent
7034 client connection after the previous request completes.
7037 NAME: ftp_client_idle_timeout
7039 LOC: Config.Timeout.ftpClientIdle
7042 How long to wait for an FTP request on a connection to Squid ftp_port.
7043 Many FTP clients do not deal with idle connection closures well,
7044 necessitating a longer default timeout than client_idle_pconn_timeout
7045 used for incoming HTTP requests.
7048 NAME: client_lifetime
7051 LOC: Config.Timeout.lifetime
7054 The maximum amount of time a client (browser) is allowed to
7055 remain connected to the cache process. This protects the Cache
7056 from having a lot of sockets (and hence file descriptors) tied up
7057 in a CLOSE_WAIT state from remote clients that go away without
7058 properly shutting down (either because of a network failure or
7059 because of a poor client implementation). The default is one
7062 NOTE: The default value is intended to be much larger than any
7063 client would ever need to be connected to your cache. You
7064 should probably change client_lifetime only as a last resort.
7065 If you seem to have many client connections tying up
7066 filedescriptors, we recommend first tuning the read_timeout,
7067 request_timeout, persistent_request_timeout and quick_abort values.
7070 NAME: pconn_lifetime
7073 LOC: Config.Timeout.pconnLifetime
7076 Desired maximum lifetime of a persistent connection.
7077 When set, Squid will close a now-idle persistent connection that
7078 exceeded configured lifetime instead of moving the connection into
7079 the idle connection pool (or equivalent). No effect on ongoing/active
7080 transactions. Connection lifetime is the time period from the
7081 connection acceptance or opening time until "now".
7083 This limit is useful in environments with long-lived connections
7084 where Squid configuration or environmental factors change during a
7085 single connection lifetime. If unrestricted, some connections may
7086 last for hours and even days, ignoring those changes that should
7087 have affected their behavior or their existence.
7089 Currently, a new lifetime value supplied via Squid reconfiguration
7090 has no effect on already idle connections unless they become busy.
7092 When set to '0' this limit is not used.
7095 NAME: half_closed_clients
7097 LOC: Config.onoff.half_closed_clients
7100 Some clients may shutdown the sending side of their TCP
7101 connections, while leaving their receiving sides open. Sometimes,
7102 Squid can not tell the difference between a half-closed and a
7103 fully-closed TCP connection.
7105 By default, Squid will immediately close client connections when
7106 read(2) returns "no more data to read."
7108 Change this option to 'on' and Squid will keep open connections
7109 until a read(2) or write(2) on the socket returns an error.
7110 This may show some benefits for reverse proxies. But if not
7111 it is recommended to leave OFF.
7114 NAME: server_idle_pconn_timeout pconn_timeout
7116 LOC: Config.Timeout.serverIdlePconn
7119 Timeout for idle persistent connections to servers and other
7126 LOC: Ident::TheConfig.timeout
7129 Maximum time to wait for IDENT lookups to complete.
7131 If this is too high, and you enabled IDENT lookups from untrusted
7132 users, you might be susceptible to denial-of-service by having
7133 many ident requests going at once.
7136 NAME: shutdown_lifetime
7139 LOC: Config.shutdownLifetime
7142 When SIGTERM or SIGHUP is received, the cache is put into
7143 "shutdown pending" mode until all active sockets are closed.
7144 This value is the lifetime to set for all open descriptors
7145 during shutdown mode. Any active clients after this many
7146 seconds will receive a 'timeout' message.
7150 ADMINISTRATIVE PARAMETERS
7151 -----------------------------------------------------------------------------
7157 LOC: Config.adminEmail
7159 Email-address of local cache manager who will receive
7160 mail if the cache dies. The default is "webmaster".
7166 LOC: Config.EmailFrom
7168 From: email-address for mail sent when the cache dies.
7169 The default is to use 'squid@unique_hostname'.
7171 See also: unique_hostname directive.
7177 LOC: Config.EmailProgram
7179 Email program used to send mail if the cache dies.
7180 The default is "mail". The specified program must comply
7181 with the standard Unix mail syntax:
7182 mail-program recipient < mailfile
7184 Optional command line options can be specified.
7187 NAME: cache_effective_user
7189 DEFAULT: @DEFAULT_CACHE_EFFECTIVE_USER@
7190 LOC: Config.effectiveUser
7192 If you start Squid as root, it will change its effective/real
7193 UID/GID to the user specified below. The default is to change
7194 to UID of @DEFAULT_CACHE_EFFECTIVE_USER@.
7195 see also; cache_effective_group
7198 NAME: cache_effective_group
7201 DEFAULT_DOC: Use system group memberships of the cache_effective_user account
7202 LOC: Config.effectiveGroup
7204 Squid sets the GID to the effective user's default group ID
7205 (taken from the password file) and supplementary group list
7206 from the groups membership.
7208 If you want Squid to run with a specific GID regardless of
7209 the group memberships of the effective user then set this
7210 to the group (or GID) you want Squid to run as. When set
7211 all other group privileges of the effective user are ignored
7212 and only this GID is effective. If Squid is not started as
7213 root the user starting Squid MUST be member of the specified
7216 This option is not recommended by the Squid Team.
7217 Our preference is for administrators to configure a secure
7218 user account for squid with UID/GID matching system policies.
7221 NAME: httpd_suppress_version_string
7225 LOC: Config.onoff.httpd_suppress_version_string
7227 Suppress Squid version string info in HTTP headers and HTML error pages.
7230 NAME: visible_hostname
7232 LOC: Config.visibleHostname
7234 DEFAULT_DOC: Automatically detect the system host name
7236 If you want to present a special hostname in error messages, etc,
7237 define this. Otherwise, the return value of gethostname()
7238 will be used. If you have multiple caches in a cluster and
7239 get errors about IP-forwarding you must set them to have individual
7240 names with this setting.
7243 NAME: unique_hostname
7245 LOC: Config.uniqueHostname
7247 DEFAULT_DOC: Copy the value from visible_hostname
7249 If you want to have multiple machines with the same
7250 'visible_hostname' you must give each machine a different
7251 'unique_hostname' so forwarding loops can be detected.
7254 NAME: hostname_aliases
7256 LOC: Config.hostnameAliases
7259 A list of other DNS names your cache has.
7267 Minimum umask which should be enforced while the proxy
7268 is running, in addition to the umask set at startup.
7270 For a traditional octal representation of umasks, start
7275 OPTIONS FOR THE CACHE REGISTRATION SERVICE
7276 -----------------------------------------------------------------------------
7278 This section contains parameters for the (optional) cache
7279 announcement service. This service is provided to help
7280 cache administrators locate one another in order to join or
7281 create cache hierarchies.
7283 An 'announcement' message is sent (via UDP) to the registration
7284 service by Squid. By default, the announcement message is NOT
7285 SENT unless you enable it with 'announce_period' below.
7287 The announcement message includes your hostname, plus the
7288 following information from this configuration file:
7294 All current information is processed regularly and made
7295 available on the Web at http://www.ircache.net/Cache/Tracker/.
7298 NAME: announce_period
7300 LOC: Config.Announce.period
7302 DEFAULT_DOC: Announcement messages disabled.
7304 This is how frequently to send cache announcements.
7306 To enable announcing your cache, just set an announce period.
7309 announce_period 1 day
7314 DEFAULT: tracker.ircache.net
7315 LOC: Config.Announce.host
7317 Set the hostname where announce registration messages will be sent.
7319 See also announce_port and announce_file
7325 LOC: Config.Announce.file
7327 The contents of this file will be included in the announce
7328 registration messages.
7334 LOC: Config.Announce.port
7336 Set the port where announce registration messages will be sent.
7338 See also announce_host and announce_file
7342 HTTPD-ACCELERATOR OPTIONS
7343 -----------------------------------------------------------------------------
7346 NAME: httpd_accel_surrogate_id
7349 DEFAULT_DOC: visible_hostname is used if no specific ID is set.
7350 LOC: Config.Accel.surrogate_id
7352 Surrogates (http://www.esi.org/architecture_spec_1.0.html)
7353 need an identification token to allow control targeting. Because
7354 a farm of surrogates may all perform the same tasks, they may share
7355 an identification token.
7357 When the surrogate is a reverse-proxy, this ID is also
7358 used as cdn-id for CDN-Loop detection (RFC 8586).
7361 NAME: http_accel_surrogate_remote
7365 LOC: Config.onoff.surrogate_is_remote
7367 Remote surrogates (such as those in a CDN) honour the header
7368 "Surrogate-Control: no-store-remote".
7370 Set this to on to have squid behave as a remote surrogate.
7374 IFDEF: USE_SQUID_ESI
7375 COMMENT: libxml2|expat
7377 LOC: ESIParser::Type
7379 DEFAULT_DOC: Selects libxml2 if available at ./configure time or libexpat otherwise.
7381 Selects the XML parsing library to use when interpreting responses with
7384 To disable ESI handling completely, ./configure Squid with --disable-esi.
7388 DELAY POOL PARAMETERS
7389 -----------------------------------------------------------------------------
7393 TYPE: delay_pool_count
7395 IFDEF: USE_DELAY_POOLS
7398 This represents the number of delay pools to be used. For example,
7399 if you have one class 2 delay pool and one class 3 delays pool, you
7400 have a total of 2 delay pools.
7402 See also delay_parameters, delay_class, delay_access for pool
7403 configuration details.
7407 TYPE: delay_pool_class
7409 IFDEF: USE_DELAY_POOLS
7412 This defines the class of each delay pool. There must be exactly one
7413 delay_class line for each delay pool. For example, to define two
7414 delay pools, one of class 2 and one of class 3, the settings above
7418 delay_pools 4 # 4 delay pools
7419 delay_class 1 2 # pool 1 is a class 2 pool
7420 delay_class 2 3 # pool 2 is a class 3 pool
7421 delay_class 3 4 # pool 3 is a class 4 pool
7422 delay_class 4 5 # pool 4 is a class 5 pool
7424 The delay pool classes are:
7426 class 1 Everything is limited by a single aggregate
7429 class 2 Everything is limited by a single aggregate
7430 bucket as well as an "individual" bucket chosen
7431 from bits 25 through 32 of the IPv4 address.
7433 class 3 Everything is limited by a single aggregate
7434 bucket as well as a "network" bucket chosen
7435 from bits 17 through 24 of the IP address and a
7436 "individual" bucket chosen from bits 17 through
7437 32 of the IPv4 address.
7439 class 4 Everything in a class 3 delay pool, with an
7440 additional limit on a per user basis. This
7441 only takes effect if the username is established
7442 in advance - by forcing authentication in your
7445 class 5 Requests are grouped according their tag (see
7446 external_acl's tag= reply).
7449 Each pool also requires a delay_parameters directive to configure the pool size
7450 and speed limits used whenever the pool is applied to a request. Along with
7451 a set of delay_access directives to determine when it is used.
7453 NOTE: If an IP address is a.b.c.d
7454 -> bits 25 through 32 are "d"
7455 -> bits 17 through 24 are "c"
7456 -> bits 17 through 32 are "c * 256 + d"
7458 NOTE-2: Due to the use of bitmasks in class 2,3,4 pools they only apply to
7459 IPv4 traffic. Class 1 and 5 pools may be used with IPv6 traffic.
7461 This clause only supports fast acl types.
7462 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
7464 See also delay_parameters and delay_access.
7468 TYPE: delay_pool_access
7470 DEFAULT_DOC: Deny using the pool, unless allow rules exist in squid.conf for the pool.
7471 IFDEF: USE_DELAY_POOLS
7474 This is used to determine which delay pool a request falls into.
7476 delay_access is sorted per pool and the matching starts with pool 1,
7477 then pool 2, ..., and finally pool N. The first delay pool where the
7478 request is allowed is selected for the request. If it does not allow
7479 the request to any pool then the request is not delayed (default).
7481 For example, if you want some_big_clients in delay
7482 pool 1 and lotsa_little_clients in delay pool 2:
7484 delay_access 1 allow some_big_clients
7485 delay_access 1 deny all
7486 delay_access 2 allow lotsa_little_clients
7487 delay_access 2 deny all
7488 delay_access 3 allow authenticated_clients
7490 See also delay_parameters and delay_class.
7494 NAME: delay_parameters
7495 TYPE: delay_pool_rates
7497 IFDEF: USE_DELAY_POOLS
7500 This defines the parameters for a delay pool. Each delay pool has
7501 a number of "buckets" associated with it, as explained in the
7502 description of delay_class.
7504 For a class 1 delay pool, the syntax is:
7506 delay_parameters pool aggregate
7508 For a class 2 delay pool:
7510 delay_parameters pool aggregate individual
7512 For a class 3 delay pool:
7514 delay_parameters pool aggregate network individual
7516 For a class 4 delay pool:
7518 delay_parameters pool aggregate network individual user
7520 For a class 5 delay pool:
7522 delay_parameters pool tagrate
7524 The option variables are:
7526 pool a pool number - ie, a number between 1 and the
7527 number specified in delay_pools as used in
7530 aggregate the speed limit parameters for the aggregate bucket
7533 individual the speed limit parameters for the individual
7534 buckets (class 2, 3).
7536 network the speed limit parameters for the network buckets
7539 user the speed limit parameters for the user buckets
7542 tagrate the speed limit parameters for the tag buckets
7545 A pair of delay parameters is written restore/maximum, where restore is
7546 the number of bytes (not bits - modem and network speeds are usually
7547 quoted in bits) per second placed into the bucket, and maximum is the
7548 maximum number of bytes which can be in the bucket at any time.
7550 There must be one delay_parameters line for each delay pool.
7553 For example, if delay pool number 1 is a class 2 delay pool as in the
7554 above example, and is being used to strictly limit each host to 64Kbit/sec
7555 (plus overheads), with no overall limit, the line is:
7557 delay_parameters 1 none 8000/8000
7559 Note that 8 x 8K Byte/sec -> 64K bit/sec.
7561 Note that the word 'none' is used to represent no limit.
7564 And, if delay pool number 2 is a class 3 delay pool as in the above
7565 example, and you want to limit it to a total of 256Kbit/sec (strict limit)
7566 with each 8-bit network permitted 64Kbit/sec (strict limit) and each
7567 individual host permitted 4800bit/sec with a bucket maximum size of 64Kbits
7568 to permit a decent web page to be downloaded at a decent speed
7569 (if the network is not being limited due to overuse) but slow down
7570 large downloads more significantly:
7572 delay_parameters 2 32000/32000 8000/8000 600/8000
7574 Note that 8 x 32K Byte/sec -> 256K bit/sec.
7575 8 x 8K Byte/sec -> 64K bit/sec.
7576 8 x 600 Byte/sec -> 4800 bit/sec.
7579 Finally, for a class 4 delay pool as in the example - each user will
7580 be limited to 128Kbits/sec no matter how many workstations they are logged into.:
7582 delay_parameters 4 32000/32000 8000/8000 600/64000 16000/16000
7585 See also delay_class and delay_access.
7589 NAME: delay_initial_bucket_level
7590 COMMENT: (percent, 0-100)
7593 IFDEF: USE_DELAY_POOLS
7594 LOC: Config.Delay.initial
7596 The initial bucket percentage is used to determine how much is put
7597 in each bucket when squid starts, is reconfigured, or first notices
7598 a host accessing it (in class 2 and class 3, individual hosts and
7599 networks only have buckets associated with them once they have been
7604 CLIENT DELAY POOL PARAMETERS
7605 -----------------------------------------------------------------------------
7608 NAME: client_delay_pools
7609 TYPE: client_delay_pool_count
7611 IFDEF: USE_DELAY_POOLS
7612 LOC: Config.ClientDelay
7614 This option specifies the number of client delay pools used. It must
7615 preceed other client_delay_* options.
7618 client_delay_pools 2
7620 See also client_delay_parameters and client_delay_access.
7623 NAME: client_delay_initial_bucket_level
7624 COMMENT: (percent, 0-no_limit)
7627 IFDEF: USE_DELAY_POOLS
7628 LOC: Config.ClientDelay.initial
7630 This option determines the initial bucket size as a percentage of
7631 max_bucket_size from client_delay_parameters. Buckets are created
7632 at the time of the "first" connection from the matching IP. Idle
7633 buckets are periodically deleted up.
7635 You can specify more than 100 percent but note that such "oversized"
7636 buckets are not refilled until their size goes down to max_bucket_size
7637 from client_delay_parameters.
7640 client_delay_initial_bucket_level 50
7643 NAME: client_delay_parameters
7644 TYPE: client_delay_pool_rates
7646 IFDEF: USE_DELAY_POOLS
7647 LOC: Config.ClientDelay
7650 This option configures client-side bandwidth limits using the
7653 client_delay_parameters pool speed_limit max_bucket_size
7655 pool is an integer ID used for client_delay_access matching.
7657 speed_limit is bytes added to the bucket per second.
7659 max_bucket_size is the maximum size of a bucket, enforced after any
7660 speed_limit additions.
7662 Please see the delay_parameters option for more information and
7666 client_delay_parameters 1 1024 2048
7667 client_delay_parameters 2 51200 16384
7669 See also client_delay_access.
7673 NAME: client_delay_access
7674 TYPE: client_delay_pool_access
7676 DEFAULT_DOC: Deny use of the pool, unless allow rules exist in squid.conf for the pool.
7677 IFDEF: USE_DELAY_POOLS
7678 LOC: Config.ClientDelay
7680 This option determines the client-side delay pool for the
7683 client_delay_access pool_ID allow|deny acl_name
7685 All client_delay_access options are checked in their pool ID
7686 order, starting with pool 1. The first checked pool with allowed
7687 request is selected for the request. If no ACL matches or there
7688 are no client_delay_access options, the request bandwidth is not
7691 The ACL-selected pool is then used to find the
7692 client_delay_parameters for the request. Client-side pools are
7693 not used to aggregate clients. Clients are always aggregated
7694 based on their source IP addresses (one bucket per source IP).
7696 This clause only supports fast acl types.
7697 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
7698 Additionally, only the client TCP connection details are available.
7699 ACLs testing HTTP properties will not work.
7701 Please see delay_access for more examples.
7704 client_delay_access 1 allow low_rate_network
7705 client_delay_access 2 allow vips_network
7708 See also client_delay_parameters and client_delay_pools.
7711 NAME: response_delay_pool
7712 TYPE: response_delay_pool_parameters
7714 IFDEF: USE_DELAY_POOLS
7715 LOC: Config.MessageDelay
7717 This option configures client response bandwidth limits using the
7720 response_delay_pool name [option=value] ...
7722 name the response delay pool name
7726 individual-restore The speed limit of an individual
7727 bucket(bytes/s). To be used in conjunction
7728 with 'individual-maximum'.
7730 individual-maximum The maximum number of bytes which can
7731 be placed into the individual bucket. To be used
7732 in conjunction with 'individual-restore'.
7734 aggregate-restore The speed limit for the aggregate
7735 bucket(bytes/s). To be used in conjunction with
7736 'aggregate-maximum'.
7738 aggregate-maximum The maximum number of bytes which can
7739 be placed into the aggregate bucket. To be used
7740 in conjunction with 'aggregate-restore'.
7742 initial-bucket-level The initial bucket size as a percentage
7743 of individual-maximum.
7745 Individual and(or) aggregate bucket options may not be specified,
7746 meaning no individual and(or) aggregate speed limitation.
7747 See also response_delay_pool_access and delay_parameters for
7748 terminology details.
7751 NAME: response_delay_pool_access
7752 TYPE: response_delay_pool_access
7754 DEFAULT_DOC: Deny use of the pool, unless allow rules exist in squid.conf for the pool.
7755 IFDEF: USE_DELAY_POOLS
7756 LOC: Config.MessageDelay
7758 Determines whether a specific named response delay pool is used
7759 for the transaction. The syntax for this directive is:
7761 response_delay_pool_access pool_name allow|deny acl_name
7763 All response_delay_pool_access options are checked in the order
7764 they appear in this configuration file. The first rule with a
7765 matching ACL wins. If (and only if) an "allow" rule won, Squid
7766 assigns the response to the corresponding named delay pool.
7770 WCCPv1 AND WCCPv2 CONFIGURATION OPTIONS
7771 -----------------------------------------------------------------------------
7776 LOC: Config.Wccp.router
7778 DEFAULT_DOC: WCCP disabled.
7781 Use this option to define your WCCP ``home'' router for
7784 wccp_router supports a single WCCP(v1) router
7786 wccp2_router supports multiple WCCPv2 routers
7788 only one of the two may be used at the same time and defines
7789 which version of WCCP to use.
7793 TYPE: IpAddress_list
7794 LOC: Config.Wccp2.router
7796 DEFAULT_DOC: WCCPv2 disabled.
7799 Use this option to define your WCCP ``home'' router for
7802 wccp_router supports a single WCCP(v1) router
7804 wccp2_router supports multiple WCCPv2 routers
7806 only one of the two may be used at the same time and defines
7807 which version of WCCP to use.
7812 LOC: Config.Wccp.version
7816 This directive is only relevant if you need to set up WCCP(v1)
7817 to some very old and end-of-life Cisco routers. In all other
7818 setups it must be left unset or at the default setting.
7819 It defines an internal version in the WCCP(v1) protocol,
7820 with version 4 being the officially documented protocol.
7822 According to some users, Cisco IOS 11.2 and earlier only
7823 support WCCP version 3. If you're using that or an earlier
7824 version of IOS, you may need to change this value to 3, otherwise
7825 do not specify this parameter.
7828 NAME: wccp2_rebuild_wait
7830 LOC: Config.Wccp2.rebuildwait
7834 If this is enabled Squid will wait for the cache dir rebuild to finish
7835 before sending the first wccp2 HereIAm packet
7838 NAME: wccp2_forwarding_method
7840 LOC: Config.Wccp2.forwarding_method
7844 WCCP2 allows the setting of forwarding methods between the
7845 router/switch and the cache. Valid values are as follows:
7847 gre - GRE encapsulation (forward the packet in a GRE/WCCP tunnel)
7848 l2 - L2 redirect (forward the packet using Layer 2/MAC rewriting)
7850 Currently (as of IOS 12.4) cisco routers only support GRE.
7851 Cisco switches only support the L2 redirect assignment method.
7854 NAME: wccp2_return_method
7856 LOC: Config.Wccp2.return_method
7860 WCCP2 allows the setting of return methods between the
7861 router/switch and the cache for packets that the cache
7862 decides not to handle. Valid values are as follows:
7864 gre - GRE encapsulation (forward the packet in a GRE/WCCP tunnel)
7865 l2 - L2 redirect (forward the packet using Layer 2/MAC rewriting)
7867 Currently (as of IOS 12.4) cisco routers only support GRE.
7868 Cisco switches only support the L2 redirect assignment.
7870 If the "ip wccp redirect exclude in" command has been
7871 enabled on the cache interface, then it is still safe for
7872 the proxy server to use a l2 redirect method even if this
7873 option is set to GRE.
7876 NAME: wccp2_assignment_method
7878 LOC: Config.Wccp2.assignment_method
7882 WCCP2 allows the setting of methods to assign the WCCP hash
7883 Valid values are as follows:
7885 hash - Hash assignment
7886 mask - Mask assignment
7888 As a general rule, cisco routers support the hash assignment method
7889 and cisco switches support the mask assignment method.
7894 LOC: Config.Wccp2.info
7895 DEFAULT_IF_NONE: standard 0
7896 DEFAULT_DOC: Use the 'web-cache' standard service.
7899 WCCP2 allows for multiple traffic services. There are two
7900 types: "standard" and "dynamic". The standard type defines
7901 one service id - http (id 0). The dynamic service ids can be from
7902 51 to 255 inclusive. In order to use a dynamic service id
7903 one must define the type of traffic to be redirected; this is done
7904 using the wccp2_service_info option.
7906 The "standard" type does not require a wccp2_service_info option,
7907 just specifying the service id will suffice.
7909 MD5 service authentication can be enabled by adding
7910 "password=<password>" to the end of this service declaration.
7914 wccp2_service standard 0 # for the 'web-cache' standard service
7915 wccp2_service dynamic 80 # a dynamic service type which will be
7916 # fleshed out with subsequent options.
7917 wccp2_service standard 0 password=foo
7920 NAME: wccp2_service_info
7921 TYPE: wccp2_service_info
7922 LOC: Config.Wccp2.info
7926 Dynamic WCCPv2 services require further information to define the
7927 traffic you wish to have diverted.
7931 wccp2_service_info <id> protocol=<protocol> flags=<flag>,<flag>..
7932 priority=<priority> ports=<port>,<port>..
7934 The relevant WCCPv2 flags:
7935 + src_ip_hash, dst_ip_hash
7936 + source_port_hash, dst_port_hash
7937 + src_ip_alt_hash, dst_ip_alt_hash
7938 + src_port_alt_hash, dst_port_alt_hash
7941 The port list can be one to eight entries.
7945 wccp2_service_info 80 protocol=tcp flags=src_ip_hash,ports_source
7946 priority=240 ports=80
7948 Note: the service id must have been defined by a previous
7949 'wccp2_service dynamic <id>' entry.
7954 LOC: Config.Wccp2.weight
7958 Each cache server gets assigned a set of the destination
7959 hash proportional to their weight.
7964 LOC: Config.Wccp.address
7966 DEFAULT_DOC: Address selected by the operating system.
7969 Use this option if you require WCCPv2 to use a specific
7972 The default behavior is to not bind to any specific address.
7977 LOC: Config.Wccp2.address
7979 DEFAULT_DOC: Address selected by the operating system.
7982 Use this option if you require WCCP to use a specific
7985 The default behavior is to not bind to any specific address.
7989 PERSISTENT CONNECTION HANDLING
7990 -----------------------------------------------------------------------------
7992 Also see "pconn_timeout" in the TIMEOUTS section
7995 NAME: client_persistent_connections
7997 LOC: Config.onoff.client_pconns
8000 Persistent connection support for clients.
8001 Squid uses persistent connections (when allowed). You can use
8002 this option to disable persistent connections with clients.
8005 NAME: server_persistent_connections
8007 LOC: Config.onoff.server_pconns
8010 Persistent connection support for servers.
8011 Squid uses persistent connections (when allowed). You can use
8012 this option to disable persistent connections with servers.
8015 NAME: persistent_connection_after_error
8017 LOC: Config.onoff.error_pconns
8020 With this directive the use of persistent connections after
8021 HTTP errors can be disabled. Useful if you have clients
8022 who fail to handle errors on persistent connections proper.
8025 NAME: detect_broken_pconn
8027 LOC: Config.onoff.detect_broken_server_pconns
8030 Some servers have been found to incorrectly signal the use
8031 of HTTP/1.0 persistent connections even on replies not
8032 compatible, causing significant delays. This server problem
8033 has mostly been seen on redirects.
8035 By enabling this directive Squid attempts to detect such
8036 broken replies and automatically assume the reply is finished
8037 after 10 seconds timeout.
8041 CACHE DIGEST OPTIONS
8042 -----------------------------------------------------------------------------
8045 NAME: digest_generation
8046 IFDEF: USE_CACHE_DIGESTS
8048 LOC: Config.onoff.digest_generation
8051 This controls whether the server will generate a Cache Digest
8052 of its contents. By default, Cache Digest generation is
8053 enabled if Squid is compiled with --enable-cache-digests defined.
8056 NAME: digest_bits_per_entry
8057 IFDEF: USE_CACHE_DIGESTS
8059 LOC: Config.digest.bits_per_entry
8062 This is the number of bits of the server's Cache Digest which
8063 will be associated with the Digest entry for a given HTTP
8064 Method and URL (public key) combination. The default is 5.
8067 NAME: digest_rebuild_period
8068 IFDEF: USE_CACHE_DIGESTS
8071 LOC: Config.digest.rebuild_period
8074 This is the wait time between Cache Digest rebuilds.
8077 NAME: digest_rewrite_period
8079 IFDEF: USE_CACHE_DIGESTS
8081 LOC: Config.digest.rewrite_period
8084 This is the wait time between Cache Digest writes to
8088 NAME: digest_swapout_chunk_size
8091 IFDEF: USE_CACHE_DIGESTS
8092 LOC: Config.digest.swapout_chunk_size
8095 This is the number of bytes of the Cache Digest to write to
8096 disk at a time. It defaults to 4096 bytes (4KB), the Squid
8100 NAME: digest_rebuild_chunk_percentage
8101 COMMENT: (percent, 0-100)
8102 IFDEF: USE_CACHE_DIGESTS
8104 LOC: Config.digest.rebuild_chunk_percentage
8107 This is the percentage of the Cache Digest to be scanned at a
8108 time. By default it is set to 10% of the Cache Digest.
8113 -----------------------------------------------------------------------------
8118 LOC: Config.Port.snmp
8120 DEFAULT_DOC: SNMP disabled.
8123 The port number where Squid listens for SNMP requests. To enable
8124 SNMP support set this to a suitable port number. Port number
8125 3401 is often used for the Squid SNMP agent. By default it's
8126 set to "0" (disabled)
8134 LOC: Config.accessList.snmp
8136 DEFAULT_DOC: Deny, unless rules exist in squid.conf.
8139 Allowing or denying access to the SNMP port.
8141 All access to the agent is denied by default.
8144 snmp_access allow|deny [!]aclname ...
8146 This clause only supports fast acl types.
8147 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
8150 snmp_access allow snmppublic localhost
8151 snmp_access deny all
8154 NAME: snmp_incoming_address
8156 LOC: Config.Addrs.snmp_incoming
8158 DEFAULT_DOC: Accept SNMP packets from all machine interfaces.
8161 Just like 'udp_incoming_address', but for the SNMP port.
8163 snmp_incoming_address is used for the SNMP socket receiving
8164 messages from SNMP agents.
8166 The default snmp_incoming_address is to listen on all
8167 available network interfaces.
8170 NAME: snmp_outgoing_address
8172 LOC: Config.Addrs.snmp_outgoing
8174 DEFAULT_DOC: Use snmp_incoming_address or an address selected by the operating system.
8177 Just like 'udp_outgoing_address', but for the SNMP port.
8179 snmp_outgoing_address is used for SNMP packets returned to SNMP
8182 If snmp_outgoing_address is not set it will use the same socket
8183 as snmp_incoming_address. Only change this if you want to have
8184 SNMP replies sent using another address than where this Squid
8185 listens for SNMP queries.
8187 NOTE, snmp_incoming_address and snmp_outgoing_address can not have
8188 the same value since they both use the same port.
8193 -----------------------------------------------------------------------------
8196 NAME: icp_port udp_port
8199 DEFAULT_DOC: ICP disabled.
8200 LOC: Config.Port.icp
8202 The port number where Squid sends and receives ICP queries to
8203 and from neighbor caches. The standard UDP port for ICP is 3130.
8206 icp_port @DEFAULT_ICP_PORT@
8213 DEFAULT_DOC: HTCP disabled.
8214 LOC: Config.Port.htcp
8216 The port number where Squid sends and receives HTCP queries to
8217 and from neighbor caches. To turn it on you want to set it to
8224 NAME: log_icp_queries
8228 LOC: Config.onoff.log_udp
8230 If set, ICP queries are logged to access.log. You may wish
8231 do disable this if your ICP load is VERY high to speed things
8232 up or to simplify log analysis.
8235 NAME: udp_incoming_address
8237 LOC:Config.Addrs.udp_incoming
8239 DEFAULT_DOC: Accept packets from all machine interfaces.
8241 udp_incoming_address is used for UDP packets received from other
8244 The default behavior is to not bind to any specific address.
8246 Only change this if you want to have all UDP queries received on
8247 a specific interface/address.
8249 NOTE: udp_incoming_address is used by the ICP, HTCP, and DNS
8250 modules. Altering it will affect all of them in the same manner.
8252 see also; udp_outgoing_address
8254 NOTE, udp_incoming_address and udp_outgoing_address can not
8255 have the same value since they both use the same port.
8258 NAME: udp_outgoing_address
8260 LOC: Config.Addrs.udp_outgoing
8262 DEFAULT_DOC: Use udp_incoming_address or an address selected by the operating system.
8264 udp_outgoing_address is used for UDP packets sent out to other
8267 The default behavior is to not bind to any specific address.
8269 Instead it will use the same socket as udp_incoming_address.
8270 Only change this if you want to have UDP queries sent using another
8271 address than where this Squid listens for UDP queries from other
8274 NOTE: udp_outgoing_address is used by the ICP, HTCP, and DNS
8275 modules. Altering it will affect all of them in the same manner.
8277 see also; udp_incoming_address
8279 NOTE, udp_incoming_address and udp_outgoing_address can not
8280 have the same value since they both use the same port.
8287 LOC: Config.onoff.icp_hit_stale
8289 If you want to return ICP_HIT for stale cache objects, set this
8290 option to 'on'. If you have sibling relationships with caches
8291 in other administrative domains, this should be 'off'. If you only
8292 have sibling relationships with caches under your control,
8293 it is probably okay to set this to 'on'.
8294 If set to 'on', your siblings should use the option "allow-miss"
8295 on their cache_peer lines for connecting to you.
8298 NAME: minimum_direct_hops
8301 LOC: Config.minDirectHops
8303 If using the ICMP pinging stuff, do direct fetches for sites
8304 which are no more than this many hops away.
8307 NAME: minimum_direct_rtt
8311 LOC: Config.minDirectRtt
8313 If using the ICMP pinging stuff, do direct fetches for sites
8314 which are no more than this many rtt milliseconds away.
8320 LOC: Config.Netdb.low
8322 The low water mark for the ICMP measurement database.
8324 Note: high watermark controlled by netdb_high directive.
8326 These watermarks are counts, not percents. The defaults are
8327 (low) 900 and (high) 1000. When the high water mark is
8328 reached, database entries will be deleted until the low
8335 LOC: Config.Netdb.high
8337 The high water mark for the ICMP measurement database.
8339 Note: low watermark controlled by netdb_low directive.
8341 These watermarks are counts, not percents. The defaults are
8342 (low) 900 and (high) 1000. When the high water mark is
8343 reached, database entries will be deleted until the low
8347 NAME: netdb_ping_period
8349 LOC: Config.Netdb.period
8352 The minimum period for measuring a site. There will be at
8353 least this much delay between successive pings to the same
8354 network. The default is five minutes.
8361 LOC: Config.onoff.query_icmp
8363 If you want to ask your peers to include ICMP data in their ICP
8364 replies, enable this option.
8366 If your peer has configured Squid (during compilation) with
8367 '--enable-icmp' that peer will send ICMP pings to origin server
8368 sites of the URLs it receives. If you enable this option the
8369 ICP replies from that peer will include the ICMP data (if available).
8370 Then, when choosing a parent cache, Squid will choose the parent with
8371 the minimal RTT to the origin server. When this happens, the
8372 hierarchy field of the access.log will be
8373 "CLOSEST_PARENT_MISS". This option is off by default.
8376 NAME: test_reachability
8380 LOC: Config.onoff.test_reachability
8382 When this is 'on', ICP MISS replies will be ICP_MISS_NOFETCH
8383 instead of ICP_MISS if the target host is NOT in the ICMP
8384 database, or has a zero RTT.
8387 NAME: icp_query_timeout
8390 DEFAULT_DOC: Dynamic detection.
8392 LOC: Config.Timeout.icp_query
8394 Normally Squid will automatically determine an optimal ICP
8395 query timeout value based on the round-trip-time of recent ICP
8396 queries. If you want to override the value determined by
8397 Squid, set this 'icp_query_timeout' to a non-zero value. This
8398 value is specified in MILLISECONDS, so, to use a 2-second
8399 timeout (the old default), you would write:
8401 icp_query_timeout 2000
8404 NAME: maximum_icp_query_timeout
8408 LOC: Config.Timeout.icp_query_max
8410 Normally the ICP query timeout is determined dynamically. But
8411 sometimes it can lead to very large values (say 5 seconds).
8412 Use this option to put an upper limit on the dynamic timeout
8413 value. Do NOT use this option to always use a fixed (instead
8414 of a dynamic) timeout value. To set a fixed timeout see the
8415 'icp_query_timeout' directive.
8418 NAME: minimum_icp_query_timeout
8422 LOC: Config.Timeout.icp_query_min
8424 Normally the ICP query timeout is determined dynamically. But
8425 sometimes it can lead to very small timeouts, even lower than
8426 the normal latency variance on your link due to traffic.
8427 Use this option to put an lower limit on the dynamic timeout
8428 value. Do NOT use this option to always use a fixed (instead
8429 of a dynamic) timeout value. To set a fixed timeout see the
8430 'icp_query_timeout' directive.
8433 NAME: background_ping_rate
8437 LOC: Config.backgroundPingRate
8439 Controls how often the ICP pings are sent to siblings that
8440 have background-ping set.
8444 MULTICAST ICP OPTIONS
8445 -----------------------------------------------------------------------------
8450 LOC: Config.mcast_group_list
8453 This tag specifies a list of multicast groups which your server
8454 should join to receive multicasted ICP queries.
8456 NOTE! Be very careful what you put here! Be sure you
8457 understand the difference between an ICP _query_ and an ICP
8458 _reply_. This option is to be set only if you want to RECEIVE
8459 multicast queries. Do NOT set this option to SEND multicast
8460 ICP (use cache_peer for that). ICP replies are always sent via
8461 unicast, so this option does not affect whether or not you will
8462 receive replies from multicast group members.
8464 You must be very careful to NOT use a multicast address which
8465 is already in use by another group of caches.
8467 If you are unsure about multicast, please read the Multicast
8468 chapter in the Squid FAQ (http://www.squid-cache.org/FAQ/).
8470 Usage: mcast_groups 239.128.16.128 224.0.1.20
8472 By default, Squid doesn't listen on any multicast groups.
8475 NAME: mcast_miss_addr
8476 IFDEF: MULTICAST_MISS_STREAM
8478 LOC: Config.mcast_miss.addr
8480 DEFAULT_DOC: disabled.
8482 If you enable this option, every "cache miss" URL will
8483 be sent out on the specified multicast address.
8485 Do not enable this option unless you are are absolutely
8486 certain you understand what you are doing.
8489 NAME: mcast_miss_ttl
8490 IFDEF: MULTICAST_MISS_STREAM
8492 LOC: Config.mcast_miss.ttl
8495 This is the time-to-live value for packets multicasted
8496 when multicasting off cache miss URLs is enabled. By
8497 default this is set to 'site scope', i.e. 16.
8500 NAME: mcast_miss_port
8501 IFDEF: MULTICAST_MISS_STREAM
8503 LOC: Config.mcast_miss.port
8506 This is the port number to be used in conjunction with
8510 NAME: mcast_miss_encode_key
8511 IFDEF: MULTICAST_MISS_STREAM
8513 LOC: Config.mcast_miss.encode_key
8514 DEFAULT: XXXXXXXXXXXXXXXX
8516 The URLs that are sent in the multicast miss stream are
8517 encrypted. This is the encryption key.
8520 NAME: mcast_icp_query_timeout
8524 LOC: Config.Timeout.mcast_icp_query
8526 For multicast peers, Squid regularly sends out ICP "probes" to
8527 count how many other peers are listening on the given multicast
8528 address. This value specifies how long Squid should wait to
8529 count all the replies. The default is 2000 msec, or 2
8534 INTERNAL ICON OPTIONS
8535 -----------------------------------------------------------------------------
8538 NAME: icon_directory
8540 LOC: Config.icons.directory
8541 DEFAULT: @DEFAULT_ICON_DIR@
8543 Where the icons are stored. These are normally kept in
8547 NAME: global_internal_static
8549 LOC: Config.onoff.global_internal_static
8552 This directive controls is Squid should intercept all requests for
8553 /squid-internal-static/ no matter which host the URL is requesting
8554 (default on setting), or if nothing special should be done for
8555 such URLs (off setting). The purpose of this directive is to make
8556 icons etc work better in complex cache hierarchies where it may
8557 not always be possible for all corners in the cache mesh to reach
8558 the server generating a directory listing.
8561 NAME: short_icon_urls
8563 LOC: Config.icons.use_short_names
8566 If this is enabled Squid will use short URLs for icons.
8567 If disabled it will revert to the old behavior of including
8568 it's own name and port in the URL.
8570 If you run a complex cache hierarchy with a mix of Squid and
8571 other proxies you may need to disable this directive.
8576 -----------------------------------------------------------------------------
8579 NAME: error_directory
8581 LOC: Config.errorDirectory
8583 DEFAULT_DOC: Send error pages in the clients preferred language
8585 If you wish to create your own versions of the default
8586 error files to customize them to suit your company copy
8587 the error/template files to another directory and point
8590 WARNING: This option will disable multi-language support
8591 on error pages if used.
8593 The squid developers are interested in making squid available in
8594 a wide variety of languages. If you are making translations for a
8595 language that Squid does not currently provide please consider
8596 contributing your translation back to the project.
8597 http://wiki.squid-cache.org/Translations
8599 The squid developers working on translations are happy to supply drop-in
8600 translated error files in exchange for any new language contributions.
8603 NAME: error_default_language
8604 IFDEF: USE_ERR_LOCALES
8606 LOC: Config.errorDefaultLanguage
8608 DEFAULT_DOC: Generate English language pages.
8610 Set the default language which squid will send error pages in
8611 if no existing translation matches the clients language
8614 If unset (default) generic English will be used.
8616 The squid developers are interested in making squid available in
8617 a wide variety of languages. If you are interested in making
8618 translations for any language see the squid wiki for details.
8619 http://wiki.squid-cache.org/Translations
8622 NAME: error_log_languages
8623 IFDEF: USE_ERR_LOCALES
8625 LOC: Config.errorLogMissingLanguages
8628 Log to cache.log what languages users are attempting to
8629 auto-negotiate for translations.
8631 Successful negotiations are not logged. Only failures
8632 have meaning to indicate that Squid may need an upgrade
8633 of its error page translations.
8636 NAME: err_page_stylesheet
8638 LOC: Config.errorStylesheet
8639 DEFAULT: @DEFAULT_CONFIG_DIR@/errorpage.css
8641 CSS Stylesheet to pattern the display of Squid default error pages.
8643 For information on CSS see http://www.w3.org/Style/CSS/
8648 LOC: Config.errHtmlText
8651 HTML text to include in error messages. Make this a "mailto"
8652 URL to your admin address, or maybe just a link to your
8653 organizations Web page.
8655 To include this in your error messages, you must rewrite
8656 the error template files (found in the "errors" directory).
8657 Wherever you want the 'err_html_text' line to appear,
8658 insert a %L tag in the error template file.
8661 NAME: email_err_data
8664 LOC: Config.onoff.emailErrData
8667 If enabled, information about the occurred error will be
8668 included in the mailto links of the ERR pages (if %W is set)
8669 so that the email body contains the data.
8670 Syntax is <A HREF="mailto:%w%W">%w</A>
8675 LOC: Config.denyInfoList
8678 Usage: deny_info err_page_name acl
8679 or deny_info http://... acl
8680 or deny_info TCP_RESET acl
8682 This can be used to return a ERR_ page for requests which
8683 do not pass the 'http_access' rules. Squid remembers the last
8684 acl it evaluated in http_access, and if a 'deny_info' line exists
8685 for that ACL Squid returns a corresponding error page.
8687 The acl is typically the last acl on the http_access deny line which
8688 denied access. The exceptions to this rule are:
8689 - When Squid needs to request authentication credentials. It's then
8690 the first authentication related acl encountered
8691 - When none of the http_access lines matches. It's then the last
8692 acl processed on the last http_access line.
8693 - When the decision to deny access was made by an adaptation service,
8694 the acl name is the corresponding eCAP or ICAP service_name.
8696 NP: If providing your own custom error pages with error_directory
8697 you may also specify them by your custom file name:
8698 Example: deny_info ERR_CUSTOM_ACCESS_DENIED bad_guys
8700 By defaut Squid will send "403 Forbidden". A different 4xx or 5xx
8701 may be specified by prefixing the file name with the code and a colon.
8702 e.g. 404:ERR_CUSTOM_ACCESS_DENIED
8704 Alternatively you can tell Squid to reset the TCP connection
8705 by specifying TCP_RESET.
8707 Or you can specify an error URL or URL pattern. The browsers will
8708 get redirected to the specified URL after formatting tags have
8709 been replaced. Redirect will be done with 302 or 307 according to
8710 HTTP/1.1 specs. A different 3xx code may be specified by prefixing
8711 the URL. e.g. 303:http://example.com/
8714 %a - username (if available. Password NOT included)
8715 %A - Local listening IP address the client connection was connected to
8718 %E - Error description
8720 %H - Request domain name
8721 %i - Client IP Address
8723 %O - Unescaped message result from external ACL helper
8724 %o - Message result from external ACL helper
8725 %p - Request Port number
8726 %P - Request Protocol name
8727 %R - Request URL path
8728 %T - Timestamp in RFC 1123 format
8729 %U - Full canonical URL from client
8730 (HTTPS URLs terminate with *)
8731 %u - Full canonical URL from client
8732 %w - Admin email from squid.conf
8734 %% - Literal percent (%) code
8739 OPTIONS INFLUENCING REQUEST FORWARDING
8740 -----------------------------------------------------------------------------
8743 NAME: nonhierarchical_direct
8745 LOC: Config.onoff.nonhierarchical_direct
8748 By default, Squid will send any non-hierarchical requests
8749 (not cacheable request type) direct to origin servers.
8751 When this is set to "off", Squid will prefer to send these
8752 requests to parents.
8754 Note that in most configurations, by turning this off you will only
8755 add latency to these request without any improvement in global hit
8758 This option only sets a preference. If the parent is unavailable a
8759 direct connection to the origin server may still be attempted. To
8760 completely prevent direct connections use never_direct.
8765 LOC: Config.onoff.prefer_direct
8768 Normally Squid tries to use parents for most requests. If you for some
8769 reason like it to first try going direct and only use a parent if
8770 going direct fails set this to on.
8772 By combining nonhierarchical_direct off and prefer_direct on you
8773 can set up Squid to use a parent as a backup path if going direct
8776 Note: If you want Squid to use parents for all requests see
8777 the never_direct directive. prefer_direct only modifies how Squid
8778 acts on cacheable requests.
8781 NAME: cache_miss_revalidate
8785 LOC: Config.onoff.cache_miss_revalidate
8787 RFC 7232 defines a conditional request mechanism to prevent
8788 response objects being unnecessarily transferred over the network.
8789 If that mechanism is used by the client and a cache MISS occurs
8790 it can prevent new cache entries being created.
8792 This option determines whether Squid on cache MISS will pass the
8793 client revalidation request to the server or tries to fetch new
8794 content for caching. It can be useful while the cache is mostly
8795 empty to more quickly have the cache populated by generating
8796 non-conditional GETs.
8798 When set to 'on' (default), Squid will pass all client If-* headers
8799 to the server. This permits server responses without a cacheable
8800 payload to be delivered and on MISS no new cache entry is created.
8802 When set to 'off' and if the request is cacheable, Squid will
8803 remove the clients If-Modified-Since and If-None-Match headers from
8804 the request sent to the server. This requests a 200 status response
8805 from the server to create a new cache entry with.
8810 LOC: Config.accessList.AlwaysDirect
8812 DEFAULT_DOC: Prevent any cache_peer being used for this request.
8814 Usage: always_direct allow|deny [!]aclname ...
8816 Here you can use ACL elements to specify requests which should
8817 ALWAYS be forwarded by Squid to the origin servers without using
8818 any peers. For example, to always directly forward requests for
8819 local servers ignoring any parents or siblings you may have use
8822 acl local-servers dstdomain my.domain.net
8823 always_direct allow local-servers
8825 To always forward FTP requests directly, use
8828 always_direct allow FTP
8830 NOTE: There is a similar, but opposite option named
8831 'never_direct'. You need to be aware that "always_direct deny
8832 foo" is NOT the same thing as "never_direct allow foo". You
8833 may need to use a deny rule to exclude a more-specific case of
8834 some other rule. Example:
8836 acl local-external dstdomain external.foo.net
8837 acl local-servers dstdomain .foo.net
8838 always_direct deny local-external
8839 always_direct allow local-servers
8841 NOTE: If your goal is to make the client forward the request
8842 directly to the origin server bypassing Squid then this needs
8843 to be done in the client configuration. Squid configuration
8844 can only tell Squid how Squid should fetch the object.
8846 NOTE: This directive is not related to caching. The replies
8847 is cached as usual even if you use always_direct. To not cache
8848 the replies see the 'cache' directive.
8850 This clause supports both fast and slow acl types.
8851 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
8856 LOC: Config.accessList.NeverDirect
8858 DEFAULT_DOC: Allow DNS results to be used for this request.
8860 Usage: never_direct allow|deny [!]aclname ...
8862 never_direct is the opposite of always_direct. Please read
8863 the description for always_direct if you have not already.
8865 With 'never_direct' you can use ACL elements to specify
8866 requests which should NEVER be forwarded directly to origin
8867 servers. For example, to force the use of a proxy for all
8868 requests, except those in your local domain use something like:
8870 acl local-servers dstdomain .foo.net
8871 never_direct deny local-servers
8872 never_direct allow all
8874 or if Squid is inside a firewall and there are local intranet
8875 servers inside the firewall use something like:
8877 acl local-intranet dstdomain .foo.net
8878 acl local-external dstdomain external.foo.net
8879 always_direct deny local-external
8880 always_direct allow local-intranet
8881 never_direct allow all
8883 This clause supports both fast and slow acl types.
8884 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
8888 ADVANCED NETWORKING OPTIONS
8889 -----------------------------------------------------------------------------
8892 NAME: incoming_udp_average incoming_icp_average
8895 LOC: Config.comm_incoming.udp.average
8897 Heavy voodoo here. I can't even believe you are reading this.
8898 Are you crazy? Don't even think about adjusting these unless
8899 you understand the algorithms in comm_select.c first!
8902 NAME: incoming_tcp_average incoming_http_average
8905 LOC: Config.comm_incoming.tcp.average
8907 Heavy voodoo here. I can't even believe you are reading this.
8908 Are you crazy? Don't even think about adjusting these unless
8909 you understand the algorithms in comm_select.c first!
8912 NAME: incoming_dns_average
8915 LOC: Config.comm_incoming.dns.average
8917 Heavy voodoo here. I can't even believe you are reading this.
8918 Are you crazy? Don't even think about adjusting these unless
8919 you understand the algorithms in comm_select.c first!
8922 NAME: min_udp_poll_cnt min_icp_poll_cnt
8925 LOC: Config.comm_incoming.udp.min_poll
8927 Heavy voodoo here. I can't even believe you are reading this.
8928 Are you crazy? Don't even think about adjusting these unless
8929 you understand the algorithms in comm_select.c first!
8932 NAME: min_dns_poll_cnt
8935 LOC: Config.comm_incoming.dns.min_poll
8937 Heavy voodoo here. I can't even believe you are reading this.
8938 Are you crazy? Don't even think about adjusting these unless
8939 you understand the algorithms in comm_select.c first!
8942 NAME: min_tcp_poll_cnt min_http_poll_cnt
8945 LOC: Config.comm_incoming.tcp.min_poll
8947 Heavy voodoo here. I can't even believe you are reading this.
8948 Are you crazy? Don't even think about adjusting these unless
8949 you understand the algorithms in comm_select.c first!
8955 LOC: Config.accept_filter
8959 The name of an accept(2) filter to install on Squid's
8960 listen socket(s). This feature is perhaps specific to
8961 FreeBSD and requires support in the kernel.
8963 The 'httpready' filter delays delivering new connections
8964 to Squid until a full HTTP request has been received.
8965 See the accf_http(9) man page for details.
8967 The 'dataready' filter delays delivering new connections
8968 to Squid until there is some data to process.
8969 See the accf_dataready(9) man page for details.
8973 The 'data' filter delays delivering of new connections
8974 to Squid until there is some data to process by TCP_ACCEPT_DEFER.
8975 You may optionally specify a number of seconds to wait by
8976 'data=N' where N is the number of seconds. Defaults to 30
8977 if not specified. See the tcp(7) man page for details.
8980 accept_filter httpready
8985 NAME: client_ip_max_connections
8987 LOC: Config.client_ip_max_connections
8989 DEFAULT_DOC: No limit.
8991 Set an absolute limit on the number of connections a single
8992 client IP can use. Any more than this and Squid will begin to drop
8993 new connections from the client until it closes some links.
8995 Note that this is a global limit. It affects all HTTP, HTCP, Gopher and FTP
8996 connections from the client. For finer control use the ACL access controls.
8998 Requires client_db to be enabled (the default).
9000 WARNING: This may noticably slow down traffic received via external proxies
9001 or NAT devices and cause them to rebound error messages back to their clients.
9004 NAME: tcp_recv_bufsize
9008 DEFAULT_DOC: Use operating system TCP defaults.
9009 LOC: Config.tcpRcvBufsz
9011 Size of receive buffer to set for TCP sockets. Probably just
9012 as easy to change your kernel's default.
9013 Omit from squid.conf to use the default buffer size.
9018 -----------------------------------------------------------------------------
9025 LOC: Adaptation::Icap::TheConfig.onoff
9028 If you want to enable the ICAP module support, set this to on.
9031 NAME: icap_connect_timeout
9034 LOC: Adaptation::Icap::TheConfig.connect_timeout_raw
9037 This parameter specifies how long to wait for the TCP connect to
9038 the requested ICAP server to complete before giving up and either
9039 terminating the HTTP transaction or bypassing the failure.
9041 The default for optional services is peer_connect_timeout.
9042 The default for essential services is connect_timeout.
9043 If this option is explicitly set, its value applies to all services.
9046 NAME: icap_io_timeout
9050 DEFAULT_DOC: Use read_timeout.
9051 LOC: Adaptation::Icap::TheConfig.io_timeout_raw
9054 This parameter specifies how long to wait for an I/O activity on
9055 an established, active ICAP connection before giving up and
9056 either terminating the HTTP transaction or bypassing the
9060 NAME: icap_service_failure_limit
9061 COMMENT: limit [in memory-depth time-units]
9062 TYPE: icap_service_failure_limit
9064 LOC: Adaptation::Icap::TheConfig
9067 The limit specifies the number of failures that Squid tolerates
9068 when establishing a new TCP connection with an ICAP service. If
9069 the number of failures exceeds the limit, the ICAP service is
9070 not used for new ICAP requests until it is time to refresh its
9073 A negative value disables the limit. Without the limit, an ICAP
9074 service will not be considered down due to connectivity failures
9075 between ICAP OPTIONS requests.
9077 Squid forgets ICAP service failures older than the specified
9078 value of memory-depth. The memory fading algorithm
9079 is approximate because Squid does not remember individual
9080 errors but groups them instead, splitting the option
9081 value into ten time slots of equal length.
9083 When memory-depth is 0 and by default this option has no
9084 effect on service failure expiration.
9086 Squid always forgets failures when updating service settings
9087 using an ICAP OPTIONS transaction, regardless of this option
9091 # suspend service usage after 10 failures in 5 seconds:
9092 icap_service_failure_limit 10 in 5 seconds
9095 NAME: icap_service_revival_delay
9098 LOC: Adaptation::Icap::TheConfig.service_revival_delay
9101 The delay specifies the number of seconds to wait after an ICAP
9102 OPTIONS request failure before requesting the options again. The
9103 failed ICAP service is considered "down" until fresh OPTIONS are
9106 The actual delay cannot be smaller than the hardcoded minimum
9107 delay of 30 seconds.
9110 NAME: icap_preview_enable
9114 LOC: Adaptation::Icap::TheConfig.preview_enable
9117 The ICAP Preview feature allows the ICAP server to handle the
9118 HTTP message by looking only at the beginning of the message body
9119 or even without receiving the body at all. In some environments,
9120 previews greatly speedup ICAP processing.
9122 During an ICAP OPTIONS transaction, the server may tell Squid what
9123 HTTP messages should be previewed and how big the preview should be.
9124 Squid will not use Preview if the server did not request one.
9126 To disable ICAP Preview for all ICAP services, regardless of
9127 individual ICAP server OPTIONS responses, set this option to "off".
9129 icap_preview_enable off
9132 NAME: icap_preview_size
9135 LOC: Adaptation::Icap::TheConfig.preview_size
9137 DEFAULT_DOC: No preview sent.
9139 The default size of preview data to be sent to the ICAP server.
9140 This value might be overwritten on a per server basis by OPTIONS requests.
9143 NAME: icap_206_enable
9147 LOC: Adaptation::Icap::TheConfig.allow206_enable
9150 206 (Partial Content) responses is an ICAP extension that allows the
9151 ICAP agents to optionally combine adapted and original HTTP message
9152 content. The decision to combine is postponed until the end of the
9153 ICAP response. Squid supports Partial Content extension by default.
9155 Activation of the Partial Content extension is negotiated with each
9156 ICAP service during OPTIONS exchange. Most ICAP servers should handle
9157 negotation correctly even if they do not support the extension, but
9158 some might fail. To disable Partial Content support for all ICAP
9159 services and to avoid any negotiation, set this option to "off".
9165 NAME: icap_default_options_ttl
9168 LOC: Adaptation::Icap::TheConfig.default_options_ttl
9171 The default TTL value for ICAP OPTIONS responses that don't have
9172 an Options-TTL header.
9175 NAME: icap_persistent_connections
9179 LOC: Adaptation::Icap::TheConfig.reuse_connections
9182 Whether or not Squid should use persistent connections to
9186 NAME: adaptation_send_client_ip icap_send_client_ip
9188 IFDEF: USE_ADAPTATION
9190 LOC: Adaptation::Config::send_client_ip
9193 If enabled, Squid shares HTTP client IP information with adaptation
9194 services. For ICAP, Squid adds the X-Client-IP header to ICAP requests.
9195 For eCAP, Squid sets the libecap::metaClientIp transaction option.
9197 See also: adaptation_uses_indirect_client
9200 NAME: adaptation_send_username icap_send_client_username
9202 IFDEF: USE_ADAPTATION
9204 LOC: Adaptation::Config::send_username
9207 This sends authenticated HTTP client username (if available) to
9208 the adaptation service.
9210 For ICAP, the username value is encoded based on the
9211 icap_client_username_encode option and is sent using the header
9212 specified by the icap_client_username_header option.
9215 NAME: icap_client_username_header
9218 LOC: Adaptation::Icap::TheConfig.client_username_header
9219 DEFAULT: X-Client-Username
9221 ICAP request header name to use for adaptation_send_username.
9224 NAME: icap_client_username_encode
9228 LOC: Adaptation::Icap::TheConfig.client_username_encode
9231 Whether to base64 encode the authenticated client username.
9235 TYPE: icap_service_type
9237 LOC: Adaptation::Icap::TheConfig
9240 Defines a single ICAP service using the following format:
9242 icap_service id vectoring_point uri [option ...]
9245 an opaque identifier or name which is used to direct traffic to
9246 this specific service. Must be unique among all adaptation
9247 services in squid.conf.
9249 vectoring_point: reqmod_precache|reqmod_postcache|respmod_precache|respmod_postcache
9250 This specifies at which point of transaction processing the
9251 ICAP service should be activated. *_postcache vectoring points
9252 are not yet supported.
9254 uri: icap://servername:port/servicepath
9255 ICAP server and service location.
9256 icaps://servername:port/servicepath
9257 The "icap:" URI scheme is used for traditional ICAP server and
9258 service location (default port is 1344, connections are not
9259 encrypted). The "icaps:" URI scheme is for Secure ICAP
9260 services that use SSL/TLS-encrypted ICAP connections (by
9261 default, on port 11344).
9263 ICAP does not allow a single service to handle both REQMOD and RESPMOD
9264 transactions. Squid does not enforce that requirement. You can specify
9265 services with the same service_url and different vectoring_points. You
9266 can even specify multiple identical services as long as their
9267 service_names differ.
9269 To activate a service, use the adaptation_access directive. To group
9270 services, use adaptation_service_chain and adaptation_service_set.
9272 Service options are separated by white space. ICAP services support
9273 the following name=value options:
9276 If set to 'on' or '1', the ICAP service is treated as
9277 optional. If the service cannot be reached or malfunctions,
9278 Squid will try to ignore any errors and process the message as
9279 if the service was not enabled. No all ICAP errors can be
9280 bypassed. If set to 0, the ICAP service is treated as
9281 essential and all ICAP errors will result in an error page
9282 returned to the HTTP client.
9284 Bypass is off by default: services are treated as essential.
9287 If set to 'on' or '1', the ICAP service is allowed to
9288 dynamically change the current message adaptation plan by
9289 returning a chain of services to be used next. The services
9290 are specified using the X-Next-Services ICAP response header
9291 value, formatted as a comma-separated list of service names.
9292 Each named service should be configured in squid.conf. Other
9293 services are ignored. An empty X-Next-Services value results
9294 in an empty plan which ends the current adaptation.
9296 Dynamic adaptation plan may cross or cover multiple supported
9297 vectoring points in their natural processing order.
9299 Routing is not allowed by default: the ICAP X-Next-Services
9300 response header is ignored.
9303 Only has effect on split-stack systems. The default on those systems
9304 is to use IPv4-only connections. When set to 'on' this option will
9305 make Squid use IPv6-only connections to contact this ICAP service.
9307 on-overload=block|bypass|wait|force
9308 If the service Max-Connections limit has been reached, do
9309 one of the following for each new ICAP transaction:
9310 * block: send an HTTP error response to the client
9311 * bypass: ignore the "over-connected" ICAP service
9312 * wait: wait (in a FIFO queue) for an ICAP connection slot
9313 * force: proceed, ignoring the Max-Connections limit
9315 In SMP mode with N workers, each worker assumes the service
9316 connection limit is Max-Connections/N, even though not all
9317 workers may use a given service.
9319 The default value is "bypass" if service is bypassable,
9320 otherwise it is set to "wait".
9324 Use the given number as the Max-Connections limit, regardless
9325 of the Max-Connections value given by the service, if any.
9327 connection-encryption=on|off
9328 Determines the ICAP service effect on the connections_encrypted
9331 The default is "on" for Secure ICAP services (i.e., those
9332 with the icaps:// service URIs scheme) and "off" for plain ICAP
9335 Does not affect ICAP connections (e.g., does not turn Secure
9338 ==== ICAPS / TLS OPTIONS ====
9340 These options are used for Secure ICAP (icaps://....) services only.
9342 tls-cert=/path/to/ssl/certificate
9343 A client X.509 certificate to use when connecting to
9346 tls-key=/path/to/ssl/key
9347 The private key corresponding to the previous
9350 If tls-key= is not specified tls-cert= is assumed to
9351 reference a PEM file containing both the certificate
9354 tls-cipher=... The list of valid TLS/SSL ciphers to use when connecting
9355 to this icap server.
9358 The minimum TLS protocol version to permit. To control
9359 SSLv3 use the tls-options= parameter.
9360 Supported Values: 1.0 (default), 1.1, 1.2
9362 tls-options=... Specify various OpenSSL library options:
9364 NO_SSLv3 Disallow the use of SSLv3
9367 Always create a new key when using
9368 temporary/ephemeral DH key exchanges
9370 ALL Enable various bug workarounds
9371 suggested as "harmless" by OpenSSL
9372 Be warned that this reduces SSL/TLS
9373 strength to some attacks.
9375 See the OpenSSL SSL_CTX_set_options documentation for a
9376 more complete list. Options relevant only to SSLv2 are
9379 tls-cafile= PEM file containing CA certificates to use when verifying
9380 the icap server certificate.
9381 Use to specify intermediate CA certificate(s) if not sent
9382 by the server. Or the full CA chain for the server when
9383 using the tls-default-ca=off flag.
9384 May be repeated to load multiple files.
9386 tls-capath=... A directory containing additional CA certificates to
9387 use when verifying the icap server certificate.
9388 Requires OpenSSL or LibreSSL.
9390 tls-crlfile=... A certificate revocation list file to use when
9391 verifying the icap server certificate.
9393 tls-flags=... Specify various flags modifying the Squid TLS implementation:
9396 Accept certificates even if they fail to
9399 Don't verify the icap server certificate
9400 matches the server name
9402 tls-default-ca[=off]
9403 Whether to use the system Trusted CAs. Default is ON.
9405 tls-domain= The icap server name as advertised in it's certificate.
9406 Used for verifying the correctness of the received icap
9407 server certificate. If not specified the icap server
9408 hostname extracted from ICAP URI will be used.
9410 Older icap_service format without optional named parameters is
9411 deprecated but supported for backward compatibility.
9414 icap_service svcBlocker reqmod_precache icap://icap1.mydomain.net:1344/reqmod bypass=0
9415 icap_service svcLogger reqmod_precache icaps://icap2.mydomain.net:11344/reqmod routing=on
9419 TYPE: icap_class_type
9424 This deprecated option was documented to define an ICAP service
9425 chain, even though it actually defined a set of similar, redundant
9426 services, and the chains were not supported.
9428 To define a set of redundant services, please use the
9429 adaptation_service_set directive. For service chains, use
9430 adaptation_service_chain.
9434 TYPE: icap_access_type
9439 This option is deprecated. Please use adaptation_access, which
9440 has the same ICAP functionality, but comes with better
9441 documentation, and eCAP support.
9446 -----------------------------------------------------------------------------
9453 LOC: Adaptation::Ecap::TheConfig.onoff
9456 Controls whether eCAP support is enabled.
9460 TYPE: ecap_service_type
9462 LOC: Adaptation::Ecap::TheConfig
9465 Defines a single eCAP service
9467 ecap_service id vectoring_point uri [option ...]
9470 an opaque identifier or name which is used to direct traffic to
9471 this specific service. Must be unique among all adaptation
9472 services in squid.conf.
9474 vectoring_point: reqmod_precache|reqmod_postcache|respmod_precache|respmod_postcache
9475 This specifies at which point of transaction processing the
9476 eCAP service should be activated. *_postcache vectoring points
9477 are not yet supported.
9479 uri: ecap://vendor/service_name?custom&cgi=style¶meters=optional
9480 Squid uses the eCAP service URI to match this configuration
9481 line with one of the dynamically loaded services. Each loaded
9482 eCAP service must have a unique URI. Obtain the right URI from
9483 the service provider.
9485 To activate a service, use the adaptation_access directive. To group
9486 services, use adaptation_service_chain and adaptation_service_set.
9488 Service options are separated by white space. eCAP services support
9489 the following name=value options:
9492 If set to 'on' or '1', the eCAP service is treated as optional.
9493 If the service cannot be reached or malfunctions, Squid will try
9494 to ignore any errors and process the message as if the service
9495 was not enabled. No all eCAP errors can be bypassed.
9496 If set to 'off' or '0', the eCAP service is treated as essential
9497 and all eCAP errors will result in an error page returned to the
9500 Bypass is off by default: services are treated as essential.
9503 If set to 'on' or '1', the eCAP service is allowed to
9504 dynamically change the current message adaptation plan by
9505 returning a chain of services to be used next.
9507 Dynamic adaptation plan may cross or cover multiple supported
9508 vectoring points in their natural processing order.
9510 Routing is not allowed by default.
9512 connection-encryption=on|off
9513 Determines the eCAP service effect on the connections_encrypted
9516 Defaults to "on", which does not taint the master transaction
9519 Does not affect eCAP API calls.
9521 Older ecap_service format without optional named parameters is
9522 deprecated but supported for backward compatibility.
9526 ecap_service s1 reqmod_precache ecap://filters.R.us/leakDetector?on_error=block bypass=off
9527 ecap_service s2 respmod_precache ecap://filters.R.us/virusFilter config=/etc/vf.cfg bypass=on
9530 NAME: loadable_modules
9532 IFDEF: USE_LOADABLE_MODULES
9533 LOC: Config.loadable_module_names
9536 Instructs Squid to load the specified dynamic module(s) or activate
9537 preloaded module(s).
9539 loadable_modules @DEFAULT_PREFIX@/lib/MinimalAdapter.so
9543 MESSAGE ADAPTATION OPTIONS
9544 -----------------------------------------------------------------------------
9547 NAME: adaptation_service_set
9548 TYPE: adaptation_service_set_type
9549 IFDEF: USE_ADAPTATION
9554 Configures an ordered set of similar, redundant services. This is
9555 useful when hot standby or backup adaptation servers are available.
9557 adaptation_service_set set_name service_name1 service_name2 ...
9559 The named services are used in the set declaration order. The first
9560 applicable adaptation service from the set is used first. The next
9561 applicable service is tried if and only if the transaction with the
9562 previous service fails and the message waiting to be adapted is still
9565 When adaptation starts, broken services are ignored as if they were
9566 not a part of the set. A broken service is a down optional service.
9568 The services in a set must be attached to the same vectoring point
9569 (e.g., pre-cache) and use the same adaptation method (e.g., REQMOD).
9571 If all services in a set are optional then adaptation failures are
9572 bypassable. If all services in the set are essential, then a
9573 transaction failure with one service may still be retried using
9574 another service from the set, but when all services fail, the master
9575 transaction fails as well.
9577 A set may contain a mix of optional and essential services, but that
9578 is likely to lead to surprising results because broken services become
9579 ignored (see above), making previously bypassable failures fatal.
9580 Technically, it is the bypassability of the last failed service that
9583 See also: adaptation_access adaptation_service_chain
9586 adaptation_service_set svcBlocker urlFilterPrimary urlFilterBackup
9587 adaptation service_set svcLogger loggerLocal loggerRemote
9590 NAME: adaptation_service_chain
9591 TYPE: adaptation_service_chain_type
9592 IFDEF: USE_ADAPTATION
9597 Configures a list of complementary services that will be applied
9598 one-by-one, forming an adaptation chain or pipeline. This is useful
9599 when Squid must perform different adaptations on the same message.
9601 adaptation_service_chain chain_name service_name1 svc_name2 ...
9603 The named services are used in the chain declaration order. The first
9604 applicable adaptation service from the chain is used first. The next
9605 applicable service is applied to the successful adaptation results of
9606 the previous service in the chain.
9608 When adaptation starts, broken services are ignored as if they were
9609 not a part of the chain. A broken service is a down optional service.
9611 Request satisfaction terminates the adaptation chain because Squid
9612 does not currently allow declaration of RESPMOD services at the
9613 "reqmod_precache" vectoring point (see icap_service or ecap_service).
9615 The services in a chain must be attached to the same vectoring point
9616 (e.g., pre-cache) and use the same adaptation method (e.g., REQMOD).
9618 A chain may contain a mix of optional and essential services. If an
9619 essential adaptation fails (or the failure cannot be bypassed for
9620 other reasons), the master transaction fails. Otherwise, the failure
9621 is bypassed as if the failed adaptation service was not in the chain.
9623 See also: adaptation_access adaptation_service_set
9626 adaptation_service_chain svcRequest requestLogger urlFilter leakDetector
9629 NAME: adaptation_access
9630 TYPE: adaptation_access_type
9631 IFDEF: USE_ADAPTATION
9634 DEFAULT_DOC: Allow, unless rules exist in squid.conf.
9636 Sends an HTTP transaction to an ICAP or eCAP adaptation service.
9638 adaptation_access service_name allow|deny [!]aclname...
9639 adaptation_access set_name allow|deny [!]aclname...
9641 At each supported vectoring point, the adaptation_access
9642 statements are processed in the order they appear in this
9643 configuration file. Statements pointing to the following services
9644 are ignored (i.e., skipped without checking their ACL):
9646 - services serving different vectoring points
9647 - "broken-but-bypassable" services
9648 - "up" services configured to ignore such transactions
9649 (e.g., based on the ICAP Transfer-Ignore header).
9651 When a set_name is used, all services in the set are checked
9652 using the same rules, to find the first applicable one. See
9653 adaptation_service_set for details.
9655 If an access list is checked and there is a match, the
9656 processing stops: For an "allow" rule, the corresponding
9657 adaptation service is used for the transaction. For a "deny"
9658 rule, no adaptation service is activated.
9660 It is currently not possible to apply more than one adaptation
9661 service at the same vectoring point to the same HTTP transaction.
9663 See also: icap_service and ecap_service
9666 adaptation_access service_1 allow all
9669 NAME: adaptation_service_iteration_limit
9671 IFDEF: USE_ADAPTATION
9672 LOC: Adaptation::Config::service_iteration_limit
9675 Limits the number of iterations allowed when applying adaptation
9676 services to a message. If your longest adaptation set or chain
9677 may have more than 16 services, increase the limit beyond its
9678 default value of 16. If detecting infinite iteration loops sooner
9679 is critical, make the iteration limit match the actual number
9680 of services in your longest adaptation set or chain.
9682 Infinite adaptation loops are most likely with routing services.
9684 See also: icap_service routing=1
9687 NAME: adaptation_masterx_shared_names
9689 IFDEF: USE_ADAPTATION
9690 LOC: Adaptation::Config::masterx_shared_name
9693 For each master transaction (i.e., the HTTP request and response
9694 sequence, including all related ICAP and eCAP exchanges), Squid
9695 maintains a table of metadata. The table entries are (name, value)
9696 pairs shared among eCAP and ICAP exchanges. The table is destroyed
9697 with the master transaction.
9699 This option specifies the table entry names that Squid must accept
9700 from and forward to the adaptation transactions.
9702 An ICAP REQMOD or RESPMOD transaction may set an entry in the
9703 shared table by returning an ICAP header field with a name
9704 specified in adaptation_masterx_shared_names.
9706 An eCAP REQMOD or RESPMOD transaction may set an entry in the
9707 shared table by implementing the libecap::visitEachOption() API
9708 to provide an option with a name specified in
9709 adaptation_masterx_shared_names.
9711 Squid will store and forward the set entry to subsequent adaptation
9712 transactions within the same master transaction scope.
9714 Only one shared entry name is supported at this time.
9717 # share authentication information among ICAP services
9718 adaptation_masterx_shared_names X-Subscriber-ID
9721 NAME: adaptation_meta
9723 IFDEF: USE_ADAPTATION
9724 LOC: Adaptation::Config::metaHeaders
9727 This option allows Squid administrator to add custom ICAP request
9728 headers or eCAP options to Squid ICAP requests or eCAP transactions.
9729 Use it to pass custom authentication tokens and other
9730 transaction-state related meta information to an ICAP/eCAP service.
9732 The addition of a meta header is ACL-driven:
9733 adaptation_meta name value [!]aclname ...
9735 Processing for a given header name stops after the first ACL list match.
9736 Thus, it is impossible to add two headers with the same name. If no ACL
9737 lists match for a given header name, no such header is added. For
9740 # do not debug transactions except for those that need debugging
9741 adaptation_meta X-Debug 1 needs_debugging
9743 # log all transactions except for those that must remain secret
9744 adaptation_meta X-Log 1 !keep_secret
9746 # mark transactions from users in the "G 1" group
9747 adaptation_meta X-Authenticated-Groups "G 1" authed_as_G1
9749 The "value" parameter may be a regular squid.conf token or a "double
9750 quoted string". Within the quoted string, use backslash (\) to escape
9751 any character, which is currently only useful for escaping backslashes
9752 and double quotes. For example,
9753 "this string has one backslash (\\) and two \"quotes\""
9755 Used adaptation_meta header values may be logged via %note
9756 logformat code. If multiple adaptation_meta headers with the same name
9757 are used during master transaction lifetime, the header values are
9758 logged in the order they were used and duplicate values are ignored
9759 (only the first repeated value will be logged).
9765 LOC: Adaptation::Icap::TheConfig.repeat
9766 DEFAULT_IF_NONE: deny all
9768 This ACL determines which retriable ICAP transactions are
9769 retried. Transactions that received a complete ICAP response
9770 and did not have to consume or produce HTTP bodies to receive
9771 that response are usually retriable.
9773 icap_retry allow|deny [!]aclname ...
9775 Squid automatically retries some ICAP I/O timeouts and errors
9776 due to persistent connection race conditions.
9778 See also: icap_retry_limit
9781 NAME: icap_retry_limit
9784 LOC: Adaptation::Icap::TheConfig.repeat_limit
9786 DEFAULT_DOC: No retries are allowed.
9788 Limits the number of retries allowed.
9790 Communication errors due to persistent connection race
9791 conditions are unavoidable, automatically retried, and do not
9792 count against this limit.
9794 See also: icap_retry
9800 -----------------------------------------------------------------------------
9803 NAME: check_hostnames
9806 LOC: Config.onoff.check_hostnames
9808 For security and stability reasons Squid can check
9809 hostnames for Internet standard RFC compliance. If you want
9810 Squid to perform these checks turn this directive on.
9813 NAME: allow_underscore
9816 LOC: Config.onoff.allow_underscore
9818 Underscore characters is not strictly allowed in Internet hostnames
9819 but nevertheless used by many sites. Set this to off if you want
9820 Squid to be strict about the standard.
9821 This check is performed only when check_hostnames is set to on.
9824 NAME: dns_retransmit_interval
9827 LOC: Config.Timeout.idns_retransmit
9829 Initial retransmit interval for DNS queries. The interval is
9830 doubled each time all configured DNS servers have been tried.
9836 LOC: Config.Timeout.idns_query
9838 DNS Query timeout. If no response is received to a DNS query
9839 within this time all DNS servers for the queried domain
9840 are assumed to be unavailable.
9843 NAME: dns_packet_max
9845 DEFAULT_DOC: EDNS disabled
9847 LOC: Config.dns.packet_max
9849 Maximum number of bytes packet size to advertise via EDNS.
9850 Set to "none" to disable EDNS large packet support.
9852 For legacy reasons DNS UDP replies will default to 512 bytes which
9853 is too small for many responses. EDNS provides a means for Squid to
9854 negotiate receiving larger responses back immediately without having
9855 to failover with repeat requests. Responses larger than this limit
9856 will retain the old behaviour of failover to TCP DNS.
9858 Squid has no real fixed limit internally, but allowing packet sizes
9859 over 1500 bytes requires network jumbogram support and is usually not
9862 WARNING: The RFC also indicates that some older resolvers will reply
9863 with failure of the whole request if the extension is added. Some
9864 resolvers have already been identified which will reply with mangled
9865 EDNS response on occasion. Usually in response to many-KB jumbogram
9866 sizes being advertised by Squid.
9867 Squid will currently treat these both as an unable-to-resolve domain
9868 even if it would be resolvable without EDNS.
9875 DEFAULT_DOC: Search for single-label domain names is disabled.
9876 LOC: Config.onoff.res_defnames
9878 Normally the RES_DEFNAMES resolver option is disabled
9879 (see res_init(3)). This prevents caches in a hierarchy
9880 from interpreting single-component hostnames locally. To allow
9881 Squid to handle single-component names, enable this option.
9884 NAME: dns_multicast_local
9888 DEFAULT_DOC: Search for .local and .arpa names is disabled.
9889 LOC: Config.onoff.dns_mdns
9891 When set to on, Squid sends multicast DNS lookups on the local
9892 network for domains ending in .local and .arpa.
9893 This enables local servers and devices to be contacted in an
9894 ad-hoc or zero-configuration network environment.
9897 NAME: dns_nameservers
9900 DEFAULT_DOC: Use operating system definitions
9901 LOC: Config.dns.nameservers
9903 Use this if you want to specify a list of DNS name servers
9904 (IP addresses) to use instead of those given in your
9905 /etc/resolv.conf file.
9907 On Windows platforms, if no value is specified here or in
9908 the /etc/resolv.conf file, the list of DNS name servers are
9909 taken from the Windows registry, both static and dynamic DHCP
9910 configurations are supported.
9912 Example: dns_nameservers 10.0.0.1 192.172.0.4
9917 DEFAULT: @DEFAULT_HOSTS@
9918 LOC: Config.etcHostsPath
9920 Location of the host-local IP name-address associations
9921 database. Most Operating Systems have such a file on different
9923 - Un*X & Linux: /etc/hosts
9924 - Windows NT/2000: %SystemRoot%\system32\drivers\etc\hosts
9925 (%SystemRoot% value install default is c:\winnt)
9926 - Windows XP/2003: %SystemRoot%\system32\drivers\etc\hosts
9927 (%SystemRoot% value install default is c:\windows)
9928 - Windows 9x/Me: %windir%\hosts
9929 (%windir% value is usually c:\windows)
9930 - Cygwin: /etc/hosts
9932 The file contains newline-separated definitions, in the
9933 form ip_address_in_dotted_form name [name ...] names are
9934 whitespace-separated. Lines beginning with an hash (#)
9935 character are comments.
9937 The file is checked at startup and upon configuration.
9938 If set to 'none', it won't be checked.
9939 If append_domain is used, that domain will be added to
9940 domain-local (i.e. not containing any dot character) host
9946 LOC: Config.appendDomain
9948 DEFAULT_DOC: Use operating system definitions
9950 Appends local domain name to hostnames without any dots in
9951 them. append_domain must begin with a period.
9953 Be warned there are now Internet names with no dots in
9954 them using only top-domain names, so setting this may
9955 cause some Internet sites to become unavailable.
9958 append_domain .yourdomain.com
9961 NAME: ignore_unknown_nameservers
9963 LOC: Config.onoff.ignore_unknown_nameservers
9966 By default Squid checks that DNS responses are received
9967 from the same IP addresses they are sent to. If they
9968 don't match, Squid ignores the response and writes a warning
9969 message to cache.log. You can allow responses from unknown
9970 nameservers by setting this option to 'off'.
9976 LOC: Config.dns.v4_first
9978 With the IPv6 Internet being as fast or faster than IPv4 Internet
9979 for most networks Squid prefers to contact websites over IPv6.
9981 This option reverses the order of preference to make Squid contact
9982 dual-stack websites over IPv4 first. Squid will still perform both
9983 IPv6 and IPv4 DNS lookups before connecting.
9986 This option will restrict the situations under which IPv6
9987 connectivity is used (and tested). Hiding network problems
9988 which would otherwise be detected and warned about.
9992 COMMENT: (number of entries)
9995 LOC: Config.ipcache.size
9997 Maximum number of DNS IP cache entries.
10004 LOC: Config.ipcache.low
10011 LOC: Config.ipcache.high
10013 The size, low-, and high-water marks for the IP cache.
10016 NAME: fqdncache_size
10017 COMMENT: (number of entries)
10020 LOC: Config.fqdncache.size
10022 Maximum number of FQDN cache entries.
10027 -----------------------------------------------------------------------------
10030 NAME: configuration_includes_quoted_values
10032 TYPE: configuration_includes_quoted_values
10034 LOC: ConfigParser::RecognizeQuotedValues
10036 If set, Squid will recognize each "quoted string" after a configuration
10037 directive as a single parameter. The quotes are stripped before the
10038 parameter value is interpreted or used.
10039 See "Values with spaces, quotes, and other special characters"
10040 section for more details.
10047 LOC: Config.onoff.mem_pools
10049 If set, Squid will keep pools of allocated (but unused) memory
10050 available for future use. If memory is a premium on your
10051 system and you believe your malloc library outperforms Squid
10052 routines, disable this.
10055 NAME: memory_pools_limit
10059 LOC: Config.MemPools.limit
10061 Used only with memory_pools on:
10062 memory_pools_limit 50 MB
10064 If set to a non-zero value, Squid will keep at most the specified
10065 limit of allocated (but unused) memory in memory pools. All free()
10066 requests that exceed this limit will be handled by your malloc
10067 library. Squid does not pre-allocate any memory, just safe-keeps
10068 objects that otherwise would be free()d. Thus, it is safe to set
10069 memory_pools_limit to a reasonably high value even if your
10070 configuration will use less memory.
10072 If set to none, Squid will keep all memory it can. That is, there
10073 will be no limit on the total amount of memory used for safe-keeping.
10075 To disable memory allocation optimization, do not set
10076 memory_pools_limit to 0 or none. Set memory_pools to "off" instead.
10078 An overhead for maintaining memory pools is not taken into account
10079 when the limit is checked. This overhead is close to four bytes per
10080 object kept. However, pools may actually _save_ memory because of
10081 reduced memory thrashing in your malloc library.
10084 NAME: forwarded_for
10085 COMMENT: on|off|transparent|truncate|delete
10088 LOC: opt_forwarded_for
10090 If set to "on", Squid will append your client's IP address
10091 in the HTTP requests it forwards. By default it looks like:
10093 X-Forwarded-For: 192.1.2.3
10095 If set to "off", it will appear as
10097 X-Forwarded-For: unknown
10099 If set to "transparent", Squid will not alter the
10100 X-Forwarded-For header in any way.
10102 If set to "delete", Squid will delete the entire
10103 X-Forwarded-For header.
10105 If set to "truncate", Squid will remove all existing
10106 X-Forwarded-For entries, and place the client IP as the sole entry.
10109 NAME: cachemgr_passwd
10110 TYPE: cachemgrpasswd
10112 DEFAULT_DOC: No password. Actions which require password are denied.
10113 LOC: Config.passwd_list
10115 Specify passwords for cachemgr operations.
10117 Usage: cachemgr_passwd password action action ...
10119 Some valid actions are (see cache manager menu for a full list):
10159 * Indicates actions which will not be performed without a
10160 valid password, others can be performed if not listed here.
10162 To disable an action, set the password to "disable".
10163 To allow performing an action without a password, set the
10164 password to "none".
10166 Use the keyword "all" to set the same password for all actions.
10169 cachemgr_passwd secret shutdown
10170 cachemgr_passwd lesssssssecret info stats/objects
10171 cachemgr_passwd disable all
10178 LOC: Config.onoff.client_db
10180 If you want to disable collecting per-client statistics,
10181 turn off client_db here.
10184 NAME: refresh_all_ims
10188 LOC: Config.onoff.refresh_all_ims
10190 When you enable this option, squid will always check
10191 the origin server for an update when a client sends an
10192 If-Modified-Since request. Many browsers use IMS
10193 requests when the user requests a reload, and this
10194 ensures those clients receive the latest version.
10196 By default (off), squid may return a Not Modified response
10197 based on the age of the cached version.
10200 NAME: reload_into_ims
10201 IFDEF: USE_HTTP_VIOLATIONS
10205 LOC: Config.onoff.reload_into_ims
10207 When you enable this option, client no-cache or ``reload''
10208 requests will be changed to If-Modified-Since requests.
10209 Doing this VIOLATES the HTTP standard. Enabling this
10210 feature could make you liable for problems which it
10213 see also refresh_pattern for a more selective approach.
10216 NAME: connect_retries
10218 LOC: Config.connect_retries
10220 DEFAULT_DOC: Do not retry failed connections.
10222 Limits the number of reopening attempts when establishing a single
10223 TCP connection. All these attempts must still complete before the
10224 applicable connection opening timeout expires.
10226 By default and when connect_retries is set to zero, Squid does not
10227 retry failed connection opening attempts.
10229 The (not recommended) maximum is 10 tries. An attempt to configure a
10230 higher value results in the value of 10 being used (with a warning).
10232 Squid may open connections to retry various high-level forwarding
10233 failures. For an outside observer, that activity may look like a
10234 low-level connection reopening attempt, but those high-level retries
10235 are governed by forward_max_tries instead.
10237 See also: connect_timeout, forward_timeout, icap_connect_timeout,
10238 ident_timeout, and forward_max_tries.
10241 NAME: retry_on_error
10243 LOC: Config.retry.onerror
10246 If set to ON Squid will automatically retry requests when
10247 receiving an error response with status 403 (Forbidden),
10248 500 (Internal Error), 501 or 503 (Service not available).
10249 Status 502 and 504 (Gateway errors) are always retried.
10251 This is mainly useful if you are in a complex cache hierarchy to
10252 work around access control errors.
10254 NOTE: This retry will attempt to find another working destination.
10255 Which is different from the server which just failed.
10258 NAME: as_whois_server
10260 LOC: Config.as_whois_server
10261 DEFAULT: whois.ra.net
10263 WHOIS server to query for AS numbers. NOTE: AS numbers are
10264 queried only when Squid starts up, not for every request.
10269 LOC: Config.onoff.offline
10272 Enable this option and Squid will never try to validate cached
10276 NAME: uri_whitespace
10277 TYPE: uri_whitespace
10278 LOC: Config.uri_whitespace
10281 What to do with requests that have whitespace characters in the
10284 strip: The whitespace characters are stripped out of the URL.
10285 This is the behavior recommended by RFC2396 and RFC3986
10286 for tolerant handling of generic URI.
10287 NOTE: This is one difference between generic URI and HTTP URLs.
10289 deny: The request is denied. The user receives an "Invalid
10291 This is the behaviour recommended by RFC2616 for safe
10292 handling of HTTP request URL.
10294 allow: The request is allowed and the URI is not changed. The
10295 whitespace characters remain in the URI. Note the
10296 whitespace is passed to redirector processes if they
10298 Note this may be considered a violation of RFC2616
10299 request parsing where whitespace is prohibited in the
10302 encode: The request is allowed and the whitespace characters are
10303 encoded according to RFC1738.
10305 chop: The request is allowed and the URI is chopped at the
10309 NOTE the current Squid implementation of encode and chop violates
10310 RFC2616 by not using a 301 redirect after altering the URL.
10315 LOC: Config.chroot_dir
10318 Specifies a directory where Squid should do a chroot() while
10319 initializing. This also causes Squid to fully drop root
10320 privileges after initializing. This means, for example, if you
10321 use a HTTP port less than 1024 and try to reconfigure, you may
10322 get an error saying that Squid can not open the port.
10325 NAME: pipeline_prefetch
10326 TYPE: pipelinePrefetch
10327 LOC: Config.pipeline_max_prefetch
10329 DEFAULT_DOC: Do not pre-parse pipelined requests.
10331 HTTP clients may send a pipeline of 1+N requests to Squid using a
10332 single connection, without waiting for Squid to respond to the first
10333 of those requests. This option limits the number of concurrent
10334 requests Squid will try to handle in parallel. If set to N, Squid
10335 will try to receive and process up to 1+N requests on the same
10336 connection concurrently.
10338 Defaults to 0 (off) for bandwidth management and access logging
10341 NOTE: pipelining requires persistent connections to clients.
10343 WARNING: pipelining breaks NTLM and Negotiate/Kerberos authentication.
10346 NAME: high_response_time_warning
10349 LOC: Config.warnings.high_rptm
10351 DEFAULT_DOC: disabled.
10353 If the one-minute median response time exceeds this value,
10354 Squid prints a WARNING with debug level 0 to get the
10355 administrators attention. The value is in milliseconds.
10358 NAME: high_page_fault_warning
10360 LOC: Config.warnings.high_pf
10362 DEFAULT_DOC: disabled.
10364 If the one-minute average page fault rate exceeds this
10365 value, Squid prints a WARNING with debug level 0 to get
10366 the administrators attention. The value is in page faults
10370 NAME: high_memory_warning
10372 LOC: Config.warnings.high_memory
10373 IFDEF: HAVE_MSTATS&&HAVE_GNUMALLOC_H
10375 DEFAULT_DOC: disabled.
10377 If the memory usage (as determined by gnumalloc, if available and used)
10378 exceeds this amount, Squid prints a WARNING with debug level 0 to get
10379 the administrators attention.
10381 # TODO: link high_memory_warning to mempools?
10383 NAME: sleep_after_fork
10384 COMMENT: (microseconds)
10386 LOC: Config.sleep_after_fork
10389 When this is set to a non-zero value, the main Squid process
10390 sleeps the specified number of microseconds after a fork()
10391 system call. This sleep may help the situation where your
10392 system reports fork() failures due to lack of (virtual)
10393 memory. Note, however, if you have a lot of child
10394 processes, these sleep delays will add up and your
10395 Squid will not service requests for some amount of time
10396 until all the child processes have been started.
10397 On Windows value less then 1000 (1 milliseconds) are
10401 NAME: windows_ipaddrchangemonitor
10402 IFDEF: _SQUID_WINDOWS_
10406 LOC: Config.onoff.WIN32_IpAddrChangeMonitor
10408 On Windows Squid by default will monitor IP address changes and will
10409 reconfigure itself after any detected event. This is very useful for
10410 proxies connected to internet with dial-up interfaces.
10411 In some cases (a Proxy server acting as VPN gateway is one) it could be
10412 desiderable to disable this behaviour setting this to 'off'.
10413 Note: after changing this, Squid service must be restarted.
10418 IFDEF: USE_SQUID_EUI
10420 LOC: Eui::TheConfig.euiLookup
10422 Whether to lookup the EUI or MAC address of a connected client.
10425 NAME: max_filedescriptors max_filedesc
10428 DEFAULT_DOC: Use operating system soft limit set by ulimit.
10429 LOC: Config.max_filedescriptors
10431 Set the maximum number of filedescriptors, either below the
10432 operating system default or up to the hard limit.
10434 Remove from squid.conf to inherit the current ulimit soft
10437 Note: Changing this requires a restart of Squid. Also
10438 not all I/O types supports large values (eg on Windows).
10441 NAME: force_request_body_continuation
10443 LOC: Config.accessList.forceRequestBodyContinuation
10445 DEFAULT_DOC: Deny, unless rules exist in squid.conf.
10447 This option controls how Squid handles data upload requests from HTTP
10448 and FTP agents that require a "Please Continue" control message response
10449 to actually send the request body to Squid. It is mostly useful in
10450 adaptation environments.
10452 When Squid receives an HTTP request with an "Expect: 100-continue"
10453 header or an FTP upload command (e.g., STOR), Squid normally sends the
10454 request headers or FTP command information to an adaptation service (or
10455 peer) and waits for a response. Most adaptation services (and some
10456 broken peers) may not respond to Squid at that stage because they may
10457 decide to wait for the HTTP request body or FTP data transfer. However,
10458 that request body or data transfer may never come because Squid has not
10459 responded with the HTTP 100 or FTP 150 (Please Continue) control message
10460 to the request sender yet!
10462 An allow match tells Squid to respond with the HTTP 100 or FTP 150
10463 (Please Continue) control message on its own, before forwarding the
10464 request to an adaptation service or peer. Such a response usually forces
10465 the request sender to proceed with sending the body. A deny match tells
10466 Squid to delay that control response until the origin server confirms
10467 that the request body is needed. Delaying is the default behavior.
10470 NAME: server_pconn_for_nonretriable
10473 DEFAULT_DOC: Open new connections for forwarding requests Squid cannot retry safely.
10474 LOC: Config.accessList.serverPconnForNonretriable
10476 This option provides fine-grained control over persistent connection
10477 reuse when forwarding HTTP requests that Squid cannot retry. It is useful
10478 in environments where opening new connections is very expensive
10479 (e.g., all connections are secured with TLS with complex client and server
10480 certificate validation) and race conditions associated with persistent
10481 connections are very rare and/or only cause minor problems.
10483 HTTP prohibits retrying unsafe and non-idempotent requests (e.g., POST).
10484 Squid limitations also prohibit retrying all requests with bodies (e.g., PUT).
10485 By default, when forwarding such "risky" requests, Squid opens a new
10486 connection to the server or cache_peer, even if there is an idle persistent
10487 connection available. When Squid is configured to risk sending a non-retriable
10488 request on a previously used persistent connection, and the server closes
10489 the connection before seeing that risky request, the user gets an error response
10490 from Squid. In most cases, that error response will be HTTP 502 (Bad Gateway)
10491 with ERR_ZERO_SIZE_OBJECT or ERR_WRITE_ERROR (peer connection reset) error detail.
10493 If an allow rule matches, Squid reuses an available idle persistent connection
10494 (if any) for the request that Squid cannot retry. If a deny rule matches, then
10495 Squid opens a new connection for the request that Squid cannot retry.
10497 This option does not affect requests that Squid can retry. They will reuse idle
10498 persistent connections (if any).
10500 This clause only supports fast acl types.
10501 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
10504 acl SpeedIsWorthTheRisk method POST
10505 server_pconn_for_nonretriable allow SpeedIsWorthTheRisk
10508 NAME: happy_eyeballs_connect_timeout
10512 LOC: Config.happyEyeballs.connect_timeout
10514 This Happy Eyeballs (RFC 8305) tuning directive specifies the minimum
10515 delay between opening a primary to-server connection and opening a
10516 spare to-server connection for the same master transaction. This delay
10517 is similar to the Connection Attempt Delay in RFC 8305, but it is only
10518 applied to the first spare connection attempt. Subsequent spare
10519 connection attempts use happy_eyeballs_connect_gap, and primary
10520 connection attempts are not artificially delayed at all.
10522 Terminology: The "primary" and "spare" designations are determined by
10523 the order of DNS answers received by Squid: If Squid DNS AAAA query
10524 was answered first, then primary connections are connections to IPv6
10525 peer addresses (while spare connections use IPv4 addresses).
10526 Similarly, if Squid DNS A query was answered first, then primary
10527 connections are connections to IPv4 peer addresses (while spare
10528 connections use IPv6 addresses).
10530 Shorter happy_eyeballs_connect_timeout values reduce master
10531 transaction response time, potentially improving user-perceived
10532 response times (i.e., making user eyeballs happier). Longer delays
10533 reduce both concurrent connection level and server bombardment with
10534 connection requests, potentially improving overall Squid performance
10535 and reducing the chance of being blocked by servers for opening too
10536 many unused connections.
10538 RFC 8305 prohibits happy_eyeballs_connect_timeout values smaller than
10539 10 (milliseconds) to "avoid congestion collapse in the presence of
10540 high packet-loss rates".
10542 The following Happy Eyeballs directives place additional connection
10543 opening restrictions: happy_eyeballs_connect_gap and
10544 happy_eyeballs_connect_limit.
10547 NAME: happy_eyeballs_connect_gap
10551 DEFAULT_DOC: no artificial delays between spare attempts
10552 LOC: Config.happyEyeballs.connect_gap
10554 This Happy Eyeballs (RFC 8305) tuning directive specifies the
10555 minimum delay between opening spare to-server connections (to any
10556 server; i.e. across all concurrent master transactions in a Squid
10557 instance). Each SMP worker currently multiplies the configured gap
10558 by the total number of workers so that the combined spare connection
10559 opening rate of a Squid instance obeys the configured limit. The
10560 workers do not coordinate connection openings yet; a micro burst
10561 of spare connection openings may violate the configured gap.
10563 This directive has similar trade-offs as
10564 happy_eyeballs_connect_timeout, but its focus is on limiting traffic
10565 amplification effects for Squid as a whole, while
10566 happy_eyeballs_connect_timeout works on an individual master
10569 The following Happy Eyeballs directives place additional connection
10570 opening restrictions: happy_eyeballs_connect_timeout and
10571 happy_eyeballs_connect_limit. See the former for related terminology.
10574 NAME: happy_eyeballs_connect_limit
10577 DEFAULT_DOC: no artificial limit on the number of concurrent spare attempts
10578 LOC: Config.happyEyeballs.connect_limit
10580 This Happy Eyeballs (RFC 8305) tuning directive specifies the
10581 maximum number of spare to-server connections (to any server; i.e.
10582 across all concurrent master transactions in a Squid instance).
10583 Each SMP worker gets an equal share of the total limit. However,
10584 the workers do not share the actual connection counts yet, so one
10585 (busier) worker cannot "borrow" spare connection slots from another
10586 (less loaded) worker.
10588 Setting this limit to zero disables concurrent use of primary and
10589 spare TCP connections: Spare connection attempts are made only after
10590 all primary attempts fail. However, Squid would still use the
10591 DNS-related optimizations of the Happy Eyeballs approach.
10593 This directive has similar trade-offs as happy_eyeballs_connect_gap,
10594 but its focus is on limiting Squid overheads, while
10595 happy_eyeballs_connect_gap focuses on the origin server and peer
10598 The following Happy Eyeballs directives place additional connection
10599 opening restrictions: happy_eyeballs_connect_timeout and
10600 happy_eyeballs_connect_gap. See the former for related terminology.
projects / thirdparty / squid.git / blob