1 ## Copyright (C) 1996-2019 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 HTTP uses iso-latin-1 as character set, while some
677 authentication backends such as LDAP expects UTF-8. If this is
678 set to on Squid will translate the HTTP iso-latin-1 charset to
679 UTF-8 before sending the username and password to the helper.
681 For NTLM and Negotiate this parameter is ignored.
683 IF HAVE_AUTH_MODULE_BASIC
684 === Basic authentication parameters ===
686 "credentialsttl" timetolive
687 Specifies how long squid assumes an externally validated
688 username:password pair is valid for - in other words how
689 often the helper program is called for that user. Set this
690 low to force revalidation with short lived passwords.
692 NOTE: setting this high does not impact your susceptibility
693 to replay attacks unless you are using an one-time password
694 system (such as SecureID). If you are using such a system,
695 you will be vulnerable to replay attacks unless you also
696 use the max_user_ip ACL in an http_access rule.
698 "casesensitive" on|off
699 Specifies if usernames are case sensitive. Most user databases
700 are case insensitive allowing the same username to be spelled
701 using both lower and upper case letters, but some are case
702 sensitive. This makes a big difference for user_max_ip ACL
703 processing and similar.
706 IF HAVE_AUTH_MODULE_DIGEST
707 === Digest authentication parameters ===
709 "nonce_garbage_interval" timeinterval
710 Specifies the interval that nonces that have been issued
711 to client_agent's are checked for validity.
713 "nonce_max_duration" timeinterval
714 Specifies the maximum length of time a given nonce will be
717 "nonce_max_count" number
718 Specifies the maximum number of times a given nonce can be
721 "nonce_strictness" on|off
722 Determines if squid requires strict increment-by-1 behavior
723 for nonce counts, or just incrementing (off - for use when
724 user agents generate nonce counts that occasionally miss 1
725 (ie, 1,2,4,6)). Default off.
727 "check_nonce_count" on|off
728 This directive if set to off can disable the nonce count check
729 completely to work around buggy digest qop implementations in
730 certain mainstream browser versions. Default on to check the
731 nonce count to protect from authentication replay attacks.
733 "post_workaround" on|off
734 This is a workaround to certain buggy browsers who send an
735 incorrect request digest in POST requests when reusing the
736 same nonce as acquired earlier on a GET request.
740 === Example Configuration ===
742 This configuration displays the recommended authentication scheme
743 order from most to least secure with recommended minimum configuration
744 settings for each scheme:
746 #auth_param negotiate program <uncomment and complete this line to activate>
747 #auth_param negotiate children 20 startup=0 idle=1
749 #auth_param digest program <uncomment and complete this line to activate>
750 #auth_param digest children 20 startup=0 idle=1
751 #auth_param digest realm Squid proxy-caching web server
752 #auth_param digest nonce_garbage_interval 5 minutes
753 #auth_param digest nonce_max_duration 30 minutes
754 #auth_param digest nonce_max_count 50
756 #auth_param ntlm program <uncomment and complete this line to activate>
757 #auth_param ntlm children 20 startup=0 idle=1
759 #auth_param basic program <uncomment and complete this line>
760 #auth_param basic children 5 startup=5 idle=1
761 #auth_param basic credentialsttl 2 hours
764 NAME: authenticate_cache_garbage_interval
768 LOC: Auth::TheConfig.garbageCollectInterval
770 The time period between garbage collection across the username cache.
771 This is a trade-off between memory utilization (long intervals - say
772 2 days) and CPU (short intervals - say 1 minute). Only change if you
776 NAME: authenticate_ttl
780 LOC: Auth::TheConfig.credentialsTtl
782 The time a user & their credentials stay in the logged in
783 user cache since their last request. When the garbage
784 interval passes, all user credentials that have passed their
785 TTL are removed from memory.
788 NAME: authenticate_ip_ttl
791 LOC: Auth::TheConfig.ipTtl
794 If you use proxy authentication and the 'max_user_ip' ACL,
795 this directive controls how long Squid remembers the IP
796 addresses associated with each user. Use a small value
797 (e.g., 60 seconds) if your users might change addresses
798 quickly, as is the case with dialup. You might be safe
799 using a larger value (e.g., 2 hours) in a corporate LAN
800 environment with relatively static address assignments.
805 -----------------------------------------------------------------------------
808 NAME: external_acl_type
809 TYPE: externalAclHelper
810 LOC: Config.externalAclHelperList
813 This option defines external acl classes using a helper program
814 to look up the status
816 external_acl_type name [options] FORMAT /path/to/helper [helper arguments]
820 ttl=n TTL in seconds for cached results (defaults to 3600
824 TTL for cached negative lookups (default same
827 grace=n Percentage remaining of TTL where a refresh of a
828 cached entry should be initiated without needing to
829 wait for a new reply. (default is for no grace period)
831 cache=n The maximum number of entries in the result cache. The
832 default limit is 262144 entries. Each cache entry usually
833 consumes at least 256 bytes. Squid currently does not remove
834 expired cache entries until the limit is reached, so a proxy
835 will sooner or later reach the limit. The expanded FORMAT
836 value is used as the cache key, so if the details in FORMAT
837 are highly variable, a larger cache may be needed to produce
838 reduction in helper load.
841 Maximum number of acl helper processes spawned to service
842 external acl lookups of this type. (default 5)
845 Minimum number of acl helper processes to spawn during
846 startup and reconfigure to service external acl lookups
847 of this type. (default 0)
850 Number of acl helper processes to keep ahead of traffic
851 loads. Squid will spawn this many at once whenever load
852 rises above the capabilities of existing processes.
853 Up to the value of children-max. (default 1)
855 concurrency=n concurrency level per process. Only used with helpers
856 capable of processing more than one query at a time.
858 queue-size=N The queue-size option sets the maximum number of
859 queued requests. A request is queued when no existing
860 helper can accept it due to concurrency limit and no
861 new helper can be started due to children-max limit.
862 If the queued requests exceed queue size, the acl is
863 ignored. The default value is set to 2*children-max.
865 protocol=2.5 Compatibility mode for Squid-2.5 external acl helpers.
867 ipv4 / ipv6 IP protocol used to communicate with this helper.
868 The default is to auto-detect IPv6 and use it when available.
871 FORMAT is a series of %macro codes. See logformat directive for a full list
872 of the accepted codes. Although note that at the time of any external ACL
873 being tested data may not be available and thus some %macro expand to '-'.
875 In addition to the logformat codes; when processing external ACLs these
876 additional macros are made available:
878 %ACL The name of the ACL being tested.
880 %DATA The ACL arguments specified in the referencing config
881 'acl ... external' line, separated by spaces (an
882 "argument string"). see acl external.
884 If there are no ACL arguments %DATA expands to '-'.
886 If you do not specify a DATA macro inside FORMAT,
887 Squid automatically appends %DATA to your FORMAT.
888 Note that Squid-3.x may expand %DATA to whitespace
889 or nothing in this case.
891 By default, Squid applies URL-encoding to each ACL
892 argument inside the argument string. If an explicit
893 encoding modifier is used (e.g., %#DATA), then Squid
894 encodes the whole argument string as a single token
895 (e.g., with %#DATA, spaces between arguments become
898 If SSL is enabled, the following formating codes become available:
900 %USER_CERT SSL User certificate in PEM format
901 %USER_CERTCHAIN SSL User certificate chain in PEM format
902 %USER_CERT_xx SSL User certificate subject attribute xx
903 %USER_CA_CERT_xx SSL User certificate issuer attribute xx
906 NOTE: all other format codes accepted by older Squid versions
910 General request syntax:
912 [channel-ID] FORMAT-values
915 FORMAT-values consists of transaction details expanded with
916 whitespace separation per the config file FORMAT specification
917 using the FORMAT macros listed above.
919 Request values sent to the helper are URL escaped to protect
920 each value in requests against whitespaces.
922 If using protocol=2.5 then the request sent to the helper is not
923 URL escaped to protect against whitespace.
925 NOTE: protocol=3.0 is deprecated as no longer necessary.
927 When using the concurrency= option the protocol is changed by
928 introducing a query channel tag in front of the request/response.
929 The query channel tag is a number between 0 and concurrency-1.
930 This value must be echoed back unchanged to Squid as the first part
931 of the response relating to its request.
934 The helper receives lines expanded per the above format specification
935 and for each input line returns 1 line starting with OK/ERR/BH result
936 code and optionally followed by additional keywords with more details.
939 General result syntax:
941 [channel-ID] result keyword=value ...
943 Result consists of one of the codes:
946 the ACL test produced a match.
949 the ACL test does not produce a match.
952 An internal error occurred in the helper, preventing
953 a result being identified.
955 The meaning of 'a match' is determined by your squid.conf
956 access control configuration. See the Squid wiki for details.
960 user= The users name (login)
962 password= The users password (for login= cache_peer option)
964 message= Message describing the reason for this response.
965 Available as %o in error pages.
966 Useful on (ERR and BH results).
968 tag= Apply a tag to a request. Only sets a tag once,
969 does not alter existing tags.
971 log= String to be logged in access.log. Available as
972 %ea in logformat specifications.
974 clt_conn_tag= Associates a TAG with the client TCP connection.
975 Please see url_rewrite_program related documentation
978 Any keywords may be sent on any response whether OK, ERR or BH.
980 All response keyword values need to be a single token with URL
981 escaping, or enclosed in double quotes (") and escaped using \ on
982 any double quotes or \ characters within the value. The wrapping
983 double quotes are removed before the value is interpreted by Squid.
984 \r and \n are also replace by CR and LF.
986 Some example key values:
990 user="J. \"Bob\" Smith"
997 DEFAULT: ssl::certHasExpired ssl_error X509_V_ERR_CERT_HAS_EXPIRED
998 DEFAULT: ssl::certNotYetValid ssl_error X509_V_ERR_CERT_NOT_YET_VALID
999 DEFAULT: ssl::certDomainMismatch ssl_error SQUID_X509_V_ERR_DOMAIN_MISMATCH
1000 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
1001 DEFAULT: ssl::certSelfSigned ssl_error X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT
1003 DEFAULT: all src all
1004 DEFAULT: manager url_regex -i ^cache_object:// +i ^https?://[^/]+/squid-internal-mgr/
1005 DEFAULT: localhost src 127.0.0.1/32 ::1
1006 DEFAULT: to_localhost dst 127.0.0.0/8 0.0.0.0/32 ::1/128 ::/128
1007 DEFAULT: CONNECT method CONNECT
1008 DEFAULT_DOC: ACLs all, manager, localhost, to_localhost, and CONNECT are predefined.
1010 Defining an Access List
1012 Every access list definition must begin with an aclname and acltype,
1013 followed by either type-specific arguments or a quoted filename that
1016 acl aclname acltype argument ...
1017 acl aclname acltype "file" ...
1019 When using "file", the file should contain one item per line.
1024 Some acl types supports options which changes their default behaviour:
1026 -i,+i By default, regular expressions are CASE-SENSITIVE. To make them
1027 case-insensitive, use the -i option. To return case-sensitive
1028 use the +i option between patterns, or make a new ACL line
1031 -n Disable lookups and address type conversions. If lookup or
1032 conversion is required because the parameter type (IP or
1033 domain name) does not match the message address type (domain
1034 name or IP), then the ACL would immediately declare a mismatch
1035 without any warnings or lookups.
1038 Perform a list membership test, interpreting values as
1039 comma-separated token lists and matching against individual
1040 tokens instead of whole values.
1041 The optional "delimiters" parameter specifies one or more
1042 alternative non-alphanumeric delimiter characters.
1043 non-alphanumeric delimiter characters.
1045 -- Used to stop processing all options, in the case the first acl
1046 value has '-' character as first character (for example the '-'
1047 is a valid domain name)
1049 Some acl types require suspending the current request in order
1050 to access some external data source.
1051 Those which do are marked with the tag [slow], those which
1052 don't are marked as [fast].
1053 See http://wiki.squid-cache.org/SquidFaq/SquidAcl
1054 for further information
1056 ***** ACL TYPES AVAILABLE *****
1058 acl aclname src ip-address/mask ... # clients IP address [fast]
1059 acl aclname src addr1-addr2/mask ... # range of addresses [fast]
1060 acl aclname dst [-n] ip-address/mask ... # URL host's IP address [slow]
1061 acl aclname localip ip-address/mask ... # IP address the client connected to [fast]
1064 acl aclname arp mac-address ...
1065 acl aclname eui64 eui64-address ...
1067 # MAC (EUI-48) and EUI-64 addresses use xx:xx:xx:xx:xx:xx notation.
1069 # The 'arp' ACL code is not portable to all operating systems.
1070 # It works on Linux, Solaris, Windows, FreeBSD, and some other
1073 # The eui_lookup directive is required to be 'on' (the default)
1074 # and Squid built with --enable-eui for MAC/EUI addresses to be
1075 # available for this ACL.
1077 # Squid can only determine the MAC/EUI address for IPv4
1078 # clients that are on the same subnet. If the client is on a
1079 # different subnet, then Squid cannot find out its address.
1081 # IPv6 protocol does not contain ARP. MAC/EUI is either
1082 # encoded directly in the IPv6 address or not available.
1084 acl aclname clientside_mark mark[/mask] ...
1085 # matches CONNMARK of an accepted connection [fast]
1086 # DEPRECATED. Use the 'client_connection_mark' instead.
1088 acl aclname client_connection_mark mark[/mask] ...
1089 # matches CONNMARK of an accepted connection [fast]
1091 # mark and mask are unsigned integers (hex, octal, or decimal).
1092 # If multiple marks are given, then the ACL matches if at least
1095 # Uses netfilter-conntrack library.
1096 # Requires building Squid with --enable-linux-netfilter.
1098 # The client, various intermediaries, and Squid itself may set
1099 # CONNMARK at various times. The last CONNMARK set wins. This ACL
1100 # checks the mark present on an accepted connection or set by
1101 # Squid afterwards, depending on the ACL check timing. This ACL
1102 # effectively ignores any mark set by other agents after Squid has
1103 # accepted the connection.
1105 acl aclname srcdomain .foo.com ...
1106 # reverse lookup, from client IP [slow]
1107 acl aclname dstdomain [-n] .foo.com ...
1108 # Destination server from URL [fast]
1109 acl aclname srcdom_regex [-i] \.foo\.com ...
1110 # regex matching client name [slow]
1111 acl aclname dstdom_regex [-n] [-i] \.foo\.com ...
1112 # regex matching server [fast]
1114 # For dstdomain and dstdom_regex a reverse lookup is tried if a IP
1115 # based URL is used and no match is found. The name "none" is used
1116 # if the reverse lookup fails.
1118 acl aclname src_as number ...
1119 acl aclname dst_as number ...
1121 # Except for access control, AS numbers can be used for
1122 # routing of requests to specific caches. Here's an
1123 # example for routing all requests for AS#1241 and only
1124 # those to mycache.mydomain.net:
1125 # acl asexample dst_as 1241
1126 # cache_peer_access mycache.mydomain.net allow asexample
1127 # cache_peer_access mycache_mydomain.net deny all
1129 acl aclname peername myPeer ...
1130 acl aclname peername_regex [-i] regex-pattern ...
1132 # match against a named cache_peer entry
1133 # set unique name= on cache_peer lines for reliable use.
1135 acl aclname time [day-abbrevs] [h1:m1-h2:m2]
1145 # h1:m1 must be less than h2:m2
1147 acl aclname url_regex [-i] ^http:// ...
1148 # regex matching on whole URL [fast]
1149 acl aclname urllogin [-i] [^a-zA-Z0-9] ...
1150 # regex matching on URL login field
1151 acl aclname urlpath_regex [-i] \.gif$ ...
1152 # regex matching on URL path [fast]
1154 acl aclname port 80 70 21 0-1024... # destination TCP port [fast]
1156 acl aclname localport 3128 ... # TCP port the client connected to [fast]
1157 # NP: for interception mode this is usually '80'
1159 acl aclname myportname 3128 ... # *_port name [fast]
1161 acl aclname proto HTTP FTP ... # request protocol [fast]
1163 acl aclname method GET POST ... # HTTP request method [fast]
1165 acl aclname http_status 200 301 500- 400-403 ...
1166 # status code in reply [fast]
1168 acl aclname browser [-i] regexp ...
1169 # pattern match on User-Agent header (see also req_header below) [fast]
1171 acl aclname referer_regex [-i] regexp ...
1172 # pattern match on Referer header [fast]
1173 # Referer is highly unreliable, so use with care
1175 acl aclname ident [-i] username ...
1176 acl aclname ident_regex [-i] pattern ...
1177 # string match on ident output [slow]
1178 # use REQUIRED to accept any non-null ident.
1180 acl aclname proxy_auth [-i] username ...
1181 acl aclname proxy_auth_regex [-i] pattern ...
1182 # perform http authentication challenge to the client and match against
1183 # supplied credentials [slow]
1185 # takes a list of allowed usernames.
1186 # use REQUIRED to accept any valid username.
1188 # Will use proxy authentication in forward-proxy scenarios, and plain
1189 # http authenticaiton in reverse-proxy scenarios
1191 # NOTE: when a Proxy-Authentication header is sent but it is not
1192 # needed during ACL checking the username is NOT logged
1195 # NOTE: proxy_auth requires a EXTERNAL authentication program
1196 # to check username/password combinations (see
1197 # auth_param directive).
1199 # NOTE: proxy_auth can't be used in a transparent/intercepting proxy
1200 # as the browser needs to be configured for using a proxy in order
1201 # to respond to proxy authentication.
1203 acl aclname snmp_community string ...
1204 # A community string to limit access to your SNMP Agent [fast]
1207 # acl snmppublic snmp_community public
1209 acl aclname maxconn number
1210 # This will be matched when the client's IP address has
1211 # more than <number> TCP connections established. [fast]
1212 # NOTE: This only measures direct TCP links so X-Forwarded-For
1213 # indirect clients are not counted.
1215 acl aclname max_user_ip [-s] number
1216 # This will be matched when the user attempts to log in from more
1217 # than <number> different ip addresses. The authenticate_ip_ttl
1218 # parameter controls the timeout on the ip entries. [fast]
1219 # If -s is specified the limit is strict, denying browsing
1220 # from any further IP addresses until the ttl has expired. Without
1221 # -s Squid will just annoy the user by "randomly" denying requests.
1222 # (the counter is reset each time the limit is reached and a
1223 # request is denied)
1224 # NOTE: in acceleration mode or where there is mesh of child proxies,
1225 # clients may appear to come from multiple addresses if they are
1226 # going through proxy farms, so a limit of 1 may cause user problems.
1228 acl aclname random probability
1229 # Pseudo-randomly match requests. Based on the probability given.
1230 # Probability may be written as a decimal (0.333), fraction (1/3)
1231 # or ratio of matches:non-matches (3:5).
1233 acl aclname req_mime_type [-i] mime-type ...
1234 # regex match against the mime type of the request generated
1235 # by the client. Can be used to detect file upload or some
1236 # types HTTP tunneling requests [fast]
1237 # NOTE: This does NOT match the reply. You cannot use this
1238 # to match the returned file type.
1240 acl aclname req_header header-name [-i] any\.regex\.here
1241 # regex match against any of the known request headers. May be
1242 # thought of as a superset of "browser", "referer" and "mime-type"
1245 acl aclname rep_mime_type [-i] mime-type ...
1246 # regex match against the mime type of the reply received by
1247 # squid. Can be used to detect file download or some
1248 # types HTTP tunneling requests. [fast]
1249 # NOTE: This has no effect in http_access rules. It only has
1250 # effect in rules that affect the reply data stream such as
1251 # http_reply_access.
1253 acl aclname rep_header header-name [-i] any\.regex\.here
1254 # regex match against any of the known reply headers. May be
1255 # thought of as a superset of "browser", "referer" and "mime-type"
1258 acl aclname external class_name [arguments...]
1259 # external ACL lookup via a helper class defined by the
1260 # external_acl_type directive [slow]
1262 acl aclname user_cert attribute values...
1263 # match against attributes in a user SSL certificate
1264 # attribute is one of DN/C/O/CN/L/ST or a numerical OID [fast]
1266 acl aclname ca_cert attribute values...
1267 # match against attributes a users issuing CA SSL certificate
1268 # attribute is one of DN/C/O/CN/L/ST or a numerical OID [fast]
1270 acl aclname ext_user [-i] username ...
1271 acl aclname ext_user_regex [-i] pattern ...
1272 # string match on username returned by external acl helper [slow]
1273 # use REQUIRED to accept any non-null user name.
1275 acl aclname tag tagvalue ...
1276 # string match on tag returned by external acl helper [fast]
1277 # DEPRECATED. Only the first tag will match with this ACL.
1278 # Use the 'note' ACL instead for handling multiple tag values.
1280 acl aclname hier_code codename ...
1281 # string match against squid hierarchy code(s); [fast]
1282 # e.g., DIRECT, PARENT_HIT, NONE, etc.
1284 # NOTE: This has no effect in http_access rules. It only has
1285 # effect in rules that affect the reply data stream such as
1286 # http_reply_access.
1288 acl aclname note [-m[=delimiters]] name [value ...]
1289 # match transaction annotation [fast]
1290 # Without values, matches any annotation with a given name.
1291 # With value(s), matches any annotation with a given name that
1292 # also has one of the given values.
1293 # If the -m flag is used, then the value of the named
1294 # annotation is interpreted as a list of tokens, and the ACL
1295 # matches individual name=token pairs rather than whole
1296 # name=value pairs. See "ACL Options" above for more info.
1297 # Annotation sources include note and adaptation_meta directives
1298 # as well as helper and eCAP responses.
1300 acl aclname annotate_transaction [-m[=delimiters]] key=value ...
1301 acl aclname annotate_transaction [-m[=delimiters]] key+=value ...
1302 # Always matches. [fast]
1303 # Used for its side effect: This ACL immediately adds a
1304 # key=value annotation to the current master transaction.
1305 # The added annotation can then be tested using note ACL and
1306 # logged (or sent to helpers) using %note format code.
1308 # Annotations can be specified using replacement and addition
1309 # formats. The key=value form replaces old same-key annotation
1310 # value(s). The key+=value form appends a new value to the old
1311 # same-key annotation. Both forms create a new key=value
1312 # annotation if no same-key annotation exists already. If
1313 # -m flag is used, then the value is interpreted as a list
1314 # and the annotation will contain key=token pair(s) instead of the
1315 # whole key=value pair.
1317 # This ACL is especially useful for recording complex multi-step
1318 # ACL-driven decisions. For example, the following configuration
1319 # avoids logging transactions accepted after aclX matched:
1321 # # First, mark transactions accepted after aclX matched
1322 # acl markSpecial annotate_transaction special=true
1323 # http_access allow acl001
1325 # http_access deny acl100
1326 # http_access allow aclX markSpecial
1328 # # Second, do not log marked transactions:
1329 # acl markedSpecial note special true
1330 # access_log ... deny markedSpecial
1332 # # Note that the following would not have worked because aclX
1333 # # alone does not determine whether the transaction was allowed:
1334 # access_log ... deny aclX # Wrong!
1336 # Warning: This ACL annotates the transaction even when negated
1337 # and even if subsequent ACLs fail to match. For example, the
1338 # following three rules will have exactly the same effect as far
1339 # as annotations set by the "mark" ACL are concerned:
1341 # some_directive acl1 ... mark # rule matches if mark is reached
1342 # some_directive acl1 ... !mark # rule never matches
1343 # some_directive acl1 ... mark !all # rule never matches
1345 acl aclname annotate_client [-m[=delimiters]] key=value ...
1346 acl aclname annotate_client [-m[=delimiters]] key+=value ...
1348 # Always matches. [fast]
1349 # Used for its side effect: This ACL immediately adds a
1350 # key=value annotation to the current client-to-Squid
1351 # connection. Connection annotations are propagated to the current
1352 # and all future master transactions on the annotated connection.
1353 # See the annotate_transaction ACL for details.
1355 # For example, the following configuration avoids rewriting URLs
1356 # of transactions bumped by SslBump:
1358 # # First, mark bumped connections:
1359 # acl markBumped annotate_client bumped=true
1360 # ssl_bump peek acl1
1361 # ssl_bump stare acl2
1362 # ssl_bump bump acl3 markBumped
1363 # ssl_bump splice all
1365 # # Second, do not send marked transactions to the redirector:
1366 # acl markedBumped note bumped true
1367 # url_rewrite_access deny markedBumped
1369 # # Note that the following would not have worked because acl3 alone
1370 # # does not determine whether the connection is going to be bumped:
1371 # url_rewrite_access deny acl3 # Wrong!
1373 acl aclname adaptation_service service ...
1374 # Matches the name of any icap_service, ecap_service,
1375 # adaptation_service_set, or adaptation_service_chain that Squid
1376 # has used (or attempted to use) for the master transaction.
1377 # This ACL must be defined after the corresponding adaptation
1378 # service is named in squid.conf. This ACL is usable with
1379 # adaptation_meta because it starts matching immediately after
1380 # the service has been selected for adaptation.
1382 acl aclname transaction_initiator initiator ...
1383 # Matches transaction's initiator [fast]
1385 # Supported initiators are:
1386 # esi: matches transactions fetching ESI resources
1387 # certificate-fetching: matches transactions fetching
1388 # a missing intermediate TLS certificate
1389 # cache-digest: matches transactions fetching Cache Digests
1391 # htcp: matches HTCP requests from peers
1392 # icp: matches ICP requests to peers
1393 # icmp: matches ICMP RTT database (NetDB) requests to peers
1394 # asn: matches asns db requests
1395 # internal: matches any of the above
1396 # client: matches transactions containing an HTTP or FTP
1397 # client request received at a Squid *_port
1398 # all: matches any transaction, including internal transactions
1399 # without a configurable initiator and hopefully rare
1400 # transactions without a known-to-Squid initiator
1402 # Multiple initiators are ORed.
1404 acl aclname has component
1405 # matches a transaction "component" [fast]
1407 # Supported transaction components are:
1408 # request: transaction has a request header (at least)
1409 # response: transaction has a response header (at least)
1410 # ALE: transaction has an internally-generated Access Log Entry
1411 # structure; bugs notwithstanding, all transaction have it
1413 # For example, the following configuration helps when dealing with HTTP
1414 # clients that close connections without sending a request header:
1416 # acl hasRequest has request
1417 # acl logMe note important_transaction
1418 # # avoid "logMe ACL is used in context without an HTTP request" warnings
1419 # access_log ... logformat=detailed hasRequest logMe
1420 # # log request-less transactions, instead of ignoring them
1421 # access_log ... logformat=brief !hasRequest
1423 # Multiple components are not supported for one "acl" rule, but
1424 # can be specified (and are ORed) using multiple same-name rules:
1426 # # OK, this strange logging daemon needs request or response,
1427 # # but can work without either a request or a response:
1428 # acl hasWhatMyLoggingDaemonNeeds has request
1429 # acl hasWhatMyLoggingDaemonNeeds has response
1432 acl aclname ssl_error errorname
1433 # match against SSL certificate validation error [fast]
1435 # For valid error names see in @DEFAULT_ERROR_DIR@/templates/error-details.txt
1438 # The following can be used as shortcuts for certificate properties:
1439 # [ssl::]certHasExpired: the "not after" field is in the past
1440 # [ssl::]certNotYetValid: the "not before" field is in the future
1441 # [ssl::]certUntrusted: The certificate issuer is not to be trusted.
1442 # [ssl::]certSelfSigned: The certificate is self signed.
1443 # [ssl::]certDomainMismatch: The certificate CN domain does not
1444 # match the name the name of the host we are connecting to.
1446 # The ssl::certHasExpired, ssl::certNotYetValid, ssl::certDomainMismatch,
1447 # ssl::certUntrusted, and ssl::certSelfSigned can also be used as
1448 # predefined ACLs, just like the 'all' ACL.
1450 # NOTE: The ssl_error ACL is only supported with sslproxy_cert_error,
1451 # sslproxy_cert_sign, and sslproxy_cert_adapt options.
1453 acl aclname server_cert_fingerprint [-sha1] fingerprint
1454 # match against server SSL certificate fingerprint [fast]
1456 # The fingerprint is the digest of the DER encoded version
1457 # of the whole certificate. The user should use the form: XX:XX:...
1458 # Optional argument specifies the digest algorithm to use.
1459 # The SHA1 digest algorithm is the default and is currently
1460 # the only algorithm supported (-sha1).
1462 acl aclname at_step step
1463 # match against the current step during ssl_bump evaluation [fast]
1464 # Never matches and should not be used outside the ssl_bump context.
1466 # At each SslBump step, Squid evaluates ssl_bump directives to find
1467 # the next bumping action (e.g., peek or splice). Valid SslBump step
1468 # values and the corresponding ssl_bump evaluation moments are:
1469 # SslBump1: After getting TCP-level and HTTP CONNECT info.
1470 # SslBump2: After getting SSL Client Hello info.
1471 # SslBump3: After getting SSL Server Hello info.
1473 acl aclname ssl::server_name [option] .foo.com ...
1474 # matches server name obtained from various sources [fast]
1476 # The ACL computes server name(s) using such information sources as
1477 # CONNECT request URI, TLS client SNI, and TLS server certificate
1478 # subject (CN and SubjectAltName). The computed server name(s) usually
1479 # change with each SslBump step, as more info becomes available:
1480 # * SNI is used as the server name instead of the request URI,
1481 # * subject name(s) from the server certificate (CN and
1482 # SubjectAltName) are used as the server names instead of SNI.
1484 # When the ACL computes multiple server names, matching any single
1485 # computed name is sufficient for the ACL to match.
1487 # The "none" name can be used to match transactions where the ACL
1488 # could not compute the server name using any information source
1489 # that was both available and allowed to be used by the ACL options at
1490 # the ACL evaluation time.
1492 # Unlike dstdomain, this ACL does not perform DNS lookups.
1494 # An ACL option below may be used to restrict what information
1495 # sources are used to extract the server names from:
1497 # --client-requested
1498 # The server name is SNI regardless of what the server says.
1500 # The server name(s) are the certificate subject name(s), regardless
1501 # of what the client has requested. If the server certificate is
1502 # unavailable, then the name is "none".
1504 # The server name is either SNI (if SNI matches at least one of the
1505 # certificate subject names) or "none" (otherwise). When the server
1506 # certificate is unavailable, the consensus server name is SNI.
1508 # Combining multiple options in one ACL is a fatal configuration
1511 # For all options: If no SNI is available, then the CONNECT request
1512 # target (a.k.a. URI) is used instead of SNI (for an intercepted
1513 # connection, this target is the destination IP address).
1515 acl aclname ssl::server_name_regex [-i] \.foo\.com ...
1516 # regex matches server name obtained from various sources [fast]
1518 acl aclname connections_encrypted
1519 # matches transactions with all HTTP messages received over TLS
1520 # transport connections. [fast]
1522 # The master transaction deals with HTTP messages received from
1523 # various sources. All sources used by the master transaction in the
1524 # past are considered by the ACL. The following rules define whether
1525 # a given message source taints the entire master transaction,
1526 # resulting in ACL mismatches:
1528 # * The HTTP client transport connection is not TLS.
1529 # * An adaptation service connection-encryption flag is off.
1530 # * The peer or origin server transport connection is not TLS.
1532 # Caching currently does not affect these rules. This cache ignorance
1533 # implies that only the current HTTP client transport and REQMOD
1534 # services status determine whether this ACL matches a from-cache
1535 # transaction. The source of the cached response does not have any
1536 # effect on future transaction that use the cached response without
1537 # revalidation. This may change.
1539 # DNS, ICP, and HTCP exchanges during the master transaction do not
1540 # affect these rules.
1542 acl aclname any-of acl1 acl2 ...
1543 # match any one of the acls [fast or slow]
1544 # The first matching ACL stops further ACL evaluation.
1546 # ACLs from multiple any-of lines with the same name are ORed.
1547 # For example, A = (a1 or a2) or (a3 or a4) can be written as
1548 # acl A any-of a1 a2
1549 # acl A any-of a3 a4
1551 # This group ACL is fast if all evaluated ACLs in the group are fast
1552 # and slow otherwise.
1554 acl aclname all-of acl1 acl2 ...
1555 # match all of the acls [fast or slow]
1556 # The first mismatching ACL stops further ACL evaluation.
1558 # ACLs from multiple all-of lines with the same name are ORed.
1559 # For example, B = (b1 and b2) or (b3 and b4) can be written as
1560 # acl B all-of b1 b2
1561 # acl B all-of b3 b4
1563 # This group ACL is fast if all evaluated ACLs in the group are fast
1564 # and slow otherwise.
1567 acl macaddress arp 09:00:2b:23:45:67
1568 acl myexample dst_as 1241
1569 acl password proxy_auth REQUIRED
1570 acl fileupload req_mime_type -i ^multipart/form-data$
1571 acl javascript rep_mime_type -i ^application/x-javascript$
1575 # Recommended minimum configuration:
1578 # Example rule allowing access from your local networks.
1579 # Adapt to list your (internal) IP networks from where browsing
1581 acl localnet src 0.0.0.1-0.255.255.255 # RFC 1122 "this" network (LAN)
1582 acl localnet src 10.0.0.0/8 # RFC 1918 local private network (LAN)
1583 acl localnet src 100.64.0.0/10 # RFC 6598 shared address space (CGN)
1584 acl localnet src 169.254.0.0/16 # RFC 3927 link-local (directly plugged) machines
1585 acl localnet src 172.16.0.0/12 # RFC 1918 local private network (LAN)
1586 acl localnet src 192.168.0.0/16 # RFC 1918 local private network (LAN)
1587 acl localnet src fc00::/7 # RFC 4193 local private network range
1588 acl localnet src fe80::/10 # RFC 4291 link-local (directly plugged) machines
1590 acl SSL_ports port 443
1591 acl Safe_ports port 80 # http
1592 acl Safe_ports port 21 # ftp
1593 acl Safe_ports port 443 # https
1594 acl Safe_ports port 70 # gopher
1595 acl Safe_ports port 210 # wais
1596 acl Safe_ports port 1025-65535 # unregistered ports
1597 acl Safe_ports port 280 # http-mgmt
1598 acl Safe_ports port 488 # gss-http
1599 acl Safe_ports port 591 # filemaker
1600 acl Safe_ports port 777 # multiling http
1604 NAME: proxy_protocol_access
1606 LOC: Config.accessList.proxyProtocol
1608 DEFAULT_DOC: all TCP connections to ports with require-proxy-header will be denied
1610 Determine which client proxies can be trusted to provide correct
1611 information regarding real client IP address using PROXY protocol.
1613 Requests may pass through a chain of several other proxies
1614 before reaching us. The original source details may by sent in:
1615 * HTTP message Forwarded header, or
1616 * HTTP message X-Forwarded-For header, or
1617 * PROXY protocol connection header.
1619 This directive is solely for validating new PROXY protocol
1620 connections received from a port flagged with require-proxy-header.
1621 It is checked only once after TCP connection setup.
1623 A deny match results in TCP connection closure.
1625 An allow match is required for Squid to permit the corresponding
1626 TCP connection, before Squid even looks for HTTP request headers.
1627 If there is an allow match, Squid starts using PROXY header information
1628 to determine the source address of the connection for all future ACL
1629 checks, logging, etc.
1631 SECURITY CONSIDERATIONS:
1633 Any host from which we accept client IP details can place
1634 incorrect information in the relevant header, and Squid
1635 will use the incorrect information as if it were the
1636 source address of the request. This may enable remote
1637 hosts to bypass any access control restrictions that are
1638 based on the client's source addresses.
1640 This clause only supports fast acl types.
1641 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
1644 NAME: follow_x_forwarded_for
1646 IFDEF: FOLLOW_X_FORWARDED_FOR
1647 LOC: Config.accessList.followXFF
1648 DEFAULT_IF_NONE: deny all
1649 DEFAULT_DOC: X-Forwarded-For header will be ignored.
1651 Determine which client proxies can be trusted to provide correct
1652 information regarding real client IP address.
1654 Requests may pass through a chain of several other proxies
1655 before reaching us. The original source details may by sent in:
1656 * HTTP message Forwarded header, or
1657 * HTTP message X-Forwarded-For header, or
1658 * PROXY protocol connection header.
1660 PROXY protocol connections are controlled by the proxy_protocol_access
1661 directive which is checked before this.
1663 If a request reaches us from a source that is allowed by this
1664 directive, then we trust the information it provides regarding
1665 the IP of the client it received from (if any).
1667 For the purpose of ACLs used in this directive the src ACL type always
1668 matches the address we are testing and srcdomain matches its rDNS.
1670 On each HTTP request Squid checks for X-Forwarded-For header fields.
1671 If found the header values are iterated in reverse order and an allow
1672 match is required for Squid to continue on to the next value.
1673 The verification ends when a value receives a deny match, cannot be
1674 tested, or there are no more values to test.
1675 NOTE: Squid does not yet follow the Forwarded HTTP header.
1677 The end result of this process is an IP address that we will
1678 refer to as the indirect client address. This address may
1679 be treated as the client address for access control, ICAP, delay
1680 pools and logging, depending on the acl_uses_indirect_client,
1681 icap_uses_indirect_client, delay_pool_uses_indirect_client,
1682 log_uses_indirect_client and tproxy_uses_indirect_client options.
1684 This clause only supports fast acl types.
1685 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
1687 SECURITY CONSIDERATIONS:
1689 Any host from which we accept client IP details can place
1690 incorrect information in the relevant header, and Squid
1691 will use the incorrect information as if it were the
1692 source address of the request. This may enable remote
1693 hosts to bypass any access control restrictions that are
1694 based on the client's source addresses.
1698 acl localhost src 127.0.0.1
1699 acl my_other_proxy srcdomain .proxy.example.com
1700 follow_x_forwarded_for allow localhost
1701 follow_x_forwarded_for allow my_other_proxy
1704 NAME: acl_uses_indirect_client
1707 IFDEF: FOLLOW_X_FORWARDED_FOR
1709 LOC: Config.onoff.acl_uses_indirect_client
1711 Controls whether the indirect client address
1712 (see follow_x_forwarded_for) is used instead of the
1713 direct client address in acl matching.
1715 NOTE: maxconn ACL considers direct TCP links and indirect
1716 clients will always have zero. So no match.
1719 NAME: delay_pool_uses_indirect_client
1722 IFDEF: FOLLOW_X_FORWARDED_FOR&&USE_DELAY_POOLS
1724 LOC: Config.onoff.delay_pool_uses_indirect_client
1726 Controls whether the indirect client address
1727 (see follow_x_forwarded_for) is used instead of the
1728 direct client address in delay pools.
1731 NAME: log_uses_indirect_client
1734 IFDEF: FOLLOW_X_FORWARDED_FOR
1736 LOC: Config.onoff.log_uses_indirect_client
1738 Controls whether the indirect client address
1739 (see follow_x_forwarded_for) is used instead of the
1740 direct client address in the access log.
1743 NAME: tproxy_uses_indirect_client
1746 IFDEF: FOLLOW_X_FORWARDED_FOR&&LINUX_NETFILTER
1748 LOC: Config.onoff.tproxy_uses_indirect_client
1750 Controls whether the indirect client address
1751 (see follow_x_forwarded_for) is used instead of the
1752 direct client address when spoofing the outgoing client.
1754 This has no effect on requests arriving in non-tproxy
1757 SECURITY WARNING: Usage of this option is dangerous
1758 and should not be used trivially. Correct configuration
1759 of follow_x_forwarded_for with a limited set of trusted
1760 sources is required to prevent abuse of your proxy.
1763 NAME: spoof_client_ip
1765 LOC: Config.accessList.spoof_client_ip
1767 DEFAULT_DOC: Allow spoofing on all TPROXY traffic.
1769 Control client IP address spoofing of TPROXY traffic based on
1770 defined access lists.
1772 spoof_client_ip allow|deny [!]aclname ...
1774 If there are no "spoof_client_ip" lines present, the default
1775 is to "allow" spoofing of any suitable request.
1777 Note that the cache_peer "no-tproxy" option overrides this ACL.
1779 This clause supports fast acl types.
1780 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
1785 LOC: Config.accessList.http
1786 DEFAULT_IF_NONE: deny all
1787 DEFAULT_DOC: Deny, unless rules exist in squid.conf.
1789 Allowing or Denying access based on defined access lists
1791 To allow or deny a message received on an HTTP, HTTPS, or FTP port:
1792 http_access allow|deny [!]aclname ...
1794 NOTE on default values:
1796 If there are no "access" lines present, the default is to deny
1799 If none of the "access" lines cause a match, the default is the
1800 opposite of the last line in the list. If the last line was
1801 deny, the default is allow. Conversely, if the last line
1802 is allow, the default will be deny. For these reasons, it is a
1803 good idea to have an "deny all" entry at the end of your access
1804 lists to avoid potential confusion.
1806 This clause supports both fast and slow acl types.
1807 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
1812 # Recommended minimum Access Permission configuration:
1814 # Deny requests to certain unsafe ports
1815 http_access deny !Safe_ports
1817 # Deny CONNECT to other than secure SSL ports
1818 http_access deny CONNECT !SSL_ports
1820 # Only allow cachemgr access from localhost
1821 http_access allow localhost manager
1822 http_access deny manager
1824 # We strongly recommend the following be uncommented to protect innocent
1825 # web applications running on the proxy server who think the only
1826 # one who can access services on "localhost" is a local user
1827 #http_access deny to_localhost
1830 # INSERT YOUR OWN RULE(S) HERE TO ALLOW ACCESS FROM YOUR CLIENTS
1833 # Example rule allowing access from your local networks.
1834 # Adapt localnet in the ACL section to list your (internal) IP networks
1835 # from where browsing should be allowed
1836 http_access allow localnet
1837 http_access allow localhost
1839 # And finally deny all other access to this proxy
1840 http_access deny all
1844 NAME: adapted_http_access http_access2
1846 LOC: Config.accessList.adapted_http
1848 DEFAULT_DOC: Allow, unless rules exist in squid.conf.
1850 Allowing or Denying access based on defined access lists
1852 Essentially identical to http_access, but runs after redirectors
1853 and ICAP/eCAP adaptation. Allowing access control based on their
1856 If not set then only http_access is used.
1859 NAME: http_reply_access
1861 LOC: Config.accessList.reply
1863 DEFAULT_DOC: Allow, unless rules exist in squid.conf.
1865 Allow replies to client requests. This is complementary to http_access.
1867 http_reply_access allow|deny [!] aclname ...
1869 NOTE: if there are no access lines present, the default is to allow
1872 If none of the access lines cause a match the opposite of the
1873 last line will apply. Thus it is good practice to end the rules
1874 with an "allow all" or "deny all" entry.
1876 This clause supports both fast and slow acl types.
1877 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
1882 LOC: Config.accessList.icp
1884 DEFAULT_DOC: Deny, unless rules exist in squid.conf.
1886 Allowing or Denying access to the ICP port based on defined
1889 icp_access allow|deny [!]aclname ...
1891 NOTE: The default if no icp_access lines are present is to
1892 deny all traffic. This default may cause problems with peers
1895 This clause only supports fast acl types.
1896 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
1898 # Allow ICP queries from local networks only
1899 #icp_access allow localnet
1900 #icp_access deny all
1906 LOC: Config.accessList.htcp
1908 DEFAULT_DOC: Deny, unless rules exist in squid.conf.
1910 Allowing or Denying access to the HTCP port based on defined
1913 htcp_access allow|deny [!]aclname ...
1915 See also htcp_clr_access for details on access control for
1916 cache purge (CLR) HTCP messages.
1918 NOTE: The default if no htcp_access lines are present is to
1919 deny all traffic. This default may cause problems with peers
1920 using the htcp option.
1922 This clause only supports fast acl types.
1923 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
1925 # Allow HTCP queries from local networks only
1926 #htcp_access allow localnet
1927 #htcp_access deny all
1930 NAME: htcp_clr_access
1933 LOC: Config.accessList.htcp_clr
1935 DEFAULT_DOC: Deny, unless rules exist in squid.conf.
1937 Allowing or Denying access to purge content using HTCP based
1938 on defined access lists.
1939 See htcp_access for details on general HTCP access control.
1941 htcp_clr_access allow|deny [!]aclname ...
1943 This clause only supports fast acl types.
1944 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
1946 # Allow HTCP CLR requests from trusted peers
1947 acl htcp_clr_peer src 192.0.2.2 2001:DB8::2
1948 htcp_clr_access allow htcp_clr_peer
1949 htcp_clr_access deny all
1954 LOC: Config.accessList.miss
1956 DEFAULT_DOC: Allow, unless rules exist in squid.conf.
1958 Determines whether network access is permitted when satisfying a request.
1961 to force your neighbors to use you as a sibling instead of
1964 acl localclients src 192.0.2.0/24 2001:DB8::a:0/64
1965 miss_access deny !localclients
1966 miss_access allow all
1968 This means only your local clients are allowed to fetch relayed/MISS
1969 replies from the network and all other clients can only fetch cached
1972 The default for this setting allows all clients who passed the
1973 http_access rules to relay via this proxy.
1975 This clause only supports fast acl types.
1976 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
1979 NAME: ident_lookup_access
1983 DEFAULT_DOC: Unless rules exist in squid.conf, IDENT is not fetched.
1984 LOC: Ident::TheConfig.identLookup
1986 A list of ACL elements which, if matched, cause an ident
1987 (RFC 931) lookup to be performed for this request. For
1988 example, you might choose to always perform ident lookups
1989 for your main multi-user Unix boxes, but not for your Macs
1990 and PCs. By default, ident lookups are not performed for
1993 To enable ident lookups for specific client addresses, you
1994 can follow this example:
1996 acl ident_aware_hosts src 198.168.1.0/24
1997 ident_lookup_access allow ident_aware_hosts
1998 ident_lookup_access deny all
2000 Only src type ACL checks are fully supported. A srcdomain
2001 ACL might work at times, but it will not always provide
2004 This clause only supports fast acl types.
2005 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
2008 NAME: reply_body_max_size
2009 COMMENT: size [acl acl...]
2012 DEFAULT_DOC: No limit is applied.
2013 LOC: Config.ReplyBodySize
2015 This option specifies the maximum size of a reply body. It can be
2016 used to prevent users from downloading very large files, such as
2017 MP3's and movies. When the reply headers are received, the
2018 reply_body_max_size lines are processed, and the first line where
2019 all (if any) listed ACLs are true is used as the maximum body size
2022 This size is checked twice. First when we get the reply headers,
2023 we check the content-length value. If the content length value exists
2024 and is larger than the allowed size, the request is denied and the
2025 user receives an error message that says "the request or reply
2026 is too large." If there is no content-length, and the reply
2027 size exceeds this limit, the client's connection is just closed
2028 and they will receive a partial reply.
2030 WARNING: downstream caches probably can not detect a partial reply
2031 if there is no content-length header, so they will cache
2032 partial responses and give them out as hits. You should NOT
2033 use this option if you have downstream caches.
2035 WARNING: A maximum size smaller than the size of squid's error messages
2036 will cause an infinite loop and crash squid. Ensure that the smallest
2037 non-zero value you use is greater that the maximum header size plus
2038 the size of your largest error page.
2040 If you set this parameter none (the default), there will be
2043 Configuration Format is:
2044 reply_body_max_size SIZE UNITS [acl ...]
2046 reply_body_max_size 10 MB
2050 NAME: on_unsupported_protocol
2051 TYPE: on_unsupported_protocol
2052 LOC: Config.accessList.on_unsupported_protocol
2054 DEFAULT_DOC: Respond with an error message to unidentifiable traffic
2056 Determines Squid behavior when encountering strange requests at the
2057 beginning of an accepted TCP connection or the beginning of a bumped
2058 CONNECT tunnel. Controlling Squid reaction to unexpected traffic is
2059 especially useful in interception environments where Squid is likely
2060 to see connections for unsupported protocols that Squid should either
2061 terminate or tunnel at TCP level.
2063 on_unsupported_protocol <action> [!]acl ...
2065 The first matching action wins. Only fast ACLs are supported.
2067 Supported actions are:
2069 tunnel: Establish a TCP connection with the intended server and
2070 blindly shovel TCP packets between the client and server.
2072 respond: Respond with an error message, using the transfer protocol
2073 for the Squid port that received the request (e.g., HTTP
2074 for connections intercepted at the http_port). This is the
2077 Squid expects the following traffic patterns:
2079 http_port: a plain HTTP request
2080 https_port: SSL/TLS handshake followed by an [encrypted] HTTP request
2081 ftp_port: a plain FTP command (no on_unsupported_protocol support yet!)
2082 CONNECT tunnel on http_port: same as https_port
2083 CONNECT tunnel on https_port: same as https_port
2085 Currently, this directive has effect on intercepted connections and
2086 bumped tunnels only. Other cases are not supported because Squid
2087 cannot know the intended destination of other traffic.
2090 # define what Squid errors indicate receiving non-HTTP traffic:
2091 acl foreignProtocol squid_error ERR_PROTOCOL_UNKNOWN ERR_TOO_BIG
2092 # define what Squid errors indicate receiving nothing:
2093 acl serverTalksFirstProtocol squid_error ERR_REQUEST_START_TIMEOUT
2094 # tunnel everything that does not look like HTTP:
2095 on_unsupported_protocol tunnel foreignProtocol
2096 # tunnel if we think the client waits for the server to talk first:
2097 on_unsupported_protocol tunnel serverTalksFirstProtocol
2098 # in all other error cases, just send an HTTP "error page" response:
2099 on_unsupported_protocol respond all
2101 See also: squid_error ACL
2107 LOC: Auth::TheConfig.schemeAccess
2109 DEFAULT_DOC: use all auth_param schemes in their configuration order
2111 Use this directive to customize authentication schemes presence and
2112 order in Squid's Unauthorized and Authentication Required responses.
2114 auth_schemes scheme1,scheme2,... [!]aclname ...
2116 where schemeN is the name of one of the authentication schemes
2117 configured using auth_param directives. At least one scheme name is
2118 required. Multiple scheme names are separated by commas. Either
2119 avoid whitespace or quote the entire schemes list.
2121 A special "ALL" scheme name expands to all auth_param-configured
2122 schemes in their configuration order. This directive cannot be used
2123 to configure Squid to offer no authentication schemes at all.
2125 The first matching auth_schemes rule determines the schemes order
2126 for the current Authentication Required transaction. Note that the
2127 future response is not yet available during auth_schemes evaluation.
2129 If this directive is not used or none of its rules match, then Squid
2130 responds with all configured authentication schemes in the order of
2131 auth_param directives in the configuration file.
2133 This directive does not determine when authentication is used or
2134 how each authentication scheme authenticates clients.
2136 The following example sends basic and negotiate authentication
2137 schemes, in that order, when requesting authentication of HTTP
2138 requests matching the isIE ACL (not shown) while sending all
2139 auth_param schemes in their configuration order to other clients:
2141 auth_schemes basic,negotiate isIE
2142 auth_schemes ALL all # explicit default
2144 This directive supports fast ACLs only.
2146 See also: auth_param.
2151 -----------------------------------------------------------------------------
2154 NAME: http_port ascii_port
2159 Usage: port [mode] [options]
2160 hostname:port [mode] [options]
2161 1.2.3.4:port [mode] [options]
2163 The socket addresses where Squid will listen for HTTP client
2164 requests. You may specify multiple socket addresses.
2165 There are three forms: port alone, hostname with port, and
2166 IP address with port. If you specify a hostname or IP
2167 address, Squid binds the socket to that specific
2168 address. Most likely, you do not need to bind to a specific
2169 address, so you can use the port number alone.
2171 If you are running Squid in accelerator mode, you
2172 probably want to listen on port 80 also, or instead.
2174 The -a command line option may be used to specify additional
2175 port(s) where Squid listens for proxy request. Such ports will
2176 be plain proxy ports with no options.
2178 You may specify multiple socket addresses on multiple lines.
2182 intercept Support for IP-Layer NAT interception delivering
2183 traffic to this Squid port.
2184 NP: disables authentication on the port.
2186 tproxy Support Linux TPROXY (or BSD divert-to) with spoofing
2187 of outgoing connections using the client IP address.
2188 NP: disables authentication on the port.
2190 accel Accelerator / reverse proxy mode
2192 ssl-bump For each CONNECT request allowed by ssl_bump ACLs,
2193 establish secure connection with the client and with
2194 the server, decrypt HTTPS messages as they pass through
2195 Squid, and treat them as unencrypted HTTP messages,
2196 becoming the man-in-the-middle.
2198 The ssl_bump option is required to fully enable
2199 bumping of CONNECT requests.
2201 Omitting the mode flag causes default forward proxy mode to be used.
2204 Accelerator Mode Options:
2206 defaultsite=domainname
2207 What to use for the Host: header if it is not present
2208 in a request. Determines what site (not origin server)
2209 accelerators should consider the default.
2211 no-vhost Disable using HTTP/1.1 Host header for virtual domain support.
2213 protocol= Protocol to reconstruct accelerated and intercepted
2214 requests with. Defaults to HTTP/1.1 for http_port and
2215 HTTPS/1.1 for https_port.
2216 When an unsupported value is configured Squid will
2217 produce a FATAL error.
2218 Values: HTTP or HTTP/1.1, HTTPS or HTTPS/1.1
2220 vport Virtual host port support. Using the http_port number
2221 instead of the port passed on Host: headers.
2223 vport=NN Virtual host port support. Using the specified port
2224 number instead of the port passed on Host: headers.
2227 Act as if this Squid is the origin server.
2228 This currently means generate new Date: and Expires:
2229 headers on HIT instead of adding Age:.
2231 ignore-cc Ignore request Cache-Control headers.
2233 WARNING: This option violates HTTP specifications if
2234 used in non-accelerator setups.
2236 allow-direct Allow direct forwarding in accelerator mode. Normally
2237 accelerated requests are denied direct forwarding as if
2238 never_direct was used.
2240 WARNING: this option opens accelerator mode to security
2241 vulnerabilities usually only affecting in interception
2242 mode. Make sure to protect forwarding with suitable
2243 http_access rules when using this.
2246 SSL Bump Mode Options:
2247 In addition to these options ssl-bump requires TLS/SSL options.
2249 generate-host-certificates[=<on|off>]
2250 Dynamically create SSL server certificates for the
2251 destination hosts of bumped CONNECT requests.When
2252 enabled, the cert and key options are used to sign
2253 generated certificates. Otherwise generated
2254 certificate will be selfsigned.
2255 If there is a CA certificate lifetime of the generated
2256 certificate equals lifetime of the CA certificate. If
2257 generated certificate is selfsigned lifetime is three
2259 This option is enabled by default when ssl-bump is used.
2260 See the ssl-bump option above for more information.
2262 dynamic_cert_mem_cache_size=SIZE
2263 Approximate total RAM size spent on cached generated
2264 certificates. If set to zero, caching is disabled. The
2265 default value is 4MB.
2269 tls-cert= Path to file containing an X.509 certificate (PEM format)
2270 to be used in the TLS handshake ServerHello.
2272 If this certificate is constrained by KeyUsage TLS
2273 feature it must allow HTTP server usage, along with
2274 any additional restrictions imposed by your choice
2275 of options= settings.
2277 When OpenSSL is used this file may also contain a
2278 chain of intermediate CA certificates to send in the
2281 When GnuTLS is used this option (and any paired
2282 tls-key= option) may be repeated to load multiple
2283 certificates for different domains.
2285 Also, when generate-host-certificates=on is configured
2286 the first tls-cert= option must be a CA certificate
2287 capable of signing the automatically generated
2290 tls-key= Path to a file containing private key file (PEM format)
2291 for the previous tls-cert= option.
2293 If tls-key= is not specified tls-cert= is assumed to
2294 reference a PEM file containing both the certificate
2297 cipher= Colon separated list of supported ciphers.
2298 NOTE: some ciphers such as EDH ciphers depend on
2299 additional settings. If those settings are
2300 omitted the ciphers may be silently ignored
2301 by the OpenSSL library.
2303 options= Various SSL implementation options. The most important
2306 NO_SSLv3 Disallow the use of SSLv3
2308 NO_TLSv1 Disallow the use of TLSv1.0
2310 NO_TLSv1_1 Disallow the use of TLSv1.1
2312 NO_TLSv1_2 Disallow the use of TLSv1.2
2315 Always create a new key when using
2316 temporary/ephemeral DH key exchanges
2319 Enable ephemeral ECDH key exchange.
2320 The adopted curve should be specified
2321 using the tls-dh option.
2324 Disable use of RFC5077 session tickets.
2325 Some servers may have problems
2326 understanding the TLS extension due
2327 to ambiguous specification in RFC4507.
2329 ALL Enable various bug workarounds
2330 suggested as "harmless" by OpenSSL
2331 Be warned that this reduces SSL/TLS
2332 strength to some attacks.
2334 See the OpenSSL SSL_CTX_set_options documentation for a
2337 clientca= File containing the list of CAs to use when
2338 requesting a client certificate.
2340 tls-cafile= PEM file containing CA certificates to use when verifying
2341 client certificates. If not configured clientca will be
2342 used. May be repeated to load multiple files.
2344 capath= Directory containing additional CA certificates
2345 and CRL lists to use when verifying client certificates.
2346 Requires OpenSSL or LibreSSL.
2348 crlfile= File of additional CRL lists to use when verifying
2349 the client certificate, in addition to CRLs stored in
2350 the capath. Implies VERIFY_CRL flag below.
2353 File containing DH parameters for temporary/ephemeral DH key
2354 exchanges, optionally prefixed by a curve for ephemeral ECDH
2356 See OpenSSL documentation for details on how to create the
2357 DH parameter file. Supported curves for ECDH can be listed
2358 using the "openssl ecparam -list_curves" command.
2359 WARNING: EDH and EECDH ciphers will be silently disabled if
2360 this option is not set.
2362 sslflags= Various flags modifying the use of SSL:
2364 Don't request client certificates
2365 immediately, but wait until acl processing
2366 requires a certificate (not yet implemented).
2368 Don't allow for session reuse. Each connection
2369 will result in a new SSL session.
2371 Verify CRL lists when accepting client
2374 Verify CRL lists for all certificates in the
2375 client certificate chain.
2377 tls-default-ca[=off]
2378 Whether to use the system Trusted CAs. Default is OFF.
2380 tls-no-npn Do not use the TLS NPN extension to advertise HTTP/1.1.
2382 sslcontext= SSL session ID context identifier.
2386 connection-auth[=on|off]
2387 use connection-auth=off to tell Squid to prevent
2388 forwarding Microsoft connection oriented authentication
2389 (NTLM, Negotiate and Kerberos)
2391 disable-pmtu-discovery=
2392 Control Path-MTU discovery usage:
2393 off lets OS decide on what to do (default).
2394 transparent disable PMTU discovery when transparent
2396 always disable always PMTU discovery.
2398 In many setups of transparently intercepting proxies
2399 Path-MTU discovery can not work on traffic towards the
2400 clients. This is the case when the intercepting device
2401 does not fully track connections and fails to forward
2402 ICMP must fragment messages to the cache server. If you
2403 have such setup and experience that certain clients
2404 sporadically hang or never complete requests set
2405 disable-pmtu-discovery option to 'transparent'.
2407 name= Specifies a internal name for the port. Defaults to
2408 the port specification (port or addr:port)
2410 tcpkeepalive[=idle,interval,timeout]
2411 Enable TCP keepalive probes of idle connections.
2412 In seconds; idle is the initial time before TCP starts
2413 probing the connection, interval how often to probe, and
2414 timeout the time before giving up.
2416 require-proxy-header
2417 Require PROXY protocol version 1 or 2 connections.
2418 The proxy_protocol_access is required to whitelist
2419 downstream proxies which can be trusted.
2421 If you run Squid on a dual-homed machine with an internal
2422 and an external interface we recommend you to specify the
2423 internal address:port in http_port. This way Squid will only be
2424 visible on the internal address.
2428 # Squid normally listens to port 3128
2429 http_port @DEFAULT_HTTP_PORT@
2434 IFDEF: USE_GNUTLS||USE_OPENSSL
2439 Usage: [ip:]port [mode] tls-cert=certificate.pem [options]
2441 The socket address where Squid will listen for client requests made
2442 over TLS or SSL connections. Commonly referred to as HTTPS.
2444 This is most useful for situations where you are running squid in
2445 accelerator mode and you want to do the TLS work at the accelerator
2448 You may specify multiple socket addresses on multiple lines,
2449 each with their own certificate and/or options.
2451 The tls-cert= option is mandatory on HTTPS ports.
2453 See http_port for a list of modes and options.
2461 Enables Native FTP proxy by specifying the socket address where Squid
2462 listens for FTP client requests. See http_port directive for various
2463 ways to specify the listening address and mode.
2465 Usage: ftp_port address [mode] [options]
2467 WARNING: This is a new, experimental, complex feature that has seen
2468 limited production exposure. Some Squid modules (e.g., caching) do not
2469 currently work with native FTP proxying, and many features have not
2470 even been tested for compatibility. Test well before deploying!
2472 Native FTP proxying differs substantially from proxying HTTP requests
2473 with ftp:// URIs because Squid works as an FTP server and receives
2474 actual FTP commands (rather than HTTP requests with FTP URLs).
2476 Native FTP commands accepted at ftp_port are internally converted or
2477 wrapped into HTTP-like messages. The same happens to Native FTP
2478 responses received from FTP origin servers. Those HTTP-like messages
2479 are shoveled through regular access control and adaptation layers
2480 between the FTP client and the FTP origin server. This allows Squid to
2481 examine, adapt, block, and log FTP exchanges. Squid reuses most HTTP
2482 mechanisms when shoveling wrapped FTP messages. For example,
2483 http_access and adaptation_access directives are used.
2487 intercept Same as http_port intercept. The FTP origin address is
2488 determined based on the intended destination of the
2489 intercepted connection.
2491 tproxy Support Linux TPROXY for spoofing outgoing
2492 connections using the client IP address.
2493 NP: disables authentication and maybe IPv6 on the port.
2495 By default (i.e., without an explicit mode option), Squid extracts the
2496 FTP origin address from the login@origin parameter of the FTP USER
2497 command. Many popular FTP clients support such native FTP proxying.
2501 name=token Specifies an internal name for the port. Defaults to
2502 the port address. Usable with myportname ACL.
2505 Enables tracking of FTP directories by injecting extra
2506 PWD commands and adjusting Request-URI (in wrapping
2507 HTTP requests) to reflect the current FTP server
2508 directory. Tracking is disabled by default.
2510 protocol=FTP Protocol to reconstruct accelerated and intercepted
2511 requests with. Defaults to FTP. No other accepted
2512 values have been tested with. An unsupported value
2513 results in a FATAL error. Accepted values are FTP,
2514 HTTP (or HTTP/1.1), and HTTPS (or HTTPS/1.1).
2516 Other http_port modes and options that are not specific to HTTP and
2517 HTTPS may also work.
2520 NAME: tcp_outgoing_tos tcp_outgoing_ds tcp_outgoing_dscp
2523 LOC: Ip::Qos::TheConfig.tosToServer
2525 Allows you to select a TOS/Diffserv value for packets outgoing
2526 on the server side, based on an ACL.
2528 tcp_outgoing_tos ds-field [!]aclname ...
2530 Example where normal_service_net uses the TOS value 0x00
2531 and good_service_net uses 0x20
2533 acl normal_service_net src 10.0.0.0/24
2534 acl good_service_net src 10.0.1.0/24
2535 tcp_outgoing_tos 0x00 normal_service_net
2536 tcp_outgoing_tos 0x20 good_service_net
2538 TOS/DSCP values really only have local significance - so you should
2539 know what you're specifying. For more information, see RFC2474,
2540 RFC2475, and RFC3260.
2542 The TOS/DSCP byte must be exactly that - a octet value 0 - 255, or
2543 "default" to use whatever default your host has.
2544 Note that only multiples of 4 are usable as the two rightmost bits have
2545 been redefined for use by ECN (RFC 3168 section 23.1).
2546 The squid parser will enforce this by masking away the ECN bits.
2548 Processing proceeds in the order specified, and stops at first fully
2551 Only fast ACLs are supported.
2554 NAME: clientside_tos
2557 LOC: Ip::Qos::TheConfig.tosToClient
2559 Allows you to select a TOS/DSCP value for packets being transmitted
2560 on the client-side, based on an ACL.
2562 clientside_tos ds-field [!]aclname ...
2564 Example where normal_service_net uses the TOS value 0x00
2565 and good_service_net uses 0x20
2567 acl normal_service_net src 10.0.0.0/24
2568 acl good_service_net src 10.0.1.0/24
2569 clientside_tos 0x00 normal_service_net
2570 clientside_tos 0x20 good_service_net
2572 Note: This feature is incompatible with qos_flows. Any TOS values set here
2573 will be overwritten by TOS values in qos_flows.
2575 The TOS/DSCP byte must be exactly that - a octet value 0 - 255, or
2576 "default" to use whatever default your host has.
2577 Note that only multiples of 4 are usable as the two rightmost bits have
2578 been redefined for use by ECN (RFC 3168 section 23.1).
2579 The squid parser will enforce this by masking away the ECN bits.
2581 This clause only supports fast acl types.
2582 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
2585 NAME: tcp_outgoing_mark
2587 IFDEF: SO_MARK&&USE_LIBCAP
2589 LOC: Ip::Qos::TheConfig.nfmarkToServer
2591 Allows you to apply a Netfilter mark value to outgoing packets
2592 on the server side, based on an ACL.
2594 tcp_outgoing_mark mark-value [!]aclname ...
2596 Example where normal_service_net uses the mark value 0x00
2597 and good_service_net uses 0x20
2599 acl normal_service_net src 10.0.0.0/24
2600 acl good_service_net src 10.0.1.0/24
2601 tcp_outgoing_mark 0x00 normal_service_net
2602 tcp_outgoing_mark 0x20 good_service_net
2604 Only fast ACLs are supported.
2607 NAME: mark_client_packet clientside_mark
2609 IFDEF: SO_MARK&&USE_LIBCAP
2611 LOC: Ip::Qos::TheConfig.nfmarkToClient
2613 Allows you to apply a Netfilter MARK value to packets being transmitted
2614 on the client-side, based on an ACL.
2616 mark_client_packet mark-value [!]aclname ...
2618 Example where normal_service_net uses the MARK value 0x00
2619 and good_service_net uses 0x20
2621 acl normal_service_net src 10.0.0.0/24
2622 acl good_service_net src 10.0.1.0/24
2623 mark_client_packet 0x00 normal_service_net
2624 mark_client_packet 0x20 good_service_net
2626 Note: This feature is incompatible with qos_flows. Any mark values set here
2627 will be overwritten by mark values in qos_flows.
2629 This clause only supports fast acl types.
2630 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
2633 NAME: mark_client_connection
2635 IFDEF: SO_MARK&&USE_LIBCAP
2637 LOC: Ip::Qos::TheConfig.nfConnmarkToClient
2639 Allows you to apply a Netfilter CONNMARK value to a connection
2640 on the client-side, based on an ACL.
2642 mark_client_connection mark-value[/mask] [!]aclname ...
2644 The mark-value and mask are unsigned integers (hex, octal, or decimal).
2645 The mask may be used to preserve marking previously set by other agents
2648 A matching rule replaces the CONNMARK value. If a mask is also
2649 specified, then the masked bits of the original value are zeroed, and
2650 the configured mark-value is ORed with that adjusted value.
2651 For example, applying a mark-value 0xAB/0xF to 0x5F CONNMARK, results
2652 in a 0xFB marking (rather than a 0xAB or 0x5B).
2654 This directive semantics is similar to iptables --set-mark rather than
2655 --set-xmark functionality.
2657 The directive does not interfere with qos_flows (which uses packet MARKs,
2660 Example where squid marks intercepted FTP connections:
2662 acl proto_ftp proto FTP
2663 mark_client_connection 0x200/0xff00 proto_ftp
2665 This clause only supports fast acl types.
2666 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
2673 LOC: Ip::Qos::TheConfig
2675 Allows you to select a TOS/DSCP value to mark outgoing
2676 connections to the client, based on where the reply was sourced.
2677 For platforms using netfilter, allows you to set a netfilter mark
2678 value instead of, or in addition to, a TOS value.
2680 By default this functionality is disabled. To enable it with the default
2681 settings simply use "qos_flows mark" or "qos_flows tos". Default
2682 settings will result in the netfilter mark or TOS value being copied
2683 from the upstream connection to the client. Note that it is the connection
2684 CONNMARK value not the packet MARK value that is copied.
2686 It is not currently possible to copy the mark or TOS value from the
2687 client to the upstream connection request.
2689 TOS values really only have local significance - so you should
2690 know what you're specifying. For more information, see RFC2474,
2691 RFC2475, and RFC3260.
2693 The TOS/DSCP byte must be exactly that - a octet value 0 - 255.
2694 Note that only multiples of 4 are usable as the two rightmost bits have
2695 been redefined for use by ECN (RFC 3168 section 23.1).
2696 The squid parser will enforce this by masking away the ECN bits.
2698 Mark values can be any unsigned 32-bit integer value.
2700 This setting is configured by setting the following values:
2702 tos|mark Whether to set TOS or netfilter mark values
2704 local-hit=0xFF Value to mark local cache hits.
2706 sibling-hit=0xFF Value to mark hits from sibling peers.
2708 parent-hit=0xFF Value to mark hits from parent peers.
2710 miss=0xFF[/mask] Value to mark cache misses. Takes precedence
2711 over the preserve-miss feature (see below), unless
2712 mask is specified, in which case only the bits
2713 specified in the mask are written.
2715 The TOS variant of the following features are only possible on Linux
2716 and require your kernel to be patched with the TOS preserving ZPH
2717 patch, available from http://zph.bratcheda.org
2718 No patch is needed to preserve the netfilter mark, which will work
2719 with all variants of netfilter.
2721 disable-preserve-miss
2722 This option disables the preservation of the TOS or netfilter
2723 mark. By default, the existing TOS or netfilter mark value of
2724 the response coming from the remote server will be retained
2725 and masked with miss-mark.
2726 NOTE: in the case of a netfilter mark, the mark must be set on
2727 the connection (using the CONNMARK target) not on the packet
2731 Allows you to mask certain bits in the TOS or mark value
2732 received from the remote server, before copying the value to
2733 the TOS sent towards clients.
2734 Default for tos: 0xFF (TOS from server is not changed).
2735 Default for mark: 0xFFFFFFFF (mark from server is not changed).
2737 All of these features require the --enable-zph-qos compilation flag
2738 (enabled by default). Netfilter marking also requires the
2739 libnetfilter_conntrack libraries (--with-netfilter-conntrack) and
2740 libcap 2.09+ (--with-libcap).
2744 NAME: tcp_outgoing_address
2747 DEFAULT_DOC: Address selection is performed by the operating system.
2748 LOC: Config.accessList.outgoing_address
2750 Allows you to map requests to different outgoing IP addresses
2751 based on the username or source address of the user making
2754 tcp_outgoing_address ipaddr [[!]aclname] ...
2757 Forwarding clients with dedicated IPs for certain subnets.
2759 acl normal_service_net src 10.0.0.0/24
2760 acl good_service_net src 10.0.2.0/24
2762 tcp_outgoing_address 2001:db8::c001 good_service_net
2763 tcp_outgoing_address 10.1.0.2 good_service_net
2765 tcp_outgoing_address 2001:db8::beef normal_service_net
2766 tcp_outgoing_address 10.1.0.1 normal_service_net
2768 tcp_outgoing_address 2001:db8::1
2769 tcp_outgoing_address 10.1.0.3
2771 Processing proceeds in the order specified, and stops at first fully
2774 Squid will add an implicit IP version test to each line.
2775 Requests going to IPv4 websites will use the outgoing 10.1.0.* addresses.
2776 Requests going to IPv6 websites will use the outgoing 2001:db8:* addresses.
2779 NOTE: The use of this directive using client dependent ACLs is
2780 incompatible with the use of server side persistent connections. To
2781 ensure correct results it is best to set server_persistent_connections
2782 to off when using this directive in such configurations.
2784 NOTE: The use of this directive to set a local IP on outgoing TCP links
2785 is incompatible with using TPROXY to set client IP out outbound TCP links.
2786 When needing to contact peers use the no-tproxy cache_peer option and the
2787 client_dst_passthru directive re-enable normal forwarding such as this.
2789 This clause only supports fast acl types.
2790 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
2793 NAME: host_verify_strict
2796 LOC: Config.onoff.hostStrictVerify
2798 Regardless of this option setting, when dealing with intercepted
2799 traffic, Squid always verifies that the destination IP address matches
2800 the Host header domain or IP (called 'authority form URL').
2802 This enforcement is performed to satisfy a MUST-level requirement in
2803 RFC 2616 section 14.23: "The Host field value MUST represent the naming
2804 authority of the origin server or gateway given by the original URL".
2807 Squid always responds with an HTTP 409 (Conflict) error
2808 page and logs a security warning if there is no match.
2810 Squid verifies that the destination IP address matches
2811 the Host header for forward-proxy and reverse-proxy traffic
2812 as well. For those traffic types, Squid also enables the
2813 following checks, comparing the corresponding Host header
2814 and Request-URI components:
2816 * The host names (domain or IP) must be identical,
2817 but valueless or missing Host header disables all checks.
2818 For the two host names to match, both must be either IP
2821 * Port numbers must be identical, but if a port is missing
2822 the scheme-default port is assumed.
2825 When set to OFF (the default):
2826 Squid allows suspicious requests to continue but logs a
2827 security warning and blocks caching of the response.
2829 * Forward-proxy traffic is not checked at all.
2831 * Reverse-proxy traffic is not checked at all.
2833 * Intercepted traffic which passes verification is handled
2834 according to client_dst_passthru.
2836 * Intercepted requests which fail verification are sent
2837 to the client original destination instead of DIRECT.
2838 This overrides 'client_dst_passthru off'.
2840 For now suspicious intercepted CONNECT requests are always
2841 responded to with an HTTP 409 (Conflict) error page.
2846 As described in CVE-2009-0801 when the Host: header alone is used
2847 to determine the destination of a request it becomes trivial for
2848 malicious scripts on remote websites to bypass browser same-origin
2849 security policy and sandboxing protections.
2851 The cause of this is that such applets are allowed to perform their
2852 own HTTP stack, in which case the same-origin policy of the browser
2853 sandbox only verifies that the applet tries to contact the same IP
2854 as from where it was loaded at the IP level. The Host: header may
2855 be different from the connected IP and approved origin.
2859 NAME: client_dst_passthru
2862 LOC: Config.onoff.client_dst_passthru
2864 With NAT or TPROXY intercepted traffic Squid may pass the request
2865 directly to the original client destination IP or seek a faster
2866 source using the HTTP Host header.
2868 Using Host to locate alternative servers can provide faster
2869 connectivity with a range of failure recovery options.
2870 But can also lead to connectivity trouble when the client and
2871 server are attempting stateful interactions unaware of the proxy.
2873 This option (on by default) prevents alternative DNS entries being
2874 located to send intercepted traffic DIRECT to an origin server.
2875 The clients original destination IP and port will be used instead.
2877 Regardless of this option setting, when dealing with intercepted
2878 traffic Squid will verify the Host: header and any traffic which
2879 fails Host verification will be treated as if this option were ON.
2881 see host_verify_strict for details on the verification process.
2886 -----------------------------------------------------------------------------
2889 NAME: tls_outgoing_options
2890 IFDEF: USE_GNUTLS||USE_OPENSSL
2891 TYPE: securePeerOptions
2892 DEFAULT: min-version=1.0
2893 LOC: Security::ProxyOutgoingConfig
2895 disable Do not support https:// URLs.
2897 cert=/path/to/client/certificate
2898 A client X.509 certificate to use when connecting.
2900 key=/path/to/client/private_key
2901 The private key corresponding to the cert= above.
2903 If key= is not specified cert= is assumed to
2904 reference a PEM file containing both the certificate
2907 cipher=... The list of valid TLS ciphers to use.
2910 The minimum TLS protocol version to permit.
2911 To control SSLv3 use the options= parameter.
2912 Supported Values: 1.0 (default), 1.1, 1.2
2914 options=... Specify various TLS/SSL implementation options.
2916 OpenSSL options most important are:
2918 NO_SSLv3 Disallow the use of SSLv3
2921 Always create a new key when using
2922 temporary/ephemeral DH key exchanges
2925 Disable use of RFC5077 session tickets.
2926 Some servers may have problems
2927 understanding the TLS extension due
2928 to ambiguous specification in RFC4507.
2930 ALL Enable various bug workarounds
2931 suggested as "harmless" by OpenSSL
2932 Be warned that this reduces SSL/TLS
2933 strength to some attacks.
2935 See the OpenSSL SSL_CTX_set_options documentation
2936 for a more complete list.
2938 GnuTLS options most important are:
2941 Disable use of RFC5077 session tickets.
2942 Some servers may have problems
2943 understanding the TLS extension due
2944 to ambiguous specification in RFC4507.
2946 See the GnuTLS Priority Strings documentation
2947 for a more complete list.
2948 http://www.gnutls.org/manual/gnutls.html#Priority-Strings
2951 cafile= PEM file containing CA certificates to use when verifying
2952 the peer certificate. May be repeated to load multiple files.
2954 capath= A directory containing additional CA certificates to
2955 use when verifying the peer certificate.
2956 Requires OpenSSL or LibreSSL.
2958 crlfile=... A certificate revocation list file to use when
2959 verifying the peer certificate.
2961 flags=... Specify various flags modifying the TLS implementation:
2964 Accept certificates even if they fail to
2967 Don't verify the peer certificate
2968 matches the server name
2971 Whether to use the system Trusted CAs. Default is ON.
2973 domain= The peer name as advertised in its certificate.
2974 Used for verifying the correctness of the received peer
2975 certificate. If not specified the peer hostname will be
2981 -----------------------------------------------------------------------------
2984 NAME: ssl_unclean_shutdown
2988 LOC: Config.SSL.unclean_shutdown
2990 Some browsers (especially MSIE) bugs out on SSL shutdown
2997 LOC: Config.SSL.ssl_engine
3000 The OpenSSL engine to use. You will need to set this if you
3001 would like to use hardware SSL acceleration for example.
3004 NAME: sslproxy_session_ttl
3007 LOC: Config.SSL.session_ttl
3010 Sets the timeout value for SSL sessions
3013 NAME: sslproxy_session_cache_size
3016 LOC: Config.SSL.sessionCacheSize
3019 Sets the cache size to use for ssl session
3022 NAME: sslproxy_foreign_intermediate_certs
3025 LOC: Config.ssl_client.foreignIntermediateCertsPath
3028 Many origin servers fail to send their full server certificate
3029 chain for verification, assuming the client already has or can
3030 easily locate any missing intermediate certificates.
3032 Squid uses the certificates from the specified file to fill in
3033 these missing chains when trying to validate origin server
3036 The file is expected to contain zero or more PEM-encoded
3037 intermediate certificates. These certificates are not treated
3038 as trusted root certificates, and any self-signed certificate in
3039 this file will be ignored.
3042 NAME: sslproxy_cert_sign_hash
3045 LOC: Config.SSL.certSignHash
3048 Sets the hashing algorithm to use when signing generated certificates.
3049 Valid algorithm names depend on the OpenSSL library used. The following
3050 names are usually available: sha1, sha256, sha512, and md5. Please see
3051 your OpenSSL library manual for the available hashes. By default, Squids
3052 that support this option use sha256 hashes.
3054 Squid does not forcefully purge cached certificates that were generated
3055 with an algorithm other than the currently configured one. They remain
3056 in the cache, subject to the regular cache eviction policy, and become
3057 useful if the algorithm changes again.
3062 TYPE: sslproxy_ssl_bump
3063 LOC: Config.accessList.ssl_bump
3064 DEFAULT_DOC: Become a TCP tunnel without decrypting proxied traffic.
3067 This option is consulted when a CONNECT request is received on
3068 an http_port (or a new connection is intercepted at an
3069 https_port), provided that port was configured with an ssl-bump
3070 flag. The subsequent data on the connection is either treated as
3071 HTTPS and decrypted OR tunneled at TCP level without decryption,
3072 depending on the first matching bumping "action".
3074 ssl_bump <action> [!]acl ...
3076 The following bumping actions are currently supported:
3079 Become a TCP tunnel without decrypting proxied traffic.
3080 This is the default action.
3083 When used on step SslBump1, establishes a secure connection
3084 with the client first, then connect to the server.
3085 When used on step SslBump2 or SslBump3, establishes a secure
3086 connection with the server and, using a mimicked server
3087 certificate, with the client.
3090 Receive client (step SslBump1) or server (step SslBump2)
3091 certificate while preserving the possibility of splicing the
3092 connection. Peeking at the server certificate (during step 2)
3093 usually precludes bumping of the connection at step 3.
3096 Receive client (step SslBump1) or server (step SslBump2)
3097 certificate while preserving the possibility of bumping the
3098 connection. Staring at the server certificate (during step 2)
3099 usually precludes splicing of the connection at step 3.
3102 Close client and server connections.
3104 Backward compatibility actions available at step SslBump1:
3107 Bump the connection. Establish a secure connection with the
3108 client first, then connect to the server. This old mode does
3109 not allow Squid to mimic server SSL certificate and does not
3110 work with intercepted SSL connections.
3113 Bump the connection. Establish a secure connection with the
3114 server first, then establish a secure connection with the
3115 client, using a mimicked server certificate. Works with both
3116 CONNECT requests and intercepted SSL connections, but does
3117 not allow to make decisions based on SSL handshake info.
3120 Decide whether to bump or splice the connection based on
3121 client-to-squid and server-to-squid SSL hello messages.
3125 Same as the "splice" action.
3127 All ssl_bump rules are evaluated at each of the supported bumping
3128 steps. Rules with actions that are impossible at the current step are
3129 ignored. The first matching ssl_bump action wins and is applied at the
3130 end of the current step. If no rules match, the splice action is used.
3131 See the at_step ACL for a list of the supported SslBump steps.
3133 This clause supports both fast and slow acl types.
3134 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
3136 See also: http_port ssl-bump, https_port ssl-bump, and acl at_step.
3139 # Example: Bump all TLS connections except those originating from
3140 # localhost or those going to example.com.
3142 acl broken_sites ssl::server_name .example.com
3143 ssl_bump splice localhost
3144 ssl_bump splice broken_sites
3148 NAME: sslproxy_cert_error
3151 DEFAULT_DOC: Server certificate errors terminate the transaction.
3152 LOC: Config.ssl_client.cert_error
3155 Use this ACL to bypass server certificate validation errors.
3157 For example, the following lines will bypass all validation errors
3158 when talking to servers for example.com. All other
3159 validation errors will result in ERR_SECURE_CONNECT_FAIL error.
3161 acl BrokenButTrustedServers dstdomain example.com
3162 sslproxy_cert_error allow BrokenButTrustedServers
3163 sslproxy_cert_error deny all
3165 This clause only supports fast acl types.
3166 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
3167 Using slow acl types may result in server crashes
3169 Without this option, all server certificate validation errors
3170 terminate the transaction to protect Squid and the client.
3172 SQUID_X509_V_ERR_INFINITE_VALIDATION error cannot be bypassed
3173 but should not happen unless your OpenSSL library is buggy.
3176 Bypassing validation errors is dangerous because an
3177 error usually implies that the server cannot be trusted
3178 and the connection may be insecure.
3180 See also: sslproxy_flags and DONT_VERIFY_PEER.
3183 NAME: sslproxy_cert_sign
3186 POSTSCRIPTUM: signUntrusted ssl::certUntrusted
3187 POSTSCRIPTUM: signSelf ssl::certSelfSigned
3188 POSTSCRIPTUM: signTrusted all
3189 TYPE: sslproxy_cert_sign
3190 LOC: Config.ssl_client.cert_sign
3193 sslproxy_cert_sign <signing algorithm> acl ...
3195 The following certificate signing algorithms are supported:
3198 Sign using the configured CA certificate which is usually
3199 placed in and trusted by end-user browsers. This is the
3200 default for trusted origin server certificates.
3203 Sign to guarantee an X509_V_ERR_CERT_UNTRUSTED browser error.
3204 This is the default for untrusted origin server certificates
3205 that are not self-signed (see ssl::certUntrusted).
3208 Sign using a self-signed certificate with the right CN to
3209 generate a X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT error in the
3210 browser. This is the default for self-signed origin server
3211 certificates (see ssl::certSelfSigned).
3213 This clause only supports fast acl types.
3215 When sslproxy_cert_sign acl(s) match, Squid uses the corresponding
3216 signing algorithm to generate the certificate and ignores all
3217 subsequent sslproxy_cert_sign options (the first match wins). If no
3218 acl(s) match, the default signing algorithm is determined by errors
3219 detected when obtaining and validating the origin server certificate.
3221 WARNING: SQUID_X509_V_ERR_DOMAIN_MISMATCH and ssl:certDomainMismatch can
3222 be used with sslproxy_cert_adapt, but if and only if Squid is bumping a
3223 CONNECT request that carries a domain name. In all other cases (CONNECT
3224 to an IP address or an intercepted SSL connection), Squid cannot detect
3225 the domain mismatch at certificate generation time when
3226 bump-server-first is used.
3229 NAME: sslproxy_cert_adapt
3232 TYPE: sslproxy_cert_adapt
3233 LOC: Config.ssl_client.cert_adapt
3236 sslproxy_cert_adapt <adaptation algorithm> acl ...
3238 The following certificate adaptation algorithms are supported:
3241 Sets the "Not After" property to the "Not After" property of
3242 the CA certificate used to sign generated certificates.
3245 Sets the "Not Before" property to the "Not Before" property of
3246 the CA certificate used to sign generated certificates.
3248 setCommonName or setCommonName{CN}
3249 Sets Subject.CN property to the host name specified as a
3250 CN parameter or, if no explicit CN parameter was specified,
3251 extracted from the CONNECT request. It is a misconfiguration
3252 to use setCommonName without an explicit parameter for
3253 intercepted or tproxied SSL connections.
3255 This clause only supports fast acl types.
3257 Squid first groups sslproxy_cert_adapt options by adaptation algorithm.
3258 Within a group, when sslproxy_cert_adapt acl(s) match, Squid uses the
3259 corresponding adaptation algorithm to generate the certificate and
3260 ignores all subsequent sslproxy_cert_adapt options in that algorithm's
3261 group (i.e., the first match wins within each algorithm group). If no
3262 acl(s) match, the default mimicking action takes place.
3264 WARNING: SQUID_X509_V_ERR_DOMAIN_MISMATCH and ssl:certDomainMismatch can
3265 be used with sslproxy_cert_adapt, but if and only if Squid is bumping a
3266 CONNECT request that carries a domain name. In all other cases (CONNECT
3267 to an IP address or an intercepted SSL connection), Squid cannot detect
3268 the domain mismatch at certificate generation time when
3269 bump-server-first is used.
3272 NAME: sslpassword_program
3275 LOC: Config.Program.ssl_password
3278 Specify a program used for entering SSL key passphrases
3279 when using encrypted SSL certificate keys. If not specified
3280 keys must either be unencrypted, or Squid started with the -N
3281 option to allow it to query interactively for the passphrase.
3283 The key file name is given as argument to the program allowing
3284 selection of the right password if you have multiple encrypted
3289 OPTIONS RELATING TO EXTERNAL SSL_CRTD
3290 -----------------------------------------------------------------------------
3293 NAME: sslcrtd_program
3296 DEFAULT: @DEFAULT_SSL_CRTD@ -s @DEFAULT_SSL_DB_DIR@ -M 4MB
3297 LOC: Ssl::TheConfig.ssl_crtd
3299 Specify the location and options of the executable for certificate
3302 @DEFAULT_SSL_CRTD@ program can use a disk cache to improve response
3303 times on repeated requests. To enable caching, specify -s and -M
3304 parameters. If those parameters are not given, the program generates
3305 a new certificate on every request.
3307 For more information use:
3308 @DEFAULT_SSL_CRTD@ -h
3311 NAME: sslcrtd_children
3312 TYPE: HelperChildConfig
3314 DEFAULT: 32 startup=5 idle=1
3315 LOC: Ssl::TheConfig.ssl_crtdChildren
3317 Specifies the maximum number of certificate generation processes that
3318 Squid may spawn (numberofchildren) and several related options. Using
3319 too few of these helper processes (a.k.a. "helpers") creates request
3320 queues. Using too many helpers wastes your system resources. Squid
3321 does not support spawning more than 32 helpers.
3323 Usage: numberofchildren [option]...
3325 The startup= and idle= options allow some measure of skew in your
3330 Sets the minimum number of processes to spawn when Squid
3331 starts or reconfigures. When set to zero the first request will
3332 cause spawning of the first child process to handle it.
3334 Starting too few children temporary slows Squid under load while it
3335 tries to spawn enough additional processes to cope with traffic.
3339 Sets a minimum of how many processes Squid is to try and keep available
3340 at all times. When traffic begins to rise above what the existing
3341 processes can handle this many more will be spawned up to the maximum
3342 configured. A minimum setting of 1 is required.
3346 Sets the maximum number of queued requests. A request is queued when
3347 no existing child is idle and no new child can be started due to
3348 numberofchildren limit. If the queued requests exceed queue size for
3349 more than 3 minutes squid aborts its operation. The default value is
3350 set to 2*numberofchildren.
3352 You must have at least one ssl_crtd process.
3355 NAME: sslcrtvalidator_program
3359 LOC: Ssl::TheConfig.ssl_crt_validator
3361 Specify the location and options of the executable for ssl_crt_validator
3364 Usage: sslcrtvalidator_program [ttl=n] [cache=n] path ...
3367 ttl=n TTL in seconds for cached results. The default is 60 secs
3368 cache=n limit the result cache size. The default value is 2048
3371 NAME: sslcrtvalidator_children
3372 TYPE: HelperChildConfig
3374 DEFAULT: 32 startup=5 idle=1 concurrency=1
3375 LOC: Ssl::TheConfig.ssl_crt_validator_Children
3377 Specifies the maximum number of certificate validation processes that
3378 Squid may spawn (numberofchildren) and several related options. Using
3379 too few of these helper processes (a.k.a. "helpers") creates request
3380 queues. Using too many helpers wastes your system resources. Squid
3381 does not support spawning more than 32 helpers.
3383 Usage: numberofchildren [option]...
3385 The startup= and idle= options allow some measure of skew in your
3390 Sets the minimum number of processes to spawn when Squid
3391 starts or reconfigures. When set to zero the first request will
3392 cause spawning of the first child process to handle it.
3394 Starting too few children temporary slows Squid under load while it
3395 tries to spawn enough additional processes to cope with traffic.
3399 Sets a minimum of how many processes Squid is to try and keep available
3400 at all times. When traffic begins to rise above what the existing
3401 processes can handle this many more will be spawned up to the maximum
3402 configured. A minimum setting of 1 is required.
3406 The number of requests each certificate validator helper can handle in
3407 parallel. A value of 0 indicates the certficate validator does not
3408 support concurrency. Defaults to 1.
3410 When this directive is set to a value >= 1 then the protocol
3411 used to communicate with the helper is modified to include
3412 a request ID in front of the request/response. The request
3413 ID from the request must be echoed back with the response
3418 Sets the maximum number of queued requests. A request is queued when
3419 no existing child can accept it due to concurrency limit and no new
3420 child can be started due to numberofchildren limit. If the queued
3421 requests exceed queue size for more than 3 minutes squid aborts its
3422 operation. The default value is set to 2*numberofchildren.
3424 You must have at least one ssl_crt_validator process.
3428 OPTIONS WHICH AFFECT THE NEIGHBOR SELECTION ALGORITHM
3429 -----------------------------------------------------------------------------
3437 To specify other caches in a hierarchy, use the format:
3439 cache_peer hostname type http-port icp-port [options]
3444 # hostname type port port options
3445 # -------------------- -------- ----- ----- -----------
3446 cache_peer parent.foo.net parent 3128 3130 default
3447 cache_peer sib1.foo.net sibling 3128 3130 proxy-only
3448 cache_peer sib2.foo.net sibling 3128 3130 proxy-only
3449 cache_peer example.com parent 80 0 default
3450 cache_peer cdn.example.com sibling 3128 0
3452 type: either 'parent', 'sibling', or 'multicast'.
3454 proxy-port: The port number where the peer accept HTTP requests.
3455 For other Squid proxies this is usually 3128
3456 For web servers this is usually 80
3458 icp-port: Used for querying neighbor caches about objects.
3459 Set to 0 if the peer does not support ICP or HTCP.
3460 See ICP and HTCP options below for additional details.
3463 ==== ICP OPTIONS ====
3465 You MUST also set icp_port and icp_access explicitly when using these options.
3466 The defaults will prevent peer traffic using ICP.
3469 no-query Disable ICP queries to this neighbor.
3472 Indicates the named peer is a member of a multicast group.
3473 ICP queries will not be sent directly to the peer, but ICP
3474 replies will be accepted from it.
3476 closest-only Indicates that, for ICP_OP_MISS replies, we'll only forward
3477 CLOSEST_PARENT_MISSes and never FIRST_PARENT_MISSes.
3480 To only send ICP queries to this neighbor infrequently.
3481 This is used to keep the neighbor round trip time updated
3482 and is usually used in conjunction with weighted-round-robin.
3485 ==== HTCP OPTIONS ====
3487 You MUST also set htcp_port and htcp_access explicitly when using these options.
3488 The defaults will prevent peer traffic using HTCP.
3491 htcp Send HTCP, instead of ICP, queries to the neighbor.
3492 You probably also want to set the "icp-port" to 4827
3493 instead of 3130. This directive accepts a comma separated
3494 list of options described below.
3496 htcp=oldsquid Send HTCP to old Squid versions (2.5 or earlier).
3498 htcp=no-clr Send HTCP to the neighbor but without
3499 sending any CLR requests. This cannot be used with
3502 htcp=only-clr Send HTCP to the neighbor but ONLY CLR requests.
3503 This cannot be used with no-clr.
3506 Send HTCP to the neighbor including CLRs but only when
3507 they do not result from PURGE requests.
3510 Forward any HTCP CLR requests this proxy receives to the peer.
3513 ==== PEER SELECTION METHODS ====
3515 The default peer selection method is ICP, with the first responding peer
3516 being used as source. These options can be used for better load balancing.
3519 default This is a parent cache which can be used as a "last-resort"
3520 if a peer cannot be located by any of the peer-selection methods.
3521 If specified more than once, only the first is used.
3523 round-robin Load-Balance parents which should be used in a round-robin
3524 fashion in the absence of any ICP queries.
3525 weight=N can be used to add bias.
3527 weighted-round-robin
3528 Load-Balance parents which should be used in a round-robin
3529 fashion with the frequency of each parent being based on the
3530 round trip time. Closer parents are used more often.
3531 Usually used for background-ping parents.
3532 weight=N can be used to add bias.
3534 carp Load-Balance parents which should be used as a CARP array.
3535 The requests will be distributed among the parents based on the
3536 CARP load balancing hash function based on their weight.
3538 userhash Load-balance parents based on the client proxy_auth or ident username.
3540 sourcehash Load-balance parents based on the client source IP.
3543 To be used only for cache peers of type "multicast".
3544 ALL members of this multicast group have "sibling"
3545 relationship with it, not "parent". This is to a multicast
3546 group when the requested object would be fetched only from
3547 a "parent" cache, anyway. It's useful, e.g., when
3548 configuring a pool of redundant Squid proxies, being
3549 members of the same multicast group.
3552 ==== PEER SELECTION OPTIONS ====
3554 weight=N use to affect the selection of a peer during any weighted
3555 peer-selection mechanisms.
3556 The weight must be an integer; default is 1,
3557 larger weights are favored more.
3558 This option does not affect parent selection if a peering
3559 protocol is not in use.
3561 basetime=N Specify a base amount to be subtracted from round trip
3563 It is subtracted before division by weight in calculating
3564 which parent to fectch from. If the rtt is less than the
3565 base time the rtt is set to a minimal value.
3567 ttl=N Specify a TTL to use when sending multicast ICP queries
3569 Only useful when sending to a multicast group.
3570 Because we don't accept ICP replies from random
3571 hosts, you must configure other group members as
3572 peers with the 'multicast-responder' option.
3574 no-delay To prevent access to this neighbor from influencing the
3577 digest-url=URL Tell Squid to fetch the cache digest (if digests are
3578 enabled) for this host from the specified URL rather
3579 than the Squid default location.
3582 ==== CARP OPTIONS ====
3584 carp-key=key-specification
3585 use a different key than the full URL to hash against the peer.
3586 the key-specification is a comma-separated list of the keywords
3587 scheme, host, port, path, params
3588 Order is not important.
3590 ==== ACCELERATOR / REVERSE-PROXY OPTIONS ====
3592 originserver Causes this parent to be contacted as an origin server.
3593 Meant to be used in accelerator setups when the peer
3597 Set the Host header of requests forwarded to this peer.
3598 Useful in accelerator setups where the server (peer)
3599 expects a certain domain name but clients may request
3600 others. ie example.com or www.example.com
3602 no-digest Disable request of cache digests.
3605 Disables requesting ICMP RTT database (NetDB).
3608 ==== AUTHENTICATION OPTIONS ====
3611 If this is a personal/workgroup proxy and your parent
3612 requires proxy authentication.
3614 Note: The string can include URL escapes (i.e. %20 for
3615 spaces). This also means % must be written as %%.
3618 Send login details received from client to this peer.
3619 Both Proxy- and WWW-Authorization headers are passed
3620 without alteration to the peer.
3621 Authentication is not required by Squid for this to work.
3623 Note: This will pass any form of authentication but
3624 only Basic auth will work through a proxy unless the
3625 connection-auth options are also used.
3627 login=PASS Send login details received from client to this peer.
3628 Authentication is not required by this option.
3630 If there are no client-provided authentication headers
3631 to pass on, but username and password are available
3632 from an external ACL user= and password= result tags
3633 they may be sent instead.
3635 Note: To combine this with proxy_auth both proxies must
3636 share the same user database as HTTP only allows for
3637 a single login (one for proxy, one for origin server).
3638 Also be warned this will expose your users proxy
3639 password to the peer. USE WITH CAUTION
3642 Send the username to the upstream cache, but with a
3643 fixed password. This is meant to be used when the peer
3644 is in another administrative domain, but it is still
3645 needed to identify each user.
3646 The star can optionally be followed by some extra
3647 information which is added to the username. This can
3648 be used to identify this proxy to the peer, similar to
3649 the login=username:password option above.
3652 If this is a personal/workgroup proxy and your parent
3653 requires a secure proxy authentication.
3654 The first principal from the default keytab or defined by
3655 the environment variable KRB5_KTNAME will be used.
3657 WARNING: The connection may transmit requests from multiple
3658 clients. Negotiate often assumes end-to-end authentication
3659 and a single-client. Which is not strictly true here.
3661 login=NEGOTIATE:principal_name
3662 If this is a personal/workgroup proxy and your parent
3663 requires a secure proxy authentication.
3664 The principal principal_name from the default keytab or
3665 defined by the environment variable KRB5_KTNAME will be
3668 WARNING: The connection may transmit requests from multiple
3669 clients. Negotiate often assumes end-to-end authentication
3670 and a single-client. Which is not strictly true here.
3672 connection-auth=on|off
3673 Tell Squid that this peer does or not support Microsoft
3674 connection oriented authentication, and any such
3675 challenges received from there should be ignored.
3676 Default is auto to automatically determine the status
3680 Do not use a keytab to authenticate to a peer when
3681 login=NEGOTIATE is specified. Let the GSSAPI
3682 implementation determine which already existing
3683 credentials cache to use instead.
3686 ==== SSL / HTTPS / TLS OPTIONS ====
3688 tls Encrypt connections to this peer with TLS.
3690 sslcert=/path/to/ssl/certificate
3691 A client X.509 certificate to use when connecting to
3694 sslkey=/path/to/ssl/key
3695 The private key corresponding to sslcert above.
3697 If sslkey= is not specified sslcert= is assumed to
3698 reference a PEM file containing both the certificate
3701 sslcipher=... The list of valid SSL ciphers to use when connecting
3705 The minimum TLS protocol version to permit. To control
3706 SSLv3 use the tls-options= parameter.
3707 Supported Values: 1.0 (default), 1.1, 1.2
3709 tls-options=... Specify various TLS implementation options.
3711 OpenSSL options most important are:
3713 NO_SSLv3 Disallow the use of SSLv3
3716 Always create a new key when using
3717 temporary/ephemeral DH key exchanges
3720 Disable use of RFC5077 session tickets.
3721 Some servers may have problems
3722 understanding the TLS extension due
3723 to ambiguous specification in RFC4507.
3725 ALL Enable various bug workarounds
3726 suggested as "harmless" by OpenSSL
3727 Be warned that this reduces SSL/TLS
3728 strength to some attacks.
3730 See the OpenSSL SSL_CTX_set_options documentation for a
3733 GnuTLS options most important are:
3736 Disable use of RFC5077 session tickets.
3737 Some servers may have problems
3738 understanding the TLS extension due
3739 to ambiguous specification in RFC4507.
3741 See the GnuTLS Priority Strings documentation
3742 for a more complete list.
3743 http://www.gnutls.org/manual/gnutls.html#Priority-Strings
3745 tls-cafile= PEM file containing CA certificates to use when verifying
3746 the peer certificate. May be repeated to load multiple files.
3748 sslcapath=... A directory containing additional CA certificates to
3749 use when verifying the peer certificate.
3750 Requires OpenSSL or LibreSSL.
3752 sslcrlfile=... A certificate revocation list file to use when
3753 verifying the peer certificate.
3755 sslflags=... Specify various flags modifying the SSL implementation:
3758 Accept certificates even if they fail to
3762 Don't verify the peer certificate
3763 matches the server name
3765 ssldomain= The peer name as advertised in it's certificate.
3766 Used for verifying the correctness of the received peer
3767 certificate. If not specified the peer hostname will be
3770 front-end-https[=off|on|auto]
3771 Enable the "Front-End-Https: On" header needed when
3772 using Squid as a SSL frontend in front of Microsoft OWA.
3773 See MS KB document Q307347 for details on this header.
3774 If set to auto the header will only be added if the
3775 request is forwarded as a https:// URL.
3777 tls-default-ca[=off]
3778 Whether to use the system Trusted CAs. Default is ON.
3780 tls-no-npn Do not use the TLS NPN extension to advertise HTTP/1.1.
3782 ==== GENERAL OPTIONS ====
3785 A peer-specific connect timeout.
3786 Also see the peer_connect_timeout directive.
3788 connect-fail-limit=N
3789 How many times connecting to a peer must fail before
3790 it is marked as down. Standby connection failures
3791 count towards this limit. Default is 10.
3793 allow-miss Disable Squid's use of only-if-cached when forwarding
3794 requests to siblings. This is primarily useful when
3795 icp_hit_stale is used by the sibling. Excessive use
3796 of this option may result in forwarding loops. One way
3797 to prevent peering loops when using this option, is to
3798 deny cache peer usage on requests from a peer:
3800 cache_peer_access peerName deny fromPeer
3802 max-conn=N Limit the number of concurrent connections the Squid
3803 may open to this peer, including already opened idle
3804 and standby connections. There is no peer-specific
3805 connection limit by default.
3807 A peer exceeding the limit is not used for new
3808 requests unless a standby connection is available.
3810 max-conn currently works poorly with idle persistent
3811 connections: When a peer reaches its max-conn limit,
3812 and there are idle persistent connections to the peer,
3813 the peer may not be selected because the limiting code
3814 does not know whether Squid can reuse those idle
3817 standby=N Maintain a pool of N "hot standby" connections to an
3818 UP peer, available for requests when no idle
3819 persistent connection is available (or safe) to use.
3820 By default and with zero N, no such pool is maintained.
3821 N must not exceed the max-conn limit (if any).
3823 At start or after reconfiguration, Squid opens new TCP
3824 standby connections until there are N connections
3825 available and then replenishes the standby pool as
3826 opened connections are used up for requests. A used
3827 connection never goes back to the standby pool, but
3828 may go to the regular idle persistent connection pool
3829 shared by all peers and origin servers.
3831 Squid never opens multiple new standby connections
3832 concurrently. This one-at-a-time approach minimizes
3833 flooding-like effect on peers. Furthermore, just a few
3834 standby connections should be sufficient in most cases
3835 to supply most new requests with a ready-to-use
3838 Standby connections obey server_idle_pconn_timeout.
3839 For the feature to work as intended, the peer must be
3840 configured to accept and keep them open longer than
3841 the idle timeout at the connecting Squid, to minimize
3842 race conditions typical to idle used persistent
3843 connections. Default request_timeout and
3844 server_idle_pconn_timeout values ensure such a
3847 name=xxx Unique name for the peer.
3848 Required if you have multiple peers on the same host
3849 but different ports.
3850 This name can be used in cache_peer_access and similar
3851 directives to identify the peer.
3852 Can be used by outgoing access controls through the
3855 no-tproxy Do not use the client-spoof TPROXY support when forwarding
3856 requests to this peer. Use normal address selection instead.
3857 This overrides the spoof_client_ip ACL.
3859 proxy-only objects fetched from the peer will not be stored locally.
3863 NAME: cache_peer_access
3866 DEFAULT_DOC: No peer usage restrictions.
3869 Restricts usage of cache_peer proxies.
3872 cache_peer_access peer-name allow|deny [!]aclname ...
3874 For the required peer-name parameter, use either the value of the
3875 cache_peer name=value parameter or, if name=value is missing, the
3876 cache_peer hostname parameter.
3878 This directive narrows down the selection of peering candidates, but
3879 does not determine the order in which the selected candidates are
3880 contacted. That order is determined by the peer selection algorithms
3881 (see PEER SELECTION sections in the cache_peer documentation).
3883 If a deny rule matches, the corresponding peer will not be contacted
3884 for the current transaction -- Squid will not send ICP queries and
3885 will not forward HTTP requests to that peer. An allow match leaves
3886 the corresponding peer in the selection. The first match for a given
3887 peer wins for that peer.
3889 The relative order of cache_peer_access directives for the same peer
3890 matters. The relative order of any two cache_peer_access directives
3891 for different peers does not matter. To ease interpretation, it is a
3892 good idea to group cache_peer_access directives for the same peer
3895 A single cache_peer_access directive may be evaluated multiple times
3896 for a given transaction because individual peer selection algorithms
3897 may check it independently from each other. These redundant checks
3898 may be optimized away in future Squid versions.
3900 This clause only supports fast acl types.
3901 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
3905 NAME: neighbor_type_domain
3906 TYPE: hostdomaintype
3908 DEFAULT_DOC: The peer type from cache_peer directive is used for all requests to that peer.
3911 Modify the cache_peer neighbor type when passing requests
3912 about specific domains to the peer.
3915 neighbor_type_domain neighbor parent|sibling domain domain ...
3918 cache_peer foo.example.com parent 3128 3130
3919 neighbor_type_domain foo.example.com sibling .au .de
3921 The above configuration treats all requests to foo.example.com as a
3922 parent proxy unless the request is for a .au or .de ccTLD domain name.
3925 NAME: dead_peer_timeout
3929 LOC: Config.Timeout.deadPeer
3931 This controls how long Squid waits to declare a peer cache
3932 as "dead." If there are no ICP replies received in this
3933 amount of time, Squid will declare the peer dead and not
3934 expect to receive any further ICP replies. However, it
3935 continues to send ICP queries, and will mark the peer as
3936 alive upon receipt of the first subsequent ICP reply.
3938 This timeout also affects when Squid expects to receive ICP
3939 replies from peers. If more than 'dead_peer' seconds have
3940 passed since the last ICP reply was received, Squid will not
3941 expect to receive an ICP reply on the next query. Thus, if
3942 your time between requests is greater than this timeout, you
3943 will see a lot of requests sent DIRECT to origin servers
3944 instead of to your parents.
3947 NAME: forward_max_tries
3950 LOC: Config.forward_max_tries
3952 Limits the number of attempts to forward the request.
3954 For the purpose of this limit, Squid counts all high-level request
3955 forwarding attempts, including any same-destination retries after
3956 certain persistent connection failures and any attempts to use a
3957 different peer. However, low-level connection reopening attempts
3958 (enabled using connect_retries) are not counted.
3960 See also: forward_timeout and connect_retries.
3964 MEMORY CACHE OPTIONS
3965 -----------------------------------------------------------------------------
3972 LOC: Config.memMaxSize
3974 NOTE: THIS PARAMETER DOES NOT SPECIFY THE MAXIMUM PROCESS SIZE.
3975 IT ONLY PLACES A LIMIT ON HOW MUCH ADDITIONAL MEMORY SQUID WILL
3976 USE AS A MEMORY CACHE OF OBJECTS. SQUID USES MEMORY FOR OTHER
3977 THINGS AS WELL. SEE THE SQUID FAQ SECTION 8 FOR DETAILS.
3979 'cache_mem' specifies the ideal amount of memory to be used
3981 * In-Transit objects
3983 * Negative-Cached objects
3985 Data for these objects are stored in 4 KB blocks. This
3986 parameter specifies the ideal upper limit on the total size of
3987 4 KB blocks allocated. In-Transit objects take the highest
3990 In-transit objects have priority over the others. When
3991 additional space is needed for incoming data, negative-cached
3992 and hot objects will be released. In other words, the
3993 negative-cached and hot objects will fill up any unused space
3994 not needed for in-transit objects.
3996 If circumstances require, this limit will be exceeded.
3997 Specifically, if your incoming request rate requires more than
3998 'cache_mem' of memory to hold in-transit objects, Squid will
3999 exceed this limit to satisfy the new requests. When the load
4000 decreases, blocks will be freed until the high-water mark is
4001 reached. Thereafter, blocks will be used to store hot
4004 If shared memory caching is enabled, Squid does not use the shared
4005 cache space for in-transit objects, but they still consume as much
4006 local memory as they need. For more details about the shared memory
4007 cache, see memory_cache_shared.
4010 NAME: maximum_object_size_in_memory
4014 LOC: Config.Store.maxInMemObjSize
4016 Objects greater than this size will not be attempted to kept in
4017 the memory cache. This should be set high enough to keep objects
4018 accessed frequently in memory to improve performance whilst low
4019 enough to keep larger objects from hoarding cache_mem.
4022 NAME: memory_cache_shared
4025 LOC: Config.memShared
4027 DEFAULT_DOC: "on" where supported if doing memory caching with multiple SMP workers.
4029 Controls whether the memory cache is shared among SMP workers.
4031 The shared memory cache is meant to occupy cache_mem bytes and replace
4032 the non-shared memory cache, although some entities may still be
4033 cached locally by workers for now (e.g., internal and in-transit
4034 objects may be served from a local memory cache even if shared memory
4035 caching is enabled).
4037 By default, the memory cache is shared if and only if all of the
4038 following conditions are satisfied: Squid runs in SMP mode with
4039 multiple workers, cache_mem is positive, and Squid environment
4040 supports required IPC primitives (e.g., POSIX shared memory segments
4041 and GCC-style atomic operations).
4043 To avoid blocking locks, shared memory uses opportunistic algorithms
4044 that do not guarantee that every cachable entity that could have been
4045 shared among SMP workers will actually be shared.
4048 NAME: memory_cache_mode
4052 DEFAULT_DOC: Keep the most recently fetched objects in memory
4054 Controls which objects to keep in the memory cache (cache_mem)
4056 always Keep most recently fetched objects in memory (default)
4058 disk Only disk cache hits are kept in memory, which means
4059 an object must first be cached on disk and then hit
4060 a second time before cached in memory.
4062 network Only objects fetched from network is kept in memory
4065 NAME: memory_replacement_policy
4067 LOC: Config.memPolicy
4070 The memory replacement policy parameter determines which
4071 objects are purged from memory when memory space is needed.
4073 See cache_replacement_policy for details on algorithms.
4078 -----------------------------------------------------------------------------
4081 NAME: cache_replacement_policy
4083 LOC: Config.replPolicy
4086 The cache replacement policy parameter determines which
4087 objects are evicted (replaced) when disk space is needed.
4089 lru : Squid's original list based LRU policy
4090 heap GDSF : Greedy-Dual Size Frequency
4091 heap LFUDA: Least Frequently Used with Dynamic Aging
4092 heap LRU : LRU policy implemented using a heap
4094 Applies to any cache_dir lines listed below this directive.
4096 The LRU policies keeps recently referenced objects.
4098 The heap GDSF policy optimizes object hit rate by keeping smaller
4099 popular objects in cache so it has a better chance of getting a
4100 hit. It achieves a lower byte hit rate than LFUDA though since
4101 it evicts larger (possibly popular) objects.
4103 The heap LFUDA policy keeps popular objects in cache regardless of
4104 their size and thus optimizes byte hit rate at the expense of
4105 hit rate since one large, popular object will prevent many
4106 smaller, slightly less popular objects from being cached.
4108 Both policies utilize a dynamic aging mechanism that prevents
4109 cache pollution that can otherwise occur with frequency-based
4110 replacement policies.
4112 NOTE: if using the LFUDA replacement policy you should increase
4113 the value of maximum_object_size above its default of 4 MB to
4114 to maximize the potential byte hit rate improvement of LFUDA.
4116 For more information about the GDSF and LFUDA cache replacement
4117 policies see http://www.hpl.hp.com/techreports/1999/HPL-1999-69.html
4118 and http://fog.hpl.external.hp.com/techreports/98/HPL-98-173.html.
4121 NAME: minimum_object_size
4125 DEFAULT_DOC: no limit
4126 LOC: Config.Store.minObjectSize
4128 Objects smaller than this size will NOT be saved on disk. The
4129 value is specified in bytes, and the default is 0 KB, which
4130 means all responses can be stored.
4133 NAME: maximum_object_size
4137 LOC: Config.Store.maxObjectSize
4139 Set the default value for max-size parameter on any cache_dir.
4140 The value is specified in bytes, and the default is 4 MB.
4142 If you wish to get a high BYTES hit ratio, you should probably
4143 increase this (one 32 MB object hit counts for 3200 10KB
4146 If you wish to increase hit ratio more than you want to
4147 save bandwidth you should leave this low.
4149 NOTE: if using the LFUDA replacement policy you should increase
4150 this value to maximize the byte hit rate improvement of LFUDA!
4151 See cache_replacement_policy for a discussion of this policy.
4157 DEFAULT_DOC: No disk cache. Store cache ojects only in memory.
4158 LOC: Config.cacheSwap
4161 cache_dir Type Directory-Name Fs-specific-data [options]
4163 You can specify multiple cache_dir lines to spread the
4164 cache among different disk partitions.
4166 Type specifies the kind of storage system to use. Only "ufs"
4167 is built by default. To enable any of the other storage systems
4168 see the --enable-storeio configure option.
4170 'Directory' is a top-level directory where cache swap
4171 files will be stored. If you want to use an entire disk
4172 for caching, this can be the mount-point directory.
4173 The directory must exist and be writable by the Squid
4174 process. Squid will NOT create this directory for you.
4176 In SMP configurations, cache_dir must not precede the workers option
4177 and should use configuration macros or conditionals to give each
4178 worker interested in disk caching a dedicated cache directory.
4181 ==== The ufs store type ====
4183 "ufs" is the old well-known Squid storage format that has always
4187 cache_dir ufs Directory-Name Mbytes L1 L2 [options]
4189 'Mbytes' is the amount of disk space (MB) to use under this
4190 directory. The default is 100 MB. Change this to suit your
4191 configuration. Do NOT put the size of your disk drive here.
4192 Instead, if you want Squid to use the entire disk drive,
4193 subtract 20% and use that value.
4195 'L1' is the number of first-level subdirectories which
4196 will be created under the 'Directory'. The default is 16.
4198 'L2' is the number of second-level subdirectories which
4199 will be created under each first-level directory. The default
4203 ==== The aufs store type ====
4205 "aufs" uses the same storage format as "ufs", utilizing
4206 POSIX-threads to avoid blocking the main Squid process on
4207 disk-I/O. This was formerly known in Squid as async-io.
4210 cache_dir aufs Directory-Name Mbytes L1 L2 [options]
4212 see argument descriptions under ufs above
4215 ==== The diskd store type ====
4217 "diskd" uses the same storage format as "ufs", utilizing a
4218 separate process to avoid blocking the main Squid process on
4222 cache_dir diskd Directory-Name Mbytes L1 L2 [options] [Q1=n] [Q2=n]
4224 see argument descriptions under ufs above
4226 Q1 specifies the number of unacknowledged I/O requests when Squid
4227 stops opening new files. If this many messages are in the queues,
4228 Squid won't open new files. Default is 64
4230 Q2 specifies the number of unacknowledged messages when Squid
4231 starts blocking. If this many messages are in the queues,
4232 Squid blocks until it receives some replies. Default is 72
4234 When Q1 < Q2 (the default), the cache directory is optimized
4235 for lower response time at the expense of a decrease in hit
4236 ratio. If Q1 > Q2, the cache directory is optimized for
4237 higher hit ratio at the expense of an increase in response
4241 ==== The rock store type ====
4244 cache_dir rock Directory-Name Mbytes [options]
4246 The Rock Store type is a database-style storage. All cached
4247 entries are stored in a "database" file, using fixed-size slots.
4248 A single entry occupies one or more slots.
4250 If possible, Squid using Rock Store creates a dedicated kid
4251 process called "disker" to avoid blocking Squid worker(s) on disk
4252 I/O. One disker kid is created for each rock cache_dir. Diskers
4253 are created only when Squid, running in daemon mode, has support
4254 for the IpcIo disk I/O module.
4256 swap-timeout=msec: Squid will not start writing a miss to or
4257 reading a hit from disk if it estimates that the swap operation
4258 will take more than the specified number of milliseconds. By
4259 default and when set to zero, disables the disk I/O time limit
4260 enforcement. Ignored when using blocking I/O module because
4261 blocking synchronous I/O does not allow Squid to estimate the
4262 expected swap wait time.
4264 max-swap-rate=swaps/sec: Artificially limits disk access using
4265 the specified I/O rate limit. Swap out requests that
4266 would cause the average I/O rate to exceed the limit are
4267 delayed. Individual swap in requests (i.e., hits or reads) are
4268 not delayed, but they do contribute to measured swap rate and
4269 since they are placed in the same FIFO queue as swap out
4270 requests, they may wait longer if max-swap-rate is smaller.
4271 This is necessary on file systems that buffer "too
4272 many" writes and then start blocking Squid and other processes
4273 while committing those writes to disk. Usually used together
4274 with swap-timeout to avoid excessive delays and queue overflows
4275 when disk demand exceeds available disk "bandwidth". By default
4276 and when set to zero, disables the disk I/O rate limit
4277 enforcement. Currently supported by IpcIo module only.
4279 slot-size=bytes: The size of a database "record" used for
4280 storing cached responses. A cached response occupies at least
4281 one slot and all database I/O is done using individual slots so
4282 increasing this parameter leads to more disk space waste while
4283 decreasing it leads to more disk I/O overheads. Should be a
4284 multiple of your operating system I/O page size. Defaults to
4285 16KBytes. A housekeeping header is stored with each slot and
4286 smaller slot-sizes will be rejected. The header is smaller than
4290 ==== COMMON OPTIONS ====
4292 no-store no new objects should be stored to this cache_dir.
4294 min-size=n the minimum object size in bytes this cache_dir
4295 will accept. It's used to restrict a cache_dir
4296 to only store large objects (e.g. AUFS) while
4297 other stores are optimized for smaller objects
4301 max-size=n the maximum object size in bytes this cache_dir
4303 The value in maximum_object_size directive sets
4304 the default unless more specific details are
4305 available (ie a small store capacity).
4307 Note: To make optimal use of the max-size limits you should order
4308 the cache_dir lines with the smallest max-size value first.
4312 # Uncomment and adjust the following to add a disk cache directory.
4313 #cache_dir ufs @DEFAULT_SWAP_DIR@ 100 16 256
4317 NAME: store_dir_select_algorithm
4319 LOC: Config.store_dir_select_algorithm
4322 How Squid selects which cache_dir to use when the response
4323 object will fit into more than one.
4325 Regardless of which algorithm is used the cache_dir min-size
4326 and max-size parameters are obeyed. As such they can affect
4327 the selection algorithm by limiting the set of considered
4334 This algorithm is suited to caches with similar cache_dir
4335 sizes and disk speeds.
4337 The disk with the least I/O pending is selected.
4338 When there are multiple disks with the same I/O load ranking
4339 the cache_dir with most available capacity is selected.
4341 When a mix of cache_dir sizes are configured the faster disks
4342 have a naturally lower I/O loading and larger disks have more
4343 capacity. So space used to store objects and data throughput
4344 may be very unbalanced towards larger disks.
4349 This algorithm is suited to caches with unequal cache_dir
4352 Each cache_dir is selected in a rotation. The next suitable
4355 Available cache_dir capacity is only considered in relation
4356 to whether the object will fit and meets the min-size and
4357 max-size parameters.
4359 Disk I/O loading is only considered to prevent overload on slow
4360 disks. This algorithm does not spread objects by size, so any
4361 I/O loading per-disk may appear very unbalanced and volatile.
4363 If several cache_dirs use similar min-size, max-size, or other
4364 limits to to reject certain responses, then do not group such
4365 cache_dir lines together, to avoid round-robin selection bias
4366 towards the first cache_dir after the group. Instead, interleave
4367 cache_dir lines from different groups. For example:
4369 store_dir_select_algorithm round-robin
4370 cache_dir rock /hdd1 ... min-size=100000
4371 cache_dir rock /ssd1 ... max-size=99999
4372 cache_dir rock /hdd2 ... min-size=100000
4373 cache_dir rock /ssd2 ... max-size=99999
4374 cache_dir rock /hdd3 ... min-size=100000
4375 cache_dir rock /ssd3 ... max-size=99999
4378 NAME: max_open_disk_fds
4380 LOC: Config.max_open_disk_fds
4382 DEFAULT_DOC: no limit
4384 To avoid having disk as the I/O bottleneck Squid can optionally
4385 bypass the on-disk cache if more than this amount of disk file
4386 descriptors are open.
4388 A value of 0 indicates no limit.
4391 NAME: cache_swap_low
4392 COMMENT: (percent, 0-100)
4395 LOC: Config.Swap.lowWaterMark
4397 The low-water mark for AUFS/UFS/diskd cache object eviction by
4398 the cache_replacement_policy algorithm.
4400 Removal begins when the swap (disk) usage of a cache_dir is
4401 above this low-water mark and attempts to maintain utilization
4402 near the low-water mark.
4404 As swap utilization increases towards the high-water mark set
4405 by cache_swap_high object eviction becomes more agressive.
4407 The value difference in percentages between low- and high-water
4408 marks represent an eviction rate of 300 objects per second and
4409 the rate continues to scale in agressiveness by multiples of
4410 this above the high-water mark.
4412 Defaults are 90% and 95%. If you have a large cache, 5% could be
4413 hundreds of MB. If this is the case you may wish to set these
4414 numbers closer together.
4416 See also cache_swap_high and cache_replacement_policy
4419 NAME: cache_swap_high
4420 COMMENT: (percent, 0-100)
4423 LOC: Config.Swap.highWaterMark
4425 The high-water mark for AUFS/UFS/diskd cache object eviction by
4426 the cache_replacement_policy algorithm.
4428 Removal begins when the swap (disk) usage of a cache_dir is
4429 above the low-water mark set by cache_swap_low and attempts to
4430 maintain utilization near the low-water mark.
4432 As swap utilization increases towards this high-water mark object
4433 eviction becomes more agressive.
4435 The value difference in percentages between low- and high-water
4436 marks represent an eviction rate of 300 objects per second and
4437 the rate continues to scale in agressiveness by multiples of
4438 this above the high-water mark.
4440 Defaults are 90% and 95%. If you have a large cache, 5% could be
4441 hundreds of MB. If this is the case you may wish to set these
4442 numbers closer together.
4444 See also cache_swap_low and cache_replacement_policy
4449 -----------------------------------------------------------------------------
4456 DEFAULT_DOC: The format definitions squid, common, combined, referrer, useragent are built in.
4460 logformat <name> <format specification>
4462 Defines an access log format.
4464 The <format specification> is a string with embedded % format codes
4466 % format codes all follow the same basic structure where all
4467 components but the formatcode are optional and usually unnecessary,
4468 especially when dealing with common codes.
4470 % [encoding] [-] [[0]width] [{arg}] formatcode [{arg}]
4472 encoding escapes or otherwise protects "special" characters:
4474 " Quoted string encoding where quote(") and
4475 backslash(\) characters are \-escaped while
4476 CR, LF, and TAB characters are encoded as \r,
4477 \n, and \t two-character sequences.
4479 [ Custom Squid encoding where percent(%), square
4480 brackets([]), backslash(\) and characters with
4481 codes outside of [32,126] range are %-encoded.
4482 SP is not encoded. Used by log_mime_hdrs.
4484 # URL encoding (a.k.a. percent-encoding) where
4485 all URL unsafe and control characters (per RFC
4486 1738) are %-encoded.
4488 / Shell-like encoding where quote(") and
4489 backslash(\) characters are \-escaped while CR
4490 and LF characters are encoded as \r and \n
4491 two-character sequences. Values containing SP
4492 character(s) are surrounded by quotes(").
4494 ' Raw/as-is encoding with no escaping/quoting.
4496 Default encoding: When no explicit encoding is
4497 specified, each %code determines its own encoding.
4498 Most %codes use raw/as-is encoding, but some codes use
4499 a so called "pass-through URL encoding" where all URL
4500 unsafe and control characters (per RFC 1738) are
4501 %-encoded, but the percent character(%) is left as is.
4505 width minimum and/or maximum field width:
4506 [width_min][.width_max]
4507 When minimum starts with 0, the field is zero-padded.
4508 String values exceeding maximum width are truncated.
4510 {arg} argument such as header name etc. This field may be
4511 placed before or after the token, but not both at once.
4515 % a literal % character
4516 sn Unique sequence number per log line entry
4517 err_code The ID of an error response served by Squid or
4518 a similar internal error identifier.
4519 err_detail Additional err_code-dependent error information.
4520 note The annotation specified by the argument. Also
4521 logs the adaptation meta headers set by the
4522 adaptation_meta configuration parameter.
4523 If no argument given all annotations logged.
4524 The argument may include a separator to use with
4527 By default, multiple note values are separated with ","
4528 and multiple notes are separated with "\r\n".
4529 When logging named notes with %{name}note, the
4530 explicitly configured separator is used between note
4531 values. When logging all notes with %note, the
4532 explicitly configured separator is used between
4533 individual notes. There is currently no way to
4534 specify both value and notes separators when logging
4535 all notes with %note.
4537 Connection related format codes:
4539 >a Client source IP address
4541 >p Client source port
4542 >eui Client source EUI (MAC address, EUI-48 or EUI-64 identifier)
4543 >la Local IP address the client connected to
4544 >lp Local port number the client connected to
4545 >qos Client connection TOS/DSCP value set by Squid
4546 >nfmark Client connection netfilter packet MARK set by Squid
4548 la Local listening IP address the client connection was connected to.
4549 lp Local listening port number the client connection was connected to.
4551 <a Server IP address of the last server or peer connection
4552 <A Server FQDN or peer name
4553 <p Server port number of the last server or peer connection
4554 <la Local IP address of the last server or peer connection
4555 <lp Local port number of the last server or peer connection
4556 <qos Server connection TOS/DSCP value set by Squid
4557 <nfmark Server connection netfilter packet MARK set by Squid
4559 >handshake Raw client handshake
4560 Initial client bytes received by Squid on a newly
4561 accepted TCP connection or inside a just established
4562 CONNECT tunnel. Squid stops accumulating handshake
4563 bytes as soon as the handshake parser succeeds or
4564 fails (determining whether the client is using the
4567 For HTTP clients, the handshake is the request line.
4568 For TLS clients, the handshake consists of all TLS
4569 records up to and including the TLS record that
4570 contains the last byte of the first ClientHello
4571 message. For clients using an unsupported protocol,
4572 this field contains the bytes received by Squid at the
4573 time of the handshake parsing failure.
4575 See the on_unsupported_protocol directive for more
4576 information on Squid handshake traffic expectations.
4578 Current support is limited to these contexts:
4579 - http_port connections, but only when the
4580 on_unsupported_protocol directive is in use.
4581 - https_port connections (and CONNECT tunnels) that
4582 are subject to the ssl_bump peek or stare action.
4584 To protect binary handshake data, this field is always
4585 base64-encoded (RFC 4648 Section 4). If logformat
4586 field encoding is configured, that encoding is applied
4587 on top of base64. Otherwise, the computed base64 value
4590 Time related format codes:
4592 ts Seconds since epoch
4593 tu subsecond time (milliseconds)
4594 tl Local time. Optional strftime format argument
4595 default %d/%b/%Y:%H:%M:%S %z
4596 tg GMT time. Optional strftime format argument
4597 default %d/%b/%Y:%H:%M:%S %z
4598 tr Response time (milliseconds)
4599 dt Total time spent making DNS lookups (milliseconds)
4600 tS Approximate master transaction start time in
4601 <full seconds since epoch>.<fractional seconds> format.
4602 Currently, Squid considers the master transaction
4603 started when a complete HTTP request header initiating
4604 the transaction is received from the client. This is
4605 the same value that Squid uses to calculate transaction
4606 response time when logging %tr to access.log. Currently,
4607 Squid uses millisecond resolution for %tS values,
4608 similar to the default access.log "current time" field
4611 Access Control related format codes:
4613 et Tag returned by external acl
4614 ea Log string returned by external acl
4615 un User name (any available)
4616 ul User name from authentication
4617 ue User name from external acl helper
4618 ui User name from ident
4619 un A user name. Expands to the first available name
4620 from the following list of information sources:
4621 - authenticated user name, like %ul
4622 - user name supplied by an external ACL, like %ue
4623 - SSL client name, like %us
4624 - ident user name, like %ui
4625 credentials Client credentials. The exact meaning depends on
4626 the authentication scheme: For Basic authentication,
4627 it is the password; for Digest, the realm sent by the
4628 client; for NTLM and Negotiate, the client challenge
4629 or client credentials prefixed with "YR " or "KK ".
4631 HTTP related format codes:
4635 [http::]rm Request method (GET/POST etc)
4636 [http::]>rm Request method from client
4637 [http::]<rm Request method sent to server or peer
4639 [http::]ru Request URL received (or computed) and sanitized
4641 Logs request URI received from the client, a
4642 request adaptation service, or a request
4643 redirector (whichever was applied last).
4645 Computed URLs are URIs of internally generated
4646 requests and various "error:..." URIs.
4648 Honors strip_query_terms and uri_whitespace.
4650 This field is not encoded by default. Encoding
4651 this field using variants of %-encoding will
4652 clash with uri_whitespace modifications that
4653 also use %-encoding.
4655 [http::]>ru Request URL received from the client (or computed)
4657 Computed URLs are URIs of internally generated
4658 requests and various "error:..." URIs.
4660 Unlike %ru, this request URI is not affected
4661 by request adaptation, URL rewriting services,
4662 and strip_query_terms.
4664 Honors uri_whitespace.
4666 This field is using pass-through URL encoding
4667 by default. Encoding this field using other
4668 variants of %-encoding will clash with
4669 uri_whitespace modifications that also use
4672 [http::]<ru Request URL sent to server or peer
4673 [http::]>rs Request URL scheme from client
4674 [http::]<rs Request URL scheme sent to server or peer
4675 [http::]>rd Request URL domain from client
4676 [http::]<rd Request URL domain sent to server or peer
4677 [http::]>rP Request URL port from client
4678 [http::]<rP Request URL port sent to server or peer
4679 [http::]rp Request URL path excluding hostname
4680 [http::]>rp Request URL path excluding hostname from client
4681 [http::]<rp Request URL path excluding hostname sent to server or peer
4682 [http::]rv Request protocol version
4683 [http::]>rv Request protocol version from client
4684 [http::]<rv Request protocol version sent to server or peer
4686 [http::]>h Original received request header.
4687 Usually differs from the request header sent by
4688 Squid, although most fields are often preserved.
4689 Accepts optional header field name/value filter
4690 argument using name[:[separator]element] format.
4691 [http::]>ha Received request header after adaptation and
4692 redirection (pre-cache REQMOD vectoring point).
4693 Usually differs from the request header sent by
4694 Squid, although most fields are often preserved.
4695 Optional header name argument as for >h
4699 [http::]<Hs HTTP status code received from the next hop
4700 [http::]>Hs HTTP status code sent to the client
4702 [http::]<h Reply header. Optional header name argument
4705 [http::]mt MIME content type
4710 [http::]st Total size of request + reply traffic with client
4711 [http::]>st Total size of request received from client.
4712 Excluding chunked encoding bytes.
4713 [http::]<st Total size of reply sent to client (after adaptation)
4715 [http::]>sh Size of request headers received from client
4716 [http::]<sh Size of reply headers sent to client (after adaptation)
4718 [http::]<sH Reply high offset sent
4719 [http::]<sS Upstream object size
4721 [http::]<bs Number of HTTP-equivalent message body bytes
4722 received from the next hop, excluding chunked
4723 transfer encoding and control messages.
4724 Generated FTP/Gopher listings are treated as
4729 [http::]<pt Peer response time in milliseconds. The timer starts
4730 when the last request byte is sent to the next hop
4731 and stops when the last response byte is received.
4732 [http::]<tt Total time in milliseconds. The timer
4733 starts with the first connect request (or write I/O)
4734 sent to the first selected peer. The timer stops
4735 with the last I/O with the last peer.
4737 Squid handling related format codes:
4739 Ss Squid request status (TCP_MISS etc)
4740 Sh Squid hierarchy status (DEFAULT_PARENT etc)
4742 SSL-related format codes:
4744 ssl::bump_mode SslBump decision for the transaction:
4746 For CONNECT requests that initiated bumping of
4747 a connection and for any request received on
4748 an already bumped connection, Squid logs the
4749 corresponding SslBump mode ("splice", "bump",
4750 "peek", "stare", "terminate", "server-first"
4751 or "client-first"). See the ssl_bump option
4752 for more information about these modes.
4754 A "none" token is logged for requests that
4755 triggered "ssl_bump" ACL evaluation matching
4758 In all other cases, a single dash ("-") is
4761 ssl::>sni SSL client SNI sent to Squid.
4764 The Subject field of the received client
4765 SSL certificate or a dash ('-') if Squid has
4766 received an invalid/malformed certificate or
4767 no certificate at all. Consider encoding the
4768 logged value because Subject often has spaces.
4771 The Issuer field of the received client
4772 SSL certificate or a dash ('-') if Squid has
4773 received an invalid/malformed certificate or
4774 no certificate at all. Consider encoding the
4775 logged value because Issuer often has spaces.
4778 The Subject field of the received server
4779 TLS certificate or a dash ('-') if this is
4780 not available. Consider encoding the logged
4781 value because Subject often has spaces.
4784 The Issuer field of the received server
4785 TLS certificate or a dash ('-') if this is
4786 not available. Consider encoding the logged
4787 value because Issuer often has spaces.
4790 The received server x509 certificate in PEM
4791 format, including BEGIN and END lines (or a
4792 dash ('-') if the certificate is unavailable).
4794 WARNING: Large certificates will exceed the
4795 current 8KB access.log record limit, resulting
4796 in truncated records. Such truncation usually
4797 happens in the middle of a record field. The
4798 limit applies to all access logging modules.
4800 The logged certificate may have failed
4801 validation and may not be trusted by Squid.
4802 This field does not include any intermediate
4803 certificates that may have been received from
4804 the server or fetched during certificate
4807 Currently, Squid only collects server
4808 certificates during step3 of SslBump
4809 processing; connections that were not subject
4810 to ssl_bump rules or that did not match a peek
4811 or stare rule at step2 will not have the
4812 server certificate information.
4814 This field is using pass-through URL encoding
4818 The list of certificate validation errors
4819 detected by Squid (including OpenSSL and
4820 certificate validation helper components). The
4821 errors are listed in the discovery order. By
4822 default, the error codes are separated by ':'.
4823 Accepts an optional separator argument.
4825 %ssl::>negotiated_version The negotiated TLS version of the
4828 %ssl::<negotiated_version The negotiated TLS version of the
4829 last server or peer connection.
4831 %ssl::>received_hello_version The TLS version of the Hello
4832 message received from TLS client.
4834 %ssl::<received_hello_version The TLS version of the Hello
4835 message received from TLS server.
4837 %ssl::>received_supported_version The maximum TLS version
4838 supported by the TLS client.
4840 %ssl::<received_supported_version The maximum TLS version
4841 supported by the TLS server.
4843 %ssl::>negotiated_cipher The negotiated cipher of the
4846 %ssl::<negotiated_cipher The negotiated cipher of the
4847 last server or peer connection.
4849 If ICAP is enabled, the following code becomes available (as
4850 well as ICAP log codes documented with the icap_log option):
4852 icap::tt Total ICAP processing time for the HTTP
4853 transaction. The timer ticks when ICAP
4854 ACLs are checked and when ICAP
4855 transaction is in progress.
4857 If adaptation is enabled the following codes become available:
4859 adapt::<last_h The header of the last ICAP response or
4860 meta-information from the last eCAP
4861 transaction related to the HTTP transaction.
4862 Like <h, accepts an optional header name
4865 adapt::sum_trs Summed adaptation transaction response
4866 times recorded as a comma-separated list in
4867 the order of transaction start time. Each time
4868 value is recorded as an integer number,
4869 representing response time of one or more
4870 adaptation (ICAP or eCAP) transaction in
4871 milliseconds. When a failed transaction is
4872 being retried or repeated, its time is not
4873 logged individually but added to the
4874 replacement (next) transaction. See also:
4877 adapt::all_trs All adaptation transaction response times.
4878 Same as adaptation_strs but response times of
4879 individual transactions are never added
4880 together. Instead, all transaction response
4881 times are recorded individually.
4883 You can prefix adapt::*_trs format codes with adaptation
4884 service name in curly braces to record response time(s) specific
4885 to that service. For example: %{my_service}adapt::sum_trs
4887 Format codes related to the PROXY protocol:
4889 proxy_protocol::>h PROXY protocol header, including optional TLVs.
4891 Supports the same field and element reporting/extraction logic
4892 as %http::>h. For configuration and reporting purposes, Squid
4893 maps each PROXY TLV to an HTTP header field: the TLV type
4894 (configured as a decimal integer) is the field name, and the
4895 TLV value is the field value. All TLVs of "LOCAL" connections
4896 (in PROXY protocol terminology) are currently skipped/ignored.
4898 Squid also maps the following standard PROXY protocol header
4899 blocks to pseudo HTTP headers (their names use PROXY
4900 terminology and start with a colon, following HTTP tradition
4901 for pseudo headers): :command, :version, :src_addr, :dst_addr,
4902 :src_port, and :dst_port.
4904 Without optional parameters, this logformat code logs
4905 pseudo headers and TLVs.
4907 This format code uses pass-through URL encoding by default.
4910 # relay custom PROXY TLV #224 to adaptation services
4911 adaptation_meta Client-Foo "%proxy_protocol::>h{224}"
4915 The default formats available (which do not need re-defining) are:
4917 logformat squid %ts.%03tu %6tr %>a %Ss/%03>Hs %<st %rm %ru %[un %Sh/%<a %mt
4918 logformat common %>a %[ui %[un [%tl] "%rm %ru HTTP/%rv" %>Hs %<st %Ss:%Sh
4919 logformat combined %>a %[ui %[un [%tl] "%rm %ru HTTP/%rv" %>Hs %<st "%{Referer}>h" "%{User-Agent}>h" %Ss:%Sh
4920 logformat referrer %ts.%03tu %>a %{Referer}>h %ru
4921 logformat useragent %>a [%tl] "%{User-Agent}>h"
4923 NOTE: When the log_mime_hdrs directive is set to ON.
4924 The squid, common and combined formats have a safely encoded copy
4925 of the mime headers appended to each line within a pair of brackets.
4927 NOTE: The common and combined formats are not quite true to the Apache definition.
4928 The logs from Squid contain an extra status and hierarchy code appended.
4932 NAME: access_log cache_access_log
4934 LOC: Config.Log.accesslogs
4935 DEFAULT_IF_NONE: daemon:@DEFAULT_ACCESS_LOG@ squid
4937 Configures whether and how Squid logs HTTP and ICP transactions.
4938 If access logging is enabled, a single line is logged for every
4939 matching HTTP or ICP request. The recommended directive formats are:
4941 access_log <module>:<place> [option ...] [acl acl ...]
4942 access_log none [acl acl ...]
4944 The following directive format is accepted but may be deprecated:
4945 access_log <module>:<place> [<logformat name> [acl acl ...]]
4947 In most cases, the first ACL name must not contain the '=' character
4948 and should not be equal to an existing logformat name. You can always
4949 start with an 'all' ACL to work around those restrictions.
4951 Will log to the specified module:place using the specified format (which
4952 must be defined in a logformat directive) those entries which match
4953 ALL the acl's specified (which must be defined in acl clauses).
4954 If no acl is specified, all requests will be logged to this destination.
4956 ===== Available options for the recommended directive format =====
4958 logformat=name Names log line format (either built-in or
4959 defined by a logformat directive). Defaults
4962 buffer-size=64KB Defines approximate buffering limit for log
4963 records (see buffered_logs). Squid should not
4964 keep more than the specified size and, hence,
4965 should flush records before the buffer becomes
4966 full to avoid overflows under normal
4967 conditions (the exact flushing algorithm is
4968 module-dependent though). The on-error option
4969 controls overflow handling.
4971 on-error=die|drop Defines action on unrecoverable errors. The
4972 'drop' action ignores (i.e., does not log)
4973 affected log records. The default 'die' action
4974 kills the affected worker. The drop action
4975 support has not been tested for modules other
4978 rotate=N Specifies the number of log file rotations to
4979 make when you run 'squid -k rotate'. The default
4980 is to obey the logfile_rotate directive. Setting
4981 rotate=0 will disable the file name rotation,
4982 but the log files are still closed and re-opened.
4983 This will enable you to rename the logfiles
4984 yourself just before sending the rotate signal.
4985 Only supported by the stdio module.
4987 ===== Modules Currently available =====
4989 none Do not log any requests matching these ACL.
4990 Do not specify Place or logformat name.
4992 stdio Write each log line to disk immediately at the completion of
4994 Place: the filename and path to be written.
4996 daemon Very similar to stdio. But instead of writing to disk the log
4997 line is passed to a daemon helper for asychronous handling instead.
4998 Place: varies depending on the daemon.
5000 log_file_daemon Place: the file name and path to be written.
5002 syslog To log each request via syslog facility.
5003 Place: The syslog facility and priority level for these entries.
5004 Place Format: facility.priority
5006 where facility could be any of:
5007 authpriv, daemon, local0 ... local7 or user.
5009 And priority could be any of:
5010 err, warning, notice, info, debug.
5012 udp To send each log line as text data to a UDP receiver.
5013 Place: The destination host name or IP and port.
5014 Place Format: //host:port
5016 tcp To send each log line as text data to a TCP receiver.
5017 Lines may be accumulated before sending (see buffered_logs).
5018 Place: The destination host name or IP and port.
5019 Place Format: //host:port
5022 access_log daemon:@DEFAULT_ACCESS_LOG@ squid
5028 LOC: Config.Log.icaplogs
5031 ICAP log files record ICAP transaction summaries, one line per
5034 The icap_log option format is:
5035 icap_log <filepath> [<logformat name> [acl acl ...]]
5036 icap_log none [acl acl ...]]
5038 Please see access_log option documentation for details. The two
5039 kinds of logs share the overall configuration approach and many
5042 ICAP processing of a single HTTP message or transaction may
5043 require multiple ICAP transactions. In such cases, multiple
5044 ICAP transaction log lines will correspond to a single access
5047 ICAP log supports many access.log logformat %codes. In ICAP context,
5048 HTTP message-related %codes are applied to the HTTP message embedded
5049 in an ICAP message. Logformat "%http::>..." codes are used for HTTP
5050 messages embedded in ICAP requests while "%http::<..." codes are used
5051 for HTTP messages embedded in ICAP responses. For example:
5053 http::>h To-be-adapted HTTP message headers sent by Squid to
5054 the ICAP service. For REQMOD transactions, these are
5055 HTTP request headers. For RESPMOD, these are HTTP
5056 response headers, but Squid currently cannot log them
5057 (i.e., %http::>h will expand to "-" for RESPMOD).
5059 http::<h Adapted HTTP message headers sent by the ICAP
5060 service to Squid (i.e., HTTP request headers in regular
5061 REQMOD; HTTP response headers in RESPMOD and during
5062 request satisfaction in REQMOD).
5064 ICAP OPTIONS transactions do not embed HTTP messages.
5066 Several logformat codes below deal with ICAP message bodies. An ICAP
5067 message body, if any, typically includes a complete HTTP message
5068 (required HTTP headers plus optional HTTP message body). When
5069 computing HTTP message body size for these logformat codes, Squid
5070 either includes or excludes chunked encoding overheads; see
5071 code-specific documentation for details.
5073 For Secure ICAP services, all size-related information is currently
5074 computed before/after TLS encryption/decryption, as if TLS was not
5077 The following format codes are also available for ICAP logs:
5079 icap::<A ICAP server IP address. Similar to <A.
5081 icap::<service_name ICAP service name from the icap_service
5082 option in Squid configuration file.
5084 icap::ru ICAP Request-URI. Similar to ru.
5086 icap::rm ICAP request method (REQMOD, RESPMOD, or
5087 OPTIONS). Similar to existing rm.
5089 icap::>st The total size of the ICAP request sent to the ICAP
5090 server (ICAP headers + ICAP body), including chunking
5093 icap::<st The total size of the ICAP response received from the
5094 ICAP server (ICAP headers + ICAP body), including
5095 chunking metadata (if any).
5097 icap::<bs The size of the ICAP response body received from the
5098 ICAP server, excluding chunking metadata (if any).
5100 icap::tr Transaction response time (in
5101 milliseconds). The timer starts when
5102 the ICAP transaction is created and
5103 stops when the transaction is completed.
5106 icap::tio Transaction I/O time (in milliseconds). The
5107 timer starts when the first ICAP request
5108 byte is scheduled for sending. The timers
5109 stops when the last byte of the ICAP response
5112 icap::to Transaction outcome: ICAP_ERR* for all
5113 transaction errors, ICAP_OPT for OPTION
5114 transactions, ICAP_ECHO for 204
5115 responses, ICAP_MOD for message
5116 modification, and ICAP_SAT for request
5117 satisfaction. Similar to Ss.
5119 icap::Hs ICAP response status code. Similar to Hs.
5121 icap::>h ICAP request header(s). Similar to >h.
5123 icap::<h ICAP response header(s). Similar to <h.
5125 The default ICAP log format, which can be used without an explicit
5126 definition, is called icap_squid:
5128 logformat icap_squid %ts.%03tu %6icap::tr %>A %icap::to/%03icap::Hs %icap::<st %icap::rm %icap::ru %un -/%icap::<A -
5130 See also: logformat and %adapt::<last_h
5133 NAME: logfile_daemon
5135 DEFAULT: @DEFAULT_LOGFILED@
5136 LOC: Log::TheConfig.logfile_daemon
5138 Specify the path to the logfile-writing daemon. This daemon is
5139 used to write the access and store logs, if configured.
5141 Squid sends a number of commands to the log daemon:
5142 L<data>\n - logfile data
5147 r<n>\n - set rotate count to <n>
5148 b<n>\n - 1 = buffer output, 0 = don't buffer output
5150 No responses is expected.
5153 NAME: stats_collection
5155 LOC: Config.accessList.stats_collection
5157 DEFAULT_DOC: Allow logging for all transactions.
5158 COMMENT: allow|deny acl acl...
5160 This options allows you to control which requests gets accounted
5161 in performance counters.
5163 This clause only supports fast acl types.
5164 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
5167 NAME: cache_store_log
5170 LOC: Config.Log.store
5172 Logs the activities of the storage manager. Shows which
5173 objects are ejected from the cache, and which objects are
5174 saved and for how long.
5175 There are not really utilities to analyze this data, so you can safely
5176 disable it (the default).
5178 Store log uses modular logging outputs. See access_log for the list
5179 of modules supported.
5182 cache_store_log stdio:@DEFAULT_STORE_LOG@
5183 cache_store_log daemon:@DEFAULT_STORE_LOG@
5186 NAME: cache_swap_state cache_swap_log
5188 LOC: Config.Log.swap
5190 DEFAULT_DOC: Store the journal inside its cache_dir
5192 Location for the cache "swap.state" file. This index file holds
5193 the metadata of objects saved on disk. It is used to rebuild
5194 the cache during startup. Normally this file resides in each
5195 'cache_dir' directory, but you may specify an alternate
5196 pathname here. Note you must give a full filename, not just
5197 a directory. Since this is the index for the whole object
5198 list you CANNOT periodically rotate it!
5200 If %s can be used in the file name it will be replaced with a
5201 a representation of the cache_dir name where each / is replaced
5202 with '.'. This is needed to allow adding/removing cache_dir
5203 lines when cache_swap_log is being used.
5205 If have more than one 'cache_dir', and %s is not used in the name
5206 these swap logs will have names such as:
5212 The numbered extension (which is added automatically)
5213 corresponds to the order of the 'cache_dir' lines in this
5214 configuration file. If you change the order of the 'cache_dir'
5215 lines in this file, these index files will NOT correspond to
5216 the correct 'cache_dir' entry (unless you manually rename
5217 them). We recommend you do NOT use this option. It is
5218 better to keep these index files in each 'cache_dir' directory.
5221 NAME: logfile_rotate
5224 LOC: Config.Log.rotateNumber
5226 Specifies the default number of logfile rotations to make when you
5227 type 'squid -k rotate'. The default is 10, which will rotate
5228 with extensions 0 through 9. Setting logfile_rotate to 0 will
5229 disable the file name rotation, but the logfiles are still closed
5230 and re-opened. This will enable you to rename the logfiles
5231 yourself just before sending the rotate signal.
5233 Note, from Squid-3.1 this option is only a default for cache.log,
5234 that log can be rotated separately by using debug_options.
5236 Note, from Squid-4 this option is only a default for access.log
5237 recorded by stdio: module. Those logs can be rotated separately by
5238 using the rotate=N option on their access_log directive.
5240 Note, the 'squid -k rotate' command normally sends a USR1
5241 signal to the running squid process. In certain situations
5242 (e.g. on Linux with Async I/O), USR1 is used for other
5243 purposes, so -k rotate uses another signal. It is best to get
5244 in the habit of using 'squid -k rotate' instead of 'kill -USR1
5251 DEFAULT: @DEFAULT_MIME_TABLE@
5252 LOC: Config.mimeTablePathname
5254 Path to Squid's icon configuration file.
5256 You shouldn't need to change this, but the default file contains
5257 examples and formatting information if you do.
5263 LOC: Config.onoff.log_mime_hdrs
5266 The Cache can record both the request and the response MIME
5267 headers for each HTTP transaction. The headers are encoded
5268 safely and will appear as two bracketed fields at the end of
5269 the access log (for either the native or httpd-emulated log
5270 formats). To enable this logging set log_mime_hdrs to 'on'.
5275 DEFAULT: @DEFAULT_PID_FILE@
5276 LOC: Config.pidFilename
5278 A filename to write the process-id to. To disable, enter "none".
5281 NAME: client_netmask
5283 LOC: Config.Addrs.client_netmask
5285 DEFAULT_DOC: Log full client IP address
5287 A netmask for client addresses in logfiles and cachemgr output.
5288 Change this to protect the privacy of your cache clients.
5289 A netmask of 255.255.255.0 will log all IP's in that range with
5290 the last digit set to '0'.
5293 NAME: strip_query_terms
5295 LOC: Config.onoff.strip_query_terms
5298 By default, Squid strips query terms from requested URLs before
5299 logging. This protects your user's privacy and reduces log size.
5301 When investigating HIT/MISS or other caching behaviour you
5302 will need to disable this to see the full URL used by Squid.
5309 LOC: Config.onoff.buffered_logs
5311 Whether to write/send access_log records ASAP or accumulate them and
5312 then write/send them in larger chunks. Buffering may improve
5313 performance because it decreases the number of I/Os. However,
5314 buffering increases the delay before log records become available to
5315 the final recipient (e.g., a disk file or logging daemon) and,
5316 hence, increases the risk of log records loss.
5318 Note that even when buffered_logs are off, Squid may have to buffer
5319 records if it cannot write/send them immediately due to pending I/Os
5320 (e.g., the I/O writing the previous log record) or connectivity loss.
5322 Currently honored by 'daemon' and 'tcp' access_log modules only.
5325 NAME: netdb_filename
5327 DEFAULT: stdio:@DEFAULT_NETDB_FILE@
5328 LOC: Config.netdbFilename
5331 Where Squid stores it's netdb journal.
5332 When enabled this journal preserves netdb state between restarts.
5334 To disable, enter "none".
5338 OPTIONS FOR TROUBLESHOOTING
5339 -----------------------------------------------------------------------------
5344 DEFAULT_IF_NONE: @DEFAULT_CACHE_LOG@
5345 LOC: Debug::cache_log
5347 Squid administrative logging file.
5349 This is where general information about Squid behavior goes. You can
5350 increase the amount of data logged to this file and how often it is
5351 rotated with "debug_options"
5357 DEFAULT_DOC: Log all critical and important messages.
5358 LOC: Debug::debugOptions
5360 Logging options are set as section,level where each source file
5361 is assigned a unique section. Lower levels result in less
5362 output, Full debugging (level 9) can result in a very large
5363 log file, so be careful.
5365 The magic word "ALL" sets debugging levels for all sections.
5366 The default is to run with "ALL,1" to record important warnings.
5368 The rotate=N option can be used to keep more or less of these logs
5369 than would otherwise be kept by logfile_rotate.
5370 For most uses a single log should be enough to monitor current
5371 events affecting Squid.
5376 LOC: Config.coredump_dir
5377 DEFAULT_IF_NONE: none
5378 DEFAULT_DOC: Use the directory from where Squid was started.
5380 By default Squid leaves core files in the directory from where
5381 it was started. If you set 'coredump_dir' to a directory
5382 that exists, Squid will chdir() to that directory at startup
5383 and coredump files will be left there.
5387 # Leave coredumps in the first cache dir
5388 coredump_dir @DEFAULT_SWAP_DIR@
5394 OPTIONS FOR FTP GATEWAYING
5395 -----------------------------------------------------------------------------
5401 LOC: Config.Ftp.anon_user
5403 If you want the anonymous login password to be more informative
5404 (and enable the use of picky FTP servers), set this to something
5405 reasonable for your domain, like wwwuser@somewhere.net
5407 The reason why this is domainless by default is the
5408 request can be made on the behalf of a user in any domain,
5409 depending on how the cache is used.
5410 Some FTP server also validate the email address is valid
5411 (for example perl.com).
5417 LOC: Config.Ftp.passive
5419 If your firewall does not allow Squid to use passive
5420 connections, turn off this option.
5422 Use of ftp_epsv_all option requires this to be ON.
5428 LOC: Config.Ftp.epsv_all
5430 FTP Protocol extensions permit the use of a special "EPSV ALL" command.
5432 NATs may be able to put the connection on a "fast path" through the
5433 translator, as the EPRT command will never be used and therefore,
5434 translation of the data portion of the segments will never be needed.
5436 When a client only expects to do two-way FTP transfers this may be
5438 If squid finds that it must do a three-way FTP transfer after issuing
5439 an EPSV ALL command, the FTP session will fail.
5441 If you have any doubts about this option do not use it.
5442 Squid will nicely attempt all other connection methods.
5444 Requires ftp_passive to be ON (default) for any effect.
5450 LOC: Config.accessList.ftp_epsv
5452 FTP Protocol extensions permit the use of a special "EPSV" command.
5454 NATs may be able to put the connection on a "fast path" through the
5455 translator using EPSV, as the EPRT command will never be used
5456 and therefore, translation of the data portion of the segments
5457 will never be needed.
5459 EPSV is often required to interoperate with FTP servers on IPv6
5460 networks. On the other hand, it may break some IPv4 servers.
5462 By default, EPSV may try EPSV with any FTP server. To fine tune
5463 that decision, you may restrict EPSV to certain clients or servers
5466 ftp_epsv allow|deny al1 acl2 ...
5468 WARNING: Disabling EPSV may cause problems with external NAT and IPv6.
5470 Only fast ACLs are supported.
5471 Requires ftp_passive to be ON (default) for any effect.
5477 LOC: Config.Ftp.eprt
5479 FTP Protocol extensions permit the use of a special "EPRT" command.
5481 This extension provides a protocol neutral alternative to the
5482 IPv4-only PORT command. When supported it enables active FTP data
5483 channels over IPv6 and efficient NAT handling.
5485 Turning this OFF will prevent EPRT being attempted and will skip
5486 straight to using PORT for IPv4 servers.
5488 Some devices are known to not handle this extension correctly and
5489 may result in crashes. Devices which suport EPRT enough to fail
5490 cleanly will result in Squid attempting PORT anyway. This directive
5491 should only be disabled when EPRT results in device failures.
5493 WARNING: Doing so will convert Squid back to the old behavior with all
5494 the related problems with external NAT devices/layers and IPv4-only FTP.
5497 NAME: ftp_sanitycheck
5500 LOC: Config.Ftp.sanitycheck
5502 For security and data integrity reasons Squid by default performs
5503 sanity checks of the addresses of FTP data connections ensure the
5504 data connection is to the requested server. If you need to allow
5505 FTP connections to servers using another IP address for the data
5506 connection turn this off.
5509 NAME: ftp_telnet_protocol
5512 LOC: Config.Ftp.telnet
5514 The FTP protocol is officially defined to use the telnet protocol
5515 as transport channel for the control connection. However, many
5516 implementations are broken and does not respect this aspect of
5519 If you have trouble accessing files with ASCII code 255 in the
5520 path or similar problems involving this ASCII code you can
5521 try setting this directive to off. If that helps, report to the
5522 operator of the FTP server in question that their FTP server
5523 is broken and does not follow the FTP standard.
5527 OPTIONS FOR EXTERNAL SUPPORT PROGRAMS
5528 -----------------------------------------------------------------------------
5533 DEFAULT: @DEFAULT_DISKD@
5534 LOC: Config.Program.diskd
5536 Specify the location of the diskd executable.
5537 Note this is only useful if you have compiled in
5538 diskd as one of the store io modules.
5541 NAME: unlinkd_program
5544 DEFAULT: @DEFAULT_UNLINKD@
5545 LOC: Config.Program.unlinkd
5547 Specify the location of the executable for file deletion process.
5550 NAME: pinger_program
5553 DEFAULT: @DEFAULT_PINGER@
5556 Specify the location of the executable for the pinger process.
5565 Control whether the pinger is active at run-time.
5566 Enables turning ICMP pinger on and off with a simple
5567 squid -k reconfigure.
5572 OPTIONS FOR URL REWRITING
5573 -----------------------------------------------------------------------------
5576 NAME: url_rewrite_program redirect_program
5578 LOC: Config.Program.redirect
5581 Specify the location of the executable URL rewriter to use.
5582 Since they can perform almost any function there isn't one included.
5584 For each requested URL, the rewriter will receive on line with the format
5586 [channel-ID <SP>] URL [<SP> extras]<NL>
5588 See url_rewrite_extras on how to send "extras" with optional values to
5590 After processing the request the helper must reply using the following format:
5592 [channel-ID <SP>] result [<SP> kv-pairs]
5594 The result code can be:
5596 OK status=30N url="..."
5597 Redirect the URL to the one supplied in 'url='.
5598 'status=' is optional and contains the status code to send
5599 the client in Squids HTTP response. It must be one of the
5600 HTTP redirect status codes: 301, 302, 303, 307, 308.
5601 When no status is given Squid will use 302.
5603 OK rewrite-url="..."
5604 Rewrite the URL to the one supplied in 'rewrite-url='.
5605 The new URL is fetched directly by Squid and returned to
5606 the client as the response to its request.
5609 When neither of url= and rewrite-url= are sent Squid does
5613 Do not change the URL.
5616 An internal error occurred in the helper, preventing
5617 a result being identified. The 'message=' key name is
5618 reserved for delivering a log message.
5621 In addition to the above kv-pairs Squid also understands the following
5622 optional kv-pairs received from URL rewriters:
5624 Associates a TAG with the client TCP connection.
5625 The TAG is treated as a regular annotation but persists across
5626 future requests on the client connection rather than just the
5627 current request. A helper may update the TAG during subsequent
5628 requests be returning a new kv-pair.
5630 When using the concurrency= option the protocol is changed by
5631 introducing a query channel tag in front of the request/response.
5632 The query channel tag is a number between 0 and concurrency-1.
5633 This value must be echoed back unchanged to Squid as the first part
5634 of the response relating to its request.
5636 WARNING: URL re-writing ability should be avoided whenever possible.
5637 Use the URL redirect form of response instead.
5639 Re-write creates a difference in the state held by the client
5640 and server. Possibly causing confusion when the server response
5641 contains snippets of its view state. Embeded URLs, response
5642 and content Location headers, etc. are not re-written by this
5645 By default, a URL rewriter is not used.
5648 NAME: url_rewrite_children redirect_children
5649 TYPE: HelperChildConfig
5650 DEFAULT: 20 startup=0 idle=1 concurrency=0
5651 LOC: Config.redirectChildren
5653 Specifies the maximum number of redirector processes that Squid may
5654 spawn (numberofchildren) and several related options. Using too few of
5655 these helper processes (a.k.a. "helpers") creates request queues.
5656 Using too many helpers wastes your system resources.
5658 Usage: numberofchildren [option]...
5660 The startup= and idle= options allow some measure of skew in your
5665 Sets a minimum of how many processes are to be spawned when Squid
5666 starts or reconfigures. When set to zero the first request will
5667 cause spawning of the first child process to handle it.
5669 Starting too few will cause an initial slowdown in traffic as Squid
5670 attempts to simultaneously spawn enough processes to cope.
5674 Sets a minimum of how many processes Squid is to try and keep available
5675 at all times. When traffic begins to rise above what the existing
5676 processes can handle this many more will be spawned up to the maximum
5677 configured. A minimum setting of 1 is required.
5681 The number of requests each redirector helper can handle in
5682 parallel. Defaults to 0 which indicates the redirector
5683 is a old-style single threaded redirector.
5685 When this directive is set to a value >= 1 then the protocol
5686 used to communicate with the helper is modified to include
5687 an ID in front of the request/response. The ID from the request
5688 must be echoed back with the response to that request.
5692 Sets the maximum number of queued requests. A request is queued when
5693 no existing child can accept it due to concurrency limit and no new
5694 child can be started due to numberofchildren limit. The default
5695 maximum is zero if url_rewrite_bypass is enabled and
5696 2*numberofchildren otherwise. If the queued requests exceed queue size
5697 and redirector_bypass configuration option is set, then redirector is
5698 bypassed. Otherwise, Squid is allowed to temporarily exceed the
5699 configured maximum, marking the affected helper as "overloaded". If
5700 the helper overload lasts more than 3 minutes, the action prescribed
5701 by the on-persistent-overload option applies.
5703 on-persistent-overload=action
5705 Specifies Squid reaction to a new helper request arriving when the helper
5706 has been overloaded for more that 3 minutes already. The number of queued
5707 requests determines whether the helper is overloaded (see the queue-size
5710 Two actions are supported:
5712 die Squid worker quits. This is the default behavior.
5714 ERR Squid treats the helper request as if it was
5715 immediately submitted, and the helper immediately
5716 replied with an ERR response. This action has no effect
5717 on the already queued and in-progress helper requests.
5720 NAME: url_rewrite_host_header redirect_rewrites_host_header
5723 LOC: Config.onoff.redir_rewrites_host
5725 To preserve same-origin security policies in browsers and
5726 prevent Host: header forgery by redirectors Squid rewrites
5727 any Host: header in redirected requests.
5729 If you are running an accelerator this may not be a wanted
5730 effect of a redirector. This directive enables you disable
5731 Host: alteration in reverse-proxy traffic.
5733 WARNING: Entries are cached on the result of the URL rewriting
5734 process, so be careful if you have domain-virtual hosts.
5736 WARNING: Squid and other software verifies the URL and Host
5737 are matching, so be careful not to relay through other proxies
5738 or inspecting firewalls with this disabled.
5741 NAME: url_rewrite_access redirector_access
5744 DEFAULT_DOC: Allow, unless rules exist in squid.conf.
5745 LOC: Config.accessList.redirector
5747 If defined, this access list specifies which requests are
5748 sent to the redirector processes.
5750 This clause supports both fast and slow acl types.
5751 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
5754 NAME: url_rewrite_bypass redirector_bypass
5756 LOC: Config.onoff.redirector_bypass
5759 When this is 'on', a request will not go through the
5760 redirector if all the helpers are busy. If this is 'off' and the
5761 redirector queue grows too large, the action is prescribed by the
5762 on-persistent-overload option. You should only enable this if the
5763 redirectors are not critical to your caching system. If you use
5764 redirectors for access control, and you enable this option,
5765 users may have access to pages they should not
5766 be allowed to request.
5768 Enabling this option sets the default url_rewrite_children queue-size
5772 NAME: url_rewrite_extras
5773 TYPE: TokenOrQuotedString
5774 LOC: Config.redirector_extras
5775 DEFAULT: "%>a/%>A %un %>rm myip=%la myport=%lp"
5777 Specifies a string to be append to request line format for the
5778 rewriter helper. "Quoted" format values may contain spaces and
5779 logformat %macros. In theory, any logformat %macro can be used.
5780 In practice, a %macro expands as a dash (-) if the helper request is
5781 sent before the required macro information is available to Squid.
5784 NAME: url_rewrite_timeout
5785 TYPE: UrlHelperTimeout
5786 LOC: Config.onUrlRewriteTimeout
5788 DEFAULT_DOC: Squid waits for the helper response forever
5790 Squid times active requests to redirector. The timeout value and Squid
5791 reaction to a timed out request are configurable using the following
5794 url_rewrite_timeout timeout time-units on_timeout=<action> [response=<quoted-response>]
5796 supported timeout actions:
5797 fail Squid return a ERR_GATEWAY_FAILURE error page
5799 bypass Do not re-write the URL
5801 retry Send the lookup to the helper again
5803 use_configured_response
5804 Use the <quoted-response> as helper response
5808 OPTIONS FOR STORE ID
5809 -----------------------------------------------------------------------------
5812 NAME: store_id_program storeurl_rewrite_program
5814 LOC: Config.Program.store_id
5817 Specify the location of the executable StoreID helper to use.
5818 Since they can perform almost any function there isn't one included.
5820 For each requested URL, the helper will receive one line with the format
5822 [channel-ID <SP>] URL [<SP> extras]<NL>
5825 After processing the request the helper must reply using the following format:
5827 [channel-ID <SP>] result [<SP> kv-pairs]
5829 The result code can be:
5832 Use the StoreID supplied in 'store-id='.
5835 The default is to use HTTP request URL as the store ID.
5838 An internal error occurred in the helper, preventing
5839 a result being identified.
5841 In addition to the above kv-pairs Squid also understands the following
5842 optional kv-pairs received from URL rewriters:
5844 Associates a TAG with the client TCP connection.
5845 Please see url_rewrite_program related documentation for this
5848 Helper programs should be prepared to receive and possibly ignore
5849 additional whitespace-separated tokens on each input line.
5851 When using the concurrency= option the protocol is changed by
5852 introducing a query channel tag in front of the request/response.
5853 The query channel tag is a number between 0 and concurrency-1.
5854 This value must be echoed back unchanged to Squid as the first part
5855 of the response relating to its request.
5857 NOTE: when using StoreID refresh_pattern will apply to the StoreID
5858 returned from the helper and not the URL.
5860 WARNING: Wrong StoreID value returned by a careless helper may result
5861 in the wrong cached response returned to the user.
5863 By default, a StoreID helper is not used.
5866 NAME: store_id_extras
5867 TYPE: TokenOrQuotedString
5868 LOC: Config.storeId_extras
5869 DEFAULT: "%>a/%>A %un %>rm myip=%la myport=%lp"
5871 Specifies a string to be append to request line format for the
5872 StoreId helper. "Quoted" format values may contain spaces and
5873 logformat %macros. In theory, any logformat %macro can be used.
5874 In practice, a %macro expands as a dash (-) if the helper request is
5875 sent before the required macro information is available to Squid.
5878 NAME: store_id_children storeurl_rewrite_children
5879 TYPE: HelperChildConfig
5880 DEFAULT: 20 startup=0 idle=1 concurrency=0
5881 LOC: Config.storeIdChildren
5883 Specifies the maximum number of StoreID helper processes that Squid
5884 may spawn (numberofchildren) and several related options. Using
5885 too few of these helper processes (a.k.a. "helpers") creates request
5886 queues. Using too many helpers wastes your system resources.
5888 Usage: numberofchildren [option]...
5890 The startup= and idle= options allow some measure of skew in your
5895 Sets a minimum of how many processes are to be spawned when Squid
5896 starts or reconfigures. When set to zero the first request will
5897 cause spawning of the first child process to handle it.
5899 Starting too few will cause an initial slowdown in traffic as Squid
5900 attempts to simultaneously spawn enough processes to cope.
5904 Sets a minimum of how many processes Squid is to try and keep available
5905 at all times. When traffic begins to rise above what the existing
5906 processes can handle this many more will be spawned up to the maximum
5907 configured. A minimum setting of 1 is required.
5911 The number of requests each storeID helper can handle in
5912 parallel. Defaults to 0 which indicates the helper
5913 is a old-style single threaded program.
5915 When this directive is set to a value >= 1 then the protocol
5916 used to communicate with the helper is modified to include
5917 an ID in front of the request/response. The ID from the request
5918 must be echoed back with the response to that request.
5922 Sets the maximum number of queued requests to N. A request is queued
5923 when no existing child can accept it due to concurrency limit and no
5924 new child can be started due to numberofchildren limit. The default
5925 maximum is 2*numberofchildren. If the queued requests exceed queue
5926 size and redirector_bypass configuration option is set, then
5927 redirector is bypassed. Otherwise, Squid is allowed to temporarily
5928 exceed the configured maximum, marking the affected helper as
5929 "overloaded". If the helper overload lasts more than 3 minutes, the
5930 action prescribed by the on-persistent-overload option applies.
5932 on-persistent-overload=action
5934 Specifies Squid reaction to a new helper request arriving when the helper
5935 has been overloaded for more that 3 minutes already. The number of queued
5936 requests determines whether the helper is overloaded (see the queue-size
5939 Two actions are supported:
5941 die Squid worker quits. This is the default behavior.
5943 ERR Squid treats the helper request as if it was
5944 immediately submitted, and the helper immediately
5945 replied with an ERR response. This action has no effect
5946 on the already queued and in-progress helper requests.
5949 NAME: store_id_access storeurl_rewrite_access
5952 DEFAULT_DOC: Allow, unless rules exist in squid.conf.
5953 LOC: Config.accessList.store_id
5955 If defined, this access list specifies which requests are
5956 sent to the StoreID processes. By default all requests
5959 This clause supports both fast and slow acl types.
5960 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
5963 NAME: store_id_bypass storeurl_rewrite_bypass
5965 LOC: Config.onoff.store_id_bypass
5968 When this is 'on', a request will not go through the
5969 helper if all helpers are busy. If this is 'off' and the helper
5970 queue grows too large, the action is prescribed by the
5971 on-persistent-overload option. You should only enable this if the
5972 helpers are not critical to your caching system. If you use
5973 helpers for critical caching components, and you enable this
5974 option, users may not get objects from cache.
5975 This options sets default queue-size option of the store_id_children
5980 OPTIONS FOR TUNING THE CACHE
5981 -----------------------------------------------------------------------------
5984 NAME: cache no_cache
5987 DEFAULT_DOC: By default, this directive is unused and has no effect.
5988 LOC: Config.accessList.noCache
5990 Requests denied by this directive will not be served from the cache
5991 and their responses will not be stored in the cache. This directive
5992 has no effect on other transactions and on already cached responses.
5994 This clause supports both fast and slow acl types.
5995 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
5997 This and the two other similar caching directives listed below are
5998 checked at different transaction processing stages, have different
5999 access to response information, affect different cache operations,
6000 and differ in slow ACLs support:
6002 * cache: Checked before Squid makes a hit/miss determination.
6003 No access to reply information!
6004 Denies both serving a hit and storing a miss.
6005 Supports both fast and slow ACLs.
6006 * send_hit: Checked after a hit was detected.
6007 Has access to reply (hit) information.
6008 Denies serving a hit only.
6009 Supports fast ACLs only.
6010 * store_miss: Checked before storing a cachable miss.
6011 Has access to reply (miss) information.
6012 Denies storing a miss only.
6013 Supports fast ACLs only.
6015 If you are not sure which of the three directives to use, apply the
6016 following decision logic:
6018 * If your ACL(s) are of slow type _and_ need response info, redesign.
6019 Squid does not support that particular combination at this time.
6021 * If your directive ACL(s) are of slow type, use "cache"; and/or
6022 * if your directive ACL(s) need no response info, use "cache".
6024 * If you do not want the response cached, use store_miss; and/or
6025 * if you do not want a hit on a cached response, use send_hit.
6031 DEFAULT_DOC: By default, this directive is unused and has no effect.
6032 LOC: Config.accessList.sendHit
6034 Responses denied by this directive will not be served from the cache
6035 (but may still be cached, see store_miss). This directive has no
6036 effect on the responses it allows and on the cached objects.
6038 Please see the "cache" directive for a summary of differences among
6039 store_miss, send_hit, and cache directives.
6041 Unlike the "cache" directive, send_hit only supports fast acl
6042 types. See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
6046 # apply custom Store ID mapping to some URLs
6047 acl MapMe dstdomain .c.example.com
6048 store_id_program ...
6049 store_id_access allow MapMe
6051 # but prevent caching of special responses
6052 # such as 302 redirects that cause StoreID loops
6053 acl Ordinary http_status 200-299
6054 store_miss deny MapMe !Ordinary
6056 # and do not serve any previously stored special responses
6057 # from the cache (in case they were already cached before
6058 # the above store_miss rule was in effect).
6059 send_hit deny MapMe !Ordinary
6065 DEFAULT_DOC: By default, this directive is unused and has no effect.
6066 LOC: Config.accessList.storeMiss
6068 Responses denied by this directive will not be cached (but may still
6069 be served from the cache, see send_hit). This directive has no
6070 effect on the responses it allows and on the already cached responses.
6072 Please see the "cache" directive for a summary of differences among
6073 store_miss, send_hit, and cache directives. See the
6074 send_hit directive for a usage example.
6076 Unlike the "cache" directive, store_miss only supports fast acl
6077 types. See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
6083 LOC: Config.maxStale
6086 This option puts an upper limit on how stale content Squid
6087 will serve from the cache if cache validation fails.
6088 Can be overriden by the refresh_pattern max-stale option.
6091 NAME: refresh_pattern
6092 TYPE: refreshpattern
6096 usage: refresh_pattern [-i] regex min percent max [options]
6098 By default, regular expressions are CASE-SENSITIVE. To make
6099 them case-insensitive, use the -i option.
6101 'Min' is the time (in minutes) an object without an explicit
6102 expiry time should be considered fresh. The recommended
6103 value is 0, any higher values may cause dynamic applications
6104 to be erroneously cached unless the application designer
6105 has taken the appropriate actions.
6107 'Percent' is a percentage of the objects age (time since last
6108 modification age) an object without explicit expiry time
6109 will be considered fresh.
6111 'Max' is an upper limit on how long objects without an explicit
6112 expiry time will be considered fresh. The value is also used
6113 to form Cache-Control: max-age header for a request sent from
6114 Squid to origin/parent.
6116 options: override-expire
6126 override-expire enforces min age even if the server
6127 sent an explicit expiry time (e.g., with the
6128 Expires: header or Cache-Control: max-age). Doing this
6129 VIOLATES the HTTP standard. Enabling this feature
6130 could make you liable for problems which it causes.
6132 Note: override-expire does not enforce staleness - it only extends
6133 freshness / min. If the server returns a Expires time which
6134 is longer than your max time, Squid will still consider
6135 the object fresh for that period of time.
6137 override-lastmod enforces min age even on objects
6138 that were modified recently.
6140 reload-into-ims changes a client no-cache or ``reload''
6141 request for a cached entry into a conditional request using
6142 If-Modified-Since and/or If-None-Match headers, provided the
6143 cached entry has a Last-Modified and/or a strong ETag header.
6144 Doing this VIOLATES the HTTP standard. Enabling this feature
6145 could make you liable for problems which it causes.
6147 ignore-reload ignores a client no-cache or ``reload''
6148 header. Doing this VIOLATES the HTTP standard. Enabling
6149 this feature could make you liable for problems which
6152 ignore-no-store ignores any ``Cache-control: no-store''
6153 headers received from a server. Doing this VIOLATES
6154 the HTTP standard. Enabling this feature could make you
6155 liable for problems which it causes.
6157 ignore-private ignores any ``Cache-control: private''
6158 headers received from a server. Doing this VIOLATES
6159 the HTTP standard. Enabling this feature could make you
6160 liable for problems which it causes.
6162 refresh-ims causes squid to contact the origin server
6163 when a client issues an If-Modified-Since request. This
6164 ensures that the client will receive an updated version
6165 if one is available.
6167 store-stale stores responses even if they don't have explicit
6168 freshness or a validator (i.e., Last-Modified or an ETag)
6169 present, or if they're already stale. By default, Squid will
6170 not cache such responses because they usually can't be
6171 reused. Note that such responses will be stale by default.
6173 max-stale=NN provide a maximum staleness factor. Squid won't
6174 serve objects more stale than this even if it failed to
6175 validate the object. Default: use the max_stale global limit.
6177 Basically a cached object is:
6179 FRESH if expire > now, else STALE
6181 FRESH if lm-factor < percent, else STALE
6185 The refresh_pattern lines are checked in the order listed here.
6186 The first entry which matches is used. If none of the entries
6187 match the default will be used.
6189 Note, you must uncomment all the default lines if you want
6190 to change one. The default setting is only active if none is
6196 # Add any of your own refresh_pattern entries above these.
6198 refresh_pattern ^ftp: 1440 20% 10080
6199 refresh_pattern ^gopher: 1440 0% 1440
6200 refresh_pattern -i (/cgi-bin/|\?) 0 0% 0
6201 refresh_pattern . 0 20% 4320
6205 NAME: quick_abort_min
6209 LOC: Config.quickAbort.min
6212 NAME: quick_abort_max
6216 LOC: Config.quickAbort.max
6219 NAME: quick_abort_pct
6223 LOC: Config.quickAbort.pct
6225 The cache by default continues downloading aborted requests
6226 which are almost completed (less than 16 KB remaining). This
6227 may be undesirable on slow (e.g. SLIP) links and/or very busy
6228 caches. Impatient users may tie up file descriptors and
6229 bandwidth by repeatedly requesting and immediately aborting
6232 When the user aborts a request, Squid will check the
6233 quick_abort values to the amount of data transferred until
6236 If the transfer has less than 'quick_abort_min' KB remaining,
6237 it will finish the retrieval.
6239 If the transfer has more than 'quick_abort_max' KB remaining,
6240 it will abort the retrieval.
6242 If more than 'quick_abort_pct' of the transfer has completed,
6243 it will finish the retrieval.
6245 If you do not want any retrieval to continue after the client
6246 has aborted, set both 'quick_abort_min' and 'quick_abort_max'
6249 If you want retrievals to always continue if they are being
6250 cached set 'quick_abort_min' to '-1 KB'.
6253 NAME: read_ahead_gap
6254 COMMENT: buffer-size
6256 LOC: Config.readAheadGap
6259 The amount of data the cache will buffer ahead of what has been
6260 sent to the client when retrieving an object from another server.
6264 IFDEF: USE_HTTP_VIOLATIONS
6267 LOC: Config.negativeTtl
6270 Set the Default Time-to-Live (TTL) for failed requests.
6271 Certain types of failures (such as "connection refused" and
6272 "404 Not Found") are able to be negatively-cached for a short time.
6273 Modern web servers should provide Expires: header, however if they
6274 do not this can provide a minimum TTL.
6275 The default is not to cache errors with unknown expiry details.
6277 Note that this is different from negative caching of DNS lookups.
6279 WARNING: Doing this VIOLATES the HTTP standard. Enabling
6280 this feature could make you liable for problems which it
6284 NAME: positive_dns_ttl
6287 LOC: Config.positiveDnsTtl
6290 Upper limit on how long Squid will cache positive DNS responses.
6291 Default is 6 hours (360 minutes). This directive must be set
6292 larger than negative_dns_ttl.
6295 NAME: negative_dns_ttl
6298 LOC: Config.negativeDnsTtl
6301 Time-to-Live (TTL) for negative caching of failed DNS lookups.
6302 This also sets the lower cache limit on positive lookups.
6303 Minimum value is 1 second, and it is not recommendable to go
6304 much below 10 seconds.
6307 NAME: range_offset_limit
6308 COMMENT: size [acl acl...]
6310 LOC: Config.rangeOffsetLimit
6313 usage: (size) [units] [[!]aclname]
6315 Sets an upper limit on how far (number of bytes) into the file
6316 a Range request may be to cause Squid to prefetch the whole file.
6317 If beyond this limit, Squid forwards the Range request as it is and
6318 the result is NOT cached.
6320 This is to stop a far ahead range request (lets say start at 17MB)
6321 from making Squid fetch the whole object up to that point before
6322 sending anything to the client.
6324 Multiple range_offset_limit lines may be specified, and they will
6325 be searched from top to bottom on each request until a match is found.
6326 The first match found will be used. If no line matches a request, the
6327 default limit of 0 bytes will be used.
6329 'size' is the limit specified as a number of units.
6331 'units' specifies whether to use bytes, KB, MB, etc.
6332 If no units are specified bytes are assumed.
6334 A size of 0 causes Squid to never fetch more than the
6335 client requested. (default)
6337 A size of 'none' causes Squid to always fetch the object from the
6338 beginning so it may cache the result. (2.0 style)
6340 'aclname' is the name of a defined ACL.
6342 NP: Using 'none' as the byte value here will override any quick_abort settings
6343 that may otherwise apply to the range request. The range request will
6344 be fully fetched from start to finish regardless of the client
6345 actions. This affects bandwidth usage.
6348 NAME: minimum_expiry_time
6351 LOC: Config.minimum_expiry_time
6354 The minimum caching time according to (Expires - Date)
6355 headers Squid honors if the object can't be revalidated.
6356 The default is 60 seconds.
6358 In reverse proxy environments it might be desirable to honor
6359 shorter object lifetimes. It is most likely better to make
6360 your server return a meaningful Last-Modified header however.
6362 In ESI environments where page fragments often have short
6363 lifetimes, this will often be best set to 0.
6366 NAME: store_avg_object_size
6370 LOC: Config.Store.avgObjectSize
6372 Average object size, used to estimate number of objects your
6373 cache can hold. The default is 13 KB.
6375 This is used to pre-seed the cache index memory allocation to
6376 reduce expensive reallocate operations while handling clients
6377 traffic. Too-large values may result in memory allocation during
6378 peak traffic, too-small values will result in wasted memory.
6380 Check the cache manager 'info' report metrics for the real
6381 object sizes seen by your Squid before tuning this.
6384 NAME: store_objects_per_bucket
6387 LOC: Config.Store.objectsPerBucket
6389 Target number of objects per bucket in the store hash table.
6390 Lowering this value increases the total number of buckets and
6391 also the storage maintenance rate. The default is 20.
6396 -----------------------------------------------------------------------------
6399 NAME: request_header_max_size
6403 LOC: Config.maxRequestHeaderSize
6405 This specifies the maximum size for HTTP headers in a request.
6406 Request headers are usually relatively small (about 512 bytes).
6407 Placing a limit on the request header size will catch certain
6408 bugs (for example with persistent connections) and possibly
6409 buffer-overflow or denial-of-service attacks.
6412 NAME: reply_header_max_size
6416 LOC: Config.maxReplyHeaderSize
6418 This specifies the maximum size for HTTP headers in a reply.
6419 Reply headers are usually relatively small (about 512 bytes).
6420 Placing a limit on the reply header size will catch certain
6421 bugs (for example with persistent connections) and possibly
6422 buffer-overflow or denial-of-service attacks.
6425 NAME: request_body_max_size
6429 DEFAULT_DOC: No limit.
6430 LOC: Config.maxRequestBodySize
6432 This specifies the maximum size for an HTTP request body.
6433 In other words, the maximum size of a PUT/POST request.
6434 A user who attempts to send a request with a body larger
6435 than this limit receives an "Invalid Request" error message.
6436 If you set this parameter to a zero (the default), there will
6437 be no limit imposed.
6439 See also client_request_buffer_max_size for an alternative
6440 limitation on client uploads which can be configured.
6443 NAME: client_request_buffer_max_size
6447 LOC: Config.maxRequestBufferSize
6449 This specifies the maximum buffer size of a client request.
6450 It prevents squid eating too much memory when somebody uploads
6455 IFDEF: USE_HTTP_VIOLATIONS
6458 DEFAULT_DOC: Obey RFC 2616.
6459 LOC: Config.accessList.brokenPosts
6461 A list of ACL elements which, if matched, causes Squid to send
6462 an extra CRLF pair after the body of a PUT/POST request.
6464 Some HTTP servers has broken implementations of PUT/POST,
6465 and rely on an extra CRLF pair sent by some WWW clients.
6467 Quote from RFC2616 section 4.1 on this matter:
6469 Note: certain buggy HTTP/1.0 client implementations generate an
6470 extra CRLF's after a POST request. To restate what is explicitly
6471 forbidden by the BNF, an HTTP/1.1 client must not preface or follow
6472 a request with an extra CRLF.
6474 This clause only supports fast acl types.
6475 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
6478 acl buggy_server url_regex ^http://....
6479 broken_posts allow buggy_server
6482 NAME: adaptation_uses_indirect_client icap_uses_indirect_client
6485 IFDEF: FOLLOW_X_FORWARDED_FOR&&USE_ADAPTATION
6487 LOC: Adaptation::Config::use_indirect_client
6489 Controls whether the indirect client IP address (instead of the direct
6490 client IP address) is passed to adaptation services.
6492 See also: follow_x_forwarded_for adaptation_send_client_ip
6496 IFDEF: USE_HTTP_VIOLATIONS
6500 LOC: Config.onoff.via
6502 If set (default), Squid will include a Via header in requests and
6503 replies as required by RFC2616.
6506 NAME: vary_ignore_expire
6509 LOC: Config.onoff.vary_ignore_expire
6512 Many HTTP servers supporting Vary gives such objects
6513 immediate expiry time with no cache-control header
6514 when requested by a HTTP/1.0 client. This option
6515 enables Squid to ignore such expiry times until
6516 HTTP/1.1 is fully implemented.
6518 WARNING: If turned on this may eventually cause some
6519 varying objects not intended for caching to get cached.
6522 NAME: request_entities
6524 LOC: Config.onoff.request_entities
6527 Squid defaults to deny GET and HEAD requests with request entities,
6528 as the meaning of such requests are undefined in the HTTP standard
6529 even if not explicitly forbidden.
6531 Set this directive to on if you have clients which insists
6532 on sending request entities in GET or HEAD requests. But be warned
6533 that there is server software (both proxies and web servers) which
6534 can fail to properly process this kind of request which may make you
6535 vulnerable to cache pollution attacks if enabled.
6538 NAME: request_header_access
6539 IFDEF: USE_HTTP_VIOLATIONS
6540 TYPE: http_header_access
6541 LOC: Config.request_header_access
6543 DEFAULT_DOC: No limits.
6545 Usage: request_header_access header_name allow|deny [!]aclname ...
6547 WARNING: Doing this VIOLATES the HTTP standard. Enabling
6548 this feature could make you liable for problems which it
6551 This option replaces the old 'anonymize_headers' and the
6552 older 'http_anonymizer' option with something that is much
6553 more configurable. A list of ACLs for each header name allows
6554 removal of specific header fields under specific conditions.
6556 This option only applies to outgoing HTTP request headers (i.e.,
6557 headers sent by Squid to the next HTTP hop such as a cache peer
6558 or an origin server). The option has no effect during cache hit
6559 detection. The equivalent adaptation vectoring point in ICAP
6560 terminology is post-cache REQMOD.
6562 The option is applied to individual outgoing request header
6563 fields. For each request header field F, Squid uses the first
6564 qualifying sets of request_header_access rules:
6566 1. Rules with header_name equal to F's name.
6567 2. Rules with header_name 'Other', provided F's name is not
6568 on the hard-coded list of commonly used HTTP header names.
6569 3. Rules with header_name 'All'.
6571 Within that qualifying rule set, rule ACLs are checked as usual.
6572 If ACLs of an "allow" rule match, the header field is allowed to
6573 go through as is. If ACLs of a "deny" rule match, the header is
6574 removed and request_header_replace is then checked to identify
6575 if the removed header has a replacement. If no rules within the
6576 set have matching ACLs, the header field is left as is.
6578 For example, to achieve the same behavior as the old
6579 'http_anonymizer standard' option, you should use:
6581 request_header_access From deny all
6582 request_header_access Referer deny all
6583 request_header_access User-Agent deny all
6585 Or, to reproduce the old 'http_anonymizer paranoid' feature
6588 request_header_access Authorization allow all
6589 request_header_access Proxy-Authorization allow all
6590 request_header_access Cache-Control allow all
6591 request_header_access Content-Length allow all
6592 request_header_access Content-Type allow all
6593 request_header_access Date allow all
6594 request_header_access Host allow all
6595 request_header_access If-Modified-Since allow all
6596 request_header_access Pragma allow all
6597 request_header_access Accept allow all
6598 request_header_access Accept-Charset allow all
6599 request_header_access Accept-Encoding allow all
6600 request_header_access Accept-Language allow all
6601 request_header_access Connection allow all
6602 request_header_access All deny all
6604 HTTP reply headers are controlled with the reply_header_access directive.
6606 By default, all headers are allowed (no anonymizing is performed).
6609 NAME: reply_header_access
6610 IFDEF: USE_HTTP_VIOLATIONS
6611 TYPE: http_header_access
6612 LOC: Config.reply_header_access
6614 DEFAULT_DOC: No limits.
6616 Usage: reply_header_access header_name allow|deny [!]aclname ...
6618 WARNING: Doing this VIOLATES the HTTP standard. Enabling
6619 this feature could make you liable for problems which it
6622 This option only applies to reply headers, i.e., from the
6623 server to the client.
6625 This is the same as request_header_access, but in the other
6626 direction. Please see request_header_access for detailed
6629 For example, to achieve the same behavior as the old
6630 'http_anonymizer standard' option, you should use:
6632 reply_header_access Server deny all
6633 reply_header_access WWW-Authenticate deny all
6634 reply_header_access Link deny all
6636 Or, to reproduce the old 'http_anonymizer paranoid' feature
6639 reply_header_access Allow allow all
6640 reply_header_access WWW-Authenticate allow all
6641 reply_header_access Proxy-Authenticate allow all
6642 reply_header_access Cache-Control allow all
6643 reply_header_access Content-Encoding allow all
6644 reply_header_access Content-Length allow all
6645 reply_header_access Content-Type allow all
6646 reply_header_access Date allow all
6647 reply_header_access Expires allow all
6648 reply_header_access Last-Modified allow all
6649 reply_header_access Location allow all
6650 reply_header_access Pragma allow all
6651 reply_header_access Content-Language allow all
6652 reply_header_access Retry-After allow all
6653 reply_header_access Title allow all
6654 reply_header_access Content-Disposition allow all
6655 reply_header_access Connection allow all
6656 reply_header_access All deny all
6658 HTTP request headers are controlled with the request_header_access directive.
6660 By default, all headers are allowed (no anonymizing is
6664 NAME: request_header_replace header_replace
6665 IFDEF: USE_HTTP_VIOLATIONS
6666 TYPE: http_header_replace
6667 LOC: Config.request_header_access
6670 Usage: request_header_replace header_name message
6671 Example: request_header_replace User-Agent Nutscrape/1.0 (CP/M; 8-bit)
6673 This option allows you to change the contents of headers
6674 denied with request_header_access above, by replacing them
6675 with some fixed string.
6677 This only applies to request headers, not reply headers.
6679 By default, headers are removed if denied.
6682 NAME: reply_header_replace
6683 IFDEF: USE_HTTP_VIOLATIONS
6684 TYPE: http_header_replace
6685 LOC: Config.reply_header_access
6688 Usage: reply_header_replace header_name message
6689 Example: reply_header_replace Server Foo/1.0
6691 This option allows you to change the contents of headers
6692 denied with reply_header_access above, by replacing them
6693 with some fixed string.
6695 This only applies to reply headers, not request headers.
6697 By default, headers are removed if denied.
6700 NAME: request_header_add
6701 TYPE: HeaderWithAclList
6702 LOC: Config.request_header_add
6705 Usage: request_header_add field-name field-value [ acl ... ]
6706 Example: request_header_add X-Client-CA "CA=%ssl::>cert_issuer" all
6708 This option adds header fields to outgoing HTTP requests (i.e.,
6709 request headers sent by Squid to the next HTTP hop such as a
6710 cache peer or an origin server). The option has no effect during
6711 cache hit detection. The equivalent adaptation vectoring point
6712 in ICAP terminology is post-cache REQMOD.
6714 Field-name is a token specifying an HTTP header name. If a
6715 standard HTTP header name is used, Squid does not check whether
6716 the new header conflicts with any existing headers or violates
6717 HTTP rules. If the request to be modified already contains a
6718 field with the same name, the old field is preserved but the
6719 header field values are not merged.
6721 Field-value is either a token or a quoted string. If quoted
6722 string format is used, then the surrounding quotes are removed
6723 while escape sequences and %macros are processed.
6725 One or more Squid ACLs may be specified to restrict header
6726 injection to matching requests. As always in squid.conf, all
6727 ACLs in the ACL list must be satisfied for the insertion to
6728 happen. The request_header_add supports fast ACLs only.
6730 See also: reply_header_add.
6733 NAME: reply_header_add
6734 TYPE: HeaderWithAclList
6735 LOC: Config.reply_header_add
6738 Usage: reply_header_add field-name field-value [ acl ... ]
6739 Example: reply_header_add X-Client-CA "CA=%ssl::>cert_issuer" all
6741 This option adds header fields to outgoing HTTP responses (i.e., response
6742 headers delivered by Squid to the client). This option has no effect on
6743 cache hit detection. The equivalent adaptation vectoring point in
6744 ICAP terminology is post-cache RESPMOD. This option does not apply to
6745 successful CONNECT replies.
6747 Field-name is a token specifying an HTTP header name. If a
6748 standard HTTP header name is used, Squid does not check whether
6749 the new header conflicts with any existing headers or violates
6750 HTTP rules. If the response to be modified already contains a
6751 field with the same name, the old field is preserved but the
6752 header field values are not merged.
6754 Field-value is either a token or a quoted string. If quoted
6755 string format is used, then the surrounding quotes are removed
6756 while escape sequences and %macros are processed.
6758 One or more Squid ACLs may be specified to restrict header
6759 injection to matching responses. As always in squid.conf, all
6760 ACLs in the ACL list must be satisfied for the insertion to
6761 happen. The reply_header_add option supports fast ACLs only.
6763 See also: request_header_add.
6771 This option used to log custom information about the master
6772 transaction. For example, an admin may configure Squid to log
6773 which "user group" the transaction belongs to, where "user group"
6774 will be determined based on a set of ACLs and not [just]
6775 authentication information.
6776 Values of key/value pairs can be logged using %{key}note macros:
6778 note key value acl ...
6779 logformat myFormat ... %{key}note ...
6782 NAME: relaxed_header_parser
6783 COMMENT: on|off|warn
6785 LOC: Config.onoff.relaxed_header_parser
6788 In the default "on" setting Squid accepts certain forms
6789 of non-compliant HTTP messages where it is unambiguous
6790 what the sending application intended even if the message
6791 is not correctly formatted. The messages is then normalized
6792 to the correct form when forwarded by Squid.
6794 If set to "warn" then a warning will be emitted in cache.log
6795 each time such HTTP error is encountered.
6797 If set to "off" then such HTTP errors will cause the request
6798 or response to be rejected.
6801 NAME: collapsed_forwarding
6804 LOC: Config.onoff.collapsed_forwarding
6807 This option controls whether Squid is allowed to merge multiple
6808 potentially cachable requests for the same URI before Squid knows
6809 whether the response is going to be cachable.
6811 When enabled, instead of forwarding each concurrent request for
6812 the same URL, Squid just sends the first of them. The other, so
6813 called "collapsed" requests, wait for the response to the first
6814 request and, if it happens to be cachable, use that response.
6815 Here, "concurrent requests" means "received after the first
6816 request headers were parsed and before the corresponding response
6817 headers were parsed".
6819 This feature is disabled by default: enabling collapsed
6820 forwarding needlessly delays forwarding requests that look
6821 cachable (when they are collapsed) but then need to be forwarded
6822 individually anyway because they end up being for uncachable
6823 content. However, in some cases, such as acceleration of highly
6824 cachable content with periodic or grouped expiration times, the
6825 gains from collapsing [large volumes of simultaneous refresh
6826 requests] outweigh losses from such delays.
6828 Squid collapses two kinds of requests: regular client requests
6829 received on one of the listening ports and internal "cache
6830 revalidation" requests which are triggered by those regular
6831 requests hitting a stale cached object. Revalidation collapsing
6832 is currently disabled for Squid instances containing SMP-aware
6833 disk or memory caches and for Vary-controlled cached objects.
6836 NAME: collapsed_forwarding_access
6839 DEFAULT_DOC: Requests may be collapsed if collapsed_forwarding is on.
6840 LOC: Config.accessList.collapsedForwardingAccess
6842 Use this directive to restrict collapsed forwarding to a subset of
6843 eligible requests. The directive is checked for regular HTTP
6844 requests, internal revalidation requests, and HTCP/ICP requests.
6846 collapsed_forwarding_access allow|deny [!]aclname ...
6848 This directive cannot force collapsing. It has no effect on
6849 collapsing unless collapsed_forwarding is 'on', and all other
6850 collapsing preconditions are satisfied.
6852 * A denied request will not collapse, and future transactions will
6853 not collapse on it (even if they are allowed to collapse).
6855 * An allowed request may collapse, or future transactions may
6856 collapse on it (provided they are allowed to collapse).
6858 This directive is evaluated before receiving HTTP response headers
6859 and without access to Squid-to-peer connection (if any).
6861 Only fast ACLs are supported.
6863 See also: collapsed_forwarding.
6866 NAME: shared_transient_entries_limit collapsed_forwarding_shared_entries_limit
6867 COMMENT: (number of entries)
6869 LOC: Config.shared_transient_entries_limit
6872 This directive limits the size of a table used for sharing current
6873 transaction information among SMP workers. A table entry stores meta
6874 information about a single cache entry being delivered to Squid
6875 client(s) by one or more SMP workers. A single table entry consumes
6876 less than 128 shared memory bytes.
6878 The limit should be significantly larger than the number of
6879 concurrent non-collapsed cachable responses leaving Squid. For a
6880 cache that handles less than 5000 concurrent requests, the default
6881 setting of 16384 should be plenty.
6883 Using excessively large values wastes shared memory. Limiting the
6884 table size too much results in hash collisions, leading to lower hit
6885 ratio and missed SMP request collapsing opportunities: Transactions
6886 left without a table entry cannot cache their responses and are
6887 invisible to other concurrent requests for the same resource.
6889 A zero limit is allowed but unsupported. A positive small limit
6890 lowers hit ratio, but zero limit disables a lot of essential
6891 synchronization among SMP workers, leading to HTTP violations (e.g.,
6892 stale hit responses). It also disables shared collapsed forwarding:
6893 A worker becomes unable to collapse its requests on transactions in
6894 other workers, resulting in more trips to the origin server and more
6900 -----------------------------------------------------------------------------
6903 NAME: forward_timeout
6906 LOC: Config.Timeout.forward
6909 This parameter specifies how long Squid should at most attempt in
6910 finding a forwarding path for the request before giving up.
6913 NAME: connect_timeout
6916 LOC: Config.Timeout.connect
6919 This parameter specifies how long to wait for the TCP connect to
6920 the requested server or peer to complete before Squid should
6921 attempt to find another path where to forward the request.
6924 NAME: peer_connect_timeout
6927 LOC: Config.Timeout.peer_connect
6930 This parameter specifies how long to wait for a pending TCP
6931 connection to a peer cache. The default is 30 seconds. You
6932 may also set different timeout values for individual neighbors
6933 with the 'connect-timeout' option on a 'cache_peer' line.
6939 LOC: Config.Timeout.read
6942 Applied on peer server connections.
6944 After each successful read(), the timeout will be extended by this
6945 amount. If no data is read again after this amount of time,
6946 the request is aborted and logged with ERR_READ_TIMEOUT.
6948 The default is 15 minutes.
6954 LOC: Config.Timeout.write
6957 This timeout is tracked for all connections that have data
6958 available for writing and are waiting for the socket to become
6959 ready. After each successful write, the timeout is extended by
6960 the configured amount. If Squid has data to write but the
6961 connection is not ready for the configured duration, the
6962 transaction associated with the connection is terminated. The
6963 default is 15 minutes.
6966 NAME: request_timeout
6968 LOC: Config.Timeout.request
6971 How long to wait for complete HTTP request headers after initial
6972 connection establishment.
6975 NAME: request_start_timeout
6977 LOC: Config.Timeout.request_start_timeout
6980 How long to wait for the first request byte after initial
6981 connection establishment.
6984 NAME: client_idle_pconn_timeout persistent_request_timeout
6986 LOC: Config.Timeout.clientIdlePconn
6989 How long to wait for the next HTTP request on a persistent
6990 client connection after the previous request completes.
6993 NAME: ftp_client_idle_timeout
6995 LOC: Config.Timeout.ftpClientIdle
6998 How long to wait for an FTP request on a connection to Squid ftp_port.
6999 Many FTP clients do not deal with idle connection closures well,
7000 necessitating a longer default timeout than client_idle_pconn_timeout
7001 used for incoming HTTP requests.
7004 NAME: client_lifetime
7007 LOC: Config.Timeout.lifetime
7010 The maximum amount of time a client (browser) is allowed to
7011 remain connected to the cache process. This protects the Cache
7012 from having a lot of sockets (and hence file descriptors) tied up
7013 in a CLOSE_WAIT state from remote clients that go away without
7014 properly shutting down (either because of a network failure or
7015 because of a poor client implementation). The default is one
7018 NOTE: The default value is intended to be much larger than any
7019 client would ever need to be connected to your cache. You
7020 should probably change client_lifetime only as a last resort.
7021 If you seem to have many client connections tying up
7022 filedescriptors, we recommend first tuning the read_timeout,
7023 request_timeout, persistent_request_timeout and quick_abort values.
7026 NAME: pconn_lifetime
7029 LOC: Config.Timeout.pconnLifetime
7032 Desired maximum lifetime of a persistent connection.
7033 When set, Squid will close a now-idle persistent connection that
7034 exceeded configured lifetime instead of moving the connection into
7035 the idle connection pool (or equivalent). No effect on ongoing/active
7036 transactions. Connection lifetime is the time period from the
7037 connection acceptance or opening time until "now".
7039 This limit is useful in environments with long-lived connections
7040 where Squid configuration or environmental factors change during a
7041 single connection lifetime. If unrestricted, some connections may
7042 last for hours and even days, ignoring those changes that should
7043 have affected their behavior or their existence.
7045 Currently, a new lifetime value supplied via Squid reconfiguration
7046 has no effect on already idle connections unless they become busy.
7048 When set to '0' this limit is not used.
7051 NAME: half_closed_clients
7053 LOC: Config.onoff.half_closed_clients
7056 Some clients may shutdown the sending side of their TCP
7057 connections, while leaving their receiving sides open. Sometimes,
7058 Squid can not tell the difference between a half-closed and a
7059 fully-closed TCP connection.
7061 By default, Squid will immediately close client connections when
7062 read(2) returns "no more data to read."
7064 Change this option to 'on' and Squid will keep open connections
7065 until a read(2) or write(2) on the socket returns an error.
7066 This may show some benefits for reverse proxies. But if not
7067 it is recommended to leave OFF.
7070 NAME: server_idle_pconn_timeout pconn_timeout
7072 LOC: Config.Timeout.serverIdlePconn
7075 Timeout for idle persistent connections to servers and other
7082 LOC: Ident::TheConfig.timeout
7085 Maximum time to wait for IDENT lookups to complete.
7087 If this is too high, and you enabled IDENT lookups from untrusted
7088 users, you might be susceptible to denial-of-service by having
7089 many ident requests going at once.
7092 NAME: shutdown_lifetime
7095 LOC: Config.shutdownLifetime
7098 When SIGTERM or SIGHUP is received, the cache is put into
7099 "shutdown pending" mode until all active sockets are closed.
7100 This value is the lifetime to set for all open descriptors
7101 during shutdown mode. Any active clients after this many
7102 seconds will receive a 'timeout' message.
7106 ADMINISTRATIVE PARAMETERS
7107 -----------------------------------------------------------------------------
7113 LOC: Config.adminEmail
7115 Email-address of local cache manager who will receive
7116 mail if the cache dies. The default is "webmaster".
7122 LOC: Config.EmailFrom
7124 From: email-address for mail sent when the cache dies.
7125 The default is to use 'squid@unique_hostname'.
7127 See also: unique_hostname directive.
7133 LOC: Config.EmailProgram
7135 Email program used to send mail if the cache dies.
7136 The default is "mail". The specified program must comply
7137 with the standard Unix mail syntax:
7138 mail-program recipient < mailfile
7140 Optional command line options can be specified.
7143 NAME: cache_effective_user
7145 DEFAULT: @DEFAULT_CACHE_EFFECTIVE_USER@
7146 LOC: Config.effectiveUser
7148 If you start Squid as root, it will change its effective/real
7149 UID/GID to the user specified below. The default is to change
7150 to UID of @DEFAULT_CACHE_EFFECTIVE_USER@.
7151 see also; cache_effective_group
7154 NAME: cache_effective_group
7157 DEFAULT_DOC: Use system group memberships of the cache_effective_user account
7158 LOC: Config.effectiveGroup
7160 Squid sets the GID to the effective user's default group ID
7161 (taken from the password file) and supplementary group list
7162 from the groups membership.
7164 If you want Squid to run with a specific GID regardless of
7165 the group memberships of the effective user then set this
7166 to the group (or GID) you want Squid to run as. When set
7167 all other group privileges of the effective user are ignored
7168 and only this GID is effective. If Squid is not started as
7169 root the user starting Squid MUST be member of the specified
7172 This option is not recommended by the Squid Team.
7173 Our preference is for administrators to configure a secure
7174 user account for squid with UID/GID matching system policies.
7177 NAME: httpd_suppress_version_string
7181 LOC: Config.onoff.httpd_suppress_version_string
7183 Suppress Squid version string info in HTTP headers and HTML error pages.
7186 NAME: visible_hostname
7188 LOC: Config.visibleHostname
7190 DEFAULT_DOC: Automatically detect the system host name
7192 If you want to present a special hostname in error messages, etc,
7193 define this. Otherwise, the return value of gethostname()
7194 will be used. If you have multiple caches in a cluster and
7195 get errors about IP-forwarding you must set them to have individual
7196 names with this setting.
7199 NAME: unique_hostname
7201 LOC: Config.uniqueHostname
7203 DEFAULT_DOC: Copy the value from visible_hostname
7205 If you want to have multiple machines with the same
7206 'visible_hostname' you must give each machine a different
7207 'unique_hostname' so forwarding loops can be detected.
7210 NAME: hostname_aliases
7212 LOC: Config.hostnameAliases
7215 A list of other DNS names your cache has.
7223 Minimum umask which should be enforced while the proxy
7224 is running, in addition to the umask set at startup.
7226 For a traditional octal representation of umasks, start
7231 OPTIONS FOR THE CACHE REGISTRATION SERVICE
7232 -----------------------------------------------------------------------------
7234 This section contains parameters for the (optional) cache
7235 announcement service. This service is provided to help
7236 cache administrators locate one another in order to join or
7237 create cache hierarchies.
7239 An 'announcement' message is sent (via UDP) to the registration
7240 service by Squid. By default, the announcement message is NOT
7241 SENT unless you enable it with 'announce_period' below.
7243 The announcement message includes your hostname, plus the
7244 following information from this configuration file:
7250 All current information is processed regularly and made
7251 available on the Web at http://www.ircache.net/Cache/Tracker/.
7254 NAME: announce_period
7256 LOC: Config.Announce.period
7258 DEFAULT_DOC: Announcement messages disabled.
7260 This is how frequently to send cache announcements.
7262 To enable announcing your cache, just set an announce period.
7265 announce_period 1 day
7270 DEFAULT: tracker.ircache.net
7271 LOC: Config.Announce.host
7273 Set the hostname where announce registration messages will be sent.
7275 See also announce_port and announce_file
7281 LOC: Config.Announce.file
7283 The contents of this file will be included in the announce
7284 registration messages.
7290 LOC: Config.Announce.port
7292 Set the port where announce registration messages will be sent.
7294 See also announce_host and announce_file
7298 HTTPD-ACCELERATOR OPTIONS
7299 -----------------------------------------------------------------------------
7302 NAME: httpd_accel_surrogate_id
7305 DEFAULT_DOC: visible_hostname is used if no specific ID is set.
7306 LOC: Config.Accel.surrogate_id
7308 Surrogates (http://www.esi.org/architecture_spec_1.0.html)
7309 need an identification token to allow control targeting. Because
7310 a farm of surrogates may all perform the same tasks, they may share
7311 an identification token.
7313 When the surrogate is a reverse-proxy, this ID is also
7314 used as cdn-id for CDN-Loop detection (RFC 8586).
7317 NAME: http_accel_surrogate_remote
7321 LOC: Config.onoff.surrogate_is_remote
7323 Remote surrogates (such as those in a CDN) honour the header
7324 "Surrogate-Control: no-store-remote".
7326 Set this to on to have squid behave as a remote surrogate.
7330 IFDEF: USE_SQUID_ESI
7331 COMMENT: libxml2|expat
7333 LOC: ESIParser::Type
7335 DEFAULT_DOC: Selects libxml2 if available at ./configure time or libexpat otherwise.
7337 Selects the XML parsing library to use when interpreting responses with
7340 To disable ESI handling completely, ./configure Squid with --disable-esi.
7344 DELAY POOL PARAMETERS
7345 -----------------------------------------------------------------------------
7349 TYPE: delay_pool_count
7351 IFDEF: USE_DELAY_POOLS
7354 This represents the number of delay pools to be used. For example,
7355 if you have one class 2 delay pool and one class 3 delays pool, you
7356 have a total of 2 delay pools.
7358 See also delay_parameters, delay_class, delay_access for pool
7359 configuration details.
7363 TYPE: delay_pool_class
7365 IFDEF: USE_DELAY_POOLS
7368 This defines the class of each delay pool. There must be exactly one
7369 delay_class line for each delay pool. For example, to define two
7370 delay pools, one of class 2 and one of class 3, the settings above
7374 delay_pools 4 # 4 delay pools
7375 delay_class 1 2 # pool 1 is a class 2 pool
7376 delay_class 2 3 # pool 2 is a class 3 pool
7377 delay_class 3 4 # pool 3 is a class 4 pool
7378 delay_class 4 5 # pool 4 is a class 5 pool
7380 The delay pool classes are:
7382 class 1 Everything is limited by a single aggregate
7385 class 2 Everything is limited by a single aggregate
7386 bucket as well as an "individual" bucket chosen
7387 from bits 25 through 32 of the IPv4 address.
7389 class 3 Everything is limited by a single aggregate
7390 bucket as well as a "network" bucket chosen
7391 from bits 17 through 24 of the IP address and a
7392 "individual" bucket chosen from bits 17 through
7393 32 of the IPv4 address.
7395 class 4 Everything in a class 3 delay pool, with an
7396 additional limit on a per user basis. This
7397 only takes effect if the username is established
7398 in advance - by forcing authentication in your
7401 class 5 Requests are grouped according their tag (see
7402 external_acl's tag= reply).
7405 Each pool also requires a delay_parameters directive to configure the pool size
7406 and speed limits used whenever the pool is applied to a request. Along with
7407 a set of delay_access directives to determine when it is used.
7409 NOTE: If an IP address is a.b.c.d
7410 -> bits 25 through 32 are "d"
7411 -> bits 17 through 24 are "c"
7412 -> bits 17 through 32 are "c * 256 + d"
7414 NOTE-2: Due to the use of bitmasks in class 2,3,4 pools they only apply to
7415 IPv4 traffic. Class 1 and 5 pools may be used with IPv6 traffic.
7417 This clause only supports fast acl types.
7418 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
7420 See also delay_parameters and delay_access.
7424 TYPE: delay_pool_access
7426 DEFAULT_DOC: Deny using the pool, unless allow rules exist in squid.conf for the pool.
7427 IFDEF: USE_DELAY_POOLS
7430 This is used to determine which delay pool a request falls into.
7432 delay_access is sorted per pool and the matching starts with pool 1,
7433 then pool 2, ..., and finally pool N. The first delay pool where the
7434 request is allowed is selected for the request. If it does not allow
7435 the request to any pool then the request is not delayed (default).
7437 For example, if you want some_big_clients in delay
7438 pool 1 and lotsa_little_clients in delay pool 2:
7440 delay_access 1 allow some_big_clients
7441 delay_access 1 deny all
7442 delay_access 2 allow lotsa_little_clients
7443 delay_access 2 deny all
7444 delay_access 3 allow authenticated_clients
7446 See also delay_parameters and delay_class.
7450 NAME: delay_parameters
7451 TYPE: delay_pool_rates
7453 IFDEF: USE_DELAY_POOLS
7456 This defines the parameters for a delay pool. Each delay pool has
7457 a number of "buckets" associated with it, as explained in the
7458 description of delay_class.
7460 For a class 1 delay pool, the syntax is:
7462 delay_parameters pool aggregate
7464 For a class 2 delay pool:
7466 delay_parameters pool aggregate individual
7468 For a class 3 delay pool:
7470 delay_parameters pool aggregate network individual
7472 For a class 4 delay pool:
7474 delay_parameters pool aggregate network individual user
7476 For a class 5 delay pool:
7478 delay_parameters pool tagrate
7480 The option variables are:
7482 pool a pool number - ie, a number between 1 and the
7483 number specified in delay_pools as used in
7486 aggregate the speed limit parameters for the aggregate bucket
7489 individual the speed limit parameters for the individual
7490 buckets (class 2, 3).
7492 network the speed limit parameters for the network buckets
7495 user the speed limit parameters for the user buckets
7498 tagrate the speed limit parameters for the tag buckets
7501 A pair of delay parameters is written restore/maximum, where restore is
7502 the number of bytes (not bits - modem and network speeds are usually
7503 quoted in bits) per second placed into the bucket, and maximum is the
7504 maximum number of bytes which can be in the bucket at any time.
7506 There must be one delay_parameters line for each delay pool.
7509 For example, if delay pool number 1 is a class 2 delay pool as in the
7510 above example, and is being used to strictly limit each host to 64Kbit/sec
7511 (plus overheads), with no overall limit, the line is:
7513 delay_parameters 1 none 8000/8000
7515 Note that 8 x 8K Byte/sec -> 64K bit/sec.
7517 Note that the word 'none' is used to represent no limit.
7520 And, if delay pool number 2 is a class 3 delay pool as in the above
7521 example, and you want to limit it to a total of 256Kbit/sec (strict limit)
7522 with each 8-bit network permitted 64Kbit/sec (strict limit) and each
7523 individual host permitted 4800bit/sec with a bucket maximum size of 64Kbits
7524 to permit a decent web page to be downloaded at a decent speed
7525 (if the network is not being limited due to overuse) but slow down
7526 large downloads more significantly:
7528 delay_parameters 2 32000/32000 8000/8000 600/8000
7530 Note that 8 x 32K Byte/sec -> 256K bit/sec.
7531 8 x 8K Byte/sec -> 64K bit/sec.
7532 8 x 600 Byte/sec -> 4800 bit/sec.
7535 Finally, for a class 4 delay pool as in the example - each user will
7536 be limited to 128Kbits/sec no matter how many workstations they are logged into.:
7538 delay_parameters 4 32000/32000 8000/8000 600/64000 16000/16000
7541 See also delay_class and delay_access.
7545 NAME: delay_initial_bucket_level
7546 COMMENT: (percent, 0-100)
7549 IFDEF: USE_DELAY_POOLS
7550 LOC: Config.Delay.initial
7552 The initial bucket percentage is used to determine how much is put
7553 in each bucket when squid starts, is reconfigured, or first notices
7554 a host accessing it (in class 2 and class 3, individual hosts and
7555 networks only have buckets associated with them once they have been
7560 CLIENT DELAY POOL PARAMETERS
7561 -----------------------------------------------------------------------------
7564 NAME: client_delay_pools
7565 TYPE: client_delay_pool_count
7567 IFDEF: USE_DELAY_POOLS
7568 LOC: Config.ClientDelay
7570 This option specifies the number of client delay pools used. It must
7571 preceed other client_delay_* options.
7574 client_delay_pools 2
7576 See also client_delay_parameters and client_delay_access.
7579 NAME: client_delay_initial_bucket_level
7580 COMMENT: (percent, 0-no_limit)
7583 IFDEF: USE_DELAY_POOLS
7584 LOC: Config.ClientDelay.initial
7586 This option determines the initial bucket size as a percentage of
7587 max_bucket_size from client_delay_parameters. Buckets are created
7588 at the time of the "first" connection from the matching IP. Idle
7589 buckets are periodically deleted up.
7591 You can specify more than 100 percent but note that such "oversized"
7592 buckets are not refilled until their size goes down to max_bucket_size
7593 from client_delay_parameters.
7596 client_delay_initial_bucket_level 50
7599 NAME: client_delay_parameters
7600 TYPE: client_delay_pool_rates
7602 IFDEF: USE_DELAY_POOLS
7603 LOC: Config.ClientDelay
7606 This option configures client-side bandwidth limits using the
7609 client_delay_parameters pool speed_limit max_bucket_size
7611 pool is an integer ID used for client_delay_access matching.
7613 speed_limit is bytes added to the bucket per second.
7615 max_bucket_size is the maximum size of a bucket, enforced after any
7616 speed_limit additions.
7618 Please see the delay_parameters option for more information and
7622 client_delay_parameters 1 1024 2048
7623 client_delay_parameters 2 51200 16384
7625 See also client_delay_access.
7629 NAME: client_delay_access
7630 TYPE: client_delay_pool_access
7632 DEFAULT_DOC: Deny use of the pool, unless allow rules exist in squid.conf for the pool.
7633 IFDEF: USE_DELAY_POOLS
7634 LOC: Config.ClientDelay
7636 This option determines the client-side delay pool for the
7639 client_delay_access pool_ID allow|deny acl_name
7641 All client_delay_access options are checked in their pool ID
7642 order, starting with pool 1. The first checked pool with allowed
7643 request is selected for the request. If no ACL matches or there
7644 are no client_delay_access options, the request bandwidth is not
7647 The ACL-selected pool is then used to find the
7648 client_delay_parameters for the request. Client-side pools are
7649 not used to aggregate clients. Clients are always aggregated
7650 based on their source IP addresses (one bucket per source IP).
7652 This clause only supports fast acl types.
7653 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
7654 Additionally, only the client TCP connection details are available.
7655 ACLs testing HTTP properties will not work.
7657 Please see delay_access for more examples.
7660 client_delay_access 1 allow low_rate_network
7661 client_delay_access 2 allow vips_network
7664 See also client_delay_parameters and client_delay_pools.
7667 NAME: response_delay_pool
7668 TYPE: response_delay_pool_parameters
7670 IFDEF: USE_DELAY_POOLS
7671 LOC: Config.MessageDelay
7673 This option configures client response bandwidth limits using the
7676 response_delay_pool name [option=value] ...
7678 name the response delay pool name
7682 individual-restore The speed limit of an individual
7683 bucket(bytes/s). To be used in conjunction
7684 with 'individual-maximum'.
7686 individual-maximum The maximum number of bytes which can
7687 be placed into the individual bucket. To be used
7688 in conjunction with 'individual-restore'.
7690 aggregate-restore The speed limit for the aggregate
7691 bucket(bytes/s). To be used in conjunction with
7692 'aggregate-maximum'.
7694 aggregate-maximum The maximum number of bytes which can
7695 be placed into the aggregate bucket. To be used
7696 in conjunction with 'aggregate-restore'.
7698 initial-bucket-level The initial bucket size as a percentage
7699 of individual-maximum.
7701 Individual and(or) aggregate bucket options may not be specified,
7702 meaning no individual and(or) aggregate speed limitation.
7703 See also response_delay_pool_access and delay_parameters for
7704 terminology details.
7707 NAME: response_delay_pool_access
7708 TYPE: response_delay_pool_access
7710 DEFAULT_DOC: Deny use of the pool, unless allow rules exist in squid.conf for the pool.
7711 IFDEF: USE_DELAY_POOLS
7712 LOC: Config.MessageDelay
7714 Determines whether a specific named response delay pool is used
7715 for the transaction. The syntax for this directive is:
7717 response_delay_pool_access pool_name allow|deny acl_name
7719 All response_delay_pool_access options are checked in the order
7720 they appear in this configuration file. The first rule with a
7721 matching ACL wins. If (and only if) an "allow" rule won, Squid
7722 assigns the response to the corresponding named delay pool.
7726 WCCPv1 AND WCCPv2 CONFIGURATION OPTIONS
7727 -----------------------------------------------------------------------------
7732 LOC: Config.Wccp.router
7734 DEFAULT_DOC: WCCP disabled.
7737 Use this option to define your WCCP ``home'' router for
7740 wccp_router supports a single WCCP(v1) router
7742 wccp2_router supports multiple WCCPv2 routers
7744 only one of the two may be used at the same time and defines
7745 which version of WCCP to use.
7749 TYPE: IpAddress_list
7750 LOC: Config.Wccp2.router
7752 DEFAULT_DOC: WCCPv2 disabled.
7755 Use this option to define your WCCP ``home'' router for
7758 wccp_router supports a single WCCP(v1) router
7760 wccp2_router supports multiple WCCPv2 routers
7762 only one of the two may be used at the same time and defines
7763 which version of WCCP to use.
7768 LOC: Config.Wccp.version
7772 This directive is only relevant if you need to set up WCCP(v1)
7773 to some very old and end-of-life Cisco routers. In all other
7774 setups it must be left unset or at the default setting.
7775 It defines an internal version in the WCCP(v1) protocol,
7776 with version 4 being the officially documented protocol.
7778 According to some users, Cisco IOS 11.2 and earlier only
7779 support WCCP version 3. If you're using that or an earlier
7780 version of IOS, you may need to change this value to 3, otherwise
7781 do not specify this parameter.
7784 NAME: wccp2_rebuild_wait
7786 LOC: Config.Wccp2.rebuildwait
7790 If this is enabled Squid will wait for the cache dir rebuild to finish
7791 before sending the first wccp2 HereIAm packet
7794 NAME: wccp2_forwarding_method
7796 LOC: Config.Wccp2.forwarding_method
7800 WCCP2 allows the setting of forwarding methods between the
7801 router/switch and the cache. Valid values are as follows:
7803 gre - GRE encapsulation (forward the packet in a GRE/WCCP tunnel)
7804 l2 - L2 redirect (forward the packet using Layer 2/MAC rewriting)
7806 Currently (as of IOS 12.4) cisco routers only support GRE.
7807 Cisco switches only support the L2 redirect assignment method.
7810 NAME: wccp2_return_method
7812 LOC: Config.Wccp2.return_method
7816 WCCP2 allows the setting of return methods between the
7817 router/switch and the cache for packets that the cache
7818 decides not to handle. Valid values are as follows:
7820 gre - GRE encapsulation (forward the packet in a GRE/WCCP tunnel)
7821 l2 - L2 redirect (forward the packet using Layer 2/MAC rewriting)
7823 Currently (as of IOS 12.4) cisco routers only support GRE.
7824 Cisco switches only support the L2 redirect assignment.
7826 If the "ip wccp redirect exclude in" command has been
7827 enabled on the cache interface, then it is still safe for
7828 the proxy server to use a l2 redirect method even if this
7829 option is set to GRE.
7832 NAME: wccp2_assignment_method
7834 LOC: Config.Wccp2.assignment_method
7838 WCCP2 allows the setting of methods to assign the WCCP hash
7839 Valid values are as follows:
7841 hash - Hash assignment
7842 mask - Mask assignment
7844 As a general rule, cisco routers support the hash assignment method
7845 and cisco switches support the mask assignment method.
7850 LOC: Config.Wccp2.info
7851 DEFAULT_IF_NONE: standard 0
7852 DEFAULT_DOC: Use the 'web-cache' standard service.
7855 WCCP2 allows for multiple traffic services. There are two
7856 types: "standard" and "dynamic". The standard type defines
7857 one service id - http (id 0). The dynamic service ids can be from
7858 51 to 255 inclusive. In order to use a dynamic service id
7859 one must define the type of traffic to be redirected; this is done
7860 using the wccp2_service_info option.
7862 The "standard" type does not require a wccp2_service_info option,
7863 just specifying the service id will suffice.
7865 MD5 service authentication can be enabled by adding
7866 "password=<password>" to the end of this service declaration.
7870 wccp2_service standard 0 # for the 'web-cache' standard service
7871 wccp2_service dynamic 80 # a dynamic service type which will be
7872 # fleshed out with subsequent options.
7873 wccp2_service standard 0 password=foo
7876 NAME: wccp2_service_info
7877 TYPE: wccp2_service_info
7878 LOC: Config.Wccp2.info
7882 Dynamic WCCPv2 services require further information to define the
7883 traffic you wish to have diverted.
7887 wccp2_service_info <id> protocol=<protocol> flags=<flag>,<flag>..
7888 priority=<priority> ports=<port>,<port>..
7890 The relevant WCCPv2 flags:
7891 + src_ip_hash, dst_ip_hash
7892 + source_port_hash, dst_port_hash
7893 + src_ip_alt_hash, dst_ip_alt_hash
7894 + src_port_alt_hash, dst_port_alt_hash
7897 The port list can be one to eight entries.
7901 wccp2_service_info 80 protocol=tcp flags=src_ip_hash,ports_source
7902 priority=240 ports=80
7904 Note: the service id must have been defined by a previous
7905 'wccp2_service dynamic <id>' entry.
7910 LOC: Config.Wccp2.weight
7914 Each cache server gets assigned a set of the destination
7915 hash proportional to their weight.
7920 LOC: Config.Wccp.address
7922 DEFAULT_DOC: Address selected by the operating system.
7925 Use this option if you require WCCPv2 to use a specific
7928 The default behavior is to not bind to any specific address.
7933 LOC: Config.Wccp2.address
7935 DEFAULT_DOC: Address selected by the operating system.
7938 Use this option if you require WCCP to use a specific
7941 The default behavior is to not bind to any specific address.
7945 PERSISTENT CONNECTION HANDLING
7946 -----------------------------------------------------------------------------
7948 Also see "pconn_timeout" in the TIMEOUTS section
7951 NAME: client_persistent_connections
7953 LOC: Config.onoff.client_pconns
7956 Persistent connection support for clients.
7957 Squid uses persistent connections (when allowed). You can use
7958 this option to disable persistent connections with clients.
7961 NAME: server_persistent_connections
7963 LOC: Config.onoff.server_pconns
7966 Persistent connection support for servers.
7967 Squid uses persistent connections (when allowed). You can use
7968 this option to disable persistent connections with servers.
7971 NAME: persistent_connection_after_error
7973 LOC: Config.onoff.error_pconns
7976 With this directive the use of persistent connections after
7977 HTTP errors can be disabled. Useful if you have clients
7978 who fail to handle errors on persistent connections proper.
7981 NAME: detect_broken_pconn
7983 LOC: Config.onoff.detect_broken_server_pconns
7986 Some servers have been found to incorrectly signal the use
7987 of HTTP/1.0 persistent connections even on replies not
7988 compatible, causing significant delays. This server problem
7989 has mostly been seen on redirects.
7991 By enabling this directive Squid attempts to detect such
7992 broken replies and automatically assume the reply is finished
7993 after 10 seconds timeout.
7997 CACHE DIGEST OPTIONS
7998 -----------------------------------------------------------------------------
8001 NAME: digest_generation
8002 IFDEF: USE_CACHE_DIGESTS
8004 LOC: Config.onoff.digest_generation
8007 This controls whether the server will generate a Cache Digest
8008 of its contents. By default, Cache Digest generation is
8009 enabled if Squid is compiled with --enable-cache-digests defined.
8012 NAME: digest_bits_per_entry
8013 IFDEF: USE_CACHE_DIGESTS
8015 LOC: Config.digest.bits_per_entry
8018 This is the number of bits of the server's Cache Digest which
8019 will be associated with the Digest entry for a given HTTP
8020 Method and URL (public key) combination. The default is 5.
8023 NAME: digest_rebuild_period
8024 IFDEF: USE_CACHE_DIGESTS
8027 LOC: Config.digest.rebuild_period
8030 This is the wait time between Cache Digest rebuilds.
8033 NAME: digest_rewrite_period
8035 IFDEF: USE_CACHE_DIGESTS
8037 LOC: Config.digest.rewrite_period
8040 This is the wait time between Cache Digest writes to
8044 NAME: digest_swapout_chunk_size
8047 IFDEF: USE_CACHE_DIGESTS
8048 LOC: Config.digest.swapout_chunk_size
8051 This is the number of bytes of the Cache Digest to write to
8052 disk at a time. It defaults to 4096 bytes (4KB), the Squid
8056 NAME: digest_rebuild_chunk_percentage
8057 COMMENT: (percent, 0-100)
8058 IFDEF: USE_CACHE_DIGESTS
8060 LOC: Config.digest.rebuild_chunk_percentage
8063 This is the percentage of the Cache Digest to be scanned at a
8064 time. By default it is set to 10% of the Cache Digest.
8069 -----------------------------------------------------------------------------
8074 LOC: Config.Port.snmp
8076 DEFAULT_DOC: SNMP disabled.
8079 The port number where Squid listens for SNMP requests. To enable
8080 SNMP support set this to a suitable port number. Port number
8081 3401 is often used for the Squid SNMP agent. By default it's
8082 set to "0" (disabled)
8090 LOC: Config.accessList.snmp
8092 DEFAULT_DOC: Deny, unless rules exist in squid.conf.
8095 Allowing or denying access to the SNMP port.
8097 All access to the agent is denied by default.
8100 snmp_access allow|deny [!]aclname ...
8102 This clause only supports fast acl types.
8103 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
8106 snmp_access allow snmppublic localhost
8107 snmp_access deny all
8110 NAME: snmp_incoming_address
8112 LOC: Config.Addrs.snmp_incoming
8114 DEFAULT_DOC: Accept SNMP packets from all machine interfaces.
8117 Just like 'udp_incoming_address', but for the SNMP port.
8119 snmp_incoming_address is used for the SNMP socket receiving
8120 messages from SNMP agents.
8122 The default snmp_incoming_address is to listen on all
8123 available network interfaces.
8126 NAME: snmp_outgoing_address
8128 LOC: Config.Addrs.snmp_outgoing
8130 DEFAULT_DOC: Use snmp_incoming_address or an address selected by the operating system.
8133 Just like 'udp_outgoing_address', but for the SNMP port.
8135 snmp_outgoing_address is used for SNMP packets returned to SNMP
8138 If snmp_outgoing_address is not set it will use the same socket
8139 as snmp_incoming_address. Only change this if you want to have
8140 SNMP replies sent using another address than where this Squid
8141 listens for SNMP queries.
8143 NOTE, snmp_incoming_address and snmp_outgoing_address can not have
8144 the same value since they both use the same port.
8149 -----------------------------------------------------------------------------
8152 NAME: icp_port udp_port
8155 DEFAULT_DOC: ICP disabled.
8156 LOC: Config.Port.icp
8158 The port number where Squid sends and receives ICP queries to
8159 and from neighbor caches. The standard UDP port for ICP is 3130.
8162 icp_port @DEFAULT_ICP_PORT@
8169 DEFAULT_DOC: HTCP disabled.
8170 LOC: Config.Port.htcp
8172 The port number where Squid sends and receives HTCP queries to
8173 and from neighbor caches. To turn it on you want to set it to
8180 NAME: log_icp_queries
8184 LOC: Config.onoff.log_udp
8186 If set, ICP queries are logged to access.log. You may wish
8187 do disable this if your ICP load is VERY high to speed things
8188 up or to simplify log analysis.
8191 NAME: udp_incoming_address
8193 LOC:Config.Addrs.udp_incoming
8195 DEFAULT_DOC: Accept packets from all machine interfaces.
8197 udp_incoming_address is used for UDP packets received from other
8200 The default behavior is to not bind to any specific address.
8202 Only change this if you want to have all UDP queries received on
8203 a specific interface/address.
8205 NOTE: udp_incoming_address is used by the ICP, HTCP, and DNS
8206 modules. Altering it will affect all of them in the same manner.
8208 see also; udp_outgoing_address
8210 NOTE, udp_incoming_address and udp_outgoing_address can not
8211 have the same value since they both use the same port.
8214 NAME: udp_outgoing_address
8216 LOC: Config.Addrs.udp_outgoing
8218 DEFAULT_DOC: Use udp_incoming_address or an address selected by the operating system.
8220 udp_outgoing_address is used for UDP packets sent out to other
8223 The default behavior is to not bind to any specific address.
8225 Instead it will use the same socket as udp_incoming_address.
8226 Only change this if you want to have UDP queries sent using another
8227 address than where this Squid listens for UDP queries from other
8230 NOTE: udp_outgoing_address is used by the ICP, HTCP, and DNS
8231 modules. Altering it will affect all of them in the same manner.
8233 see also; udp_incoming_address
8235 NOTE, udp_incoming_address and udp_outgoing_address can not
8236 have the same value since they both use the same port.
8243 LOC: Config.onoff.icp_hit_stale
8245 If you want to return ICP_HIT for stale cache objects, set this
8246 option to 'on'. If you have sibling relationships with caches
8247 in other administrative domains, this should be 'off'. If you only
8248 have sibling relationships with caches under your control,
8249 it is probably okay to set this to 'on'.
8250 If set to 'on', your siblings should use the option "allow-miss"
8251 on their cache_peer lines for connecting to you.
8254 NAME: minimum_direct_hops
8257 LOC: Config.minDirectHops
8259 If using the ICMP pinging stuff, do direct fetches for sites
8260 which are no more than this many hops away.
8263 NAME: minimum_direct_rtt
8267 LOC: Config.minDirectRtt
8269 If using the ICMP pinging stuff, do direct fetches for sites
8270 which are no more than this many rtt milliseconds away.
8276 LOC: Config.Netdb.low
8278 The low water mark for the ICMP measurement database.
8280 Note: high watermark controlled by netdb_high directive.
8282 These watermarks are counts, not percents. The defaults are
8283 (low) 900 and (high) 1000. When the high water mark is
8284 reached, database entries will be deleted until the low
8291 LOC: Config.Netdb.high
8293 The high water mark for the ICMP measurement database.
8295 Note: low watermark controlled by netdb_low directive.
8297 These watermarks are counts, not percents. The defaults are
8298 (low) 900 and (high) 1000. When the high water mark is
8299 reached, database entries will be deleted until the low
8303 NAME: netdb_ping_period
8305 LOC: Config.Netdb.period
8308 The minimum period for measuring a site. There will be at
8309 least this much delay between successive pings to the same
8310 network. The default is five minutes.
8317 LOC: Config.onoff.query_icmp
8319 If you want to ask your peers to include ICMP data in their ICP
8320 replies, enable this option.
8322 If your peer has configured Squid (during compilation) with
8323 '--enable-icmp' that peer will send ICMP pings to origin server
8324 sites of the URLs it receives. If you enable this option the
8325 ICP replies from that peer will include the ICMP data (if available).
8326 Then, when choosing a parent cache, Squid will choose the parent with
8327 the minimal RTT to the origin server. When this happens, the
8328 hierarchy field of the access.log will be
8329 "CLOSEST_PARENT_MISS". This option is off by default.
8332 NAME: test_reachability
8336 LOC: Config.onoff.test_reachability
8338 When this is 'on', ICP MISS replies will be ICP_MISS_NOFETCH
8339 instead of ICP_MISS if the target host is NOT in the ICMP
8340 database, or has a zero RTT.
8343 NAME: icp_query_timeout
8346 DEFAULT_DOC: Dynamic detection.
8348 LOC: Config.Timeout.icp_query
8350 Normally Squid will automatically determine an optimal ICP
8351 query timeout value based on the round-trip-time of recent ICP
8352 queries. If you want to override the value determined by
8353 Squid, set this 'icp_query_timeout' to a non-zero value. This
8354 value is specified in MILLISECONDS, so, to use a 2-second
8355 timeout (the old default), you would write:
8357 icp_query_timeout 2000
8360 NAME: maximum_icp_query_timeout
8364 LOC: Config.Timeout.icp_query_max
8366 Normally the ICP query timeout is determined dynamically. But
8367 sometimes it can lead to very large values (say 5 seconds).
8368 Use this option to put an upper limit on the dynamic timeout
8369 value. Do NOT use this option to always use a fixed (instead
8370 of a dynamic) timeout value. To set a fixed timeout see the
8371 'icp_query_timeout' directive.
8374 NAME: minimum_icp_query_timeout
8378 LOC: Config.Timeout.icp_query_min
8380 Normally the ICP query timeout is determined dynamically. But
8381 sometimes it can lead to very small timeouts, even lower than
8382 the normal latency variance on your link due to traffic.
8383 Use this option to put an lower limit on the dynamic timeout
8384 value. Do NOT use this option to always use a fixed (instead
8385 of a dynamic) timeout value. To set a fixed timeout see the
8386 'icp_query_timeout' directive.
8389 NAME: background_ping_rate
8393 LOC: Config.backgroundPingRate
8395 Controls how often the ICP pings are sent to siblings that
8396 have background-ping set.
8400 MULTICAST ICP OPTIONS
8401 -----------------------------------------------------------------------------
8406 LOC: Config.mcast_group_list
8409 This tag specifies a list of multicast groups which your server
8410 should join to receive multicasted ICP queries.
8412 NOTE! Be very careful what you put here! Be sure you
8413 understand the difference between an ICP _query_ and an ICP
8414 _reply_. This option is to be set only if you want to RECEIVE
8415 multicast queries. Do NOT set this option to SEND multicast
8416 ICP (use cache_peer for that). ICP replies are always sent via
8417 unicast, so this option does not affect whether or not you will
8418 receive replies from multicast group members.
8420 You must be very careful to NOT use a multicast address which
8421 is already in use by another group of caches.
8423 If you are unsure about multicast, please read the Multicast
8424 chapter in the Squid FAQ (http://www.squid-cache.org/FAQ/).
8426 Usage: mcast_groups 239.128.16.128 224.0.1.20
8428 By default, Squid doesn't listen on any multicast groups.
8431 NAME: mcast_miss_addr
8432 IFDEF: MULTICAST_MISS_STREAM
8434 LOC: Config.mcast_miss.addr
8436 DEFAULT_DOC: disabled.
8438 If you enable this option, every "cache miss" URL will
8439 be sent out on the specified multicast address.
8441 Do not enable this option unless you are are absolutely
8442 certain you understand what you are doing.
8445 NAME: mcast_miss_ttl
8446 IFDEF: MULTICAST_MISS_STREAM
8448 LOC: Config.mcast_miss.ttl
8451 This is the time-to-live value for packets multicasted
8452 when multicasting off cache miss URLs is enabled. By
8453 default this is set to 'site scope', i.e. 16.
8456 NAME: mcast_miss_port
8457 IFDEF: MULTICAST_MISS_STREAM
8459 LOC: Config.mcast_miss.port
8462 This is the port number to be used in conjunction with
8466 NAME: mcast_miss_encode_key
8467 IFDEF: MULTICAST_MISS_STREAM
8469 LOC: Config.mcast_miss.encode_key
8470 DEFAULT: XXXXXXXXXXXXXXXX
8472 The URLs that are sent in the multicast miss stream are
8473 encrypted. This is the encryption key.
8476 NAME: mcast_icp_query_timeout
8480 LOC: Config.Timeout.mcast_icp_query
8482 For multicast peers, Squid regularly sends out ICP "probes" to
8483 count how many other peers are listening on the given multicast
8484 address. This value specifies how long Squid should wait to
8485 count all the replies. The default is 2000 msec, or 2
8490 INTERNAL ICON OPTIONS
8491 -----------------------------------------------------------------------------
8494 NAME: icon_directory
8496 LOC: Config.icons.directory
8497 DEFAULT: @DEFAULT_ICON_DIR@
8499 Where the icons are stored. These are normally kept in
8503 NAME: global_internal_static
8505 LOC: Config.onoff.global_internal_static
8508 This directive controls is Squid should intercept all requests for
8509 /squid-internal-static/ no matter which host the URL is requesting
8510 (default on setting), or if nothing special should be done for
8511 such URLs (off setting). The purpose of this directive is to make
8512 icons etc work better in complex cache hierarchies where it may
8513 not always be possible for all corners in the cache mesh to reach
8514 the server generating a directory listing.
8517 NAME: short_icon_urls
8519 LOC: Config.icons.use_short_names
8522 If this is enabled Squid will use short URLs for icons.
8523 If disabled it will revert to the old behavior of including
8524 it's own name and port in the URL.
8526 If you run a complex cache hierarchy with a mix of Squid and
8527 other proxies you may need to disable this directive.
8532 -----------------------------------------------------------------------------
8535 NAME: error_directory
8537 LOC: Config.errorDirectory
8539 DEFAULT_DOC: Send error pages in the clients preferred language
8541 If you wish to create your own versions of the default
8542 error files to customize them to suit your company copy
8543 the error/template files to another directory and point
8546 WARNING: This option will disable multi-language support
8547 on error pages if used.
8549 The squid developers are interested in making squid available in
8550 a wide variety of languages. If you are making translations for a
8551 language that Squid does not currently provide please consider
8552 contributing your translation back to the project.
8553 http://wiki.squid-cache.org/Translations
8555 The squid developers working on translations are happy to supply drop-in
8556 translated error files in exchange for any new language contributions.
8559 NAME: error_default_language
8560 IFDEF: USE_ERR_LOCALES
8562 LOC: Config.errorDefaultLanguage
8564 DEFAULT_DOC: Generate English language pages.
8566 Set the default language which squid will send error pages in
8567 if no existing translation matches the clients language
8570 If unset (default) generic English will be used.
8572 The squid developers are interested in making squid available in
8573 a wide variety of languages. If you are interested in making
8574 translations for any language see the squid wiki for details.
8575 http://wiki.squid-cache.org/Translations
8578 NAME: error_log_languages
8579 IFDEF: USE_ERR_LOCALES
8581 LOC: Config.errorLogMissingLanguages
8584 Log to cache.log what languages users are attempting to
8585 auto-negotiate for translations.
8587 Successful negotiations are not logged. Only failures
8588 have meaning to indicate that Squid may need an upgrade
8589 of its error page translations.
8592 NAME: err_page_stylesheet
8594 LOC: Config.errorStylesheet
8595 DEFAULT: @DEFAULT_CONFIG_DIR@/errorpage.css
8597 CSS Stylesheet to pattern the display of Squid default error pages.
8599 For information on CSS see http://www.w3.org/Style/CSS/
8604 LOC: Config.errHtmlText
8607 HTML text to include in error messages. Make this a "mailto"
8608 URL to your admin address, or maybe just a link to your
8609 organizations Web page.
8611 To include this in your error messages, you must rewrite
8612 the error template files (found in the "errors" directory).
8613 Wherever you want the 'err_html_text' line to appear,
8614 insert a %L tag in the error template file.
8617 NAME: email_err_data
8620 LOC: Config.onoff.emailErrData
8623 If enabled, information about the occurred error will be
8624 included in the mailto links of the ERR pages (if %W is set)
8625 so that the email body contains the data.
8626 Syntax is <A HREF="mailto:%w%W">%w</A>
8631 LOC: Config.denyInfoList
8634 Usage: deny_info err_page_name acl
8635 or deny_info http://... acl
8636 or deny_info TCP_RESET acl
8638 This can be used to return a ERR_ page for requests which
8639 do not pass the 'http_access' rules. Squid remembers the last
8640 acl it evaluated in http_access, and if a 'deny_info' line exists
8641 for that ACL Squid returns a corresponding error page.
8643 The acl is typically the last acl on the http_access deny line which
8644 denied access. The exceptions to this rule are:
8645 - When Squid needs to request authentication credentials. It's then
8646 the first authentication related acl encountered
8647 - When none of the http_access lines matches. It's then the last
8648 acl processed on the last http_access line.
8649 - When the decision to deny access was made by an adaptation service,
8650 the acl name is the corresponding eCAP or ICAP service_name.
8652 NP: If providing your own custom error pages with error_directory
8653 you may also specify them by your custom file name:
8654 Example: deny_info ERR_CUSTOM_ACCESS_DENIED bad_guys
8656 By defaut Squid will send "403 Forbidden". A different 4xx or 5xx
8657 may be specified by prefixing the file name with the code and a colon.
8658 e.g. 404:ERR_CUSTOM_ACCESS_DENIED
8660 Alternatively you can tell Squid to reset the TCP connection
8661 by specifying TCP_RESET.
8663 Or you can specify an error URL or URL pattern. The browsers will
8664 get redirected to the specified URL after formatting tags have
8665 been replaced. Redirect will be done with 302 or 307 according to
8666 HTTP/1.1 specs. A different 3xx code may be specified by prefixing
8667 the URL. e.g. 303:http://example.com/
8670 %a - username (if available. Password NOT included)
8671 %A - Local listening IP address the client connection was connected to
8674 %E - Error description
8676 %H - Request domain name
8677 %i - Client IP Address
8679 %O - Unescaped message result from external ACL helper
8680 %o - Message result from external ACL helper
8681 %p - Request Port number
8682 %P - Request Protocol name
8683 %R - Request URL path
8684 %T - Timestamp in RFC 1123 format
8685 %U - Full canonical URL from client
8686 (HTTPS URLs terminate with *)
8687 %u - Full canonical URL from client
8688 %w - Admin email from squid.conf
8690 %% - Literal percent (%) code
8695 OPTIONS INFLUENCING REQUEST FORWARDING
8696 -----------------------------------------------------------------------------
8699 NAME: nonhierarchical_direct
8701 LOC: Config.onoff.nonhierarchical_direct
8704 By default, Squid will send any non-hierarchical requests
8705 (not cacheable request type) direct to origin servers.
8707 When this is set to "off", Squid will prefer to send these
8708 requests to parents.
8710 Note that in most configurations, by turning this off you will only
8711 add latency to these request without any improvement in global hit
8714 This option only sets a preference. If the parent is unavailable a
8715 direct connection to the origin server may still be attempted. To
8716 completely prevent direct connections use never_direct.
8721 LOC: Config.onoff.prefer_direct
8724 Normally Squid tries to use parents for most requests. If you for some
8725 reason like it to first try going direct and only use a parent if
8726 going direct fails set this to on.
8728 By combining nonhierarchical_direct off and prefer_direct on you
8729 can set up Squid to use a parent as a backup path if going direct
8732 Note: If you want Squid to use parents for all requests see
8733 the never_direct directive. prefer_direct only modifies how Squid
8734 acts on cacheable requests.
8737 NAME: cache_miss_revalidate
8741 LOC: Config.onoff.cache_miss_revalidate
8743 RFC 7232 defines a conditional request mechanism to prevent
8744 response objects being unnecessarily transferred over the network.
8745 If that mechanism is used by the client and a cache MISS occurs
8746 it can prevent new cache entries being created.
8748 This option determines whether Squid on cache MISS will pass the
8749 client revalidation request to the server or tries to fetch new
8750 content for caching. It can be useful while the cache is mostly
8751 empty to more quickly have the cache populated by generating
8752 non-conditional GETs.
8754 When set to 'on' (default), Squid will pass all client If-* headers
8755 to the server. This permits server responses without a cacheable
8756 payload to be delivered and on MISS no new cache entry is created.
8758 When set to 'off' and if the request is cacheable, Squid will
8759 remove the clients If-Modified-Since and If-None-Match headers from
8760 the request sent to the server. This requests a 200 status response
8761 from the server to create a new cache entry with.
8766 LOC: Config.accessList.AlwaysDirect
8768 DEFAULT_DOC: Prevent any cache_peer being used for this request.
8770 Usage: always_direct allow|deny [!]aclname ...
8772 Here you can use ACL elements to specify requests which should
8773 ALWAYS be forwarded by Squid to the origin servers without using
8774 any peers. For example, to always directly forward requests for
8775 local servers ignoring any parents or siblings you may have use
8778 acl local-servers dstdomain my.domain.net
8779 always_direct allow local-servers
8781 To always forward FTP requests directly, use
8784 always_direct allow FTP
8786 NOTE: There is a similar, but opposite option named
8787 'never_direct'. You need to be aware that "always_direct deny
8788 foo" is NOT the same thing as "never_direct allow foo". You
8789 may need to use a deny rule to exclude a more-specific case of
8790 some other rule. Example:
8792 acl local-external dstdomain external.foo.net
8793 acl local-servers dstdomain .foo.net
8794 always_direct deny local-external
8795 always_direct allow local-servers
8797 NOTE: If your goal is to make the client forward the request
8798 directly to the origin server bypassing Squid then this needs
8799 to be done in the client configuration. Squid configuration
8800 can only tell Squid how Squid should fetch the object.
8802 NOTE: This directive is not related to caching. The replies
8803 is cached as usual even if you use always_direct. To not cache
8804 the replies see the 'cache' directive.
8806 This clause supports both fast and slow acl types.
8807 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
8812 LOC: Config.accessList.NeverDirect
8814 DEFAULT_DOC: Allow DNS results to be used for this request.
8816 Usage: never_direct allow|deny [!]aclname ...
8818 never_direct is the opposite of always_direct. Please read
8819 the description for always_direct if you have not already.
8821 With 'never_direct' you can use ACL elements to specify
8822 requests which should NEVER be forwarded directly to origin
8823 servers. For example, to force the use of a proxy for all
8824 requests, except those in your local domain use something like:
8826 acl local-servers dstdomain .foo.net
8827 never_direct deny local-servers
8828 never_direct allow all
8830 or if Squid is inside a firewall and there are local intranet
8831 servers inside the firewall use something like:
8833 acl local-intranet dstdomain .foo.net
8834 acl local-external dstdomain external.foo.net
8835 always_direct deny local-external
8836 always_direct allow local-intranet
8837 never_direct allow all
8839 This clause supports both fast and slow acl types.
8840 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
8844 ADVANCED NETWORKING OPTIONS
8845 -----------------------------------------------------------------------------
8848 NAME: incoming_udp_average incoming_icp_average
8851 LOC: Config.comm_incoming.udp.average
8853 Heavy voodoo here. I can't even believe you are reading this.
8854 Are you crazy? Don't even think about adjusting these unless
8855 you understand the algorithms in comm_select.c first!
8858 NAME: incoming_tcp_average incoming_http_average
8861 LOC: Config.comm_incoming.tcp.average
8863 Heavy voodoo here. I can't even believe you are reading this.
8864 Are you crazy? Don't even think about adjusting these unless
8865 you understand the algorithms in comm_select.c first!
8868 NAME: incoming_dns_average
8871 LOC: Config.comm_incoming.dns.average
8873 Heavy voodoo here. I can't even believe you are reading this.
8874 Are you crazy? Don't even think about adjusting these unless
8875 you understand the algorithms in comm_select.c first!
8878 NAME: min_udp_poll_cnt min_icp_poll_cnt
8881 LOC: Config.comm_incoming.udp.min_poll
8883 Heavy voodoo here. I can't even believe you are reading this.
8884 Are you crazy? Don't even think about adjusting these unless
8885 you understand the algorithms in comm_select.c first!
8888 NAME: min_dns_poll_cnt
8891 LOC: Config.comm_incoming.dns.min_poll
8893 Heavy voodoo here. I can't even believe you are reading this.
8894 Are you crazy? Don't even think about adjusting these unless
8895 you understand the algorithms in comm_select.c first!
8898 NAME: min_tcp_poll_cnt min_http_poll_cnt
8901 LOC: Config.comm_incoming.tcp.min_poll
8903 Heavy voodoo here. I can't even believe you are reading this.
8904 Are you crazy? Don't even think about adjusting these unless
8905 you understand the algorithms in comm_select.c first!
8911 LOC: Config.accept_filter
8915 The name of an accept(2) filter to install on Squid's
8916 listen socket(s). This feature is perhaps specific to
8917 FreeBSD and requires support in the kernel.
8919 The 'httpready' filter delays delivering new connections
8920 to Squid until a full HTTP request has been received.
8921 See the accf_http(9) man page for details.
8923 The 'dataready' filter delays delivering new connections
8924 to Squid until there is some data to process.
8925 See the accf_dataready(9) man page for details.
8929 The 'data' filter delays delivering of new connections
8930 to Squid until there is some data to process by TCP_ACCEPT_DEFER.
8931 You may optionally specify a number of seconds to wait by
8932 'data=N' where N is the number of seconds. Defaults to 30
8933 if not specified. See the tcp(7) man page for details.
8936 accept_filter httpready
8941 NAME: client_ip_max_connections
8943 LOC: Config.client_ip_max_connections
8945 DEFAULT_DOC: No limit.
8947 Set an absolute limit on the number of connections a single
8948 client IP can use. Any more than this and Squid will begin to drop
8949 new connections from the client until it closes some links.
8951 Note that this is a global limit. It affects all HTTP, HTCP, Gopher and FTP
8952 connections from the client. For finer control use the ACL access controls.
8954 Requires client_db to be enabled (the default).
8956 WARNING: This may noticably slow down traffic received via external proxies
8957 or NAT devices and cause them to rebound error messages back to their clients.
8960 NAME: tcp_recv_bufsize
8964 DEFAULT_DOC: Use operating system TCP defaults.
8965 LOC: Config.tcpRcvBufsz
8967 Size of receive buffer to set for TCP sockets. Probably just
8968 as easy to change your kernel's default.
8969 Omit from squid.conf to use the default buffer size.
8974 -----------------------------------------------------------------------------
8981 LOC: Adaptation::Icap::TheConfig.onoff
8984 If you want to enable the ICAP module support, set this to on.
8987 NAME: icap_connect_timeout
8990 LOC: Adaptation::Icap::TheConfig.connect_timeout_raw
8993 This parameter specifies how long to wait for the TCP connect to
8994 the requested ICAP server to complete before giving up and either
8995 terminating the HTTP transaction or bypassing the failure.
8997 The default for optional services is peer_connect_timeout.
8998 The default for essential services is connect_timeout.
8999 If this option is explicitly set, its value applies to all services.
9002 NAME: icap_io_timeout
9006 DEFAULT_DOC: Use read_timeout.
9007 LOC: Adaptation::Icap::TheConfig.io_timeout_raw
9010 This parameter specifies how long to wait for an I/O activity on
9011 an established, active ICAP connection before giving up and
9012 either terminating the HTTP transaction or bypassing the
9016 NAME: icap_service_failure_limit
9017 COMMENT: limit [in memory-depth time-units]
9018 TYPE: icap_service_failure_limit
9020 LOC: Adaptation::Icap::TheConfig
9023 The limit specifies the number of failures that Squid tolerates
9024 when establishing a new TCP connection with an ICAP service. If
9025 the number of failures exceeds the limit, the ICAP service is
9026 not used for new ICAP requests until it is time to refresh its
9029 A negative value disables the limit. Without the limit, an ICAP
9030 service will not be considered down due to connectivity failures
9031 between ICAP OPTIONS requests.
9033 Squid forgets ICAP service failures older than the specified
9034 value of memory-depth. The memory fading algorithm
9035 is approximate because Squid does not remember individual
9036 errors but groups them instead, splitting the option
9037 value into ten time slots of equal length.
9039 When memory-depth is 0 and by default this option has no
9040 effect on service failure expiration.
9042 Squid always forgets failures when updating service settings
9043 using an ICAP OPTIONS transaction, regardless of this option
9047 # suspend service usage after 10 failures in 5 seconds:
9048 icap_service_failure_limit 10 in 5 seconds
9051 NAME: icap_service_revival_delay
9054 LOC: Adaptation::Icap::TheConfig.service_revival_delay
9057 The delay specifies the number of seconds to wait after an ICAP
9058 OPTIONS request failure before requesting the options again. The
9059 failed ICAP service is considered "down" until fresh OPTIONS are
9062 The actual delay cannot be smaller than the hardcoded minimum
9063 delay of 30 seconds.
9066 NAME: icap_preview_enable
9070 LOC: Adaptation::Icap::TheConfig.preview_enable
9073 The ICAP Preview feature allows the ICAP server to handle the
9074 HTTP message by looking only at the beginning of the message body
9075 or even without receiving the body at all. In some environments,
9076 previews greatly speedup ICAP processing.
9078 During an ICAP OPTIONS transaction, the server may tell Squid what
9079 HTTP messages should be previewed and how big the preview should be.
9080 Squid will not use Preview if the server did not request one.
9082 To disable ICAP Preview for all ICAP services, regardless of
9083 individual ICAP server OPTIONS responses, set this option to "off".
9085 icap_preview_enable off
9088 NAME: icap_preview_size
9091 LOC: Adaptation::Icap::TheConfig.preview_size
9093 DEFAULT_DOC: No preview sent.
9095 The default size of preview data to be sent to the ICAP server.
9096 This value might be overwritten on a per server basis by OPTIONS requests.
9099 NAME: icap_206_enable
9103 LOC: Adaptation::Icap::TheConfig.allow206_enable
9106 206 (Partial Content) responses is an ICAP extension that allows the
9107 ICAP agents to optionally combine adapted and original HTTP message
9108 content. The decision to combine is postponed until the end of the
9109 ICAP response. Squid supports Partial Content extension by default.
9111 Activation of the Partial Content extension is negotiated with each
9112 ICAP service during OPTIONS exchange. Most ICAP servers should handle
9113 negotation correctly even if they do not support the extension, but
9114 some might fail. To disable Partial Content support for all ICAP
9115 services and to avoid any negotiation, set this option to "off".
9121 NAME: icap_default_options_ttl
9124 LOC: Adaptation::Icap::TheConfig.default_options_ttl
9127 The default TTL value for ICAP OPTIONS responses that don't have
9128 an Options-TTL header.
9131 NAME: icap_persistent_connections
9135 LOC: Adaptation::Icap::TheConfig.reuse_connections
9138 Whether or not Squid should use persistent connections to
9142 NAME: adaptation_send_client_ip icap_send_client_ip
9144 IFDEF: USE_ADAPTATION
9146 LOC: Adaptation::Config::send_client_ip
9149 If enabled, Squid shares HTTP client IP information with adaptation
9150 services. For ICAP, Squid adds the X-Client-IP header to ICAP requests.
9151 For eCAP, Squid sets the libecap::metaClientIp transaction option.
9153 See also: adaptation_uses_indirect_client
9156 NAME: adaptation_send_username icap_send_client_username
9158 IFDEF: USE_ADAPTATION
9160 LOC: Adaptation::Config::send_username
9163 This sends authenticated HTTP client username (if available) to
9164 the adaptation service.
9166 For ICAP, the username value is encoded based on the
9167 icap_client_username_encode option and is sent using the header
9168 specified by the icap_client_username_header option.
9171 NAME: icap_client_username_header
9174 LOC: Adaptation::Icap::TheConfig.client_username_header
9175 DEFAULT: X-Client-Username
9177 ICAP request header name to use for adaptation_send_username.
9180 NAME: icap_client_username_encode
9184 LOC: Adaptation::Icap::TheConfig.client_username_encode
9187 Whether to base64 encode the authenticated client username.
9191 TYPE: icap_service_type
9193 LOC: Adaptation::Icap::TheConfig
9196 Defines a single ICAP service using the following format:
9198 icap_service id vectoring_point uri [option ...]
9201 an opaque identifier or name which is used to direct traffic to
9202 this specific service. Must be unique among all adaptation
9203 services in squid.conf.
9205 vectoring_point: reqmod_precache|reqmod_postcache|respmod_precache|respmod_postcache
9206 This specifies at which point of transaction processing the
9207 ICAP service should be activated. *_postcache vectoring points
9208 are not yet supported.
9210 uri: icap://servername:port/servicepath
9211 ICAP server and service location.
9212 icaps://servername:port/servicepath
9213 The "icap:" URI scheme is used for traditional ICAP server and
9214 service location (default port is 1344, connections are not
9215 encrypted). The "icaps:" URI scheme is for Secure ICAP
9216 services that use SSL/TLS-encrypted ICAP connections (by
9217 default, on port 11344).
9219 ICAP does not allow a single service to handle both REQMOD and RESPMOD
9220 transactions. Squid does not enforce that requirement. You can specify
9221 services with the same service_url and different vectoring_points. You
9222 can even specify multiple identical services as long as their
9223 service_names differ.
9225 To activate a service, use the adaptation_access directive. To group
9226 services, use adaptation_service_chain and adaptation_service_set.
9228 Service options are separated by white space. ICAP services support
9229 the following name=value options:
9232 If set to 'on' or '1', the ICAP service is treated as
9233 optional. If the service cannot be reached or malfunctions,
9234 Squid will try to ignore any errors and process the message as
9235 if the service was not enabled. No all ICAP errors can be
9236 bypassed. If set to 0, the ICAP service is treated as
9237 essential and all ICAP errors will result in an error page
9238 returned to the HTTP client.
9240 Bypass is off by default: services are treated as essential.
9243 If set to 'on' or '1', the ICAP service is allowed to
9244 dynamically change the current message adaptation plan by
9245 returning a chain of services to be used next. The services
9246 are specified using the X-Next-Services ICAP response header
9247 value, formatted as a comma-separated list of service names.
9248 Each named service should be configured in squid.conf. Other
9249 services are ignored. An empty X-Next-Services value results
9250 in an empty plan which ends the current adaptation.
9252 Dynamic adaptation plan may cross or cover multiple supported
9253 vectoring points in their natural processing order.
9255 Routing is not allowed by default: the ICAP X-Next-Services
9256 response header is ignored.
9259 Only has effect on split-stack systems. The default on those systems
9260 is to use IPv4-only connections. When set to 'on' this option will
9261 make Squid use IPv6-only connections to contact this ICAP service.
9263 on-overload=block|bypass|wait|force
9264 If the service Max-Connections limit has been reached, do
9265 one of the following for each new ICAP transaction:
9266 * block: send an HTTP error response to the client
9267 * bypass: ignore the "over-connected" ICAP service
9268 * wait: wait (in a FIFO queue) for an ICAP connection slot
9269 * force: proceed, ignoring the Max-Connections limit
9271 In SMP mode with N workers, each worker assumes the service
9272 connection limit is Max-Connections/N, even though not all
9273 workers may use a given service.
9275 The default value is "bypass" if service is bypassable,
9276 otherwise it is set to "wait".
9280 Use the given number as the Max-Connections limit, regardless
9281 of the Max-Connections value given by the service, if any.
9283 connection-encryption=on|off
9284 Determines the ICAP service effect on the connections_encrypted
9287 The default is "on" for Secure ICAP services (i.e., those
9288 with the icaps:// service URIs scheme) and "off" for plain ICAP
9291 Does not affect ICAP connections (e.g., does not turn Secure
9294 ==== ICAPS / TLS OPTIONS ====
9296 These options are used for Secure ICAP (icaps://....) services only.
9298 tls-cert=/path/to/ssl/certificate
9299 A client X.509 certificate to use when connecting to
9302 tls-key=/path/to/ssl/key
9303 The private key corresponding to the previous
9306 If tls-key= is not specified tls-cert= is assumed to
9307 reference a PEM file containing both the certificate
9310 tls-cipher=... The list of valid TLS/SSL ciphers to use when connecting
9311 to this icap server.
9314 The minimum TLS protocol version to permit. To control
9315 SSLv3 use the tls-options= parameter.
9316 Supported Values: 1.0 (default), 1.1, 1.2
9318 tls-options=... Specify various OpenSSL library options:
9320 NO_SSLv3 Disallow the use of SSLv3
9323 Always create a new key when using
9324 temporary/ephemeral DH key exchanges
9326 ALL Enable various bug workarounds
9327 suggested as "harmless" by OpenSSL
9328 Be warned that this reduces SSL/TLS
9329 strength to some attacks.
9331 See the OpenSSL SSL_CTX_set_options documentation for a
9332 more complete list. Options relevant only to SSLv2 are
9335 tls-cafile= PEM file containing CA certificates to use when verifying
9336 the icap server certificate.
9337 Use to specify intermediate CA certificate(s) if not sent
9338 by the server. Or the full CA chain for the server when
9339 using the tls-default-ca=off flag.
9340 May be repeated to load multiple files.
9342 tls-capath=... A directory containing additional CA certificates to
9343 use when verifying the icap server certificate.
9344 Requires OpenSSL or LibreSSL.
9346 tls-crlfile=... A certificate revocation list file to use when
9347 verifying the icap server certificate.
9349 tls-flags=... Specify various flags modifying the Squid TLS implementation:
9352 Accept certificates even if they fail to
9355 Don't verify the icap server certificate
9356 matches the server name
9358 tls-default-ca[=off]
9359 Whether to use the system Trusted CAs. Default is ON.
9361 tls-domain= The icap server name as advertised in it's certificate.
9362 Used for verifying the correctness of the received icap
9363 server certificate. If not specified the icap server
9364 hostname extracted from ICAP URI will be used.
9366 Older icap_service format without optional named parameters is
9367 deprecated but supported for backward compatibility.
9370 icap_service svcBlocker reqmod_precache icap://icap1.mydomain.net:1344/reqmod bypass=0
9371 icap_service svcLogger reqmod_precache icaps://icap2.mydomain.net:11344/reqmod routing=on
9375 TYPE: icap_class_type
9380 This deprecated option was documented to define an ICAP service
9381 chain, even though it actually defined a set of similar, redundant
9382 services, and the chains were not supported.
9384 To define a set of redundant services, please use the
9385 adaptation_service_set directive. For service chains, use
9386 adaptation_service_chain.
9390 TYPE: icap_access_type
9395 This option is deprecated. Please use adaptation_access, which
9396 has the same ICAP functionality, but comes with better
9397 documentation, and eCAP support.
9402 -----------------------------------------------------------------------------
9409 LOC: Adaptation::Ecap::TheConfig.onoff
9412 Controls whether eCAP support is enabled.
9416 TYPE: ecap_service_type
9418 LOC: Adaptation::Ecap::TheConfig
9421 Defines a single eCAP service
9423 ecap_service id vectoring_point uri [option ...]
9426 an opaque identifier or name which is used to direct traffic to
9427 this specific service. Must be unique among all adaptation
9428 services in squid.conf.
9430 vectoring_point: reqmod_precache|reqmod_postcache|respmod_precache|respmod_postcache
9431 This specifies at which point of transaction processing the
9432 eCAP service should be activated. *_postcache vectoring points
9433 are not yet supported.
9435 uri: ecap://vendor/service_name?custom&cgi=style¶meters=optional
9436 Squid uses the eCAP service URI to match this configuration
9437 line with one of the dynamically loaded services. Each loaded
9438 eCAP service must have a unique URI. Obtain the right URI from
9439 the service provider.
9441 To activate a service, use the adaptation_access directive. To group
9442 services, use adaptation_service_chain and adaptation_service_set.
9444 Service options are separated by white space. eCAP services support
9445 the following name=value options:
9448 If set to 'on' or '1', the eCAP service is treated as optional.
9449 If the service cannot be reached or malfunctions, Squid will try
9450 to ignore any errors and process the message as if the service
9451 was not enabled. No all eCAP errors can be bypassed.
9452 If set to 'off' or '0', the eCAP service is treated as essential
9453 and all eCAP errors will result in an error page returned to the
9456 Bypass is off by default: services are treated as essential.
9459 If set to 'on' or '1', the eCAP service is allowed to
9460 dynamically change the current message adaptation plan by
9461 returning a chain of services to be used next.
9463 Dynamic adaptation plan may cross or cover multiple supported
9464 vectoring points in their natural processing order.
9466 Routing is not allowed by default.
9468 connection-encryption=on|off
9469 Determines the eCAP service effect on the connections_encrypted
9472 Defaults to "on", which does not taint the master transaction
9475 Does not affect eCAP API calls.
9477 Older ecap_service format without optional named parameters is
9478 deprecated but supported for backward compatibility.
9482 ecap_service s1 reqmod_precache ecap://filters.R.us/leakDetector?on_error=block bypass=off
9483 ecap_service s2 respmod_precache ecap://filters.R.us/virusFilter config=/etc/vf.cfg bypass=on
9486 NAME: loadable_modules
9488 IFDEF: USE_LOADABLE_MODULES
9489 LOC: Config.loadable_module_names
9492 Instructs Squid to load the specified dynamic module(s) or activate
9493 preloaded module(s).
9495 loadable_modules @DEFAULT_PREFIX@/lib/MinimalAdapter.so
9499 MESSAGE ADAPTATION OPTIONS
9500 -----------------------------------------------------------------------------
9503 NAME: adaptation_service_set
9504 TYPE: adaptation_service_set_type
9505 IFDEF: USE_ADAPTATION
9510 Configures an ordered set of similar, redundant services. This is
9511 useful when hot standby or backup adaptation servers are available.
9513 adaptation_service_set set_name service_name1 service_name2 ...
9515 The named services are used in the set declaration order. The first
9516 applicable adaptation service from the set is used first. The next
9517 applicable service is tried if and only if the transaction with the
9518 previous service fails and the message waiting to be adapted is still
9521 When adaptation starts, broken services are ignored as if they were
9522 not a part of the set. A broken service is a down optional service.
9524 The services in a set must be attached to the same vectoring point
9525 (e.g., pre-cache) and use the same adaptation method (e.g., REQMOD).
9527 If all services in a set are optional then adaptation failures are
9528 bypassable. If all services in the set are essential, then a
9529 transaction failure with one service may still be retried using
9530 another service from the set, but when all services fail, the master
9531 transaction fails as well.
9533 A set may contain a mix of optional and essential services, but that
9534 is likely to lead to surprising results because broken services become
9535 ignored (see above), making previously bypassable failures fatal.
9536 Technically, it is the bypassability of the last failed service that
9539 See also: adaptation_access adaptation_service_chain
9542 adaptation_service_set svcBlocker urlFilterPrimary urlFilterBackup
9543 adaptation service_set svcLogger loggerLocal loggerRemote
9546 NAME: adaptation_service_chain
9547 TYPE: adaptation_service_chain_type
9548 IFDEF: USE_ADAPTATION
9553 Configures a list of complementary services that will be applied
9554 one-by-one, forming an adaptation chain or pipeline. This is useful
9555 when Squid must perform different adaptations on the same message.
9557 adaptation_service_chain chain_name service_name1 svc_name2 ...
9559 The named services are used in the chain declaration order. The first
9560 applicable adaptation service from the chain is used first. The next
9561 applicable service is applied to the successful adaptation results of
9562 the previous service in the chain.
9564 When adaptation starts, broken services are ignored as if they were
9565 not a part of the chain. A broken service is a down optional service.
9567 Request satisfaction terminates the adaptation chain because Squid
9568 does not currently allow declaration of RESPMOD services at the
9569 "reqmod_precache" vectoring point (see icap_service or ecap_service).
9571 The services in a chain must be attached to the same vectoring point
9572 (e.g., pre-cache) and use the same adaptation method (e.g., REQMOD).
9574 A chain may contain a mix of optional and essential services. If an
9575 essential adaptation fails (or the failure cannot be bypassed for
9576 other reasons), the master transaction fails. Otherwise, the failure
9577 is bypassed as if the failed adaptation service was not in the chain.
9579 See also: adaptation_access adaptation_service_set
9582 adaptation_service_chain svcRequest requestLogger urlFilter leakDetector
9585 NAME: adaptation_access
9586 TYPE: adaptation_access_type
9587 IFDEF: USE_ADAPTATION
9590 DEFAULT_DOC: Allow, unless rules exist in squid.conf.
9592 Sends an HTTP transaction to an ICAP or eCAP adaptation service.
9594 adaptation_access service_name allow|deny [!]aclname...
9595 adaptation_access set_name allow|deny [!]aclname...
9597 At each supported vectoring point, the adaptation_access
9598 statements are processed in the order they appear in this
9599 configuration file. Statements pointing to the following services
9600 are ignored (i.e., skipped without checking their ACL):
9602 - services serving different vectoring points
9603 - "broken-but-bypassable" services
9604 - "up" services configured to ignore such transactions
9605 (e.g., based on the ICAP Transfer-Ignore header).
9607 When a set_name is used, all services in the set are checked
9608 using the same rules, to find the first applicable one. See
9609 adaptation_service_set for details.
9611 If an access list is checked and there is a match, the
9612 processing stops: For an "allow" rule, the corresponding
9613 adaptation service is used for the transaction. For a "deny"
9614 rule, no adaptation service is activated.
9616 It is currently not possible to apply more than one adaptation
9617 service at the same vectoring point to the same HTTP transaction.
9619 See also: icap_service and ecap_service
9622 adaptation_access service_1 allow all
9625 NAME: adaptation_service_iteration_limit
9627 IFDEF: USE_ADAPTATION
9628 LOC: Adaptation::Config::service_iteration_limit
9631 Limits the number of iterations allowed when applying adaptation
9632 services to a message. If your longest adaptation set or chain
9633 may have more than 16 services, increase the limit beyond its
9634 default value of 16. If detecting infinite iteration loops sooner
9635 is critical, make the iteration limit match the actual number
9636 of services in your longest adaptation set or chain.
9638 Infinite adaptation loops are most likely with routing services.
9640 See also: icap_service routing=1
9643 NAME: adaptation_masterx_shared_names
9645 IFDEF: USE_ADAPTATION
9646 LOC: Adaptation::Config::masterx_shared_name
9649 For each master transaction (i.e., the HTTP request and response
9650 sequence, including all related ICAP and eCAP exchanges), Squid
9651 maintains a table of metadata. The table entries are (name, value)
9652 pairs shared among eCAP and ICAP exchanges. The table is destroyed
9653 with the master transaction.
9655 This option specifies the table entry names that Squid must accept
9656 from and forward to the adaptation transactions.
9658 An ICAP REQMOD or RESPMOD transaction may set an entry in the
9659 shared table by returning an ICAP header field with a name
9660 specified in adaptation_masterx_shared_names.
9662 An eCAP REQMOD or RESPMOD transaction may set an entry in the
9663 shared table by implementing the libecap::visitEachOption() API
9664 to provide an option with a name specified in
9665 adaptation_masterx_shared_names.
9667 Squid will store and forward the set entry to subsequent adaptation
9668 transactions within the same master transaction scope.
9670 Only one shared entry name is supported at this time.
9673 # share authentication information among ICAP services
9674 adaptation_masterx_shared_names X-Subscriber-ID
9677 NAME: adaptation_meta
9679 IFDEF: USE_ADAPTATION
9680 LOC: Adaptation::Config::metaHeaders
9683 This option allows Squid administrator to add custom ICAP request
9684 headers or eCAP options to Squid ICAP requests or eCAP transactions.
9685 Use it to pass custom authentication tokens and other
9686 transaction-state related meta information to an ICAP/eCAP service.
9688 The addition of a meta header is ACL-driven:
9689 adaptation_meta name value [!]aclname ...
9691 Processing for a given header name stops after the first ACL list match.
9692 Thus, it is impossible to add two headers with the same name. If no ACL
9693 lists match for a given header name, no such header is added. For
9696 # do not debug transactions except for those that need debugging
9697 adaptation_meta X-Debug 1 needs_debugging
9699 # log all transactions except for those that must remain secret
9700 adaptation_meta X-Log 1 !keep_secret
9702 # mark transactions from users in the "G 1" group
9703 adaptation_meta X-Authenticated-Groups "G 1" authed_as_G1
9705 The "value" parameter may be a regular squid.conf token or a "double
9706 quoted string". Within the quoted string, use backslash (\) to escape
9707 any character, which is currently only useful for escaping backslashes
9708 and double quotes. For example,
9709 "this string has one backslash (\\) and two \"quotes\""
9711 Used adaptation_meta header values may be logged via %note
9712 logformat code. If multiple adaptation_meta headers with the same name
9713 are used during master transaction lifetime, the header values are
9714 logged in the order they were used and duplicate values are ignored
9715 (only the first repeated value will be logged).
9721 LOC: Adaptation::Icap::TheConfig.repeat
9722 DEFAULT_IF_NONE: deny all
9724 This ACL determines which retriable ICAP transactions are
9725 retried. Transactions that received a complete ICAP response
9726 and did not have to consume or produce HTTP bodies to receive
9727 that response are usually retriable.
9729 icap_retry allow|deny [!]aclname ...
9731 Squid automatically retries some ICAP I/O timeouts and errors
9732 due to persistent connection race conditions.
9734 See also: icap_retry_limit
9737 NAME: icap_retry_limit
9740 LOC: Adaptation::Icap::TheConfig.repeat_limit
9742 DEFAULT_DOC: No retries are allowed.
9744 Limits the number of retries allowed.
9746 Communication errors due to persistent connection race
9747 conditions are unavoidable, automatically retried, and do not
9748 count against this limit.
9750 See also: icap_retry
9756 -----------------------------------------------------------------------------
9759 NAME: check_hostnames
9762 LOC: Config.onoff.check_hostnames
9764 For security and stability reasons Squid can check
9765 hostnames for Internet standard RFC compliance. If you want
9766 Squid to perform these checks turn this directive on.
9769 NAME: allow_underscore
9772 LOC: Config.onoff.allow_underscore
9774 Underscore characters is not strictly allowed in Internet hostnames
9775 but nevertheless used by many sites. Set this to off if you want
9776 Squid to be strict about the standard.
9777 This check is performed only when check_hostnames is set to on.
9780 NAME: dns_retransmit_interval
9783 LOC: Config.Timeout.idns_retransmit
9785 Initial retransmit interval for DNS queries. The interval is
9786 doubled each time all configured DNS servers have been tried.
9792 LOC: Config.Timeout.idns_query
9794 DNS Query timeout. If no response is received to a DNS query
9795 within this time all DNS servers for the queried domain
9796 are assumed to be unavailable.
9799 NAME: dns_packet_max
9801 DEFAULT_DOC: EDNS disabled
9803 LOC: Config.dns.packet_max
9805 Maximum number of bytes packet size to advertise via EDNS.
9806 Set to "none" to disable EDNS large packet support.
9808 For legacy reasons DNS UDP replies will default to 512 bytes which
9809 is too small for many responses. EDNS provides a means for Squid to
9810 negotiate receiving larger responses back immediately without having
9811 to failover with repeat requests. Responses larger than this limit
9812 will retain the old behaviour of failover to TCP DNS.
9814 Squid has no real fixed limit internally, but allowing packet sizes
9815 over 1500 bytes requires network jumbogram support and is usually not
9818 WARNING: The RFC also indicates that some older resolvers will reply
9819 with failure of the whole request if the extension is added. Some
9820 resolvers have already been identified which will reply with mangled
9821 EDNS response on occasion. Usually in response to many-KB jumbogram
9822 sizes being advertised by Squid.
9823 Squid will currently treat these both as an unable-to-resolve domain
9824 even if it would be resolvable without EDNS.
9831 DEFAULT_DOC: Search for single-label domain names is disabled.
9832 LOC: Config.onoff.res_defnames
9834 Normally the RES_DEFNAMES resolver option is disabled
9835 (see res_init(3)). This prevents caches in a hierarchy
9836 from interpreting single-component hostnames locally. To allow
9837 Squid to handle single-component names, enable this option.
9840 NAME: dns_multicast_local
9844 DEFAULT_DOC: Search for .local and .arpa names is disabled.
9845 LOC: Config.onoff.dns_mdns
9847 When set to on, Squid sends multicast DNS lookups on the local
9848 network for domains ending in .local and .arpa.
9849 This enables local servers and devices to be contacted in an
9850 ad-hoc or zero-configuration network environment.
9853 NAME: dns_nameservers
9856 DEFAULT_DOC: Use operating system definitions
9857 LOC: Config.dns.nameservers
9859 Use this if you want to specify a list of DNS name servers
9860 (IP addresses) to use instead of those given in your
9861 /etc/resolv.conf file.
9863 On Windows platforms, if no value is specified here or in
9864 the /etc/resolv.conf file, the list of DNS name servers are
9865 taken from the Windows registry, both static and dynamic DHCP
9866 configurations are supported.
9868 Example: dns_nameservers 10.0.0.1 192.172.0.4
9873 DEFAULT: @DEFAULT_HOSTS@
9874 LOC: Config.etcHostsPath
9876 Location of the host-local IP name-address associations
9877 database. Most Operating Systems have such a file on different
9879 - Un*X & Linux: /etc/hosts
9880 - Windows NT/2000: %SystemRoot%\system32\drivers\etc\hosts
9881 (%SystemRoot% value install default is c:\winnt)
9882 - Windows XP/2003: %SystemRoot%\system32\drivers\etc\hosts
9883 (%SystemRoot% value install default is c:\windows)
9884 - Windows 9x/Me: %windir%\hosts
9885 (%windir% value is usually c:\windows)
9886 - Cygwin: /etc/hosts
9888 The file contains newline-separated definitions, in the
9889 form ip_address_in_dotted_form name [name ...] names are
9890 whitespace-separated. Lines beginning with an hash (#)
9891 character are comments.
9893 The file is checked at startup and upon configuration.
9894 If set to 'none', it won't be checked.
9895 If append_domain is used, that domain will be added to
9896 domain-local (i.e. not containing any dot character) host
9902 LOC: Config.appendDomain
9904 DEFAULT_DOC: Use operating system definitions
9906 Appends local domain name to hostnames without any dots in
9907 them. append_domain must begin with a period.
9909 Be warned there are now Internet names with no dots in
9910 them using only top-domain names, so setting this may
9911 cause some Internet sites to become unavailable.
9914 append_domain .yourdomain.com
9917 NAME: ignore_unknown_nameservers
9919 LOC: Config.onoff.ignore_unknown_nameservers
9922 By default Squid checks that DNS responses are received
9923 from the same IP addresses they are sent to. If they
9924 don't match, Squid ignores the response and writes a warning
9925 message to cache.log. You can allow responses from unknown
9926 nameservers by setting this option to 'off'.
9932 LOC: Config.dns.v4_first
9934 With the IPv6 Internet being as fast or faster than IPv4 Internet
9935 for most networks Squid prefers to contact websites over IPv6.
9937 This option reverses the order of preference to make Squid contact
9938 dual-stack websites over IPv4 first. Squid will still perform both
9939 IPv6 and IPv4 DNS lookups before connecting.
9942 This option will restrict the situations under which IPv6
9943 connectivity is used (and tested). Hiding network problems
9944 which would otherwise be detected and warned about.
9948 COMMENT: (number of entries)
9951 LOC: Config.ipcache.size
9953 Maximum number of DNS IP cache entries.
9960 LOC: Config.ipcache.low
9967 LOC: Config.ipcache.high
9969 The size, low-, and high-water marks for the IP cache.
9972 NAME: fqdncache_size
9973 COMMENT: (number of entries)
9976 LOC: Config.fqdncache.size
9978 Maximum number of FQDN cache entries.
9983 -----------------------------------------------------------------------------
9986 NAME: configuration_includes_quoted_values
9988 TYPE: configuration_includes_quoted_values
9990 LOC: ConfigParser::RecognizeQuotedValues
9992 If set, Squid will recognize each "quoted string" after a configuration
9993 directive as a single parameter. The quotes are stripped before the
9994 parameter value is interpreted or used.
9995 See "Values with spaces, quotes, and other special characters"
9996 section for more details.
10003 LOC: Config.onoff.mem_pools
10005 If set, Squid will keep pools of allocated (but unused) memory
10006 available for future use. If memory is a premium on your
10007 system and you believe your malloc library outperforms Squid
10008 routines, disable this.
10011 NAME: memory_pools_limit
10015 LOC: Config.MemPools.limit
10017 Used only with memory_pools on:
10018 memory_pools_limit 50 MB
10020 If set to a non-zero value, Squid will keep at most the specified
10021 limit of allocated (but unused) memory in memory pools. All free()
10022 requests that exceed this limit will be handled by your malloc
10023 library. Squid does not pre-allocate any memory, just safe-keeps
10024 objects that otherwise would be free()d. Thus, it is safe to set
10025 memory_pools_limit to a reasonably high value even if your
10026 configuration will use less memory.
10028 If set to none, Squid will keep all memory it can. That is, there
10029 will be no limit on the total amount of memory used for safe-keeping.
10031 To disable memory allocation optimization, do not set
10032 memory_pools_limit to 0 or none. Set memory_pools to "off" instead.
10034 An overhead for maintaining memory pools is not taken into account
10035 when the limit is checked. This overhead is close to four bytes per
10036 object kept. However, pools may actually _save_ memory because of
10037 reduced memory thrashing in your malloc library.
10040 NAME: forwarded_for
10041 COMMENT: on|off|transparent|truncate|delete
10044 LOC: opt_forwarded_for
10046 If set to "on", Squid will append your client's IP address
10047 in the HTTP requests it forwards. By default it looks like:
10049 X-Forwarded-For: 192.1.2.3
10051 If set to "off", it will appear as
10053 X-Forwarded-For: unknown
10055 If set to "transparent", Squid will not alter the
10056 X-Forwarded-For header in any way.
10058 If set to "delete", Squid will delete the entire
10059 X-Forwarded-For header.
10061 If set to "truncate", Squid will remove all existing
10062 X-Forwarded-For entries, and place the client IP as the sole entry.
10065 NAME: cachemgr_passwd
10066 TYPE: cachemgrpasswd
10068 DEFAULT_DOC: No password. Actions which require password are denied.
10069 LOC: Config.passwd_list
10071 Specify passwords for cachemgr operations.
10073 Usage: cachemgr_passwd password action action ...
10075 Some valid actions are (see cache manager menu for a full list):
10115 * Indicates actions which will not be performed without a
10116 valid password, others can be performed if not listed here.
10118 To disable an action, set the password to "disable".
10119 To allow performing an action without a password, set the
10120 password to "none".
10122 Use the keyword "all" to set the same password for all actions.
10125 cachemgr_passwd secret shutdown
10126 cachemgr_passwd lesssssssecret info stats/objects
10127 cachemgr_passwd disable all
10134 LOC: Config.onoff.client_db
10136 If you want to disable collecting per-client statistics,
10137 turn off client_db here.
10140 NAME: refresh_all_ims
10144 LOC: Config.onoff.refresh_all_ims
10146 When you enable this option, squid will always check
10147 the origin server for an update when a client sends an
10148 If-Modified-Since request. Many browsers use IMS
10149 requests when the user requests a reload, and this
10150 ensures those clients receive the latest version.
10152 By default (off), squid may return a Not Modified response
10153 based on the age of the cached version.
10156 NAME: reload_into_ims
10157 IFDEF: USE_HTTP_VIOLATIONS
10161 LOC: Config.onoff.reload_into_ims
10163 When you enable this option, client no-cache or ``reload''
10164 requests will be changed to If-Modified-Since requests.
10165 Doing this VIOLATES the HTTP standard. Enabling this
10166 feature could make you liable for problems which it
10169 see also refresh_pattern for a more selective approach.
10172 NAME: connect_retries
10174 LOC: Config.connect_retries
10176 DEFAULT_DOC: Do not retry failed connections.
10178 Limits the number of reopening attempts when establishing a single
10179 TCP connection. All these attempts must still complete before the
10180 applicable connection opening timeout expires.
10182 By default and when connect_retries is set to zero, Squid does not
10183 retry failed connection opening attempts.
10185 The (not recommended) maximum is 10 tries. An attempt to configure a
10186 higher value results in the value of 10 being used (with a warning).
10188 Squid may open connections to retry various high-level forwarding
10189 failures. For an outside observer, that activity may look like a
10190 low-level connection reopening attempt, but those high-level retries
10191 are governed by forward_max_tries instead.
10193 See also: connect_timeout, forward_timeout, icap_connect_timeout,
10194 ident_timeout, and forward_max_tries.
10197 NAME: retry_on_error
10199 LOC: Config.retry.onerror
10202 If set to ON Squid will automatically retry requests when
10203 receiving an error response with status 403 (Forbidden),
10204 500 (Internal Error), 501 or 503 (Service not available).
10205 Status 502 and 504 (Gateway errors) are always retried.
10207 This is mainly useful if you are in a complex cache hierarchy to
10208 work around access control errors.
10210 NOTE: This retry will attempt to find another working destination.
10211 Which is different from the server which just failed.
10214 NAME: as_whois_server
10216 LOC: Config.as_whois_server
10217 DEFAULT: whois.ra.net
10219 WHOIS server to query for AS numbers. NOTE: AS numbers are
10220 queried only when Squid starts up, not for every request.
10225 LOC: Config.onoff.offline
10228 Enable this option and Squid will never try to validate cached
10232 NAME: uri_whitespace
10233 TYPE: uri_whitespace
10234 LOC: Config.uri_whitespace
10237 What to do with requests that have whitespace characters in the
10240 strip: The whitespace characters are stripped out of the URL.
10241 This is the behavior recommended by RFC2396 and RFC3986
10242 for tolerant handling of generic URI.
10243 NOTE: This is one difference between generic URI and HTTP URLs.
10245 deny: The request is denied. The user receives an "Invalid
10247 This is the behaviour recommended by RFC2616 for safe
10248 handling of HTTP request URL.
10250 allow: The request is allowed and the URI is not changed. The
10251 whitespace characters remain in the URI. Note the
10252 whitespace is passed to redirector processes if they
10254 Note this may be considered a violation of RFC2616
10255 request parsing where whitespace is prohibited in the
10258 encode: The request is allowed and the whitespace characters are
10259 encoded according to RFC1738.
10261 chop: The request is allowed and the URI is chopped at the
10265 NOTE the current Squid implementation of encode and chop violates
10266 RFC2616 by not using a 301 redirect after altering the URL.
10271 LOC: Config.chroot_dir
10274 Specifies a directory where Squid should do a chroot() while
10275 initializing. This also causes Squid to fully drop root
10276 privileges after initializing. This means, for example, if you
10277 use a HTTP port less than 1024 and try to reconfigure, you may
10278 get an error saying that Squid can not open the port.
10281 NAME: pipeline_prefetch
10282 TYPE: pipelinePrefetch
10283 LOC: Config.pipeline_max_prefetch
10285 DEFAULT_DOC: Do not pre-parse pipelined requests.
10287 HTTP clients may send a pipeline of 1+N requests to Squid using a
10288 single connection, without waiting for Squid to respond to the first
10289 of those requests. This option limits the number of concurrent
10290 requests Squid will try to handle in parallel. If set to N, Squid
10291 will try to receive and process up to 1+N requests on the same
10292 connection concurrently.
10294 Defaults to 0 (off) for bandwidth management and access logging
10297 NOTE: pipelining requires persistent connections to clients.
10299 WARNING: pipelining breaks NTLM and Negotiate/Kerberos authentication.
10302 NAME: high_response_time_warning
10305 LOC: Config.warnings.high_rptm
10307 DEFAULT_DOC: disabled.
10309 If the one-minute median response time exceeds this value,
10310 Squid prints a WARNING with debug level 0 to get the
10311 administrators attention. The value is in milliseconds.
10314 NAME: high_page_fault_warning
10316 LOC: Config.warnings.high_pf
10318 DEFAULT_DOC: disabled.
10320 If the one-minute average page fault rate exceeds this
10321 value, Squid prints a WARNING with debug level 0 to get
10322 the administrators attention. The value is in page faults
10326 NAME: high_memory_warning
10328 LOC: Config.warnings.high_memory
10329 IFDEF: HAVE_MSTATS&&HAVE_GNUMALLOC_H
10331 DEFAULT_DOC: disabled.
10333 If the memory usage (as determined by gnumalloc, if available and used)
10334 exceeds this amount, Squid prints a WARNING with debug level 0 to get
10335 the administrators attention.
10337 # TODO: link high_memory_warning to mempools?
10339 NAME: sleep_after_fork
10340 COMMENT: (microseconds)
10342 LOC: Config.sleep_after_fork
10345 When this is set to a non-zero value, the main Squid process
10346 sleeps the specified number of microseconds after a fork()
10347 system call. This sleep may help the situation where your
10348 system reports fork() failures due to lack of (virtual)
10349 memory. Note, however, if you have a lot of child
10350 processes, these sleep delays will add up and your
10351 Squid will not service requests for some amount of time
10352 until all the child processes have been started.
10353 On Windows value less then 1000 (1 milliseconds) are
10357 NAME: windows_ipaddrchangemonitor
10358 IFDEF: _SQUID_WINDOWS_
10362 LOC: Config.onoff.WIN32_IpAddrChangeMonitor
10364 On Windows Squid by default will monitor IP address changes and will
10365 reconfigure itself after any detected event. This is very useful for
10366 proxies connected to internet with dial-up interfaces.
10367 In some cases (a Proxy server acting as VPN gateway is one) it could be
10368 desiderable to disable this behaviour setting this to 'off'.
10369 Note: after changing this, Squid service must be restarted.
10374 IFDEF: USE_SQUID_EUI
10376 LOC: Eui::TheConfig.euiLookup
10378 Whether to lookup the EUI or MAC address of a connected client.
10381 NAME: max_filedescriptors max_filedesc
10384 DEFAULT_DOC: Use operating system limits set by ulimit.
10385 LOC: Config.max_filedescriptors
10387 Reduce the maximum number of filedescriptors supported below
10388 the usual operating system defaults.
10390 Remove from squid.conf to inherit the current ulimit setting.
10392 Note: Changing this requires a restart of Squid. Also
10393 not all I/O types supports large values (eg on Windows).
10396 NAME: force_request_body_continuation
10398 LOC: Config.accessList.forceRequestBodyContinuation
10400 DEFAULT_DOC: Deny, unless rules exist in squid.conf.
10402 This option controls how Squid handles data upload requests from HTTP
10403 and FTP agents that require a "Please Continue" control message response
10404 to actually send the request body to Squid. It is mostly useful in
10405 adaptation environments.
10407 When Squid receives an HTTP request with an "Expect: 100-continue"
10408 header or an FTP upload command (e.g., STOR), Squid normally sends the
10409 request headers or FTP command information to an adaptation service (or
10410 peer) and waits for a response. Most adaptation services (and some
10411 broken peers) may not respond to Squid at that stage because they may
10412 decide to wait for the HTTP request body or FTP data transfer. However,
10413 that request body or data transfer may never come because Squid has not
10414 responded with the HTTP 100 or FTP 150 (Please Continue) control message
10415 to the request sender yet!
10417 An allow match tells Squid to respond with the HTTP 100 or FTP 150
10418 (Please Continue) control message on its own, before forwarding the
10419 request to an adaptation service or peer. Such a response usually forces
10420 the request sender to proceed with sending the body. A deny match tells
10421 Squid to delay that control response until the origin server confirms
10422 that the request body is needed. Delaying is the default behavior.
10425 NAME: server_pconn_for_nonretriable
10428 DEFAULT_DOC: Open new connections for forwarding requests Squid cannot retry safely.
10429 LOC: Config.accessList.serverPconnForNonretriable
10431 This option provides fine-grained control over persistent connection
10432 reuse when forwarding HTTP requests that Squid cannot retry. It is useful
10433 in environments where opening new connections is very expensive
10434 (e.g., all connections are secured with TLS with complex client and server
10435 certificate validation) and race conditions associated with persistent
10436 connections are very rare and/or only cause minor problems.
10438 HTTP prohibits retrying unsafe and non-idempotent requests (e.g., POST).
10439 Squid limitations also prohibit retrying all requests with bodies (e.g., PUT).
10440 By default, when forwarding such "risky" requests, Squid opens a new
10441 connection to the server or cache_peer, even if there is an idle persistent
10442 connection available. When Squid is configured to risk sending a non-retriable
10443 request on a previously used persistent connection, and the server closes
10444 the connection before seeing that risky request, the user gets an error response
10445 from Squid. In most cases, that error response will be HTTP 502 (Bad Gateway)
10446 with ERR_ZERO_SIZE_OBJECT or ERR_WRITE_ERROR (peer connection reset) error detail.
10448 If an allow rule matches, Squid reuses an available idle persistent connection
10449 (if any) for the request that Squid cannot retry. If a deny rule matches, then
10450 Squid opens a new connection for the request that Squid cannot retry.
10452 This option does not affect requests that Squid can retry. They will reuse idle
10453 persistent connections (if any).
10455 This clause only supports fast acl types.
10456 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
10459 acl SpeedIsWorthTheRisk method POST
10460 server_pconn_for_nonretriable allow SpeedIsWorthTheRisk
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