1 ## Copyright (C) 1996-2016 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: chunked_request_body_max_size
258 Remove this line. Squid is now HTTP/1.1 compliant.
261 NAME: dns_v4_fallback
264 Remove this line. Squid performs a 'Happy Eyeballs' algorithm, the 'fallback' algorithm is no longer relevant.
267 NAME: emulate_httpd_log
270 Replace this with an access_log directive using the format 'common' or 'combined'.
276 Use a regular access.log with ACL limiting it to MISS events.
282 Remove this line. Configure FTP page display using the CSS controls in errorpages.css instead.
285 NAME: ignore_expect_100
288 Remove this line. The HTTP/1.1 feature is now fully supported by default.
294 Remove this option from your config. To log FQDN use %>A in the log format.
297 NAME: log_ip_on_direct
300 Remove this option from your config. To log server or peer names use %<A in the log format.
303 NAME: maximum_single_addr_tries
306 Replaced by connect_retries. The behaviour has changed, please read the documentation before altering.
309 NAME: referer_log referrer_log
312 Replace this with an access_log directive using the format 'referrer'.
318 Remove this line. The feature is supported by default in storage types where update is implemented.
321 NAME: url_rewrite_concurrency
324 Remove this line. Set the 'concurrency=' option of url_rewrite_children instead.
330 Replace this with an access_log directive using the format 'useragent'.
333 # Options Removed in 3.1
337 Remove this line. DNS is no longer tested on startup.
340 NAME: extension_methods
343 Remove this line. All valid methods for HTTP are accepted by default.
346 # 2.7 Options Removed/Replaced in 3.2
351 # 2.7 Options Removed/Replaced in 3.1
359 Remove this line. HTTP/1.1 is supported by default.
362 NAME: upgrade_http0.9
365 Remove this line. ICY/1.0 streaming protocol is supported by default.
368 NAME: zph_local zph_mode zph_option zph_parent zph_sibling
371 Alter these entries. Use the qos_flows directive instead.
374 # Options Removed in 3.0
378 Since squid-3.0 replace with request_header_access or reply_header_access
379 depending on whether you wish to match client requests or server replies.
382 NAME: httpd_accel_no_pmtu_disc
385 Since squid-3.0 use the 'disable-pmtu-discovery' flag on http_port instead.
388 NAME: wais_relay_host
391 Replace this line with 'cache_peer' configuration.
394 NAME: wais_relay_port
397 Replace this line with 'cache_peer' configuration.
402 -----------------------------------------------------------------------------
409 DEFAULT_DOC: SMP support disabled.
411 Number of main Squid processes or "workers" to fork and maintain.
412 0: "no daemon" mode, like running "squid -N ..."
413 1: "no SMP" mode, start one main Squid process daemon (default)
414 N: start N main Squid process daemons (i.e., SMP mode)
416 In SMP mode, each worker does nearly all what a single Squid daemon
417 does (e.g., listen on http_port and forward HTTP requests).
420 NAME: cpu_affinity_map
422 LOC: Config.cpuAffinityMap
424 DEFAULT_DOC: Let operating system decide.
426 Usage: cpu_affinity_map process_numbers=P1,P2,... cores=C1,C2,...
428 Sets 1:1 mapping between Squid processes and CPU cores. For example,
430 cpu_affinity_map process_numbers=1,2,3,4 cores=1,3,5,7
432 affects processes 1 through 4 only and places them on the first
433 four even cores, starting with core #1.
435 CPU cores are numbered starting from 1. Requires support for
436 sched_getaffinity(2) and sched_setaffinity(2) system calls.
438 Multiple cpu_affinity_map options are merged.
443 NAME: shared_memory_locking
446 LOC: Config.shmLocking
449 Whether to ensure that all required shared memory is available by
450 "locking" that shared memory into RAM when Squid starts. The
451 alternative is faster startup time followed by slightly slower
452 performance and, if not enough RAM is actually available during
453 runtime, mysterious crashes.
455 SMP Squid uses many shared memory segments. These segments are
456 brought into Squid memory space using an mmap(2) system call. During
457 Squid startup, the mmap() call often succeeds regardless of whether
458 the system has enough RAM. In general, Squid cannot tell whether the
459 kernel applies this "optimistic" memory allocation policy (but
460 popular modern kernels usually use it).
462 Later, if Squid attempts to actually access the mapped memory
463 regions beyond what the kernel is willing to allocate, the
464 "optimistic" kernel simply kills Squid kid with a SIGBUS signal.
465 Some of the memory limits enforced by the kernel are currently
466 poorly understood: We do not know how to detect and check them. This
467 option ensures that the mapped memory will be available.
469 This option may have a positive performance side-effect: Locking
470 memory at start avoids runtime paging I/O. Paging slows Squid down.
472 Locking memory may require a large enough RLIMIT_MEMLOCK OS limit,
473 CAP_IPC_LOCK capability, or equivalent.
477 OPTIONS FOR AUTHENTICATION
478 -----------------------------------------------------------------------------
487 This is used to define parameters for the various authentication
488 schemes supported by Squid.
490 format: auth_param scheme parameter [setting]
492 The order in which authentication schemes are presented to the client is
493 dependent on the order the scheme first appears in config file. IE
494 has a bug (it's not RFC 2617 compliant) in that it will use the basic
495 scheme if basic is the first entry presented, even if more secure
496 schemes are presented. For now use the order in the recommended
497 settings section below. If other browsers have difficulties (don't
498 recognize the schemes offered even if you are using basic) either
499 put basic first, or disable the other schemes (by commenting out their
502 Once an authentication scheme is fully configured, it can only be
503 shutdown by shutting squid down and restarting. Changes can be made on
504 the fly and activated with a reconfigure. I.E. You can change to a
505 different helper, but not unconfigure the helper completely.
507 Please note that while this directive defines how Squid processes
508 authentication it does not automatically activate authentication.
509 To use authentication you must in addition make use of ACLs based
510 on login name in http_access (proxy_auth, proxy_auth_regex or
511 external with %LOGIN used in the format tag). The browser will be
512 challenged for authentication on the first such acl encountered
513 in http_access processing and will also be re-challenged for new
514 login credentials if the request is being denied by a proxy_auth
517 WARNING: authentication can't be used in a transparently intercepting
518 proxy as the client then thinks it is talking to an origin server and
519 not the proxy. This is a limitation of bending the TCP/IP protocol to
520 transparently intercepting port 80, not a limitation in Squid.
521 Ports flagged 'transparent', 'intercept', or 'tproxy' have
522 authentication disabled.
524 === Parameters common to all schemes. ===
527 Specifies the command for the external authenticator.
529 By default, each authentication scheme is not used unless a
530 program is specified.
532 See http://wiki.squid-cache.org/Features/AddonHelpers for
533 more details on helper operations and creating your own.
536 Specifies a string to be append to request line format for
537 the authentication helper. "Quoted" format values may contain
538 spaces and logformat %macros. In theory, any logformat %macro
539 can be used. In practice, a %macro expands as a dash (-) if
540 the helper request is sent before the required macro
541 information is available to Squid.
543 By default, Squid uses request formats provided in
544 scheme-specific examples below (search for %credentials).
546 The expanded key_extras value is added to the Squid credentials
547 cache and, hence, will affect authentication. It can be used to
548 autenticate different users with identical user names (e.g.,
549 when user authentication depends on http_port).
551 Avoid adding frequently changing information to key_extras. For
552 example, if you add user source IP, and it changes frequently
553 in your environment, then max_user_ip ACL is going to treat
554 every user+IP combination as a unique "user", breaking the ACL
555 and wasting a lot of memory on those user records. It will also
556 force users to authenticate from scratch whenever their IP
560 Specifies the protection scope (aka realm name) which is to be
561 reported to the client for the authentication scheme. It is
562 commonly part of the text the user will see when prompted for
563 their username and password.
565 For Basic the default is "Squid proxy-caching web server".
566 For Digest there is no default, this parameter is mandatory.
567 For NTLM and Negotiate this parameter is ignored.
569 "children" numberofchildren [startup=N] [idle=N] [concurrency=N] [queue-size=N]
571 The maximum number of authenticator processes to spawn. If
572 you start too few Squid will have to wait for them to process
573 a backlog of credential verifications, slowing it down. When
574 password verifications are done via a (slow) network you are
575 likely to need lots of authenticator processes.
577 The startup= and idle= options permit some skew in the exact
578 amount run. A minimum of startup=N will begin during startup
579 and reconfigure. Squid will start more in groups of up to
580 idle=N in an attempt to meet traffic needs and to keep idle=N
581 free above those traffic needs up to the maximum.
583 The concurrency= option sets the number of concurrent requests
584 the helper can process. The default of 0 is used for helpers
585 who only supports one request at a time. Setting this to a
586 number greater than 0 changes the protocol used to include a
587 channel ID field first on the request/response line, allowing
588 multiple requests to be sent to the same helper in parallel
589 without waiting for the response.
591 Concurrency must not be set unless it's known the helper
592 supports the input format with channel-ID fields.
594 The queue-size= option sets the maximum number of queued
595 requests. If the queued requests exceed queue size for more
596 than 3 minutes then squid aborts its operation.
597 The default value is set to 2*numberofchildren/
599 NOTE: NTLM and Negotiate schemes do not support concurrency
600 in the Squid code module even though some helpers can.
603 IF HAVE_AUTH_MODULE_BASIC
604 === Basic authentication parameters ===
607 HTTP uses iso-latin-1 as character set, while some
608 authentication backends such as LDAP expects UTF-8. If this is
609 set to on Squid will translate the HTTP iso-latin-1 charset to
610 UTF-8 before sending the username and password to the helper.
612 "credentialsttl" timetolive
613 Specifies how long squid assumes an externally validated
614 username:password pair is valid for - in other words how
615 often the helper program is called for that user. Set this
616 low to force revalidation with short lived passwords.
618 NOTE: setting this high does not impact your susceptibility
619 to replay attacks unless you are using an one-time password
620 system (such as SecureID). If you are using such a system,
621 you will be vulnerable to replay attacks unless you also
622 use the max_user_ip ACL in an http_access rule.
624 "casesensitive" on|off
625 Specifies if usernames are case sensitive. Most user databases
626 are case insensitive allowing the same username to be spelled
627 using both lower and upper case letters, but some are case
628 sensitive. This makes a big difference for user_max_ip ACL
629 processing and similar.
632 IF HAVE_AUTH_MODULE_DIGEST
633 === Digest authentication parameters ===
636 HTTP uses iso-latin-1 as character set, while some
637 authentication backends such as LDAP expects UTF-8. If this is
638 set to on Squid will translate the HTTP iso-latin-1 charset to
639 UTF-8 before sending the username and password to the helper.
641 "nonce_garbage_interval" timeinterval
642 Specifies the interval that nonces that have been issued
643 to client_agent's are checked for validity.
645 "nonce_max_duration" timeinterval
646 Specifies the maximum length of time a given nonce will be
649 "nonce_max_count" number
650 Specifies the maximum number of times a given nonce can be
653 "nonce_strictness" on|off
654 Determines if squid requires strict increment-by-1 behavior
655 for nonce counts, or just incrementing (off - for use when
656 user agents generate nonce counts that occasionally miss 1
657 (ie, 1,2,4,6)). Default off.
659 "check_nonce_count" on|off
660 This directive if set to off can disable the nonce count check
661 completely to work around buggy digest qop implementations in
662 certain mainstream browser versions. Default on to check the
663 nonce count to protect from authentication replay attacks.
665 "post_workaround" on|off
666 This is a workaround to certain buggy browsers who send an
667 incorrect request digest in POST requests when reusing the
668 same nonce as acquired earlier on a GET request.
671 IF HAVE_AUTH_MODULE_NEGOTIATE
672 === Negotiate authentication parameters ===
675 If you experience problems with PUT/POST requests when using
676 the this authentication scheme then you can try setting this
677 to off. This will cause Squid to forcibly close the connection
678 on the initial request where the browser asks which schemes
679 are supported by the proxy.
682 IF HAVE_AUTH_MODULE_NTLM
683 === NTLM authentication parameters ===
686 If you experience problems with PUT/POST requests when using
687 the this authentication scheme then you can try setting this
688 to off. This will cause Squid to forcibly close the connection
689 on the initial request where the browser asks which schemes
690 are supported by the proxy.
693 === Example Configuration ===
695 This configuration displays the recommended authentication scheme
696 order from most to least secure with recommended minimum configuration
697 settings for each scheme:
699 #auth_param negotiate program <uncomment and complete this line to activate>
700 #auth_param negotiate children 20 startup=0 idle=1
701 #auth_param negotiate keep_alive on
703 #auth_param digest program <uncomment and complete this line to activate>
704 #auth_param digest children 20 startup=0 idle=1
705 #auth_param digest realm Squid proxy-caching web server
706 #auth_param digest nonce_garbage_interval 5 minutes
707 #auth_param digest nonce_max_duration 30 minutes
708 #auth_param digest nonce_max_count 50
710 #auth_param ntlm program <uncomment and complete this line to activate>
711 #auth_param ntlm children 20 startup=0 idle=1
712 #auth_param ntlm keep_alive on
714 #auth_param basic program <uncomment and complete this line>
715 #auth_param basic children 5 startup=5 idle=1
716 #auth_param basic realm Squid proxy-caching web server
717 #auth_param basic credentialsttl 2 hours
720 NAME: authenticate_cache_garbage_interval
723 LOC: Config.authenticateGCInterval
725 The time period between garbage collection across the username cache.
726 This is a trade-off between memory utilization (long intervals - say
727 2 days) and CPU (short intervals - say 1 minute). Only change if you
731 NAME: authenticate_ttl
734 LOC: Config.authenticateTTL
736 The time a user & their credentials stay in the logged in
737 user cache since their last request. When the garbage
738 interval passes, all user credentials that have passed their
739 TTL are removed from memory.
742 NAME: authenticate_ip_ttl
744 LOC: Config.authenticateIpTTL
747 If you use proxy authentication and the 'max_user_ip' ACL,
748 this directive controls how long Squid remembers the IP
749 addresses associated with each user. Use a small value
750 (e.g., 60 seconds) if your users might change addresses
751 quickly, as is the case with dialup. You might be safe
752 using a larger value (e.g., 2 hours) in a corporate LAN
753 environment with relatively static address assignments.
758 -----------------------------------------------------------------------------
761 NAME: external_acl_type
762 TYPE: externalAclHelper
763 LOC: Config.externalAclHelperList
766 This option defines external acl classes using a helper program
767 to look up the status
769 external_acl_type name [options] FORMAT /path/to/helper [helper arguments]
773 ttl=n TTL in seconds for cached results (defaults to 3600
777 TTL for cached negative lookups (default same
780 grace=n Percentage remaining of TTL where a refresh of a
781 cached entry should be initiated without needing to
782 wait for a new reply. (default is for no grace period)
784 cache=n The maximum number of entries in the result cache. The
785 default limit is 262144 entries. Each cache entry usually
786 consumes at least 256 bytes. Squid currently does not remove
787 expired cache entries until the limit is reached, so a proxy
788 will sooner or later reach the limit. The expanded FORMAT
789 value is used as the cache key, so if the details in FORMAT
790 are highly variable, a larger cache may be needed to produce
791 reduction in helper load.
794 Maximum number of acl helper processes spawned to service
795 external acl lookups of this type. (default 20)
798 Minimum number of acl helper processes to spawn during
799 startup and reconfigure to service external acl lookups
800 of this type. (default 0)
803 Number of acl helper processes to keep ahead of traffic
804 loads. Squid will spawn this many at once whenever load
805 rises above the capabilities of existing processes.
806 Up to the value of children-max. (default 1)
808 concurrency=n concurrency level per process. Only used with helpers
809 capable of processing more than one query at a time.
811 queue-size=N The queue-size= option sets the maximum number of queued
812 requests. If the queued requests exceed queue size
814 The default value is set to 2*children-max.
816 protocol=2.5 Compatibility mode for Squid-2.5 external acl helpers.
818 ipv4 / ipv6 IP protocol used to communicate with this helper.
819 The default is to auto-detect IPv6 and use it when available.
822 FORMAT is a series of %macro codes. See logformat directive for a full list
823 of the accepted codes. Although note that at the time of any external ACL
824 being tested data may not be available and thus some %macro expand to '-'.
826 In addition to the logformat codes; when processing external ACLs these
827 additional macros are made available:
829 %ACL The name of the ACL being tested.
831 %DATA The ACL arguments specified in the referencing config
832 'acl ... external' line, separated by spaces (an
833 "argument string"). see acl external.
835 If there are no ACL arguments %DATA expands to '-'.
837 If you do not specify a DATA macro inside FORMAT,
838 Squid automatically appends %DATA to your FORMAT.
840 By default, Squid applies URL-encoding to each ACL
841 argument inside the argument string. If an explicit
842 encoding modifier is used (e.g., %#DATA), then Squid
843 encodes the whole argument string as a single token
844 (e.g., with %#DATA, spaces between arguments become
847 If SSL is enabled, the following formating codes become available:
849 %USER_CERT SSL User certificate in PEM format
850 %USER_CERTCHAIN SSL User certificate chain in PEM format
851 %USER_CERT_xx SSL User certificate subject attribute xx
852 %USER_CA_CERT_xx SSL User certificate issuer attribute xx
855 NOTE: all other format codes accepted by older Squid versions
859 General request syntax:
861 [channel-ID] FORMAT-values
864 FORMAT-values consists of transaction details expanded with
865 whitespace separation per the config file FORMAT specification
866 using the FORMAT macros listed above.
868 Request values sent to the helper are URL escaped to protect
869 each value in requests against whitespaces.
871 If using protocol=2.5 then the request sent to the helper is not
872 URL escaped to protect against whitespace.
874 NOTE: protocol=3.0 is deprecated as no longer necessary.
876 When using the concurrency= option the protocol is changed by
877 introducing a query channel tag in front of the request/response.
878 The query channel tag is a number between 0 and concurrency-1.
879 This value must be echoed back unchanged to Squid as the first part
880 of the response relating to its request.
883 The helper receives lines expanded per the above format specification
884 and for each input line returns 1 line starting with OK/ERR/BH result
885 code and optionally followed by additional keywords with more details.
888 General result syntax:
890 [channel-ID] result keyword=value ...
892 Result consists of one of the codes:
895 the ACL test produced a match.
898 the ACL test does not produce a match.
901 An internal error occurred in the helper, preventing
902 a result being identified.
904 The meaning of 'a match' is determined by your squid.conf
905 access control configuration. See the Squid wiki for details.
909 user= The users name (login)
911 password= The users password (for login= cache_peer option)
913 message= Message describing the reason for this response.
914 Available as %o in error pages.
915 Useful on (ERR and BH results).
917 tag= Apply a tag to a request. Only sets a tag once,
918 does not alter existing tags.
920 log= String to be logged in access.log. Available as
921 %ea in logformat specifications.
923 clt_conn_tag= Associates a TAG with the client TCP connection.
924 Please see url_rewrite_program related documentation
927 Any keywords may be sent on any response whether OK, ERR or BH.
929 All response keyword values need to be a single token with URL
930 escaping, or enclosed in double quotes (") and escaped using \ on
931 any double quotes or \ characters within the value. The wrapping
932 double quotes are removed before the value is interpreted by Squid.
933 \r and \n are also replace by CR and LF.
935 Some example key values:
939 user="J. \"Bob\" Smith"
946 DEFAULT: ssl::certHasExpired ssl_error X509_V_ERR_CERT_HAS_EXPIRED
947 DEFAULT: ssl::certNotYetValid ssl_error X509_V_ERR_CERT_NOT_YET_VALID
948 DEFAULT: ssl::certDomainMismatch ssl_error SQUID_X509_V_ERR_DOMAIN_MISMATCH
949 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
950 DEFAULT: ssl::certSelfSigned ssl_error X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT
953 DEFAULT: manager url_regex -i ^cache_object:// +i ^https?://[^/]+/squid-internal-mgr/
954 DEFAULT: localhost src 127.0.0.1/32 ::1
955 DEFAULT: to_localhost dst 127.0.0.0/8 0.0.0.0/32 ::1
956 DEFAULT_DOC: ACLs all, manager, localhost, and to_localhost are predefined.
958 Defining an Access List
960 Every access list definition must begin with an aclname and acltype,
961 followed by either type-specific arguments or a quoted filename that
964 acl aclname acltype argument ...
965 acl aclname acltype "file" ...
967 When using "file", the file should contain one item per line.
972 Some acl types supports options which changes their default behaviour:
974 -i,+i By default, regular expressions are CASE-SENSITIVE. To make them
975 case-insensitive, use the -i option. To return case-sensitive
976 use the +i option between patterns, or make a new ACL line
979 -n Disable lookups and address type conversions. If lookup or
980 conversion is required because the parameter type (IP or
981 domain name) does not match the message address type (domain
982 name or IP), then the ACL would immediately declare a mismatch
983 without any warnings or lookups.
986 Perform a list membership test, interpreting values as
987 comma-separated token lists and matching against individual
988 tokens instead of whole values.
989 The optional "delimiters" parameter specifies one or more
990 alternative non-alphanumeric delimiter characters.
991 non-alphanumeric delimiter characters.
993 -- Used to stop processing all options, in the case the first acl
994 value has '-' character as first character (for example the '-'
995 is a valid domain name)
997 Some acl types require suspending the current request in order
998 to access some external data source.
999 Those which do are marked with the tag [slow], those which
1000 don't are marked as [fast].
1001 See http://wiki.squid-cache.org/SquidFaq/SquidAcl
1002 for further information
1004 ***** ACL TYPES AVAILABLE *****
1006 acl aclname src ip-address/mask ... # clients IP address [fast]
1007 acl aclname src addr1-addr2/mask ... # range of addresses [fast]
1008 acl aclname dst [-n] ip-address/mask ... # URL host's IP address [slow]
1009 acl aclname localip ip-address/mask ... # IP address the client connected to [fast]
1011 acl aclname arp mac-address ... (xx:xx:xx:xx:xx:xx notation)
1013 # The 'arp' ACL code is not portable to all operating systems.
1014 # It works on Linux, Solaris, Windows, FreeBSD, and some other
1017 # NOTE: Squid can only determine the MAC/EUI address for IPv4
1018 # clients that are on the same subnet. If the client is on a
1019 # different subnet, then Squid cannot find out its address.
1021 # NOTE 2: IPv6 protocol does not contain ARP. MAC/EUI is either
1022 # encoded directly in the IPv6 address or not available.
1024 acl aclname srcdomain .foo.com ...
1025 # reverse lookup, from client IP [slow]
1026 acl aclname dstdomain [-n] .foo.com ...
1027 # Destination server from URL [fast]
1028 acl aclname srcdom_regex [-i] \.foo\.com ...
1029 # regex matching client name [slow]
1030 acl aclname dstdom_regex [-n] [-i] \.foo\.com ...
1031 # regex matching server [fast]
1033 # For dstdomain and dstdom_regex a reverse lookup is tried if a IP
1034 # based URL is used and no match is found. The name "none" is used
1035 # if the reverse lookup fails.
1037 acl aclname src_as number ...
1038 acl aclname dst_as number ...
1040 # Except for access control, AS numbers can be used for
1041 # routing of requests to specific caches. Here's an
1042 # example for routing all requests for AS#1241 and only
1043 # those to mycache.mydomain.net:
1044 # acl asexample dst_as 1241
1045 # cache_peer_access mycache.mydomain.net allow asexample
1046 # cache_peer_access mycache_mydomain.net deny all
1048 acl aclname peername myPeer ...
1050 # match against a named cache_peer entry
1051 # set unique name= on cache_peer lines for reliable use.
1053 acl aclname time [day-abbrevs] [h1:m1-h2:m2]
1063 # h1:m1 must be less than h2:m2
1065 acl aclname url_regex [-i] ^http:// ...
1066 # regex matching on whole URL [fast]
1067 acl aclname urllogin [-i] [^a-zA-Z0-9] ...
1068 # regex matching on URL login field
1069 acl aclname urlpath_regex [-i] \.gif$ ...
1070 # regex matching on URL path [fast]
1072 acl aclname port 80 70 21 0-1024... # destination TCP port [fast]
1074 acl aclname localport 3128 ... # TCP port the client connected to [fast]
1075 # NP: for interception mode this is usually '80'
1077 acl aclname myportname 3128 ... # *_port name [fast]
1079 acl aclname proto HTTP FTP ... # request protocol [fast]
1081 acl aclname method GET POST ... # HTTP request method [fast]
1083 acl aclname http_status 200 301 500- 400-403 ...
1084 # status code in reply [fast]
1086 acl aclname browser [-i] regexp ...
1087 # pattern match on User-Agent header (see also req_header below) [fast]
1089 acl aclname referer_regex [-i] regexp ...
1090 # pattern match on Referer header [fast]
1091 # Referer is highly unreliable, so use with care
1093 acl aclname ident username ...
1094 acl aclname ident_regex [-i] pattern ...
1095 # string match on ident output [slow]
1096 # use REQUIRED to accept any non-null ident.
1098 acl aclname proxy_auth [-i] username ...
1099 acl aclname proxy_auth_regex [-i] pattern ...
1100 # perform http authentication challenge to the client and match against
1101 # supplied credentials [slow]
1103 # takes a list of allowed usernames.
1104 # use REQUIRED to accept any valid username.
1106 # Will use proxy authentication in forward-proxy scenarios, and plain
1107 # http authenticaiton in reverse-proxy scenarios
1109 # NOTE: when a Proxy-Authentication header is sent but it is not
1110 # needed during ACL checking the username is NOT logged
1113 # NOTE: proxy_auth requires a EXTERNAL authentication program
1114 # to check username/password combinations (see
1115 # auth_param directive).
1117 # NOTE: proxy_auth can't be used in a transparent/intercepting proxy
1118 # as the browser needs to be configured for using a proxy in order
1119 # to respond to proxy authentication.
1121 acl aclname snmp_community string ...
1122 # A community string to limit access to your SNMP Agent [fast]
1125 # acl snmppublic snmp_community public
1127 acl aclname maxconn number
1128 # This will be matched when the client's IP address has
1129 # more than <number> TCP connections established. [fast]
1130 # NOTE: This only measures direct TCP links so X-Forwarded-For
1131 # indirect clients are not counted.
1133 acl aclname max_user_ip [-s] number
1134 # This will be matched when the user attempts to log in from more
1135 # than <number> different ip addresses. The authenticate_ip_ttl
1136 # parameter controls the timeout on the ip entries. [fast]
1137 # If -s is specified the limit is strict, denying browsing
1138 # from any further IP addresses until the ttl has expired. Without
1139 # -s Squid will just annoy the user by "randomly" denying requests.
1140 # (the counter is reset each time the limit is reached and a
1141 # request is denied)
1142 # NOTE: in acceleration mode or where there is mesh of child proxies,
1143 # clients may appear to come from multiple addresses if they are
1144 # going through proxy farms, so a limit of 1 may cause user problems.
1146 acl aclname random probability
1147 # Pseudo-randomly match requests. Based on the probability given.
1148 # Probability may be written as a decimal (0.333), fraction (1/3)
1149 # or ratio of matches:non-matches (3:5).
1151 acl aclname req_mime_type [-i] mime-type ...
1152 # regex match against the mime type of the request generated
1153 # by the client. Can be used to detect file upload or some
1154 # types HTTP tunneling requests [fast]
1155 # NOTE: This does NOT match the reply. You cannot use this
1156 # to match the returned file type.
1158 acl aclname req_header header-name [-i] any\.regex\.here
1159 # regex match against any of the known request headers. May be
1160 # thought of as a superset of "browser", "referer" and "mime-type"
1163 acl aclname rep_mime_type [-i] mime-type ...
1164 # regex match against the mime type of the reply received by
1165 # squid. Can be used to detect file download or some
1166 # types HTTP tunneling requests. [fast]
1167 # NOTE: This has no effect in http_access rules. It only has
1168 # effect in rules that affect the reply data stream such as
1169 # http_reply_access.
1171 acl aclname rep_header header-name [-i] any\.regex\.here
1172 # regex match against any of the known reply headers. May be
1173 # thought of as a superset of "browser", "referer" and "mime-type"
1176 acl aclname external class_name [arguments...]
1177 # external ACL lookup via a helper class defined by the
1178 # external_acl_type directive [slow]
1180 acl aclname user_cert attribute values...
1181 # match against attributes in a user SSL certificate
1182 # attribute is one of DN/C/O/CN/L/ST or a numerical OID [fast]
1184 acl aclname ca_cert attribute values...
1185 # match against attributes a users issuing CA SSL certificate
1186 # attribute is one of DN/C/O/CN/L/ST or a numerical OID [fast]
1188 acl aclname ext_user username ...
1189 acl aclname ext_user_regex [-i] pattern ...
1190 # string match on username returned by external acl helper [slow]
1191 # use REQUIRED to accept any non-null user name.
1193 acl aclname tag tagvalue ...
1194 # string match on tag returned by external acl helper [fast]
1195 # DEPRECATED. Only the first tag will match with this ACL.
1196 # Use the 'note' ACL instead for handling multiple tag values.
1198 acl aclname hier_code codename ...
1199 # string match against squid hierarchy code(s); [fast]
1200 # e.g., DIRECT, PARENT_HIT, NONE, etc.
1202 # NOTE: This has no effect in http_access rules. It only has
1203 # effect in rules that affect the reply data stream such as
1204 # http_reply_access.
1206 acl aclname note [-m[=delimiters]] name [value ...]
1207 # match transaction annotation [fast]
1208 # Without values, matches any annotation with a given name.
1209 # With value(s), matches any annotation with a given name that
1210 # also has one of the given values.
1211 # If the -m flag is used, then the value of the named
1212 # annotation is interpreted as a list of tokens, and the ACL
1213 # matches individual name=token pairs rather than whole
1214 # name=value pairs. See "ACL Options" above for more info.
1215 # Annotation sources include note and adaptation_meta directives
1216 # as well as helper and eCAP responses.
1218 acl aclname adaptation_service service ...
1219 # Matches the name of any icap_service, ecap_service,
1220 # adaptation_service_set, or adaptation_service_chain that Squid
1221 # has used (or attempted to use) for the master transaction.
1222 # This ACL must be defined after the corresponding adaptation
1223 # service is named in squid.conf. This ACL is usable with
1224 # adaptation_meta because it starts matching immediately after
1225 # the service has been selected for adaptation.
1228 acl aclname ssl_error errorname
1229 # match against SSL certificate validation error [fast]
1231 # For valid error names see in @DEFAULT_ERROR_DIR@/templates/error-details.txt
1234 # The following can be used as shortcuts for certificate properties:
1235 # [ssl::]certHasExpired: the "not after" field is in the past
1236 # [ssl::]certNotYetValid: the "not before" field is in the future
1237 # [ssl::]certUntrusted: The certificate issuer is not to be trusted.
1238 # [ssl::]certSelfSigned: The certificate is self signed.
1239 # [ssl::]certDomainMismatch: The certificate CN domain does not
1240 # match the name the name of the host we are connecting to.
1242 # The ssl::certHasExpired, ssl::certNotYetValid, ssl::certDomainMismatch,
1243 # ssl::certUntrusted, and ssl::certSelfSigned can also be used as
1244 # predefined ACLs, just like the 'all' ACL.
1246 # NOTE: The ssl_error ACL is only supported with sslproxy_cert_error,
1247 # sslproxy_cert_sign, and sslproxy_cert_adapt options.
1249 acl aclname server_cert_fingerprint [-sha1] fingerprint
1250 # match against server SSL certificate fingerprint [fast]
1252 # The fingerprint is the digest of the DER encoded version
1253 # of the whole certificate. The user should use the form: XX:XX:...
1254 # Optional argument specifies the digest algorithm to use.
1255 # The SHA1 digest algorithm is the default and is currently
1256 # the only algorithm supported (-sha1).
1258 acl aclname at_step step
1259 # match against the current step during ssl_bump evaluation [fast]
1260 # Never matches and should not be used outside the ssl_bump context.
1262 # At each SslBump step, Squid evaluates ssl_bump directives to find
1263 # the next bumping action (e.g., peek or splice). Valid SslBump step
1264 # values and the corresponding ssl_bump evaluation moments are:
1265 # SslBump1: After getting TCP-level and HTTP CONNECT info.
1266 # SslBump2: After getting SSL Client Hello info.
1267 # SslBump3: After getting SSL Server Hello info.
1269 acl aclname ssl::server_name .foo.com ...
1270 # matches server name obtained from various sources [fast]
1272 # The server name is obtained during Ssl-Bump steps from such sources
1273 # as CONNECT request URI, client SNI, and SSL server certificate CN.
1274 # During each Ssl-Bump step, Squid may improve its understanding of a
1275 # "true server name". Unlike dstdomain, this ACL does not perform
1278 acl aclname ssl::server_name_regex [-i] \.foo\.com ...
1279 # regex matches server name obtained from various sources [fast]
1281 acl aclname connections_encrypted
1282 # matches transactions with all HTTP messages received over TLS
1283 # transport connections. [fast]
1285 # The master transaction deals with HTTP messages received from
1286 # various sources. All sources used by the master transaction in the
1287 # past are considered by the ACL. The following rules define whether
1288 # a given message source taints the entire master transaction,
1289 # resulting in ACL mismatches:
1291 # * The HTTP client transport connection is not TLS.
1292 # * An adaptation service connection-encryption flag is off.
1293 # * The peer or origin server transport connection is not TLS.
1295 # Caching currently does not affect these rules. This cache ignorance
1296 # implies that only the current HTTP client transport and REQMOD
1297 # services status determine whether this ACL matches a from-cache
1298 # transaction. The source of the cached response does not have any
1299 # effect on future transaction that use the cached response without
1300 # revalidation. This may change.
1302 # DNS, ICP, and HTCP exchanges during the master transaction do not
1303 # affect these rules.
1305 acl aclname any-of acl1 acl2 ...
1306 # match any one of the acls [fast or slow]
1307 # The first matching ACL stops further ACL evaluation.
1309 # ACLs from multiple any-of lines with the same name are ORed.
1310 # For example, A = (a1 or a2) or (a3 or a4) can be written as
1311 # acl A any-of a1 a2
1312 # acl A any-of a3 a4
1314 # This group ACL is fast if all evaluated ACLs in the group are fast
1315 # and slow otherwise.
1317 acl aclname all-of acl1 acl2 ...
1318 # match all of the acls [fast or slow]
1319 # The first mismatching ACL stops further ACL evaluation.
1321 # ACLs from multiple all-of lines with the same name are ORed.
1322 # For example, B = (b1 and b2) or (b3 and b4) can be written as
1323 # acl B all-of b1 b2
1324 # acl B all-of b3 b4
1326 # This group ACL is fast if all evaluated ACLs in the group are fast
1327 # and slow otherwise.
1330 acl macaddress arp 09:00:2b:23:45:67
1331 acl myexample dst_as 1241
1332 acl password proxy_auth REQUIRED
1333 acl fileupload req_mime_type -i ^multipart/form-data$
1334 acl javascript rep_mime_type -i ^application/x-javascript$
1338 # Recommended minimum configuration:
1341 # Example rule allowing access from your local networks.
1342 # Adapt to list your (internal) IP networks from where browsing
1344 acl localnet src 0.0.0.1-0.255.255.255 # RFC 1122 "this" network (LAN)
1345 acl localnet src 10.0.0.0/8 # RFC 1918 local private network (LAN)
1346 acl localnet src 100.64.0.0/10 # RFC 6598 shared address space (CGN)
1347 acl localhet src 169.254.0.0/16 # RFC 3927 link-local (directly plugged) machines
1348 acl localnet src 172.16.0.0/12 # RFC 1918 local private network (LAN)
1349 acl localnet src 192.168.0.0/16 # RFC 1918 local private network (LAN)
1350 acl localnet src fc00::/7 # RFC 4193 local private network range
1351 acl localnet src fe80::/10 # RFC 4291 link-local (directly plugged) machines
1353 acl SSL_ports port 443
1354 acl Safe_ports port 80 # http
1355 acl Safe_ports port 21 # ftp
1356 acl Safe_ports port 443 # https
1357 acl Safe_ports port 70 # gopher
1358 acl Safe_ports port 210 # wais
1359 acl Safe_ports port 1025-65535 # unregistered ports
1360 acl Safe_ports port 280 # http-mgmt
1361 acl Safe_ports port 488 # gss-http
1362 acl Safe_ports port 591 # filemaker
1363 acl Safe_ports port 777 # multiling http
1364 acl CONNECT method CONNECT
1368 NAME: proxy_protocol_access
1370 LOC: Config.accessList.proxyProtocol
1372 DEFAULT_DOC: all TCP connections to ports with require-proxy-header will be denied
1374 Determine which client proxies can be trusted to provide correct
1375 information regarding real client IP address using PROXY protocol.
1377 Requests may pass through a chain of several other proxies
1378 before reaching us. The original source details may by sent in:
1379 * HTTP message Forwarded header, or
1380 * HTTP message X-Forwarded-For header, or
1381 * PROXY protocol connection header.
1383 This directive is solely for validating new PROXY protocol
1384 connections received from a port flagged with require-proxy-header.
1385 It is checked only once after TCP connection setup.
1387 A deny match results in TCP connection closure.
1389 An allow match is required for Squid to permit the corresponding
1390 TCP connection, before Squid even looks for HTTP request headers.
1391 If there is an allow match, Squid starts using PROXY header information
1392 to determine the source address of the connection for all future ACL
1393 checks, logging, etc.
1395 SECURITY CONSIDERATIONS:
1397 Any host from which we accept client IP details can place
1398 incorrect information in the relevant header, and Squid
1399 will use the incorrect information as if it were the
1400 source address of the request. This may enable remote
1401 hosts to bypass any access control restrictions that are
1402 based on the client's source addresses.
1404 This clause only supports fast acl types.
1405 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
1408 NAME: follow_x_forwarded_for
1410 IFDEF: FOLLOW_X_FORWARDED_FOR
1411 LOC: Config.accessList.followXFF
1412 DEFAULT_IF_NONE: deny all
1413 DEFAULT_DOC: X-Forwarded-For header will be ignored.
1415 Determine which client proxies can be trusted to provide correct
1416 information regarding real client IP address.
1418 Requests may pass through a chain of several other proxies
1419 before reaching us. The original source details may by sent in:
1420 * HTTP message Forwarded header, or
1421 * HTTP message X-Forwarded-For header, or
1422 * PROXY protocol connection header.
1424 PROXY protocol connections are controlled by the proxy_protocol_access
1425 directive which is checked before this.
1427 If a request reaches us from a source that is allowed by this
1428 directive, then we trust the information it provides regarding
1429 the IP of the client it received from (if any).
1431 For the purpose of ACLs used in this directive the src ACL type always
1432 matches the address we are testing and srcdomain matches its rDNS.
1434 On each HTTP request Squid checks for X-Forwarded-For header fields.
1435 If found the header values are iterated in reverse order and an allow
1436 match is required for Squid to continue on to the next value.
1437 The verification ends when a value receives a deny match, cannot be
1438 tested, or there are no more values to test.
1439 NOTE: Squid does not yet follow the Forwarded HTTP header.
1441 The end result of this process is an IP address that we will
1442 refer to as the indirect client address. This address may
1443 be treated as the client address for access control, ICAP, delay
1444 pools and logging, depending on the acl_uses_indirect_client,
1445 icap_uses_indirect_client, delay_pool_uses_indirect_client,
1446 log_uses_indirect_client and tproxy_uses_indirect_client options.
1448 This clause only supports fast acl types.
1449 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
1451 SECURITY CONSIDERATIONS:
1453 Any host from which we accept client IP details can place
1454 incorrect information in the relevant header, and Squid
1455 will use the incorrect information as if it were the
1456 source address of the request. This may enable remote
1457 hosts to bypass any access control restrictions that are
1458 based on the client's source addresses.
1462 acl localhost src 127.0.0.1
1463 acl my_other_proxy srcdomain .proxy.example.com
1464 follow_x_forwarded_for allow localhost
1465 follow_x_forwarded_for allow my_other_proxy
1468 NAME: acl_uses_indirect_client
1471 IFDEF: FOLLOW_X_FORWARDED_FOR
1473 LOC: Config.onoff.acl_uses_indirect_client
1475 Controls whether the indirect client address
1476 (see follow_x_forwarded_for) is used instead of the
1477 direct client address in acl matching.
1479 NOTE: maxconn ACL considers direct TCP links and indirect
1480 clients will always have zero. So no match.
1483 NAME: delay_pool_uses_indirect_client
1486 IFDEF: FOLLOW_X_FORWARDED_FOR&&USE_DELAY_POOLS
1488 LOC: Config.onoff.delay_pool_uses_indirect_client
1490 Controls whether the indirect client address
1491 (see follow_x_forwarded_for) is used instead of the
1492 direct client address in delay pools.
1495 NAME: log_uses_indirect_client
1498 IFDEF: FOLLOW_X_FORWARDED_FOR
1500 LOC: Config.onoff.log_uses_indirect_client
1502 Controls whether the indirect client address
1503 (see follow_x_forwarded_for) is used instead of the
1504 direct client address in the access log.
1507 NAME: tproxy_uses_indirect_client
1510 IFDEF: FOLLOW_X_FORWARDED_FOR&&LINUX_NETFILTER
1512 LOC: Config.onoff.tproxy_uses_indirect_client
1514 Controls whether the indirect client address
1515 (see follow_x_forwarded_for) is used instead of the
1516 direct client address when spoofing the outgoing client.
1518 This has no effect on requests arriving in non-tproxy
1521 SECURITY WARNING: Usage of this option is dangerous
1522 and should not be used trivially. Correct configuration
1523 of follow_x_forwarded_for with a limited set of trusted
1524 sources is required to prevent abuse of your proxy.
1527 NAME: spoof_client_ip
1529 LOC: Config.accessList.spoof_client_ip
1531 DEFAULT_DOC: Allow spoofing on all TPROXY traffic.
1533 Control client IP address spoofing of TPROXY traffic based on
1534 defined access lists.
1536 spoof_client_ip allow|deny [!]aclname ...
1538 If there are no "spoof_client_ip" lines present, the default
1539 is to "allow" spoofing of any suitable request.
1541 Note that the cache_peer "no-tproxy" option overrides this ACL.
1543 This clause supports fast acl types.
1544 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
1549 LOC: Config.accessList.http
1550 DEFAULT_IF_NONE: deny all
1551 DEFAULT_DOC: Deny, unless rules exist in squid.conf.
1553 Allowing or Denying access based on defined access lists
1555 To allow or deny a message received on an HTTP, HTTPS, or FTP port:
1556 http_access allow|deny [!]aclname ...
1558 NOTE on default values:
1560 If there are no "access" lines present, the default is to deny
1563 If none of the "access" lines cause a match, the default is the
1564 opposite of the last line in the list. If the last line was
1565 deny, the default is allow. Conversely, if the last line
1566 is allow, the default will be deny. For these reasons, it is a
1567 good idea to have an "deny all" entry at the end of your access
1568 lists to avoid potential confusion.
1570 This clause supports both fast and slow acl types.
1571 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
1576 # Recommended minimum Access Permission configuration:
1578 # Deny requests to certain unsafe ports
1579 http_access deny !Safe_ports
1581 # Deny CONNECT to other than secure SSL ports
1582 http_access deny CONNECT !SSL_ports
1584 # Only allow cachemgr access from localhost
1585 http_access allow localhost manager
1586 http_access deny manager
1588 # We strongly recommend the following be uncommented to protect innocent
1589 # web applications running on the proxy server who think the only
1590 # one who can access services on "localhost" is a local user
1591 #http_access deny to_localhost
1594 # INSERT YOUR OWN RULE(S) HERE TO ALLOW ACCESS FROM YOUR CLIENTS
1597 # Example rule allowing access from your local networks.
1598 # Adapt localnet in the ACL section to list your (internal) IP networks
1599 # from where browsing should be allowed
1600 http_access allow localnet
1601 http_access allow localhost
1603 # And finally deny all other access to this proxy
1604 http_access deny all
1608 NAME: adapted_http_access http_access2
1610 LOC: Config.accessList.adapted_http
1612 DEFAULT_DOC: Allow, unless rules exist in squid.conf.
1614 Allowing or Denying access based on defined access lists
1616 Essentially identical to http_access, but runs after redirectors
1617 and ICAP/eCAP adaptation. Allowing access control based on their
1620 If not set then only http_access is used.
1623 NAME: http_reply_access
1625 LOC: Config.accessList.reply
1627 DEFAULT_DOC: Allow, unless rules exist in squid.conf.
1629 Allow replies to client requests. This is complementary to http_access.
1631 http_reply_access allow|deny [!] aclname ...
1633 NOTE: if there are no access lines present, the default is to allow
1636 If none of the access lines cause a match the opposite of the
1637 last line will apply. Thus it is good practice to end the rules
1638 with an "allow all" or "deny all" entry.
1640 This clause supports both fast and slow acl types.
1641 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
1646 LOC: Config.accessList.icp
1648 DEFAULT_DOC: Deny, unless rules exist in squid.conf.
1650 Allowing or Denying access to the ICP port based on defined
1653 icp_access allow|deny [!]aclname ...
1655 NOTE: The default if no icp_access lines are present is to
1656 deny all traffic. This default may cause problems with peers
1659 This clause only supports fast acl types.
1660 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
1662 # Allow ICP queries from local networks only
1663 #icp_access allow localnet
1664 #icp_access deny all
1670 LOC: Config.accessList.htcp
1672 DEFAULT_DOC: Deny, unless rules exist in squid.conf.
1674 Allowing or Denying access to the HTCP port based on defined
1677 htcp_access allow|deny [!]aclname ...
1679 See also htcp_clr_access for details on access control for
1680 cache purge (CLR) HTCP messages.
1682 NOTE: The default if no htcp_access lines are present is to
1683 deny all traffic. This default may cause problems with peers
1684 using the htcp option.
1686 This clause only supports fast acl types.
1687 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
1689 # Allow HTCP queries from local networks only
1690 #htcp_access allow localnet
1691 #htcp_access deny all
1694 NAME: htcp_clr_access
1697 LOC: Config.accessList.htcp_clr
1699 DEFAULT_DOC: Deny, unless rules exist in squid.conf.
1701 Allowing or Denying access to purge content using HTCP based
1702 on defined access lists.
1703 See htcp_access for details on general HTCP access control.
1705 htcp_clr_access allow|deny [!]aclname ...
1707 This clause only supports fast acl types.
1708 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
1710 # Allow HTCP CLR requests from trusted peers
1711 acl htcp_clr_peer src 192.0.2.2 2001:DB8::2
1712 htcp_clr_access allow htcp_clr_peer
1713 htcp_clr_access deny all
1718 LOC: Config.accessList.miss
1720 DEFAULT_DOC: Allow, unless rules exist in squid.conf.
1722 Determines whether network access is permitted when satisfying a request.
1725 to force your neighbors to use you as a sibling instead of
1728 acl localclients src 192.0.2.0/24 2001:DB8::a:0/64
1729 miss_access deny !localclients
1730 miss_access allow all
1732 This means only your local clients are allowed to fetch relayed/MISS
1733 replies from the network and all other clients can only fetch cached
1736 The default for this setting allows all clients who passed the
1737 http_access rules to relay via this proxy.
1739 This clause only supports fast acl types.
1740 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
1743 NAME: ident_lookup_access
1747 DEFAULT_DOC: Unless rules exist in squid.conf, IDENT is not fetched.
1748 LOC: Ident::TheConfig.identLookup
1750 A list of ACL elements which, if matched, cause an ident
1751 (RFC 931) lookup to be performed for this request. For
1752 example, you might choose to always perform ident lookups
1753 for your main multi-user Unix boxes, but not for your Macs
1754 and PCs. By default, ident lookups are not performed for
1757 To enable ident lookups for specific client addresses, you
1758 can follow this example:
1760 acl ident_aware_hosts src 198.168.1.0/24
1761 ident_lookup_access allow ident_aware_hosts
1762 ident_lookup_access deny all
1764 Only src type ACL checks are fully supported. A srcdomain
1765 ACL might work at times, but it will not always provide
1768 This clause only supports fast acl types.
1769 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
1772 NAME: reply_body_max_size
1773 COMMENT: size [acl acl...]
1776 DEFAULT_DOC: No limit is applied.
1777 LOC: Config.ReplyBodySize
1779 This option specifies the maximum size of a reply body. It can be
1780 used to prevent users from downloading very large files, such as
1781 MP3's and movies. When the reply headers are received, the
1782 reply_body_max_size lines are processed, and the first line where
1783 all (if any) listed ACLs are true is used as the maximum body size
1786 This size is checked twice. First when we get the reply headers,
1787 we check the content-length value. If the content length value exists
1788 and is larger than the allowed size, the request is denied and the
1789 user receives an error message that says "the request or reply
1790 is too large." If there is no content-length, and the reply
1791 size exceeds this limit, the client's connection is just closed
1792 and they will receive a partial reply.
1794 WARNING: downstream caches probably can not detect a partial reply
1795 if there is no content-length header, so they will cache
1796 partial responses and give them out as hits. You should NOT
1797 use this option if you have downstream caches.
1799 WARNING: A maximum size smaller than the size of squid's error messages
1800 will cause an infinite loop and crash squid. Ensure that the smallest
1801 non-zero value you use is greater that the maximum header size plus
1802 the size of your largest error page.
1804 If you set this parameter none (the default), there will be
1807 Configuration Format is:
1808 reply_body_max_size SIZE UNITS [acl ...]
1810 reply_body_max_size 10 MB
1814 NAME: on_unsupported_protocol
1815 TYPE: on_unsupported_protocol
1816 LOC: Config.accessList.on_unsupported_protocol
1818 DEFAULT_DOC: Respond with an error message to unidentifiable traffic
1820 Determines Squid behavior when encountering strange requests at the
1821 beginning of an accepted TCP connection or the beginning of a bumped
1822 CONNECT tunnel. Controlling Squid reaction to unexpected traffic is
1823 especially useful in interception environments where Squid is likely
1824 to see connections for unsupported protocols that Squid should either
1825 terminate or tunnel at TCP level.
1827 on_unsupported_protocol <action> [!]acl ...
1829 The first matching action wins. Only fast ACLs are supported.
1831 Supported actions are:
1833 tunnel: Establish a TCP connection with the intended server and
1834 blindly shovel TCP packets between the client and server.
1836 respond: Respond with an error message, using the transfer protocol
1837 for the Squid port that received the request (e.g., HTTP
1838 for connections intercepted at the http_port). This is the
1841 Squid expects the following traffic patterns:
1843 http_port: a plain HTTP request
1844 https_port: SSL/TLS handshake followed by an [encrypted] HTTP request
1845 ftp_port: a plain FTP command (no on_unsupported_protocol support yet!)
1846 CONNECT tunnel on http_port: same as https_port
1847 CONNECT tunnel on https_port: same as https_port
1849 Currently, this directive has effect on intercepted connections and
1850 bumped tunnels only. Other cases are not supported because Squid
1851 cannot know the intended destination of other traffic.
1854 # define what Squid errors indicate receiving non-HTTP traffic:
1855 acl foreignProtocol squid_error ERR_PROTOCOL_UNKNOWN ERR_TOO_BIG
1856 # define what Squid errors indicate receiving nothing:
1857 acl serverTalksFirstProtocol squid_error ERR_REQUEST_START_TIMEOUT
1858 # tunnel everything that does not look like HTTP:
1859 on_unsupported_protocol tunnel foreignProtocol
1860 # tunnel if we think the client waits for the server to talk first:
1861 on_unsupported_protocol tunnel serverTalksFirstProtocol
1862 # in all other error cases, just send an HTTP "error page" response:
1863 on_unsupported_protocol respond all
1865 See also: squid_error ACL
1870 -----------------------------------------------------------------------------
1873 NAME: http_port ascii_port
1878 Usage: port [mode] [options]
1879 hostname:port [mode] [options]
1880 1.2.3.4:port [mode] [options]
1882 The socket addresses where Squid will listen for HTTP client
1883 requests. You may specify multiple socket addresses.
1884 There are three forms: port alone, hostname with port, and
1885 IP address with port. If you specify a hostname or IP
1886 address, Squid binds the socket to that specific
1887 address. Most likely, you do not need to bind to a specific
1888 address, so you can use the port number alone.
1890 If you are running Squid in accelerator mode, you
1891 probably want to listen on port 80 also, or instead.
1893 The -a command line option may be used to specify additional
1894 port(s) where Squid listens for proxy request. Such ports will
1895 be plain proxy ports with no options.
1897 You may specify multiple socket addresses on multiple lines.
1901 intercept Support for IP-Layer NAT interception delivering
1902 traffic to this Squid port.
1903 NP: disables authentication on the port.
1905 tproxy Support Linux TPROXY (or BSD divert-to) with spoofing
1906 of outgoing connections using the client IP address.
1907 NP: disables authentication on the port.
1909 accel Accelerator / reverse proxy mode
1911 ssl-bump For each CONNECT request allowed by ssl_bump ACLs,
1912 establish secure connection with the client and with
1913 the server, decrypt HTTPS messages as they pass through
1914 Squid, and treat them as unencrypted HTTP messages,
1915 becoming the man-in-the-middle.
1917 The ssl_bump option is required to fully enable
1918 bumping of CONNECT requests.
1920 Omitting the mode flag causes default forward proxy mode to be used.
1923 Accelerator Mode Options:
1925 defaultsite=domainname
1926 What to use for the Host: header if it is not present
1927 in a request. Determines what site (not origin server)
1928 accelerators should consider the default.
1930 no-vhost Disable using HTTP/1.1 Host header for virtual domain support.
1932 protocol= Protocol to reconstruct accelerated and intercepted
1933 requests with. Defaults to HTTP/1.1 for http_port and
1934 HTTPS/1.1 for https_port.
1935 When an unsupported value is configured Squid will
1936 produce a FATAL error.
1937 Values: HTTP or HTTP/1.1, HTTPS or HTTPS/1.1
1939 vport Virtual host port support. Using the http_port number
1940 instead of the port passed on Host: headers.
1942 vport=NN Virtual host port support. Using the specified port
1943 number instead of the port passed on Host: headers.
1946 Act as if this Squid is the origin server.
1947 This currently means generate new Date: and Expires:
1948 headers on HIT instead of adding Age:.
1950 ignore-cc Ignore request Cache-Control headers.
1952 WARNING: This option violates HTTP specifications if
1953 used in non-accelerator setups.
1955 allow-direct Allow direct forwarding in accelerator mode. Normally
1956 accelerated requests are denied direct forwarding as if
1957 never_direct was used.
1959 WARNING: this option opens accelerator mode to security
1960 vulnerabilities usually only affecting in interception
1961 mode. Make sure to protect forwarding with suitable
1962 http_access rules when using this.
1965 SSL Bump Mode Options:
1966 In addition to these options ssl-bump requires TLS/SSL options.
1968 generate-host-certificates[=<on|off>]
1969 Dynamically create SSL server certificates for the
1970 destination hosts of bumped CONNECT requests.When
1971 enabled, the cert and key options are used to sign
1972 generated certificates. Otherwise generated
1973 certificate will be selfsigned.
1974 If there is a CA certificate lifetime of the generated
1975 certificate equals lifetime of the CA certificate. If
1976 generated certificate is selfsigned lifetime is three
1978 This option is enabled by default when ssl-bump is used.
1979 See the ssl-bump option above for more information.
1981 dynamic_cert_mem_cache_size=SIZE
1982 Approximate total RAM size spent on cached generated
1983 certificates. If set to zero, caching is disabled. The
1984 default value is 4MB.
1988 cert= Path to SSL certificate (PEM format).
1990 key= Path to SSL private key file (PEM format)
1991 if not specified, the certificate file is
1992 assumed to be a combined certificate and
1995 cipher= Colon separated list of supported ciphers.
1996 NOTE: some ciphers such as EDH ciphers depend on
1997 additional settings. If those settings are
1998 omitted the ciphers may be silently ignored
1999 by the OpenSSL library.
2001 options= Various SSL implementation options. The most important
2004 NO_SSLv3 Disallow the use of SSLv3
2006 NO_TLSv1 Disallow the use of TLSv1.0
2008 NO_TLSv1_1 Disallow the use of TLSv1.1
2010 NO_TLSv1_2 Disallow the use of TLSv1.2
2013 Always create a new key when using
2014 temporary/ephemeral DH key exchanges
2017 Enable ephemeral ECDH key exchange.
2018 The adopted curve should be specified
2019 using the tls-dh option.
2022 Disable use of RFC5077 session tickets.
2023 Some servers may have problems
2024 understanding the TLS extension due
2025 to ambiguous specification in RFC4507.
2027 ALL Enable various bug workarounds
2028 suggested as "harmless" by OpenSSL
2029 Be warned that this reduces SSL/TLS
2030 strength to some attacks.
2032 See the OpenSSL SSL_CTX_set_options documentation for a
2035 clientca= File containing the list of CAs to use when
2036 requesting a client certificate.
2038 tls-cafile= PEM file containing CA certificates to use when verifying
2039 client certificates. If not configured clientca will be
2040 used. May be repeated to load multiple files.
2042 capath= Directory containing additional CA certificates
2043 and CRL lists to use when verifying client certificates.
2044 Requires OpenSSL or LibreSSL.
2046 crlfile= File of additional CRL lists to use when verifying
2047 the client certificate, in addition to CRLs stored in
2048 the capath. Implies VERIFY_CRL flag below.
2051 File containing DH parameters for temporary/ephemeral DH key
2052 exchanges, optionally prefixed by a curve for ephemeral ECDH
2054 See OpenSSL documentation for details on how to create the
2055 DH parameter file. Supported curves for ECDH can be listed
2056 using the "openssl ecparam -list_curves" command.
2057 WARNING: EDH and EECDH ciphers will be silently disabled if
2058 this option is not set.
2060 sslflags= Various flags modifying the use of SSL:
2062 Don't request client certificates
2063 immediately, but wait until acl processing
2064 requires a certificate (not yet implemented).
2066 Don't allow for session reuse. Each connection
2067 will result in a new SSL session.
2069 Verify CRL lists when accepting client
2072 Verify CRL lists for all certificates in the
2073 client certificate chain.
2075 tls-default-ca[=off]
2076 Whether to use the system Trusted CAs. Default is OFF.
2078 tls-no-npn Do not use the TLS NPN extension to advertise HTTP/1.1.
2080 sslcontext= SSL session ID context identifier.
2084 connection-auth[=on|off]
2085 use connection-auth=off to tell Squid to prevent
2086 forwarding Microsoft connection oriented authentication
2087 (NTLM, Negotiate and Kerberos)
2089 disable-pmtu-discovery=
2090 Control Path-MTU discovery usage:
2091 off lets OS decide on what to do (default).
2092 transparent disable PMTU discovery when transparent
2094 always disable always PMTU discovery.
2096 In many setups of transparently intercepting proxies
2097 Path-MTU discovery can not work on traffic towards the
2098 clients. This is the case when the intercepting device
2099 does not fully track connections and fails to forward
2100 ICMP must fragment messages to the cache server. If you
2101 have such setup and experience that certain clients
2102 sporadically hang or never complete requests set
2103 disable-pmtu-discovery option to 'transparent'.
2105 name= Specifies a internal name for the port. Defaults to
2106 the port specification (port or addr:port)
2108 tcpkeepalive[=idle,interval,timeout]
2109 Enable TCP keepalive probes of idle connections.
2110 In seconds; idle is the initial time before TCP starts
2111 probing the connection, interval how often to probe, and
2112 timeout the time before giving up.
2114 require-proxy-header
2115 Require PROXY protocol version 1 or 2 connections.
2116 The proxy_protocol_access is required to whitelist
2117 downstream proxies which can be trusted.
2119 If you run Squid on a dual-homed machine with an internal
2120 and an external interface we recommend you to specify the
2121 internal address:port in http_port. This way Squid will only be
2122 visible on the internal address.
2126 # Squid normally listens to port 3128
2127 http_port @DEFAULT_HTTP_PORT@
2132 IFDEF: USE_GNUTLS||USE_OPENSSL
2137 Usage: [ip:]port [mode] cert=certificate.pem [options]
2139 The socket address where Squid will listen for client requests made
2140 over TLS or SSL connections. Commonly referred to as HTTPS.
2142 This is most useful for situations where you are running squid in
2143 accelerator mode and you want to do the TLS work at the accelerator level.
2145 You may specify multiple socket addresses on multiple lines,
2146 each with their own certificate and/or options.
2148 The TLS cert= option is mandatory on HTTPS ports.
2150 See http_port for a list of modes and options.
2158 Enables Native FTP proxy by specifying the socket address where Squid
2159 listens for FTP client requests. See http_port directive for various
2160 ways to specify the listening address and mode.
2162 Usage: ftp_port address [mode] [options]
2164 WARNING: This is a new, experimental, complex feature that has seen
2165 limited production exposure. Some Squid modules (e.g., caching) do not
2166 currently work with native FTP proxying, and many features have not
2167 even been tested for compatibility. Test well before deploying!
2169 Native FTP proxying differs substantially from proxying HTTP requests
2170 with ftp:// URIs because Squid works as an FTP server and receives
2171 actual FTP commands (rather than HTTP requests with FTP URLs).
2173 Native FTP commands accepted at ftp_port are internally converted or
2174 wrapped into HTTP-like messages. The same happens to Native FTP
2175 responses received from FTP origin servers. Those HTTP-like messages
2176 are shoveled through regular access control and adaptation layers
2177 between the FTP client and the FTP origin server. This allows Squid to
2178 examine, adapt, block, and log FTP exchanges. Squid reuses most HTTP
2179 mechanisms when shoveling wrapped FTP messages. For example,
2180 http_access and adaptation_access directives are used.
2184 intercept Same as http_port intercept. The FTP origin address is
2185 determined based on the intended destination of the
2186 intercepted connection.
2188 tproxy Support Linux TPROXY for spoofing outgoing
2189 connections using the client IP address.
2190 NP: disables authentication and maybe IPv6 on the port.
2192 By default (i.e., without an explicit mode option), Squid extracts the
2193 FTP origin address from the login@origin parameter of the FTP USER
2194 command. Many popular FTP clients support such native FTP proxying.
2198 name=token Specifies an internal name for the port. Defaults to
2199 the port address. Usable with myportname ACL.
2202 Enables tracking of FTP directories by injecting extra
2203 PWD commands and adjusting Request-URI (in wrapping
2204 HTTP requests) to reflect the current FTP server
2205 directory. Tracking is disabled by default.
2207 protocol=FTP Protocol to reconstruct accelerated and intercepted
2208 requests with. Defaults to FTP. No other accepted
2209 values have been tested with. An unsupported value
2210 results in a FATAL error. Accepted values are FTP,
2211 HTTP (or HTTP/1.1), and HTTPS (or HTTPS/1.1).
2213 Other http_port modes and options that are not specific to HTTP and
2214 HTTPS may also work.
2217 NAME: tcp_outgoing_tos tcp_outgoing_ds tcp_outgoing_dscp
2220 LOC: Ip::Qos::TheConfig.tosToServer
2222 Allows you to select a TOS/Diffserv value for packets outgoing
2223 on the server side, based on an ACL.
2225 tcp_outgoing_tos ds-field [!]aclname ...
2227 Example where normal_service_net uses the TOS value 0x00
2228 and good_service_net uses 0x20
2230 acl normal_service_net src 10.0.0.0/24
2231 acl good_service_net src 10.0.1.0/24
2232 tcp_outgoing_tos 0x00 normal_service_net
2233 tcp_outgoing_tos 0x20 good_service_net
2235 TOS/DSCP values really only have local significance - so you should
2236 know what you're specifying. For more information, see RFC2474,
2237 RFC2475, and RFC3260.
2239 The TOS/DSCP byte must be exactly that - a octet value 0 - 255, or
2240 "default" to use whatever default your host has.
2241 Note that only multiples of 4 are usable as the two rightmost bits have
2242 been redefined for use by ECN (RFC 3168 section 23.1).
2243 The squid parser will enforce this by masking away the ECN bits.
2245 Processing proceeds in the order specified, and stops at first fully
2248 Only fast ACLs are supported.
2251 NAME: clientside_tos
2254 LOC: Ip::Qos::TheConfig.tosToClient
2256 Allows you to select a TOS/DSCP value for packets being transmitted
2257 on the client-side, based on an ACL.
2259 clientside_tos ds-field [!]aclname ...
2261 Example where normal_service_net uses the TOS value 0x00
2262 and good_service_net uses 0x20
2264 acl normal_service_net src 10.0.0.0/24
2265 acl good_service_net src 10.0.1.0/24
2266 clientside_tos 0x00 normal_service_net
2267 clientside_tos 0x20 good_service_net
2269 Note: This feature is incompatible with qos_flows. Any TOS values set here
2270 will be overwritten by TOS values in qos_flows.
2272 The TOS/DSCP byte must be exactly that - a octet value 0 - 255, or
2273 "default" to use whatever default your host has.
2274 Note that only multiples of 4 are usable as the two rightmost bits have
2275 been redefined for use by ECN (RFC 3168 section 23.1).
2276 The squid parser will enforce this by masking away the ECN bits.
2280 NAME: tcp_outgoing_mark
2282 IFDEF: SO_MARK&&USE_LIBCAP
2284 LOC: Ip::Qos::TheConfig.nfmarkToServer
2286 Allows you to apply a Netfilter mark value to outgoing packets
2287 on the server side, based on an ACL.
2289 tcp_outgoing_mark mark-value [!]aclname ...
2291 Example where normal_service_net uses the mark value 0x00
2292 and good_service_net uses 0x20
2294 acl normal_service_net src 10.0.0.0/24
2295 acl good_service_net src 10.0.1.0/24
2296 tcp_outgoing_mark 0x00 normal_service_net
2297 tcp_outgoing_mark 0x20 good_service_net
2299 Only fast ACLs are supported.
2302 NAME: clientside_mark
2304 IFDEF: SO_MARK&&USE_LIBCAP
2306 LOC: Ip::Qos::TheConfig.nfmarkToClient
2308 Allows you to apply a Netfilter mark value to packets being transmitted
2309 on the client-side, based on an ACL.
2311 clientside_mark mark-value [!]aclname ...
2313 Example where normal_service_net uses the mark value 0x00
2314 and good_service_net uses 0x20
2316 acl normal_service_net src 10.0.0.0/24
2317 acl good_service_net src 10.0.1.0/24
2318 clientside_mark 0x00 normal_service_net
2319 clientside_mark 0x20 good_service_net
2321 Note: This feature is incompatible with qos_flows. Any mark values set here
2322 will be overwritten by mark values in qos_flows.
2329 LOC: Ip::Qos::TheConfig
2331 Allows you to select a TOS/DSCP value to mark outgoing
2332 connections to the client, based on where the reply was sourced.
2333 For platforms using netfilter, allows you to set a netfilter mark
2334 value instead of, or in addition to, a TOS value.
2336 By default this functionality is disabled. To enable it with the default
2337 settings simply use "qos_flows mark" or "qos_flows tos". Default
2338 settings will result in the netfilter mark or TOS value being copied
2339 from the upstream connection to the client. Note that it is the connection
2340 CONNMARK value not the packet MARK value that is copied.
2342 It is not currently possible to copy the mark or TOS value from the
2343 client to the upstream connection request.
2345 TOS values really only have local significance - so you should
2346 know what you're specifying. For more information, see RFC2474,
2347 RFC2475, and RFC3260.
2349 The TOS/DSCP byte must be exactly that - a octet value 0 - 255.
2350 Note that only multiples of 4 are usable as the two rightmost bits have
2351 been redefined for use by ECN (RFC 3168 section 23.1).
2352 The squid parser will enforce this by masking away the ECN bits.
2354 Mark values can be any unsigned 32-bit integer value.
2356 This setting is configured by setting the following values:
2358 tos|mark Whether to set TOS or netfilter mark values
2360 local-hit=0xFF Value to mark local cache hits.
2362 sibling-hit=0xFF Value to mark hits from sibling peers.
2364 parent-hit=0xFF Value to mark hits from parent peers.
2366 miss=0xFF[/mask] Value to mark cache misses. Takes precedence
2367 over the preserve-miss feature (see below), unless
2368 mask is specified, in which case only the bits
2369 specified in the mask are written.
2371 The TOS variant of the following features are only possible on Linux
2372 and require your kernel to be patched with the TOS preserving ZPH
2373 patch, available from http://zph.bratcheda.org
2374 No patch is needed to preserve the netfilter mark, which will work
2375 with all variants of netfilter.
2377 disable-preserve-miss
2378 This option disables the preservation of the TOS or netfilter
2379 mark. By default, the existing TOS or netfilter mark value of
2380 the response coming from the remote server will be retained
2381 and masked with miss-mark.
2382 NOTE: in the case of a netfilter mark, the mark must be set on
2383 the connection (using the CONNMARK target) not on the packet
2387 Allows you to mask certain bits in the TOS or mark value
2388 received from the remote server, before copying the value to
2389 the TOS sent towards clients.
2390 Default for tos: 0xFF (TOS from server is not changed).
2391 Default for mark: 0xFFFFFFFF (mark from server is not changed).
2393 All of these features require the --enable-zph-qos compilation flag
2394 (enabled by default). Netfilter marking also requires the
2395 libnetfilter_conntrack libraries (--with-netfilter-conntrack) and
2396 libcap 2.09+ (--with-libcap).
2400 NAME: tcp_outgoing_address
2403 DEFAULT_DOC: Address selection is performed by the operating system.
2404 LOC: Config.accessList.outgoing_address
2406 Allows you to map requests to different outgoing IP addresses
2407 based on the username or source address of the user making
2410 tcp_outgoing_address ipaddr [[!]aclname] ...
2413 Forwarding clients with dedicated IPs for certain subnets.
2415 acl normal_service_net src 10.0.0.0/24
2416 acl good_service_net src 10.0.2.0/24
2418 tcp_outgoing_address 2001:db8::c001 good_service_net
2419 tcp_outgoing_address 10.1.0.2 good_service_net
2421 tcp_outgoing_address 2001:db8::beef normal_service_net
2422 tcp_outgoing_address 10.1.0.1 normal_service_net
2424 tcp_outgoing_address 2001:db8::1
2425 tcp_outgoing_address 10.1.0.3
2427 Processing proceeds in the order specified, and stops at first fully
2430 Squid will add an implicit IP version test to each line.
2431 Requests going to IPv4 websites will use the outgoing 10.1.0.* addresses.
2432 Requests going to IPv6 websites will use the outgoing 2001:db8:* addresses.
2435 NOTE: The use of this directive using client dependent ACLs is
2436 incompatible with the use of server side persistent connections. To
2437 ensure correct results it is best to set server_persistent_connections
2438 to off when using this directive in such configurations.
2440 NOTE: The use of this directive to set a local IP on outgoing TCP links
2441 is incompatible with using TPROXY to set client IP out outbound TCP links.
2442 When needing to contact peers use the no-tproxy cache_peer option and the
2443 client_dst_passthru directive re-enable normal forwarding such as this.
2447 NAME: host_verify_strict
2450 LOC: Config.onoff.hostStrictVerify
2452 Regardless of this option setting, when dealing with intercepted
2453 traffic, Squid always verifies that the destination IP address matches
2454 the Host header domain or IP (called 'authority form URL').
2456 This enforcement is performed to satisfy a MUST-level requirement in
2457 RFC 2616 section 14.23: "The Host field value MUST represent the naming
2458 authority of the origin server or gateway given by the original URL".
2461 Squid always responds with an HTTP 409 (Conflict) error
2462 page and logs a security warning if there is no match.
2464 Squid verifies that the destination IP address matches
2465 the Host header for forward-proxy and reverse-proxy traffic
2466 as well. For those traffic types, Squid also enables the
2467 following checks, comparing the corresponding Host header
2468 and Request-URI components:
2470 * The host names (domain or IP) must be identical,
2471 but valueless or missing Host header disables all checks.
2472 For the two host names to match, both must be either IP
2475 * Port numbers must be identical, but if a port is missing
2476 the scheme-default port is assumed.
2479 When set to OFF (the default):
2480 Squid allows suspicious requests to continue but logs a
2481 security warning and blocks caching of the response.
2483 * Forward-proxy traffic is not checked at all.
2485 * Reverse-proxy traffic is not checked at all.
2487 * Intercepted traffic which passes verification is handled
2488 according to client_dst_passthru.
2490 * Intercepted requests which fail verification are sent
2491 to the client original destination instead of DIRECT.
2492 This overrides 'client_dst_passthru off'.
2494 For now suspicious intercepted CONNECT requests are always
2495 responded to with an HTTP 409 (Conflict) error page.
2500 As described in CVE-2009-0801 when the Host: header alone is used
2501 to determine the destination of a request it becomes trivial for
2502 malicious scripts on remote websites to bypass browser same-origin
2503 security policy and sandboxing protections.
2505 The cause of this is that such applets are allowed to perform their
2506 own HTTP stack, in which case the same-origin policy of the browser
2507 sandbox only verifies that the applet tries to contact the same IP
2508 as from where it was loaded at the IP level. The Host: header may
2509 be different from the connected IP and approved origin.
2513 NAME: client_dst_passthru
2516 LOC: Config.onoff.client_dst_passthru
2518 With NAT or TPROXY intercepted traffic Squid may pass the request
2519 directly to the original client destination IP or seek a faster
2520 source using the HTTP Host header.
2522 Using Host to locate alternative servers can provide faster
2523 connectivity with a range of failure recovery options.
2524 But can also lead to connectivity trouble when the client and
2525 server are attempting stateful interactions unaware of the proxy.
2527 This option (on by default) prevents alternative DNS entries being
2528 located to send intercepted traffic DIRECT to an origin server.
2529 The clients original destination IP and port will be used instead.
2531 Regardless of this option setting, when dealing with intercepted
2532 traffic Squid will verify the Host: header and any traffic which
2533 fails Host verification will be treated as if this option were ON.
2535 see host_verify_strict for details on the verification process.
2540 -----------------------------------------------------------------------------
2543 NAME: tls_outgoing_options
2544 IFDEF: USE_GNUTLS||USE_OPENSSL
2545 TYPE: securePeerOptions
2546 DEFAULT: min-version=1.0
2547 LOC: Security::ProxyOutgoingConfig
2549 disable Do not support https:// URLs.
2551 cert=/path/to/client/certificate
2552 A client TLS certificate to use when connecting.
2554 key=/path/to/client/private_key
2555 The private TLS key corresponding to the cert= above.
2556 If key= is not specified cert= is assumed to reference
2557 a PEM file containing both the certificate and the key.
2559 cipher=... The list of valid TLS ciphers to use.
2562 The minimum TLS protocol version to permit.
2563 To control SSLv3 use the options= parameter.
2564 Supported Values: 1.0 (default), 1.1, 1.2
2566 options=... Specify various TLS/SSL implementation options:
2568 NO_SSLv3 Disallow the use of SSLv3
2570 NO_TLSv1 Disallow the use of TLSv1.0
2572 NO_TLSv1_1 Disallow the use of TLSv1.1
2574 NO_TLSv1_2 Disallow the use of TLSv1.2
2577 Always create a new key when using
2578 temporary/ephemeral DH key exchanges
2581 Disable use of RFC5077 session tickets.
2582 Some servers may have problems
2583 understanding the TLS extension due
2584 to ambiguous specification in RFC4507.
2586 ALL Enable various bug workarounds
2587 suggested as "harmless" by OpenSSL
2588 Be warned that this reduces SSL/TLS
2589 strength to some attacks.
2591 See the OpenSSL SSL_CTX_set_options documentation for a
2594 cafile= PEM file containing CA certificates to use when verifying
2595 the peer certificate. May be repeated to load multiple files.
2597 capath= A directory containing additional CA certificates to
2598 use when verifying the peer certificate.
2599 Requires OpenSSL or LibreSSL.
2601 crlfile=... A certificate revocation list file to use when
2602 verifying the peer certificate.
2604 flags=... Specify various flags modifying the TLS implementation:
2607 Accept certificates even if they fail to
2610 Don't verify the peer certificate
2611 matches the server name
2614 Whether to use the system Trusted CAs. Default is ON.
2616 domain= The peer name as advertised in its certificate.
2617 Used for verifying the correctness of the received peer
2618 certificate. If not specified the peer hostname will be
2624 -----------------------------------------------------------------------------
2627 NAME: ssl_unclean_shutdown
2631 LOC: Config.SSL.unclean_shutdown
2633 Some browsers (especially MSIE) bugs out on SSL shutdown
2640 LOC: Config.SSL.ssl_engine
2643 The OpenSSL engine to use. You will need to set this if you
2644 would like to use hardware SSL acceleration for example.
2647 NAME: sslproxy_session_ttl
2650 LOC: Config.SSL.session_ttl
2653 Sets the timeout value for SSL sessions
2656 NAME: sslproxy_session_cache_size
2659 LOC: Config.SSL.sessionCacheSize
2662 Sets the cache size to use for ssl session
2665 NAME: sslproxy_foreign_intermediate_certs
2668 LOC: Config.ssl_client.foreignIntermediateCertsPath
2671 Many origin servers fail to send their full server certificate
2672 chain for verification, assuming the client already has or can
2673 easily locate any missing intermediate certificates.
2675 Squid uses the certificates from the specified file to fill in
2676 these missing chains when trying to validate origin server
2679 The file is expected to contain zero or more PEM-encoded
2680 intermediate certificates. These certificates are not treated
2681 as trusted root certificates, and any self-signed certificate in
2682 this file will be ignored.
2685 NAME: sslproxy_cert_sign_hash
2688 LOC: Config.SSL.certSignHash
2691 Sets the hashing algorithm to use when signing generated certificates.
2692 Valid algorithm names depend on the OpenSSL library used. The following
2693 names are usually available: sha1, sha256, sha512, and md5. Please see
2694 your OpenSSL library manual for the available hashes. By default, Squids
2695 that support this option use sha256 hashes.
2697 Squid does not forcefully purge cached certificates that were generated
2698 with an algorithm other than the currently configured one. They remain
2699 in the cache, subject to the regular cache eviction policy, and become
2700 useful if the algorithm changes again.
2705 TYPE: sslproxy_ssl_bump
2706 LOC: Config.accessList.ssl_bump
2707 DEFAULT_DOC: Become a TCP tunnel without decrypting proxied traffic.
2710 This option is consulted when a CONNECT request is received on
2711 an http_port (or a new connection is intercepted at an
2712 https_port), provided that port was configured with an ssl-bump
2713 flag. The subsequent data on the connection is either treated as
2714 HTTPS and decrypted OR tunneled at TCP level without decryption,
2715 depending on the first matching bumping "action".
2717 ssl_bump <action> [!]acl ...
2719 The following bumping actions are currently supported:
2722 Become a TCP tunnel without decrypting proxied traffic.
2723 This is the default action.
2726 Establish a secure connection with the server and, using a
2727 mimicked server certificate, with the client.
2730 Receive client (step SslBump1) or server (step SslBump2)
2731 certificate while preserving the possibility of splicing the
2732 connection. Peeking at the server certificate (during step 2)
2733 usually precludes bumping of the connection at step 3.
2736 Receive client (step SslBump1) or server (step SslBump2)
2737 certificate while preserving the possibility of bumping the
2738 connection. Staring at the server certificate (during step 2)
2739 usually precludes splicing of the connection at step 3.
2742 Close client and server connections.
2744 Backward compatibility actions available at step SslBump1:
2747 Bump the connection. Establish a secure connection with the
2748 client first, then connect to the server. This old mode does
2749 not allow Squid to mimic server SSL certificate and does not
2750 work with intercepted SSL connections.
2753 Bump the connection. Establish a secure connection with the
2754 server first, then establish a secure connection with the
2755 client, using a mimicked server certificate. Works with both
2756 CONNECT requests and intercepted SSL connections, but does
2757 not allow to make decisions based on SSL handshake info.
2760 Decide whether to bump or splice the connection based on
2761 client-to-squid and server-to-squid SSL hello messages.
2765 Same as the "splice" action.
2767 All ssl_bump rules are evaluated at each of the supported bumping
2768 steps. Rules with actions that are impossible at the current step are
2769 ignored. The first matching ssl_bump action wins and is applied at the
2770 end of the current step. If no rules match, the splice action is used.
2771 See the at_step ACL for a list of the supported SslBump steps.
2773 This clause supports both fast and slow acl types.
2774 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
2776 See also: http_port ssl-bump, https_port ssl-bump, and acl at_step.
2779 # Example: Bump all TLS connections except those originating from
2780 # localhost or those going to example.com.
2782 acl broken_sites ssl::server_name .example.com
2783 ssl_bump splice localhost
2784 ssl_bump splice broken_sites
2788 NAME: sslproxy_cert_error
2791 DEFAULT_DOC: Server certificate errors terminate the transaction.
2792 LOC: Config.ssl_client.cert_error
2795 Use this ACL to bypass server certificate validation errors.
2797 For example, the following lines will bypass all validation errors
2798 when talking to servers for example.com. All other
2799 validation errors will result in ERR_SECURE_CONNECT_FAIL error.
2801 acl BrokenButTrustedServers dstdomain example.com
2802 sslproxy_cert_error allow BrokenButTrustedServers
2803 sslproxy_cert_error deny all
2805 This clause only supports fast acl types.
2806 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
2807 Using slow acl types may result in server crashes
2809 Without this option, all server certificate validation errors
2810 terminate the transaction to protect Squid and the client.
2812 SQUID_X509_V_ERR_INFINITE_VALIDATION error cannot be bypassed
2813 but should not happen unless your OpenSSL library is buggy.
2816 Bypassing validation errors is dangerous because an
2817 error usually implies that the server cannot be trusted
2818 and the connection may be insecure.
2820 See also: sslproxy_flags and DONT_VERIFY_PEER.
2823 NAME: sslproxy_cert_sign
2826 POSTSCRIPTUM: signUntrusted ssl::certUntrusted
2827 POSTSCRIPTUM: signSelf ssl::certSelfSigned
2828 POSTSCRIPTUM: signTrusted all
2829 TYPE: sslproxy_cert_sign
2830 LOC: Config.ssl_client.cert_sign
2833 sslproxy_cert_sign <signing algorithm> acl ...
2835 The following certificate signing algorithms are supported:
2838 Sign using the configured CA certificate which is usually
2839 placed in and trusted by end-user browsers. This is the
2840 default for trusted origin server certificates.
2843 Sign to guarantee an X509_V_ERR_CERT_UNTRUSTED browser error.
2844 This is the default for untrusted origin server certificates
2845 that are not self-signed (see ssl::certUntrusted).
2848 Sign using a self-signed certificate with the right CN to
2849 generate a X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT error in the
2850 browser. This is the default for self-signed origin server
2851 certificates (see ssl::certSelfSigned).
2853 This clause only supports fast acl types.
2855 When sslproxy_cert_sign acl(s) match, Squid uses the corresponding
2856 signing algorithm to generate the certificate and ignores all
2857 subsequent sslproxy_cert_sign options (the first match wins). If no
2858 acl(s) match, the default signing algorithm is determined by errors
2859 detected when obtaining and validating the origin server certificate.
2861 WARNING: SQUID_X509_V_ERR_DOMAIN_MISMATCH and ssl:certDomainMismatch can
2862 be used with sslproxy_cert_adapt, but if and only if Squid is bumping a
2863 CONNECT request that carries a domain name. In all other cases (CONNECT
2864 to an IP address or an intercepted SSL connection), Squid cannot detect
2865 the domain mismatch at certificate generation time when
2866 bump-server-first is used.
2869 NAME: sslproxy_cert_adapt
2872 TYPE: sslproxy_cert_adapt
2873 LOC: Config.ssl_client.cert_adapt
2876 sslproxy_cert_adapt <adaptation algorithm> acl ...
2878 The following certificate adaptation algorithms are supported:
2881 Sets the "Not After" property to the "Not After" property of
2882 the CA certificate used to sign generated certificates.
2885 Sets the "Not Before" property to the "Not Before" property of
2886 the CA certificate used to sign generated certificates.
2888 setCommonName or setCommonName{CN}
2889 Sets Subject.CN property to the host name specified as a
2890 CN parameter or, if no explicit CN parameter was specified,
2891 extracted from the CONNECT request. It is a misconfiguration
2892 to use setCommonName without an explicit parameter for
2893 intercepted or tproxied SSL connections.
2895 This clause only supports fast acl types.
2897 Squid first groups sslproxy_cert_adapt options by adaptation algorithm.
2898 Within a group, when sslproxy_cert_adapt acl(s) match, Squid uses the
2899 corresponding adaptation algorithm to generate the certificate and
2900 ignores all subsequent sslproxy_cert_adapt options in that algorithm's
2901 group (i.e., the first match wins within each algorithm group). If no
2902 acl(s) match, the default mimicking action takes place.
2904 WARNING: SQUID_X509_V_ERR_DOMAIN_MISMATCH and ssl:certDomainMismatch can
2905 be used with sslproxy_cert_adapt, but if and only if Squid is bumping a
2906 CONNECT request that carries a domain name. In all other cases (CONNECT
2907 to an IP address or an intercepted SSL connection), Squid cannot detect
2908 the domain mismatch at certificate generation time when
2909 bump-server-first is used.
2912 NAME: sslpassword_program
2915 LOC: Config.Program.ssl_password
2918 Specify a program used for entering SSL key passphrases
2919 when using encrypted SSL certificate keys. If not specified
2920 keys must either be unencrypted, or Squid started with the -N
2921 option to allow it to query interactively for the passphrase.
2923 The key file name is given as argument to the program allowing
2924 selection of the right password if you have multiple encrypted
2929 OPTIONS RELATING TO EXTERNAL SSL_CRTD
2930 -----------------------------------------------------------------------------
2933 NAME: sslcrtd_program
2936 DEFAULT: @DEFAULT_SSL_CRTD@ -s @DEFAULT_SSL_DB_DIR@ -M 4MB
2937 LOC: Ssl::TheConfig.ssl_crtd
2939 Specify the location and options of the executable for certificate
2941 @DEFAULT_SSL_CRTD@ program requires -s and -M parameters
2942 For more information use:
2943 @DEFAULT_SSL_CRTD@ -h
2946 NAME: sslcrtd_children
2947 TYPE: HelperChildConfig
2949 DEFAULT: 32 startup=5 idle=1
2950 LOC: Ssl::TheConfig.ssl_crtdChildren
2952 The maximum number of processes spawn to service ssl server.
2953 The maximum this may be safely set to is 32.
2955 The startup= and idle= options allow some measure of skew in your
2960 Sets the minimum number of processes to spawn when Squid
2961 starts or reconfigures. When set to zero the first request will
2962 cause spawning of the first child process to handle it.
2964 Starting too few children temporary slows Squid under load while it
2965 tries to spawn enough additional processes to cope with traffic.
2969 Sets a minimum of how many processes Squid is to try and keep available
2970 at all times. When traffic begins to rise above what the existing
2971 processes can handle this many more will be spawned up to the maximum
2972 configured. A minimum setting of 1 is required.
2976 Sets the maximum number of queued requests.
2977 If the queued requests exceed queue size for more than 3 minutes
2978 squid aborts its operation.
2979 The default value is set to 2*numberofchildren.
2981 You must have at least one ssl_crtd process.
2984 NAME: sslcrtvalidator_program
2988 LOC: Ssl::TheConfig.ssl_crt_validator
2990 Specify the location and options of the executable for ssl_crt_validator
2993 Usage: sslcrtvalidator_program [ttl=n] [cache=n] path ...
2996 ttl=n TTL in seconds for cached results. The default is 60 secs
2997 cache=n limit the result cache size. The default value is 2048
3000 NAME: sslcrtvalidator_children
3001 TYPE: HelperChildConfig
3003 DEFAULT: 32 startup=5 idle=1 concurrency=1
3004 LOC: Ssl::TheConfig.ssl_crt_validator_Children
3006 The maximum number of processes spawn to service SSL server.
3007 The maximum this may be safely set to is 32.
3009 The startup= and idle= options allow some measure of skew in your
3014 Sets the minimum number of processes to spawn when Squid
3015 starts or reconfigures. When set to zero the first request will
3016 cause spawning of the first child process to handle it.
3018 Starting too few children temporary slows Squid under load while it
3019 tries to spawn enough additional processes to cope with traffic.
3023 Sets a minimum of how many processes Squid is to try and keep available
3024 at all times. When traffic begins to rise above what the existing
3025 processes can handle this many more will be spawned up to the maximum
3026 configured. A minimum setting of 1 is required.
3030 The number of requests each certificate validator helper can handle in
3031 parallel. A value of 0 indicates the certficate validator does not
3032 support concurrency. Defaults to 1.
3034 When this directive is set to a value >= 1 then the protocol
3035 used to communicate with the helper is modified to include
3036 a request ID in front of the request/response. The request
3037 ID from the request must be echoed back with the response
3042 Sets the maximum number of queued requests.
3043 If the queued requests exceed queue size for more than 3 minutes
3044 squid aborts its operation.
3045 The default value is set to 2*numberofchildren.
3047 You must have at least one ssl_crt_validator process.
3051 OPTIONS WHICH AFFECT THE NEIGHBOR SELECTION ALGORITHM
3052 -----------------------------------------------------------------------------
3060 To specify other caches in a hierarchy, use the format:
3062 cache_peer hostname type http-port icp-port [options]
3067 # hostname type port port options
3068 # -------------------- -------- ----- ----- -----------
3069 cache_peer parent.foo.net parent 3128 3130 default
3070 cache_peer sib1.foo.net sibling 3128 3130 proxy-only
3071 cache_peer sib2.foo.net sibling 3128 3130 proxy-only
3072 cache_peer example.com parent 80 0 default
3073 cache_peer cdn.example.com sibling 3128 0
3075 type: either 'parent', 'sibling', or 'multicast'.
3077 proxy-port: The port number where the peer accept HTTP requests.
3078 For other Squid proxies this is usually 3128
3079 For web servers this is usually 80
3081 icp-port: Used for querying neighbor caches about objects.
3082 Set to 0 if the peer does not support ICP or HTCP.
3083 See ICP and HTCP options below for additional details.
3086 ==== ICP OPTIONS ====
3088 You MUST also set icp_port and icp_access explicitly when using these options.
3089 The defaults will prevent peer traffic using ICP.
3092 no-query Disable ICP queries to this neighbor.
3095 Indicates the named peer is a member of a multicast group.
3096 ICP queries will not be sent directly to the peer, but ICP
3097 replies will be accepted from it.
3099 closest-only Indicates that, for ICP_OP_MISS replies, we'll only forward
3100 CLOSEST_PARENT_MISSes and never FIRST_PARENT_MISSes.
3103 To only send ICP queries to this neighbor infrequently.
3104 This is used to keep the neighbor round trip time updated
3105 and is usually used in conjunction with weighted-round-robin.
3108 ==== HTCP OPTIONS ====
3110 You MUST also set htcp_port and htcp_access explicitly when using these options.
3111 The defaults will prevent peer traffic using HTCP.
3114 htcp Send HTCP, instead of ICP, queries to the neighbor.
3115 You probably also want to set the "icp-port" to 4827
3116 instead of 3130. This directive accepts a comma separated
3117 list of options described below.
3119 htcp=oldsquid Send HTCP to old Squid versions (2.5 or earlier).
3121 htcp=no-clr Send HTCP to the neighbor but without
3122 sending any CLR requests. This cannot be used with
3125 htcp=only-clr Send HTCP to the neighbor but ONLY CLR requests.
3126 This cannot be used with no-clr.
3129 Send HTCP to the neighbor including CLRs but only when
3130 they do not result from PURGE requests.
3133 Forward any HTCP CLR requests this proxy receives to the peer.
3136 ==== PEER SELECTION METHODS ====
3138 The default peer selection method is ICP, with the first responding peer
3139 being used as source. These options can be used for better load balancing.
3142 default This is a parent cache which can be used as a "last-resort"
3143 if a peer cannot be located by any of the peer-selection methods.
3144 If specified more than once, only the first is used.
3146 round-robin Load-Balance parents which should be used in a round-robin
3147 fashion in the absence of any ICP queries.
3148 weight=N can be used to add bias.
3150 weighted-round-robin
3151 Load-Balance parents which should be used in a round-robin
3152 fashion with the frequency of each parent being based on the
3153 round trip time. Closer parents are used more often.
3154 Usually used for background-ping parents.
3155 weight=N can be used to add bias.
3157 carp Load-Balance parents which should be used as a CARP array.
3158 The requests will be distributed among the parents based on the
3159 CARP load balancing hash function based on their weight.
3161 userhash Load-balance parents based on the client proxy_auth or ident username.
3163 sourcehash Load-balance parents based on the client source IP.
3166 To be used only for cache peers of type "multicast".
3167 ALL members of this multicast group have "sibling"
3168 relationship with it, not "parent". This is to a multicast
3169 group when the requested object would be fetched only from
3170 a "parent" cache, anyway. It's useful, e.g., when
3171 configuring a pool of redundant Squid proxies, being
3172 members of the same multicast group.
3175 ==== PEER SELECTION OPTIONS ====
3177 weight=N use to affect the selection of a peer during any weighted
3178 peer-selection mechanisms.
3179 The weight must be an integer; default is 1,
3180 larger weights are favored more.
3181 This option does not affect parent selection if a peering
3182 protocol is not in use.
3184 basetime=N Specify a base amount to be subtracted from round trip
3186 It is subtracted before division by weight in calculating
3187 which parent to fectch from. If the rtt is less than the
3188 base time the rtt is set to a minimal value.
3190 ttl=N Specify a TTL to use when sending multicast ICP queries
3192 Only useful when sending to a multicast group.
3193 Because we don't accept ICP replies from random
3194 hosts, you must configure other group members as
3195 peers with the 'multicast-responder' option.
3197 no-delay To prevent access to this neighbor from influencing the
3200 digest-url=URL Tell Squid to fetch the cache digest (if digests are
3201 enabled) for this host from the specified URL rather
3202 than the Squid default location.
3205 ==== CARP OPTIONS ====
3207 carp-key=key-specification
3208 use a different key than the full URL to hash against the peer.
3209 the key-specification is a comma-separated list of the keywords
3210 scheme, host, port, path, params
3211 Order is not important.
3213 ==== ACCELERATOR / REVERSE-PROXY OPTIONS ====
3215 originserver Causes this parent to be contacted as an origin server.
3216 Meant to be used in accelerator setups when the peer
3220 Set the Host header of requests forwarded to this peer.
3221 Useful in accelerator setups where the server (peer)
3222 expects a certain domain name but clients may request
3223 others. ie example.com or www.example.com
3225 no-digest Disable request of cache digests.
3228 Disables requesting ICMP RTT database (NetDB).
3231 ==== AUTHENTICATION OPTIONS ====
3234 If this is a personal/workgroup proxy and your parent
3235 requires proxy authentication.
3237 Note: The string can include URL escapes (i.e. %20 for
3238 spaces). This also means % must be written as %%.
3241 Send login details received from client to this peer.
3242 Both Proxy- and WWW-Authorization headers are passed
3243 without alteration to the peer.
3244 Authentication is not required by Squid for this to work.
3246 Note: This will pass any form of authentication but
3247 only Basic auth will work through a proxy unless the
3248 connection-auth options are also used.
3250 login=PASS Send login details received from client to this peer.
3251 Authentication is not required by this option.
3253 If there are no client-provided authentication headers
3254 to pass on, but username and password are available
3255 from an external ACL user= and password= result tags
3256 they may be sent instead.
3258 Note: To combine this with proxy_auth both proxies must
3259 share the same user database as HTTP only allows for
3260 a single login (one for proxy, one for origin server).
3261 Also be warned this will expose your users proxy
3262 password to the peer. USE WITH CAUTION
3265 Send the username to the upstream cache, but with a
3266 fixed password. This is meant to be used when the peer
3267 is in another administrative domain, but it is still
3268 needed to identify each user.
3269 The star can optionally be followed by some extra
3270 information which is added to the username. This can
3271 be used to identify this proxy to the peer, similar to
3272 the login=username:password option above.
3275 If this is a personal/workgroup proxy and your parent
3276 requires a secure proxy authentication.
3277 The first principal from the default keytab or defined by
3278 the environment variable KRB5_KTNAME will be used.
3280 WARNING: The connection may transmit requests from multiple
3281 clients. Negotiate often assumes end-to-end authentication
3282 and a single-client. Which is not strictly true here.
3284 login=NEGOTIATE:principal_name
3285 If this is a personal/workgroup proxy and your parent
3286 requires a secure proxy authentication.
3287 The principal principal_name from the default keytab or
3288 defined by the environment variable KRB5_KTNAME will be
3291 WARNING: The connection may transmit requests from multiple
3292 clients. Negotiate often assumes end-to-end authentication
3293 and a single-client. Which is not strictly true here.
3295 connection-auth=on|off
3296 Tell Squid that this peer does or not support Microsoft
3297 connection oriented authentication, and any such
3298 challenges received from there should be ignored.
3299 Default is auto to automatically determine the status
3303 Do not use a keytab to authenticate to a peer when
3304 login=NEGOTIATE is specified. Let the GSSAPI
3305 implementation determine which already existing
3306 credentials cache to use instead.
3309 ==== SSL / HTTPS / TLS OPTIONS ====
3311 tls Encrypt connections to this peer with TLS.
3313 sslcert=/path/to/ssl/certificate
3314 A client SSL certificate to use when connecting to
3317 sslkey=/path/to/ssl/key
3318 The private SSL key corresponding to sslcert above.
3319 If 'sslkey' is not specified 'sslcert' is assumed to
3320 reference a combined file containing both the
3321 certificate and the key.
3323 sslcipher=... The list of valid SSL ciphers to use when connecting
3327 The minimum TLS protocol version to permit. To control
3328 SSLv3 use the ssloptions= parameter.
3329 Supported Values: 1.0 (default), 1.1, 1.2
3331 ssloptions=... Specify various SSL implementation options:
3333 NO_SSLv3 Disallow the use of SSLv3
3335 NO_TLSv1 Disallow the use of TLSv1.0
3337 NO_TLSv1_1 Disallow the use of TLSv1.1
3339 NO_TLSv1_2 Disallow the use of TLSv1.2
3342 Always create a new key when using
3343 temporary/ephemeral DH key exchanges
3346 Disable use of RFC5077 session tickets.
3347 Some servers may have problems
3348 understanding the TLS extension due
3349 to ambiguous specification in RFC4507.
3351 ALL Enable various bug workarounds
3352 suggested as "harmless" by OpenSSL
3353 Be warned that this reduces SSL/TLS
3354 strength to some attacks.
3356 See the OpenSSL SSL_CTX_set_options documentation for a
3359 tls-cafile= PEM file containing CA certificates to use when verifying
3360 the peer certificate. May be repeated to load multiple files.
3362 sslcapath=... A directory containing additional CA certificates to
3363 use when verifying the peer certificate.
3364 Requires OpenSSL or LibreSSL.
3366 sslcrlfile=... A certificate revocation list file to use when
3367 verifying the peer certificate.
3369 sslflags=... Specify various flags modifying the SSL implementation:
3372 Accept certificates even if they fail to
3376 Don't verify the peer certificate
3377 matches the server name
3379 ssldomain= The peer name as advertised in it's certificate.
3380 Used for verifying the correctness of the received peer
3381 certificate. If not specified the peer hostname will be
3385 Enable the "Front-End-Https: On" header needed when
3386 using Squid as a SSL frontend in front of Microsoft OWA.
3387 See MS KB document Q307347 for details on this header.
3388 If set to auto the header will only be added if the
3389 request is forwarded as a https:// URL.
3391 tls-default-ca[=off]
3392 Whether to use the system Trusted CAs. Default is ON.
3394 tls-no-npn Do not use the TLS NPN extension to advertise HTTP/1.1.
3396 ==== GENERAL OPTIONS ====
3399 A peer-specific connect timeout.
3400 Also see the peer_connect_timeout directive.
3402 connect-fail-limit=N
3403 How many times connecting to a peer must fail before
3404 it is marked as down. Standby connection failures
3405 count towards this limit. Default is 10.
3407 allow-miss Disable Squid's use of only-if-cached when forwarding
3408 requests to siblings. This is primarily useful when
3409 icp_hit_stale is used by the sibling. Excessive use
3410 of this option may result in forwarding loops. One way
3411 to prevent peering loops when using this option, is to
3412 deny cache peer usage on requests from a peer:
3414 cache_peer_access peerName deny fromPeer
3416 max-conn=N Limit the number of concurrent connections the Squid
3417 may open to this peer, including already opened idle
3418 and standby connections. There is no peer-specific
3419 connection limit by default.
3421 A peer exceeding the limit is not used for new
3422 requests unless a standby connection is available.
3424 max-conn currently works poorly with idle persistent
3425 connections: When a peer reaches its max-conn limit,
3426 and there are idle persistent connections to the peer,
3427 the peer may not be selected because the limiting code
3428 does not know whether Squid can reuse those idle
3431 standby=N Maintain a pool of N "hot standby" connections to an
3432 UP peer, available for requests when no idle
3433 persistent connection is available (or safe) to use.
3434 By default and with zero N, no such pool is maintained.
3435 N must not exceed the max-conn limit (if any).
3437 At start or after reconfiguration, Squid opens new TCP
3438 standby connections until there are N connections
3439 available and then replenishes the standby pool as
3440 opened connections are used up for requests. A used
3441 connection never goes back to the standby pool, but
3442 may go to the regular idle persistent connection pool
3443 shared by all peers and origin servers.
3445 Squid never opens multiple new standby connections
3446 concurrently. This one-at-a-time approach minimizes
3447 flooding-like effect on peers. Furthermore, just a few
3448 standby connections should be sufficient in most cases
3449 to supply most new requests with a ready-to-use
3452 Standby connections obey server_idle_pconn_timeout.
3453 For the feature to work as intended, the peer must be
3454 configured to accept and keep them open longer than
3455 the idle timeout at the connecting Squid, to minimize
3456 race conditions typical to idle used persistent
3457 connections. Default request_timeout and
3458 server_idle_pconn_timeout values ensure such a
3461 name=xxx Unique name for the peer.
3462 Required if you have multiple peers on the same host
3463 but different ports.
3464 This name can be used in cache_peer_access and similar
3465 directives to identify the peer.
3466 Can be used by outgoing access controls through the
3469 no-tproxy Do not use the client-spoof TPROXY support when forwarding
3470 requests to this peer. Use normal address selection instead.
3471 This overrides the spoof_client_ip ACL.
3473 proxy-only objects fetched from the peer will not be stored locally.
3477 NAME: cache_peer_access
3480 DEFAULT_DOC: No peer usage restrictions.
3483 Restricts usage of cache_peer proxies.
3486 cache_peer_access peer-name allow|deny [!]aclname ...
3488 For the required peer-name parameter, use either the value of the
3489 cache_peer name=value parameter or, if name=value is missing, the
3490 cache_peer hostname parameter.
3492 This directive narrows down the selection of peering candidates, but
3493 does not determine the order in which the selected candidates are
3494 contacted. That order is determined by the peer selection algorithms
3495 (see PEER SELECTION sections in the cache_peer documentation).
3497 If a deny rule matches, the corresponding peer will not be contacted
3498 for the current transaction -- Squid will not send ICP queries and
3499 will not forward HTTP requests to that peer. An allow match leaves
3500 the corresponding peer in the selection. The first match for a given
3501 peer wins for that peer.
3503 The relative order of cache_peer_access directives for the same peer
3504 matters. The relative order of any two cache_peer_access directives
3505 for different peers does not matter. To ease interpretation, it is a
3506 good idea to group cache_peer_access directives for the same peer
3509 A single cache_peer_access directive may be evaluated multiple times
3510 for a given transaction because individual peer selection algorithms
3511 may check it independently from each other. These redundant checks
3512 may be optimized away in future Squid versions.
3514 This clause only supports fast acl types.
3515 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
3519 NAME: neighbor_type_domain
3520 TYPE: hostdomaintype
3522 DEFAULT_DOC: The peer type from cache_peer directive is used for all requests to that peer.
3525 Modify the cache_peer neighbor type when passing requests
3526 about specific domains to the peer.
3529 neighbor_type_domain neighbor parent|sibling domain domain ...
3532 cache_peer foo.example.com parent 3128 3130
3533 neighbor_type_domain foo.example.com sibling .au .de
3535 The above configuration treats all requests to foo.example.com as a
3536 parent proxy unless the request is for a .au or .de ccTLD domain name.
3539 NAME: dead_peer_timeout
3543 LOC: Config.Timeout.deadPeer
3545 This controls how long Squid waits to declare a peer cache
3546 as "dead." If there are no ICP replies received in this
3547 amount of time, Squid will declare the peer dead and not
3548 expect to receive any further ICP replies. However, it
3549 continues to send ICP queries, and will mark the peer as
3550 alive upon receipt of the first subsequent ICP reply.
3552 This timeout also affects when Squid expects to receive ICP
3553 replies from peers. If more than 'dead_peer' seconds have
3554 passed since the last ICP reply was received, Squid will not
3555 expect to receive an ICP reply on the next query. Thus, if
3556 your time between requests is greater than this timeout, you
3557 will see a lot of requests sent DIRECT to origin servers
3558 instead of to your parents.
3561 NAME: forward_max_tries
3564 LOC: Config.forward_max_tries
3566 Controls how many different forward paths Squid will try
3567 before giving up. See also forward_timeout.
3569 NOTE: connect_retries (default: none) can make each of these
3570 possible forwarding paths be tried multiple times.
3574 MEMORY CACHE OPTIONS
3575 -----------------------------------------------------------------------------
3582 LOC: Config.memMaxSize
3584 NOTE: THIS PARAMETER DOES NOT SPECIFY THE MAXIMUM PROCESS SIZE.
3585 IT ONLY PLACES A LIMIT ON HOW MUCH ADDITIONAL MEMORY SQUID WILL
3586 USE AS A MEMORY CACHE OF OBJECTS. SQUID USES MEMORY FOR OTHER
3587 THINGS AS WELL. SEE THE SQUID FAQ SECTION 8 FOR DETAILS.
3589 'cache_mem' specifies the ideal amount of memory to be used
3591 * In-Transit objects
3593 * Negative-Cached objects
3595 Data for these objects are stored in 4 KB blocks. This
3596 parameter specifies the ideal upper limit on the total size of
3597 4 KB blocks allocated. In-Transit objects take the highest
3600 In-transit objects have priority over the others. When
3601 additional space is needed for incoming data, negative-cached
3602 and hot objects will be released. In other words, the
3603 negative-cached and hot objects will fill up any unused space
3604 not needed for in-transit objects.
3606 If circumstances require, this limit will be exceeded.
3607 Specifically, if your incoming request rate requires more than
3608 'cache_mem' of memory to hold in-transit objects, Squid will
3609 exceed this limit to satisfy the new requests. When the load
3610 decreases, blocks will be freed until the high-water mark is
3611 reached. Thereafter, blocks will be used to store hot
3614 If shared memory caching is enabled, Squid does not use the shared
3615 cache space for in-transit objects, but they still consume as much
3616 local memory as they need. For more details about the shared memory
3617 cache, see memory_cache_shared.
3620 NAME: maximum_object_size_in_memory
3624 LOC: Config.Store.maxInMemObjSize
3626 Objects greater than this size will not be attempted to kept in
3627 the memory cache. This should be set high enough to keep objects
3628 accessed frequently in memory to improve performance whilst low
3629 enough to keep larger objects from hoarding cache_mem.
3632 NAME: memory_cache_shared
3635 LOC: Config.memShared
3637 DEFAULT_DOC: "on" where supported if doing memory caching with multiple SMP workers.
3639 Controls whether the memory cache is shared among SMP workers.
3641 The shared memory cache is meant to occupy cache_mem bytes and replace
3642 the non-shared memory cache, although some entities may still be
3643 cached locally by workers for now (e.g., internal and in-transit
3644 objects may be served from a local memory cache even if shared memory
3645 caching is enabled).
3647 By default, the memory cache is shared if and only if all of the
3648 following conditions are satisfied: Squid runs in SMP mode with
3649 multiple workers, cache_mem is positive, and Squid environment
3650 supports required IPC primitives (e.g., POSIX shared memory segments
3651 and GCC-style atomic operations).
3653 To avoid blocking locks, shared memory uses opportunistic algorithms
3654 that do not guarantee that every cachable entity that could have been
3655 shared among SMP workers will actually be shared.
3658 NAME: memory_cache_mode
3662 DEFAULT_DOC: Keep the most recently fetched objects in memory
3664 Controls which objects to keep in the memory cache (cache_mem)
3666 always Keep most recently fetched objects in memory (default)
3668 disk Only disk cache hits are kept in memory, which means
3669 an object must first be cached on disk and then hit
3670 a second time before cached in memory.
3672 network Only objects fetched from network is kept in memory
3675 NAME: memory_replacement_policy
3677 LOC: Config.memPolicy
3680 The memory replacement policy parameter determines which
3681 objects are purged from memory when memory space is needed.
3683 See cache_replacement_policy for details on algorithms.
3688 -----------------------------------------------------------------------------
3691 NAME: cache_replacement_policy
3693 LOC: Config.replPolicy
3696 The cache replacement policy parameter determines which
3697 objects are evicted (replaced) when disk space is needed.
3699 lru : Squid's original list based LRU policy
3700 heap GDSF : Greedy-Dual Size Frequency
3701 heap LFUDA: Least Frequently Used with Dynamic Aging
3702 heap LRU : LRU policy implemented using a heap
3704 Applies to any cache_dir lines listed below this directive.
3706 The LRU policies keeps recently referenced objects.
3708 The heap GDSF policy optimizes object hit rate by keeping smaller
3709 popular objects in cache so it has a better chance of getting a
3710 hit. It achieves a lower byte hit rate than LFUDA though since
3711 it evicts larger (possibly popular) objects.
3713 The heap LFUDA policy keeps popular objects in cache regardless of
3714 their size and thus optimizes byte hit rate at the expense of
3715 hit rate since one large, popular object will prevent many
3716 smaller, slightly less popular objects from being cached.
3718 Both policies utilize a dynamic aging mechanism that prevents
3719 cache pollution that can otherwise occur with frequency-based
3720 replacement policies.
3722 NOTE: if using the LFUDA replacement policy you should increase
3723 the value of maximum_object_size above its default of 4 MB to
3724 to maximize the potential byte hit rate improvement of LFUDA.
3726 For more information about the GDSF and LFUDA cache replacement
3727 policies see http://www.hpl.hp.com/techreports/1999/HPL-1999-69.html
3728 and http://fog.hpl.external.hp.com/techreports/98/HPL-98-173.html.
3731 NAME: minimum_object_size
3735 DEFAULT_DOC: no limit
3736 LOC: Config.Store.minObjectSize
3738 Objects smaller than this size will NOT be saved on disk. The
3739 value is specified in bytes, and the default is 0 KB, which
3740 means all responses can be stored.
3743 NAME: maximum_object_size
3747 LOC: Config.Store.maxObjectSize
3749 Set the default value for max-size parameter on any cache_dir.
3750 The value is specified in bytes, and the default is 4 MB.
3752 If you wish to get a high BYTES hit ratio, you should probably
3753 increase this (one 32 MB object hit counts for 3200 10KB
3756 If you wish to increase hit ratio more than you want to
3757 save bandwidth you should leave this low.
3759 NOTE: if using the LFUDA replacement policy you should increase
3760 this value to maximize the byte hit rate improvement of LFUDA!
3761 See cache_replacement_policy for a discussion of this policy.
3767 DEFAULT_DOC: No disk cache. Store cache ojects only in memory.
3768 LOC: Config.cacheSwap
3771 cache_dir Type Directory-Name Fs-specific-data [options]
3773 You can specify multiple cache_dir lines to spread the
3774 cache among different disk partitions.
3776 Type specifies the kind of storage system to use. Only "ufs"
3777 is built by default. To enable any of the other storage systems
3778 see the --enable-storeio configure option.
3780 'Directory' is a top-level directory where cache swap
3781 files will be stored. If you want to use an entire disk
3782 for caching, this can be the mount-point directory.
3783 The directory must exist and be writable by the Squid
3784 process. Squid will NOT create this directory for you.
3786 In SMP configurations, cache_dir must not precede the workers option
3787 and should use configuration macros or conditionals to give each
3788 worker interested in disk caching a dedicated cache directory.
3791 ==== The ufs store type ====
3793 "ufs" is the old well-known Squid storage format that has always
3797 cache_dir ufs Directory-Name Mbytes L1 L2 [options]
3799 'Mbytes' is the amount of disk space (MB) to use under this
3800 directory. The default is 100 MB. Change this to suit your
3801 configuration. Do NOT put the size of your disk drive here.
3802 Instead, if you want Squid to use the entire disk drive,
3803 subtract 20% and use that value.
3805 'L1' is the number of first-level subdirectories which
3806 will be created under the 'Directory'. The default is 16.
3808 'L2' is the number of second-level subdirectories which
3809 will be created under each first-level directory. The default
3813 ==== The aufs store type ====
3815 "aufs" uses the same storage format as "ufs", utilizing
3816 POSIX-threads to avoid blocking the main Squid process on
3817 disk-I/O. This was formerly known in Squid as async-io.
3820 cache_dir aufs Directory-Name Mbytes L1 L2 [options]
3822 see argument descriptions under ufs above
3825 ==== The diskd store type ====
3827 "diskd" uses the same storage format as "ufs", utilizing a
3828 separate process to avoid blocking the main Squid process on
3832 cache_dir diskd Directory-Name Mbytes L1 L2 [options] [Q1=n] [Q2=n]
3834 see argument descriptions under ufs above
3836 Q1 specifies the number of unacknowledged I/O requests when Squid
3837 stops opening new files. If this many messages are in the queues,
3838 Squid won't open new files. Default is 64
3840 Q2 specifies the number of unacknowledged messages when Squid
3841 starts blocking. If this many messages are in the queues,
3842 Squid blocks until it receives some replies. Default is 72
3844 When Q1 < Q2 (the default), the cache directory is optimized
3845 for lower response time at the expense of a decrease in hit
3846 ratio. If Q1 > Q2, the cache directory is optimized for
3847 higher hit ratio at the expense of an increase in response
3851 ==== The rock store type ====
3854 cache_dir rock Directory-Name Mbytes [options]
3856 The Rock Store type is a database-style storage. All cached
3857 entries are stored in a "database" file, using fixed-size slots.
3858 A single entry occupies one or more slots.
3860 If possible, Squid using Rock Store creates a dedicated kid
3861 process called "disker" to avoid blocking Squid worker(s) on disk
3862 I/O. One disker kid is created for each rock cache_dir. Diskers
3863 are created only when Squid, running in daemon mode, has support
3864 for the IpcIo disk I/O module.
3866 swap-timeout=msec: Squid will not start writing a miss to or
3867 reading a hit from disk if it estimates that the swap operation
3868 will take more than the specified number of milliseconds. By
3869 default and when set to zero, disables the disk I/O time limit
3870 enforcement. Ignored when using blocking I/O module because
3871 blocking synchronous I/O does not allow Squid to estimate the
3872 expected swap wait time.
3874 max-swap-rate=swaps/sec: Artificially limits disk access using
3875 the specified I/O rate limit. Swap out requests that
3876 would cause the average I/O rate to exceed the limit are
3877 delayed. Individual swap in requests (i.e., hits or reads) are
3878 not delayed, but they do contribute to measured swap rate and
3879 since they are placed in the same FIFO queue as swap out
3880 requests, they may wait longer if max-swap-rate is smaller.
3881 This is necessary on file systems that buffer "too
3882 many" writes and then start blocking Squid and other processes
3883 while committing those writes to disk. Usually used together
3884 with swap-timeout to avoid excessive delays and queue overflows
3885 when disk demand exceeds available disk "bandwidth". By default
3886 and when set to zero, disables the disk I/O rate limit
3887 enforcement. Currently supported by IpcIo module only.
3889 slot-size=bytes: The size of a database "record" used for
3890 storing cached responses. A cached response occupies at least
3891 one slot and all database I/O is done using individual slots so
3892 increasing this parameter leads to more disk space waste while
3893 decreasing it leads to more disk I/O overheads. Should be a
3894 multiple of your operating system I/O page size. Defaults to
3895 16KBytes. A housekeeping header is stored with each slot and
3896 smaller slot-sizes will be rejected. The header is smaller than
3900 ==== COMMON OPTIONS ====
3902 no-store no new objects should be stored to this cache_dir.
3904 min-size=n the minimum object size in bytes this cache_dir
3905 will accept. It's used to restrict a cache_dir
3906 to only store large objects (e.g. AUFS) while
3907 other stores are optimized for smaller objects
3911 max-size=n the maximum object size in bytes this cache_dir
3913 The value in maximum_object_size directive sets
3914 the default unless more specific details are
3915 available (ie a small store capacity).
3917 Note: To make optimal use of the max-size limits you should order
3918 the cache_dir lines with the smallest max-size value first.
3922 # Uncomment and adjust the following to add a disk cache directory.
3923 #cache_dir ufs @DEFAULT_SWAP_DIR@ 100 16 256
3927 NAME: store_dir_select_algorithm
3929 LOC: Config.store_dir_select_algorithm
3932 How Squid selects which cache_dir to use when the response
3933 object will fit into more than one.
3935 Regardless of which algorithm is used the cache_dir min-size
3936 and max-size parameters are obeyed. As such they can affect
3937 the selection algorithm by limiting the set of considered
3944 This algorithm is suited to caches with similar cache_dir
3945 sizes and disk speeds.
3947 The disk with the least I/O pending is selected.
3948 When there are multiple disks with the same I/O load ranking
3949 the cache_dir with most available capacity is selected.
3951 When a mix of cache_dir sizes are configured the faster disks
3952 have a naturally lower I/O loading and larger disks have more
3953 capacity. So space used to store objects and data throughput
3954 may be very unbalanced towards larger disks.
3959 This algorithm is suited to caches with unequal cache_dir
3962 Each cache_dir is selected in a rotation. The next suitable
3965 Available cache_dir capacity is only considered in relation
3966 to whether the object will fit and meets the min-size and
3967 max-size parameters.
3969 Disk I/O loading is only considered to prevent overload on slow
3970 disks. This algorithm does not spread objects by size, so any
3971 I/O loading per-disk may appear very unbalanced and volatile.
3973 If several cache_dirs use similar min-size, max-size, or other
3974 limits to to reject certain responses, then do not group such
3975 cache_dir lines together, to avoid round-robin selection bias
3976 towards the first cache_dir after the group. Instead, interleave
3977 cache_dir lines from different groups. For example:
3979 store_dir_select_algorithm round-robin
3980 cache_dir rock /hdd1 ... min-size=100000
3981 cache_dir rock /ssd1 ... max-size=99999
3982 cache_dir rock /hdd2 ... min-size=100000
3983 cache_dir rock /ssd2 ... max-size=99999
3984 cache_dir rock /hdd3 ... min-size=100000
3985 cache_dir rock /ssd3 ... max-size=99999
3988 NAME: max_open_disk_fds
3990 LOC: Config.max_open_disk_fds
3992 DEFAULT_DOC: no limit
3994 To avoid having disk as the I/O bottleneck Squid can optionally
3995 bypass the on-disk cache if more than this amount of disk file
3996 descriptors are open.
3998 A value of 0 indicates no limit.
4001 NAME: cache_swap_low
4002 COMMENT: (percent, 0-100)
4005 LOC: Config.Swap.lowWaterMark
4007 The low-water mark for AUFS/UFS/diskd cache object eviction by
4008 the cache_replacement_policy algorithm.
4010 Removal begins when the swap (disk) usage of a cache_dir is
4011 above this low-water mark and attempts to maintain utilization
4012 near the low-water mark.
4014 As swap utilization increases towards the high-water mark set
4015 by cache_swap_high object eviction becomes more agressive.
4017 The value difference in percentages between low- and high-water
4018 marks represent an eviction rate of 300 objects per second and
4019 the rate continues to scale in agressiveness by multiples of
4020 this above the high-water mark.
4022 Defaults are 90% and 95%. If you have a large cache, 5% could be
4023 hundreds of MB. If this is the case you may wish to set these
4024 numbers closer together.
4026 See also cache_swap_high and cache_replacement_policy
4029 NAME: cache_swap_high
4030 COMMENT: (percent, 0-100)
4033 LOC: Config.Swap.highWaterMark
4035 The high-water mark for AUFS/UFS/diskd cache object eviction by
4036 the cache_replacement_policy algorithm.
4038 Removal begins when the swap (disk) usage of a cache_dir is
4039 above the low-water mark set by cache_swap_low and attempts to
4040 maintain utilization near the low-water mark.
4042 As swap utilization increases towards this high-water mark object
4043 eviction becomes more agressive.
4045 The value difference in percentages between low- and high-water
4046 marks represent an eviction rate of 300 objects per second and
4047 the rate continues to scale in agressiveness by multiples of
4048 this above the high-water mark.
4050 Defaults are 90% and 95%. If you have a large cache, 5% could be
4051 hundreds of MB. If this is the case you may wish to set these
4052 numbers closer together.
4054 See also cache_swap_low and cache_replacement_policy
4059 -----------------------------------------------------------------------------
4066 DEFAULT_DOC: The format definitions squid, common, combined, referrer, useragent are built in.
4070 logformat <name> <format specification>
4072 Defines an access log format.
4074 The <format specification> is a string with embedded % format codes
4076 % format codes all follow the same basic structure where all but
4077 the formatcode is optional. Output strings are automatically escaped
4078 as required according to their context and the output format
4079 modifiers are usually not needed, but can be specified if an explicit
4080 output format is desired.
4082 % ["|[|'|#|/] [-] [[0]width] [{arg}] formatcode [{arg}]
4084 " output in quoted string format
4085 [ output in squid text log format as used by log_mime_hdrs
4086 # output in URL quoted format
4087 / output in shell \-escaped format
4092 width minimum and/or maximum field width:
4093 [width_min][.width_max]
4094 When minimum starts with 0, the field is zero-padded.
4095 String values exceeding maximum width are truncated.
4097 {arg} argument such as header name etc. This field may be
4098 placed before or after the token, but not both at once.
4102 % a literal % character
4103 sn Unique sequence number per log line entry
4104 err_code The ID of an error response served by Squid or
4105 a similar internal error identifier.
4106 err_detail Additional err_code-dependent error information.
4107 note The annotation specified by the argument. Also
4108 logs the adaptation meta headers set by the
4109 adaptation_meta configuration parameter.
4110 If no argument given all annotations logged.
4111 The argument may include a separator to use with
4114 By default, multiple note values are separated with ","
4115 and multiple notes are separated with "\r\n".
4116 When logging named notes with %{name}note, the
4117 explicitly configured separator is used between note
4118 values. When logging all notes with %note, the
4119 explicitly configured separator is used between
4120 individual notes. There is currently no way to
4121 specify both value and notes separators when logging
4122 all notes with %note.
4124 Connection related format codes:
4126 >a Client source IP address
4128 >p Client source port
4129 >eui Client source EUI (MAC address, EUI-48 or EUI-64 identifier)
4130 >la Local IP address the client connected to
4131 >lp Local port number the client connected to
4132 >qos Client connection TOS/DSCP value set by Squid
4133 >nfmark Client connection netfilter mark set by Squid
4135 la Local listening IP address the client connection was connected to.
4136 lp Local listening port number the client connection was connected to.
4138 <a Server IP address of the last server or peer connection
4139 <A Server FQDN or peer name
4140 <p Server port number of the last server or peer connection
4141 <la Local IP address of the last server or peer connection
4142 <lp Local port number of the last server or peer connection
4143 <qos Server connection TOS/DSCP value set by Squid
4144 <nfmark Server connection netfilter mark set by Squid
4146 Time related format codes:
4148 ts Seconds since epoch
4149 tu subsecond time (milliseconds)
4150 tl Local time. Optional strftime format argument
4151 default %d/%b/%Y:%H:%M:%S %z
4152 tg GMT time. Optional strftime format argument
4153 default %d/%b/%Y:%H:%M:%S %z
4154 tr Response time (milliseconds)
4155 dt Total time spent making DNS lookups (milliseconds)
4156 tS Approximate master transaction start time in
4157 <full seconds since epoch>.<fractional seconds> format.
4158 Currently, Squid considers the master transaction
4159 started when a complete HTTP request header initiating
4160 the transaction is received from the client. This is
4161 the same value that Squid uses to calculate transaction
4162 response time when logging %tr to access.log. Currently,
4163 Squid uses millisecond resolution for %tS values,
4164 similar to the default access.log "current time" field
4167 Access Control related format codes:
4169 et Tag returned by external acl
4170 ea Log string returned by external acl
4171 un User name (any available)
4172 ul User name from authentication
4173 ue User name from external acl helper
4174 ui User name from ident
4175 un A user name. Expands to the first available name
4176 from the following list of information sources:
4177 - authenticated user name, like %ul
4178 - user name supplied by an external ACL, like %ue
4179 - SSL client name, like %us
4180 - ident user name, like %ui
4181 credentials Client credentials. The exact meaning depends on
4182 the authentication scheme: For Basic authentication,
4183 it is the password; for Digest, the realm sent by the
4184 client; for NTLM and Negotiate, the client challenge
4185 or client credentials prefixed with "YR " or "KK ".
4187 HTTP related format codes:
4191 [http::]rm Request method (GET/POST etc)
4192 [http::]>rm Request method from client
4193 [http::]<rm Request method sent to server or peer
4194 [http::]ru Request URL from client (historic, filtered for logging)
4195 [http::]>ru Request URL from client
4196 [http::]<ru Request URL sent to server or peer
4197 [http::]>rs Request URL scheme from client
4198 [http::]<rs Request URL scheme sent to server or peer
4199 [http::]>rd Request URL domain from client
4200 [http::]<rd Request URL domain sent to server or peer
4201 [http::]>rP Request URL port from client
4202 [http::]<rP Request URL port sent to server or peer
4203 [http::]rp Request URL path excluding hostname
4204 [http::]>rp Request URL path excluding hostname from client
4205 [http::]<rp Request URL path excluding hostname sent to server or peer
4206 [http::]rv Request protocol version
4207 [http::]>rv Request protocol version from client
4208 [http::]<rv Request protocol version sent to server or peer
4210 [http::]>h Original received request header.
4211 Usually differs from the request header sent by
4212 Squid, although most fields are often preserved.
4213 Accepts optional header field name/value filter
4214 argument using name[:[separator]element] format.
4215 [http::]>ha Received request header after adaptation and
4216 redirection (pre-cache REQMOD vectoring point).
4217 Usually differs from the request header sent by
4218 Squid, although most fields are often preserved.
4219 Optional header name argument as for >h
4223 [http::]<Hs HTTP status code received from the next hop
4224 [http::]>Hs HTTP status code sent to the client
4226 [http::]<h Reply header. Optional header name argument
4229 [http::]mt MIME content type
4234 [http::]st Total size of request + reply traffic with client
4235 [http::]>st Total size of request received from client.
4236 Excluding chunked encoding bytes.
4237 [http::]<st Total size of reply sent to client (after adaptation)
4239 [http::]>sh Size of request headers received from client
4240 [http::]<sh Size of reply headers sent to client (after adaptation)
4242 [http::]<sH Reply high offset sent
4243 [http::]<sS Upstream object size
4245 [http::]<bs Number of HTTP-equivalent message body bytes
4246 received from the next hop, excluding chunked
4247 transfer encoding and control messages.
4248 Generated FTP/Gopher listings are treated as
4253 [http::]<pt Peer response time in milliseconds. The timer starts
4254 when the last request byte is sent to the next hop
4255 and stops when the last response byte is received.
4256 [http::]<tt Total time in milliseconds. The timer
4257 starts with the first connect request (or write I/O)
4258 sent to the first selected peer. The timer stops
4259 with the last I/O with the last peer.
4261 Squid handling related format codes:
4263 Ss Squid request status (TCP_MISS etc)
4264 Sh Squid hierarchy status (DEFAULT_PARENT etc)
4266 SSL-related format codes:
4268 ssl::bump_mode SslBump decision for the transaction:
4270 For CONNECT requests that initiated bumping of
4271 a connection and for any request received on
4272 an already bumped connection, Squid logs the
4273 corresponding SslBump mode ("server-first" or
4274 "client-first"). See the ssl_bump option for
4275 more information about these modes.
4277 A "none" token is logged for requests that
4278 triggered "ssl_bump" ACL evaluation matching
4279 either a "none" rule or no rules at all.
4281 In all other cases, a single dash ("-") is
4284 ssl::>sni SSL client SNI sent to Squid. Available only
4285 after the peek, stare, or splice SSL bumping
4289 The Subject field of the received client
4290 SSL certificate or a dash ('-') if Squid has
4291 received an invalid/malformed certificate or
4292 no certificate at all. Consider encoding the
4293 logged value because Subject often has spaces.
4296 The Issuer field of the received client
4297 SSL certificate or a dash ('-') if Squid has
4298 received an invalid/malformed certificate or
4299 no certificate at all. Consider encoding the
4300 logged value because Issuer often has spaces.
4303 The list of certificate validation errors
4304 detected by Squid (including OpenSSL and
4305 certificate validation helper components). The
4306 errors are listed in the discovery order. By
4307 default, the error codes are separated by ':'.
4308 Accepts an optional separator argument.
4310 %ssl::>negotiated_version The negotiated TLS version of the
4313 %ssl::<negotiated_version The negotiated TLS version of the
4314 last server or peer connection.
4316 %ssl::>received_hello_version The TLS version of the Hello
4317 message received from TLS client.
4319 %ssl::<received_hello_version The TLS version of the Hello
4320 message received from TLS server.
4322 %ssl::>received_supported_version The maximum TLS version
4323 supported by the TLS client.
4325 %ssl::<received_supported_version The maximum TLS version
4326 supported by the TLS server.
4328 %ssl::>negotiated_cipher The negotiated cipher of the
4331 %ssl::<negotiated_cipher The negotiated cipher of the
4332 last server or peer connection.
4334 If ICAP is enabled, the following code becomes available (as
4335 well as ICAP log codes documented with the icap_log option):
4337 icap::tt Total ICAP processing time for the HTTP
4338 transaction. The timer ticks when ICAP
4339 ACLs are checked and when ICAP
4340 transaction is in progress.
4342 If adaptation is enabled the following codes become available:
4344 adapt::<last_h The header of the last ICAP response or
4345 meta-information from the last eCAP
4346 transaction related to the HTTP transaction.
4347 Like <h, accepts an optional header name
4350 adapt::sum_trs Summed adaptation transaction response
4351 times recorded as a comma-separated list in
4352 the order of transaction start time. Each time
4353 value is recorded as an integer number,
4354 representing response time of one or more
4355 adaptation (ICAP or eCAP) transaction in
4356 milliseconds. When a failed transaction is
4357 being retried or repeated, its time is not
4358 logged individually but added to the
4359 replacement (next) transaction. See also:
4362 adapt::all_trs All adaptation transaction response times.
4363 Same as adaptation_strs but response times of
4364 individual transactions are never added
4365 together. Instead, all transaction response
4366 times are recorded individually.
4368 You can prefix adapt::*_trs format codes with adaptation
4369 service name in curly braces to record response time(s) specific
4370 to that service. For example: %{my_service}adapt::sum_trs
4372 The default formats available (which do not need re-defining) are:
4374 logformat squid %ts.%03tu %6tr %>a %Ss/%03>Hs %<st %rm %ru %[un %Sh/%<a %mt
4375 logformat common %>a %[ui %[un [%tl] "%rm %ru HTTP/%rv" %>Hs %<st %Ss:%Sh
4376 logformat combined %>a %[ui %[un [%tl] "%rm %ru HTTP/%rv" %>Hs %<st "%{Referer}>h" "%{User-Agent}>h" %Ss:%Sh
4377 logformat referrer %ts.%03tu %>a %{Referer}>h %ru
4378 logformat useragent %>a [%tl] "%{User-Agent}>h"
4380 NOTE: When the log_mime_hdrs directive is set to ON.
4381 The squid, common and combined formats have a safely encoded copy
4382 of the mime headers appended to each line within a pair of brackets.
4384 NOTE: The common and combined formats are not quite true to the Apache definition.
4385 The logs from Squid contain an extra status and hierarchy code appended.
4389 NAME: access_log cache_access_log
4391 LOC: Config.Log.accesslogs
4392 DEFAULT_IF_NONE: daemon:@DEFAULT_ACCESS_LOG@ squid
4394 Configures whether and how Squid logs HTTP and ICP transactions.
4395 If access logging is enabled, a single line is logged for every
4396 matching HTTP or ICP request. The recommended directive formats are:
4398 access_log <module>:<place> [option ...] [acl acl ...]
4399 access_log none [acl acl ...]
4401 The following directive format is accepted but may be deprecated:
4402 access_log <module>:<place> [<logformat name> [acl acl ...]]
4404 In most cases, the first ACL name must not contain the '=' character
4405 and should not be equal to an existing logformat name. You can always
4406 start with an 'all' ACL to work around those restrictions.
4408 Will log to the specified module:place using the specified format (which
4409 must be defined in a logformat directive) those entries which match
4410 ALL the acl's specified (which must be defined in acl clauses).
4411 If no acl is specified, all requests will be logged to this destination.
4413 ===== Available options for the recommended directive format =====
4415 logformat=name Names log line format (either built-in or
4416 defined by a logformat directive). Defaults
4419 buffer-size=64KB Defines approximate buffering limit for log
4420 records (see buffered_logs). Squid should not
4421 keep more than the specified size and, hence,
4422 should flush records before the buffer becomes
4423 full to avoid overflows under normal
4424 conditions (the exact flushing algorithm is
4425 module-dependent though). The on-error option
4426 controls overflow handling.
4428 on-error=die|drop Defines action on unrecoverable errors. The
4429 'drop' action ignores (i.e., does not log)
4430 affected log records. The default 'die' action
4431 kills the affected worker. The drop action
4432 support has not been tested for modules other
4435 rotate=N Specifies the number of log file rotations to
4436 make when you run 'squid -k rotate'. The default
4437 is to obey the logfile_rotate directive. Setting
4438 rotate=0 will disable the file name rotation,
4439 but the log files are still closed and re-opened.
4440 This will enable you to rename the logfiles
4441 yourself just before sending the rotate signal.
4442 Only supported by the stdio module.
4444 ===== Modules Currently available =====
4446 none Do not log any requests matching these ACL.
4447 Do not specify Place or logformat name.
4449 stdio Write each log line to disk immediately at the completion of
4451 Place: the filename and path to be written.
4453 daemon Very similar to stdio. But instead of writing to disk the log
4454 line is passed to a daemon helper for asychronous handling instead.
4455 Place: varies depending on the daemon.
4457 log_file_daemon Place: the file name and path to be written.
4459 syslog To log each request via syslog facility.
4460 Place: The syslog facility and priority level for these entries.
4461 Place Format: facility.priority
4463 where facility could be any of:
4464 authpriv, daemon, local0 ... local7 or user.
4466 And priority could be any of:
4467 err, warning, notice, info, debug.
4469 udp To send each log line as text data to a UDP receiver.
4470 Place: The destination host name or IP and port.
4471 Place Format: //host:port
4473 tcp To send each log line as text data to a TCP receiver.
4474 Lines may be accumulated before sending (see buffered_logs).
4475 Place: The destination host name or IP and port.
4476 Place Format: //host:port
4479 access_log daemon:@DEFAULT_ACCESS_LOG@ squid
4485 LOC: Config.Log.icaplogs
4488 ICAP log files record ICAP transaction summaries, one line per
4491 The icap_log option format is:
4492 icap_log <filepath> [<logformat name> [acl acl ...]]
4493 icap_log none [acl acl ...]]
4495 Please see access_log option documentation for details. The two
4496 kinds of logs share the overall configuration approach and many
4499 ICAP processing of a single HTTP message or transaction may
4500 require multiple ICAP transactions. In such cases, multiple
4501 ICAP transaction log lines will correspond to a single access
4504 ICAP log uses logformat codes that make sense for an ICAP
4505 transaction. Header-related codes are applied to the HTTP header
4506 embedded in an ICAP server response, with the following caveats:
4507 For REQMOD, there is no HTTP response header unless the ICAP
4508 server performed request satisfaction. For RESPMOD, the HTTP
4509 request header is the header sent to the ICAP server. For
4510 OPTIONS, there are no HTTP headers.
4512 The following format codes are also available for ICAP logs:
4514 icap::<A ICAP server IP address. Similar to <A.
4516 icap::<service_name ICAP service name from the icap_service
4517 option in Squid configuration file.
4519 icap::ru ICAP Request-URI. Similar to ru.
4521 icap::rm ICAP request method (REQMOD, RESPMOD, or
4522 OPTIONS). Similar to existing rm.
4524 icap::>st Bytes sent to the ICAP server (TCP payload
4525 only; i.e., what Squid writes to the socket).
4527 icap::<st Bytes received from the ICAP server (TCP
4528 payload only; i.e., what Squid reads from
4531 icap::<bs Number of message body bytes received from the
4532 ICAP server. ICAP message body, if any, usually
4533 includes encapsulated HTTP message headers and
4534 possibly encapsulated HTTP message body. The
4535 HTTP body part is dechunked before its size is
4538 icap::tr Transaction response time (in
4539 milliseconds). The timer starts when
4540 the ICAP transaction is created and
4541 stops when the transaction is completed.
4544 icap::tio Transaction I/O time (in milliseconds). The
4545 timer starts when the first ICAP request
4546 byte is scheduled for sending. The timers
4547 stops when the last byte of the ICAP response
4550 icap::to Transaction outcome: ICAP_ERR* for all
4551 transaction errors, ICAP_OPT for OPTION
4552 transactions, ICAP_ECHO for 204
4553 responses, ICAP_MOD for message
4554 modification, and ICAP_SAT for request
4555 satisfaction. Similar to Ss.
4557 icap::Hs ICAP response status code. Similar to Hs.
4559 icap::>h ICAP request header(s). Similar to >h.
4561 icap::<h ICAP response header(s). Similar to <h.
4563 The default ICAP log format, which can be used without an explicit
4564 definition, is called icap_squid:
4566 logformat icap_squid %ts.%03tu %6icap::tr %>a %icap::to/%03icap::Hs %icap::<size %icap::rm %icap::ru% %un -/%icap::<A -
4568 See also: logformat, log_icap, and %adapt::<last_h
4571 NAME: logfile_daemon
4573 DEFAULT: @DEFAULT_LOGFILED@
4574 LOC: Log::TheConfig.logfile_daemon
4576 Specify the path to the logfile-writing daemon. This daemon is
4577 used to write the access and store logs, if configured.
4579 Squid sends a number of commands to the log daemon:
4580 L<data>\n - logfile data
4585 r<n>\n - set rotate count to <n>
4586 b<n>\n - 1 = buffer output, 0 = don't buffer output
4588 No responses is expected.
4591 NAME: stats_collection
4593 LOC: Config.accessList.stats_collection
4595 DEFAULT_DOC: Allow logging for all transactions.
4596 COMMENT: allow|deny acl acl...
4598 This options allows you to control which requests gets accounted
4599 in performance counters.
4601 This clause only supports fast acl types.
4602 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
4605 NAME: cache_store_log
4608 LOC: Config.Log.store
4610 Logs the activities of the storage manager. Shows which
4611 objects are ejected from the cache, and which objects are
4612 saved and for how long.
4613 There are not really utilities to analyze this data, so you can safely
4614 disable it (the default).
4616 Store log uses modular logging outputs. See access_log for the list
4617 of modules supported.
4620 cache_store_log stdio:@DEFAULT_STORE_LOG@
4621 cache_store_log daemon:@DEFAULT_STORE_LOG@
4624 NAME: cache_swap_state cache_swap_log
4626 LOC: Config.Log.swap
4628 DEFAULT_DOC: Store the journal inside its cache_dir
4630 Location for the cache "swap.state" file. This index file holds
4631 the metadata of objects saved on disk. It is used to rebuild
4632 the cache during startup. Normally this file resides in each
4633 'cache_dir' directory, but you may specify an alternate
4634 pathname here. Note you must give a full filename, not just
4635 a directory. Since this is the index for the whole object
4636 list you CANNOT periodically rotate it!
4638 If %s can be used in the file name it will be replaced with a
4639 a representation of the cache_dir name where each / is replaced
4640 with '.'. This is needed to allow adding/removing cache_dir
4641 lines when cache_swap_log is being used.
4643 If have more than one 'cache_dir', and %s is not used in the name
4644 these swap logs will have names such as:
4650 The numbered extension (which is added automatically)
4651 corresponds to the order of the 'cache_dir' lines in this
4652 configuration file. If you change the order of the 'cache_dir'
4653 lines in this file, these index files will NOT correspond to
4654 the correct 'cache_dir' entry (unless you manually rename
4655 them). We recommend you do NOT use this option. It is
4656 better to keep these index files in each 'cache_dir' directory.
4659 NAME: logfile_rotate
4662 LOC: Config.Log.rotateNumber
4664 Specifies the default number of logfile rotations to make when you
4665 type 'squid -k rotate'. The default is 10, which will rotate
4666 with extensions 0 through 9. Setting logfile_rotate to 0 will
4667 disable the file name rotation, but the logfiles are still closed
4668 and re-opened. This will enable you to rename the logfiles
4669 yourself just before sending the rotate signal.
4671 Note, from Squid-3.1 this option is only a default for cache.log,
4672 that log can be rotated separately by using debug_options.
4674 Note, from Squid-3.6 this option is only a default for access.log
4675 recorded by stdio: module. Those logs can be rotated separately by
4676 using the rotate=N option on their access_log directive.
4678 Note, the 'squid -k rotate' command normally sends a USR1
4679 signal to the running squid process. In certain situations
4680 (e.g. on Linux with Async I/O), USR1 is used for other
4681 purposes, so -k rotate uses another signal. It is best to get
4682 in the habit of using 'squid -k rotate' instead of 'kill -USR1
4689 DEFAULT: @DEFAULT_MIME_TABLE@
4690 LOC: Config.mimeTablePathname
4692 Path to Squid's icon configuration file.
4694 You shouldn't need to change this, but the default file contains
4695 examples and formatting information if you do.
4701 LOC: Config.onoff.log_mime_hdrs
4704 The Cache can record both the request and the response MIME
4705 headers for each HTTP transaction. The headers are encoded
4706 safely and will appear as two bracketed fields at the end of
4707 the access log (for either the native or httpd-emulated log
4708 formats). To enable this logging set log_mime_hdrs to 'on'.
4713 DEFAULT: @DEFAULT_PID_FILE@
4714 LOC: Config.pidFilename
4716 A filename to write the process-id to. To disable, enter "none".
4719 NAME: client_netmask
4721 LOC: Config.Addrs.client_netmask
4723 DEFAULT_DOC: Log full client IP address
4725 A netmask for client addresses in logfiles and cachemgr output.
4726 Change this to protect the privacy of your cache clients.
4727 A netmask of 255.255.255.0 will log all IP's in that range with
4728 the last digit set to '0'.
4731 NAME: strip_query_terms
4733 LOC: Config.onoff.strip_query_terms
4736 By default, Squid strips query terms from requested URLs before
4737 logging. This protects your user's privacy and reduces log size.
4739 When investigating HIT/MISS or other caching behaviour you
4740 will need to disable this to see the full URL used by Squid.
4747 LOC: Config.onoff.buffered_logs
4749 Whether to write/send access_log records ASAP or accumulate them and
4750 then write/send them in larger chunks. Buffering may improve
4751 performance because it decreases the number of I/Os. However,
4752 buffering increases the delay before log records become available to
4753 the final recipient (e.g., a disk file or logging daemon) and,
4754 hence, increases the risk of log records loss.
4756 Note that even when buffered_logs are off, Squid may have to buffer
4757 records if it cannot write/send them immediately due to pending I/Os
4758 (e.g., the I/O writing the previous log record) or connectivity loss.
4760 Currently honored by 'daemon' and 'tcp' access_log modules only.
4763 NAME: netdb_filename
4765 DEFAULT: stdio:@DEFAULT_NETDB_FILE@
4766 LOC: Config.netdbFilename
4769 Where Squid stores it's netdb journal.
4770 When enabled this journal preserves netdb state between restarts.
4772 To disable, enter "none".
4776 OPTIONS FOR TROUBLESHOOTING
4777 -----------------------------------------------------------------------------
4782 DEFAULT_IF_NONE: @DEFAULT_CACHE_LOG@
4783 LOC: Debug::cache_log
4785 Squid administrative logging file.
4787 This is where general information about Squid behavior goes. You can
4788 increase the amount of data logged to this file and how often it is
4789 rotated with "debug_options"
4795 DEFAULT_DOC: Log all critical and important messages.
4796 LOC: Debug::debugOptions
4798 Logging options are set as section,level where each source file
4799 is assigned a unique section. Lower levels result in less
4800 output, Full debugging (level 9) can result in a very large
4801 log file, so be careful.
4803 The magic word "ALL" sets debugging levels for all sections.
4804 The default is to run with "ALL,1" to record important warnings.
4806 The rotate=N option can be used to keep more or less of these logs
4807 than would otherwise be kept by logfile_rotate.
4808 For most uses a single log should be enough to monitor current
4809 events affecting Squid.
4814 LOC: Config.coredump_dir
4815 DEFAULT_IF_NONE: none
4816 DEFAULT_DOC: Use the directory from where Squid was started.
4818 By default Squid leaves core files in the directory from where
4819 it was started. If you set 'coredump_dir' to a directory
4820 that exists, Squid will chdir() to that directory at startup
4821 and coredump files will be left there.
4825 # Leave coredumps in the first cache dir
4826 coredump_dir @DEFAULT_SWAP_DIR@
4832 OPTIONS FOR FTP GATEWAYING
4833 -----------------------------------------------------------------------------
4839 LOC: Config.Ftp.anon_user
4841 If you want the anonymous login password to be more informative
4842 (and enable the use of picky FTP servers), set this to something
4843 reasonable for your domain, like wwwuser@somewhere.net
4845 The reason why this is domainless by default is the
4846 request can be made on the behalf of a user in any domain,
4847 depending on how the cache is used.
4848 Some FTP server also validate the email address is valid
4849 (for example perl.com).
4855 LOC: Config.Ftp.passive
4857 If your firewall does not allow Squid to use passive
4858 connections, turn off this option.
4860 Use of ftp_epsv_all option requires this to be ON.
4866 LOC: Config.Ftp.epsv_all
4868 FTP Protocol extensions permit the use of a special "EPSV ALL" command.
4870 NATs may be able to put the connection on a "fast path" through the
4871 translator, as the EPRT command will never be used and therefore,
4872 translation of the data portion of the segments will never be needed.
4874 When a client only expects to do two-way FTP transfers this may be
4876 If squid finds that it must do a three-way FTP transfer after issuing
4877 an EPSV ALL command, the FTP session will fail.
4879 If you have any doubts about this option do not use it.
4880 Squid will nicely attempt all other connection methods.
4882 Requires ftp_passive to be ON (default) for any effect.
4888 LOC: Config.accessList.ftp_epsv
4890 FTP Protocol extensions permit the use of a special "EPSV" command.
4892 NATs may be able to put the connection on a "fast path" through the
4893 translator using EPSV, as the EPRT command will never be used
4894 and therefore, translation of the data portion of the segments
4895 will never be needed.
4897 EPSV is often required to interoperate with FTP servers on IPv6
4898 networks. On the other hand, it may break some IPv4 servers.
4900 By default, EPSV may try EPSV with any FTP server. To fine tune
4901 that decision, you may restrict EPSV to certain clients or servers
4904 ftp_epsv allow|deny al1 acl2 ...
4906 WARNING: Disabling EPSV may cause problems with external NAT and IPv6.
4908 Only fast ACLs are supported.
4909 Requires ftp_passive to be ON (default) for any effect.
4915 LOC: Config.Ftp.eprt
4917 FTP Protocol extensions permit the use of a special "EPRT" command.
4919 This extension provides a protocol neutral alternative to the
4920 IPv4-only PORT command. When supported it enables active FTP data
4921 channels over IPv6 and efficient NAT handling.
4923 Turning this OFF will prevent EPRT being attempted and will skip
4924 straight to using PORT for IPv4 servers.
4926 Some devices are known to not handle this extension correctly and
4927 may result in crashes. Devices which suport EPRT enough to fail
4928 cleanly will result in Squid attempting PORT anyway. This directive
4929 should only be disabled when EPRT results in device failures.
4931 WARNING: Doing so will convert Squid back to the old behavior with all
4932 the related problems with external NAT devices/layers and IPv4-only FTP.
4935 NAME: ftp_sanitycheck
4938 LOC: Config.Ftp.sanitycheck
4940 For security and data integrity reasons Squid by default performs
4941 sanity checks of the addresses of FTP data connections ensure the
4942 data connection is to the requested server. If you need to allow
4943 FTP connections to servers using another IP address for the data
4944 connection turn this off.
4947 NAME: ftp_telnet_protocol
4950 LOC: Config.Ftp.telnet
4952 The FTP protocol is officially defined to use the telnet protocol
4953 as transport channel for the control connection. However, many
4954 implementations are broken and does not respect this aspect of
4957 If you have trouble accessing files with ASCII code 255 in the
4958 path or similar problems involving this ASCII code you can
4959 try setting this directive to off. If that helps, report to the
4960 operator of the FTP server in question that their FTP server
4961 is broken and does not follow the FTP standard.
4965 OPTIONS FOR EXTERNAL SUPPORT PROGRAMS
4966 -----------------------------------------------------------------------------
4971 DEFAULT: @DEFAULT_DISKD@
4972 LOC: Config.Program.diskd
4974 Specify the location of the diskd executable.
4975 Note this is only useful if you have compiled in
4976 diskd as one of the store io modules.
4979 NAME: unlinkd_program
4982 DEFAULT: @DEFAULT_UNLINKD@
4983 LOC: Config.Program.unlinkd
4985 Specify the location of the executable for file deletion process.
4988 NAME: pinger_program
4991 DEFAULT: @DEFAULT_PINGER@
4994 Specify the location of the executable for the pinger process.
5003 Control whether the pinger is active at run-time.
5004 Enables turning ICMP pinger on and off with a simple
5005 squid -k reconfigure.
5010 OPTIONS FOR URL REWRITING
5011 -----------------------------------------------------------------------------
5014 NAME: url_rewrite_program redirect_program
5016 LOC: Config.Program.redirect
5019 Specify the location of the executable URL rewriter to use.
5020 Since they can perform almost any function there isn't one included.
5022 For each requested URL, the rewriter will receive on line with the format
5024 [channel-ID <SP>] URL [<SP> extras]<NL>
5026 See url_rewrite_extras on how to send "extras" with optional values to
5028 After processing the request the helper must reply using the following format:
5030 [channel-ID <SP>] result [<SP> kv-pairs]
5032 The result code can be:
5034 OK status=30N url="..."
5035 Redirect the URL to the one supplied in 'url='.
5036 'status=' is optional and contains the status code to send
5037 the client in Squids HTTP response. It must be one of the
5038 HTTP redirect status codes: 301, 302, 303, 307, 308.
5039 When no status is given Squid will use 302.
5041 OK rewrite-url="..."
5042 Rewrite the URL to the one supplied in 'rewrite-url='.
5043 The new URL is fetched directly by Squid and returned to
5044 the client as the response to its request.
5047 When neither of url= and rewrite-url= are sent Squid does
5051 Do not change the URL.
5054 An internal error occurred in the helper, preventing
5055 a result being identified. The 'message=' key name is
5056 reserved for delivering a log message.
5059 In addition to the above kv-pairs Squid also understands the following
5060 optional kv-pairs received from URL rewriters:
5062 Associates a TAG with the client TCP connection.
5063 The TAG is treated as a regular annotation but persists across
5064 future requests on the client connection rather than just the
5065 current request. A helper may update the TAG during subsequent
5066 requests be returning a new kv-pair.
5068 When using the concurrency= option the protocol is changed by
5069 introducing a query channel tag in front of the request/response.
5070 The query channel tag is a number between 0 and concurrency-1.
5071 This value must be echoed back unchanged to Squid as the first part
5072 of the response relating to its request.
5074 WARNING: URL re-writing ability should be avoided whenever possible.
5075 Use the URL redirect form of response instead.
5077 Re-write creates a difference in the state held by the client
5078 and server. Possibly causing confusion when the server response
5079 contains snippets of its view state. Embeded URLs, response
5080 and content Location headers, etc. are not re-written by this
5083 By default, a URL rewriter is not used.
5086 NAME: url_rewrite_children redirect_children
5087 TYPE: HelperChildConfig
5088 DEFAULT: 20 startup=0 idle=1 concurrency=0
5089 LOC: Config.redirectChildren
5091 The maximum number of redirector processes to spawn. If you limit
5092 it too few Squid will have to wait for them to process a backlog of
5093 URLs, slowing it down. If you allow too many they will use RAM
5094 and other system resources noticably.
5096 The startup= and idle= options allow some measure of skew in your
5101 Sets a minimum of how many processes are to be spawned when Squid
5102 starts or reconfigures. When set to zero the first request will
5103 cause spawning of the first child process to handle it.
5105 Starting too few will cause an initial slowdown in traffic as Squid
5106 attempts to simultaneously spawn enough processes to cope.
5110 Sets a minimum of how many processes Squid is to try and keep available
5111 at all times. When traffic begins to rise above what the existing
5112 processes can handle this many more will be spawned up to the maximum
5113 configured. A minimum setting of 1 is required.
5117 The number of requests each redirector helper can handle in
5118 parallel. Defaults to 0 which indicates the redirector
5119 is a old-style single threaded redirector.
5121 When this directive is set to a value >= 1 then the protocol
5122 used to communicate with the helper is modified to include
5123 an ID in front of the request/response. The ID from the request
5124 must be echoed back with the response to that request.
5128 Sets the maximum number of queued requests.
5129 If the queued requests exceed queue size and redirector_bypass
5130 configuration option is set, then redirector is bypassed. Otherwise, if
5131 overloading persists squid may abort its operation.
5132 The default value is set to 2*numberofchildren.
5135 NAME: url_rewrite_host_header redirect_rewrites_host_header
5138 LOC: Config.onoff.redir_rewrites_host
5140 To preserve same-origin security policies in browsers and
5141 prevent Host: header forgery by redirectors Squid rewrites
5142 any Host: header in redirected requests.
5144 If you are running an accelerator this may not be a wanted
5145 effect of a redirector. This directive enables you disable
5146 Host: alteration in reverse-proxy traffic.
5148 WARNING: Entries are cached on the result of the URL rewriting
5149 process, so be careful if you have domain-virtual hosts.
5151 WARNING: Squid and other software verifies the URL and Host
5152 are matching, so be careful not to relay through other proxies
5153 or inspecting firewalls with this disabled.
5156 NAME: url_rewrite_access redirector_access
5159 DEFAULT_DOC: Allow, unless rules exist in squid.conf.
5160 LOC: Config.accessList.redirector
5162 If defined, this access list specifies which requests are
5163 sent to the redirector processes.
5165 This clause supports both fast and slow acl types.
5166 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
5169 NAME: url_rewrite_bypass redirector_bypass
5171 LOC: Config.onoff.redirector_bypass
5174 When this is 'on', a request will not go through the
5175 redirector if all the helpers are busy. If this is 'off'
5176 and the redirector queue grows too large, Squid will exit
5177 with a FATAL error and ask you to increase the number of
5178 redirectors. You should only enable this if the redirectors
5179 are not critical to your caching system. If you use
5180 redirectors for access control, and you enable this option,
5181 users may have access to pages they should not
5182 be allowed to request.
5183 This options sets default queue-size option of the url_rewrite_children
5187 NAME: url_rewrite_extras
5188 TYPE: TokenOrQuotedString
5189 LOC: Config.redirector_extras
5190 DEFAULT: "%>a/%>A %un %>rm myip=%la myport=%lp"
5192 Specifies a string to be append to request line format for the
5193 rewriter helper. "Quoted" format values may contain spaces and
5194 logformat %macros. In theory, any logformat %macro can be used.
5195 In practice, a %macro expands as a dash (-) if the helper request is
5196 sent before the required macro information is available to Squid.
5199 NAME: url_rewrite_timeout
5200 TYPE: UrlHelperTimeout
5201 LOC: Config.onUrlRewriteTimeout
5203 DEFAULT_DOC: Squid waits for the helper response forever
5205 Squid times active requests to redirector. The timeout value and Squid
5206 reaction to a timed out request are configurable using the following
5209 url_rewrite_timeout timeout time-units on_timeout=<action> [response=<quoted-response>]
5211 supported timeout actions:
5212 fail Squid return a ERR_GATEWAY_FAILURE error page
5214 bypass Do not re-write the URL
5216 retry Send the lookup to the helper again
5218 use_configured_response
5219 Use the <quoted-response> as helper response
5223 OPTIONS FOR STORE ID
5224 -----------------------------------------------------------------------------
5227 NAME: store_id_program storeurl_rewrite_program
5229 LOC: Config.Program.store_id
5232 Specify the location of the executable StoreID helper to use.
5233 Since they can perform almost any function there isn't one included.
5235 For each requested URL, the helper will receive one line with the format
5237 [channel-ID <SP>] URL [<SP> extras]<NL>
5240 After processing the request the helper must reply using the following format:
5242 [channel-ID <SP>] result [<SP> kv-pairs]
5244 The result code can be:
5247 Use the StoreID supplied in 'store-id='.
5250 The default is to use HTTP request URL as the store ID.
5253 An internal error occured in the helper, preventing
5254 a result being identified.
5256 In addition to the above kv-pairs Squid also understands the following
5257 optional kv-pairs received from URL rewriters:
5259 Associates a TAG with the client TCP connection.
5260 Please see url_rewrite_program related documentation for this
5263 Helper programs should be prepared to receive and possibly ignore
5264 additional whitespace-separated tokens on each input line.
5266 When using the concurrency= option the protocol is changed by
5267 introducing a query channel tag in front of the request/response.
5268 The query channel tag is a number between 0 and concurrency-1.
5269 This value must be echoed back unchanged to Squid as the first part
5270 of the response relating to its request.
5272 NOTE: when using StoreID refresh_pattern will apply to the StoreID
5273 returned from the helper and not the URL.
5275 WARNING: Wrong StoreID value returned by a careless helper may result
5276 in the wrong cached response returned to the user.
5278 By default, a StoreID helper is not used.
5281 NAME: store_id_extras
5282 TYPE: TokenOrQuotedString
5283 LOC: Config.storeId_extras
5284 DEFAULT: "%>a/%>A %un %>rm myip=%la myport=%lp"
5286 Specifies a string to be append to request line format for the
5287 StoreId helper. "Quoted" format values may contain spaces and
5288 logformat %macros. In theory, any logformat %macro can be used.
5289 In practice, a %macro expands as a dash (-) if the helper request is
5290 sent before the required macro information is available to Squid.
5293 NAME: store_id_children storeurl_rewrite_children
5294 TYPE: HelperChildConfig
5295 DEFAULT: 20 startup=0 idle=1 concurrency=0
5296 LOC: Config.storeIdChildren
5298 The maximum number of StoreID helper processes to spawn. If you limit
5299 it too few Squid will have to wait for them to process a backlog of
5300 requests, slowing it down. If you allow too many they will use RAM
5301 and other system resources noticably.
5303 The startup= and idle= options allow some measure of skew in your
5308 Sets a minimum of how many processes are to be spawned when Squid
5309 starts or reconfigures. When set to zero the first request will
5310 cause spawning of the first child process to handle it.
5312 Starting too few will cause an initial slowdown in traffic as Squid
5313 attempts to simultaneously spawn enough processes to cope.
5317 Sets a minimum of how many processes Squid is to try and keep available
5318 at all times. When traffic begins to rise above what the existing
5319 processes can handle this many more will be spawned up to the maximum
5320 configured. A minimum setting of 1 is required.
5324 The number of requests each storeID helper can handle in
5325 parallel. Defaults to 0 which indicates the helper
5326 is a old-style single threaded program.
5328 When this directive is set to a value >= 1 then the protocol
5329 used to communicate with the helper is modified to include
5330 an ID in front of the request/response. The ID from the request
5331 must be echoed back with the response to that request.
5335 Sets the maximum number of queued requests.
5336 If the queued requests exceed queue size and store_id_bypass
5337 configuration option is set, then storeID helper is bypassed. Otherwise,
5338 if overloading persists squid may abort its operation.
5339 The default value is set to 2*numberofchildren.
5342 NAME: store_id_access storeurl_rewrite_access
5345 DEFAULT_DOC: Allow, unless rules exist in squid.conf.
5346 LOC: Config.accessList.store_id
5348 If defined, this access list specifies which requests are
5349 sent to the StoreID processes. By default all requests
5352 This clause supports both fast and slow acl types.
5353 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
5356 NAME: store_id_bypass storeurl_rewrite_bypass
5358 LOC: Config.onoff.store_id_bypass
5361 When this is 'on', a request will not go through the
5362 helper if all helpers are busy. If this is 'off'
5363 and the helper queue grows too large, Squid will exit
5364 with a FATAL error and ask you to increase the number of
5365 helpers. You should only enable this if the helperss
5366 are not critical to your caching system. If you use
5367 helpers for critical caching components, and you enable this
5368 option, users may not get objects from cache.
5369 This options sets default queue-size option of the store_id_children
5374 OPTIONS FOR TUNING THE CACHE
5375 -----------------------------------------------------------------------------
5378 NAME: cache no_cache
5381 DEFAULT_DOC: By default, this directive is unused and has no effect.
5382 LOC: Config.accessList.noCache
5384 Requests denied by this directive will not be served from the cache
5385 and their responses will not be stored in the cache. This directive
5386 has no effect on other transactions and on already cached responses.
5388 This clause supports both fast and slow acl types.
5389 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
5391 This and the two other similar caching directives listed below are
5392 checked at different transaction processing stages, have different
5393 access to response information, affect different cache operations,
5394 and differ in slow ACLs support:
5396 * cache: Checked before Squid makes a hit/miss determination.
5397 No access to reply information!
5398 Denies both serving a hit and storing a miss.
5399 Supports both fast and slow ACLs.
5400 * send_hit: Checked after a hit was detected.
5401 Has access to reply (hit) information.
5402 Denies serving a hit only.
5403 Supports fast ACLs only.
5404 * store_miss: Checked before storing a cachable miss.
5405 Has access to reply (miss) information.
5406 Denies storing a miss only.
5407 Supports fast ACLs only.
5409 If you are not sure which of the three directives to use, apply the
5410 following decision logic:
5412 * If your ACL(s) are of slow type _and_ need response info, redesign.
5413 Squid does not support that particular combination at this time.
5415 * If your directive ACL(s) are of slow type, use "cache"; and/or
5416 * if your directive ACL(s) need no response info, use "cache".
5418 * If you do not want the response cached, use store_miss; and/or
5419 * if you do not want a hit on a cached response, use send_hit.
5425 DEFAULT_DOC: By default, this directive is unused and has no effect.
5426 LOC: Config.accessList.sendHit
5428 Responses denied by this directive will not be served from the cache
5429 (but may still be cached, see store_miss). This directive has no
5430 effect on the responses it allows and on the cached objects.
5432 Please see the "cache" directive for a summary of differences among
5433 store_miss, send_hit, and cache directives.
5435 Unlike the "cache" directive, send_hit only supports fast acl
5436 types. See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
5440 # apply custom Store ID mapping to some URLs
5441 acl MapMe dstdomain .c.example.com
5442 store_id_program ...
5443 store_id_access allow MapMe
5445 # but prevent caching of special responses
5446 # such as 302 redirects that cause StoreID loops
5447 acl Ordinary http_status 200-299
5448 store_miss deny MapMe !Ordinary
5450 # and do not serve any previously stored special responses
5451 # from the cache (in case they were already cached before
5452 # the above store_miss rule was in effect).
5453 send_hit deny MapMe !Ordinary
5459 DEFAULT_DOC: By default, this directive is unused and has no effect.
5460 LOC: Config.accessList.storeMiss
5462 Responses denied by this directive will not be cached (but may still
5463 be served from the cache, see send_hit). This directive has no
5464 effect on the responses it allows and on the already cached responses.
5466 Please see the "cache" directive for a summary of differences among
5467 store_miss, send_hit, and cache directives. See the
5468 send_hit directive for a usage example.
5470 Unlike the "cache" directive, store_miss only supports fast acl
5471 types. See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
5477 LOC: Config.maxStale
5480 This option puts an upper limit on how stale content Squid
5481 will serve from the cache if cache validation fails.
5482 Can be overriden by the refresh_pattern max-stale option.
5485 NAME: refresh_pattern
5486 TYPE: refreshpattern
5490 usage: refresh_pattern [-i] regex min percent max [options]
5492 By default, regular expressions are CASE-SENSITIVE. To make
5493 them case-insensitive, use the -i option.
5495 'Min' is the time (in minutes) an object without an explicit
5496 expiry time should be considered fresh. The recommended
5497 value is 0, any higher values may cause dynamic applications
5498 to be erroneously cached unless the application designer
5499 has taken the appropriate actions.
5501 'Percent' is a percentage of the objects age (time since last
5502 modification age) an object without explicit expiry time
5503 will be considered fresh.
5505 'Max' is an upper limit on how long objects without an explicit
5506 expiry time will be considered fresh.
5508 options: override-expire
5518 override-expire enforces min age even if the server
5519 sent an explicit expiry time (e.g., with the
5520 Expires: header or Cache-Control: max-age). Doing this
5521 VIOLATES the HTTP standard. Enabling this feature
5522 could make you liable for problems which it causes.
5524 Note: override-expire does not enforce staleness - it only extends
5525 freshness / min. If the server returns a Expires time which
5526 is longer than your max time, Squid will still consider
5527 the object fresh for that period of time.
5529 override-lastmod enforces min age even on objects
5530 that were modified recently.
5532 reload-into-ims changes a client no-cache or ``reload''
5533 request for a cached entry into a conditional request using
5534 If-Modified-Since and/or If-None-Match headers, provided the
5535 cached entry has a Last-Modified and/or a strong ETag header.
5536 Doing this VIOLATES the HTTP standard. Enabling this feature
5537 could make you liable for problems which it causes.
5539 ignore-reload ignores a client no-cache or ``reload''
5540 header. Doing this VIOLATES the HTTP standard. Enabling
5541 this feature could make you liable for problems which
5544 ignore-no-store ignores any ``Cache-control: no-store''
5545 headers received from a server. Doing this VIOLATES
5546 the HTTP standard. Enabling this feature could make you
5547 liable for problems which it causes.
5549 ignore-private ignores any ``Cache-control: private''
5550 headers received from a server. Doing this VIOLATES
5551 the HTTP standard. Enabling this feature could make you
5552 liable for problems which it causes.
5554 refresh-ims causes squid to contact the origin server
5555 when a client issues an If-Modified-Since request. This
5556 ensures that the client will receive an updated version
5557 if one is available.
5559 store-stale stores responses even if they don't have explicit
5560 freshness or a validator (i.e., Last-Modified or an ETag)
5561 present, or if they're already stale. By default, Squid will
5562 not cache such responses because they usually can't be
5563 reused. Note that such responses will be stale by default.
5565 max-stale=NN provide a maximum staleness factor. Squid won't
5566 serve objects more stale than this even if it failed to
5567 validate the object. Default: use the max_stale global limit.
5569 Basically a cached object is:
5571 FRESH if expire > now, else STALE
5573 FRESH if lm-factor < percent, else STALE
5577 The refresh_pattern lines are checked in the order listed here.
5578 The first entry which matches is used. If none of the entries
5579 match the default will be used.
5581 Note, you must uncomment all the default lines if you want
5582 to change one. The default setting is only active if none is
5588 # Add any of your own refresh_pattern entries above these.
5590 refresh_pattern ^ftp: 1440 20% 10080
5591 refresh_pattern ^gopher: 1440 0% 1440
5592 refresh_pattern -i (/cgi-bin/|\?) 0 0% 0
5593 refresh_pattern . 0 20% 4320
5597 NAME: quick_abort_min
5601 LOC: Config.quickAbort.min
5604 NAME: quick_abort_max
5608 LOC: Config.quickAbort.max
5611 NAME: quick_abort_pct
5615 LOC: Config.quickAbort.pct
5617 The cache by default continues downloading aborted requests
5618 which are almost completed (less than 16 KB remaining). This
5619 may be undesirable on slow (e.g. SLIP) links and/or very busy
5620 caches. Impatient users may tie up file descriptors and
5621 bandwidth by repeatedly requesting and immediately aborting
5624 When the user aborts a request, Squid will check the
5625 quick_abort values to the amount of data transferred until
5628 If the transfer has less than 'quick_abort_min' KB remaining,
5629 it will finish the retrieval.
5631 If the transfer has more than 'quick_abort_max' KB remaining,
5632 it will abort the retrieval.
5634 If more than 'quick_abort_pct' of the transfer has completed,
5635 it will finish the retrieval.
5637 If you do not want any retrieval to continue after the client
5638 has aborted, set both 'quick_abort_min' and 'quick_abort_max'
5641 If you want retrievals to always continue if they are being
5642 cached set 'quick_abort_min' to '-1 KB'.
5645 NAME: read_ahead_gap
5646 COMMENT: buffer-size
5648 LOC: Config.readAheadGap
5651 The amount of data the cache will buffer ahead of what has been
5652 sent to the client when retrieving an object from another server.
5656 IFDEF: USE_HTTP_VIOLATIONS
5659 LOC: Config.negativeTtl
5662 Set the Default Time-to-Live (TTL) for failed requests.
5663 Certain types of failures (such as "connection refused" and
5664 "404 Not Found") are able to be negatively-cached for a short time.
5665 Modern web servers should provide Expires: header, however if they
5666 do not this can provide a minimum TTL.
5667 The default is not to cache errors with unknown expiry details.
5669 Note that this is different from negative caching of DNS lookups.
5671 WARNING: Doing this VIOLATES the HTTP standard. Enabling
5672 this feature could make you liable for problems which it
5676 NAME: positive_dns_ttl
5679 LOC: Config.positiveDnsTtl
5682 Upper limit on how long Squid will cache positive DNS responses.
5683 Default is 6 hours (360 minutes). This directive must be set
5684 larger than negative_dns_ttl.
5687 NAME: negative_dns_ttl
5690 LOC: Config.negativeDnsTtl
5693 Time-to-Live (TTL) for negative caching of failed DNS lookups.
5694 This also sets the lower cache limit on positive lookups.
5695 Minimum value is 1 second, and it is not recommendable to go
5696 much below 10 seconds.
5699 NAME: range_offset_limit
5700 COMMENT: size [acl acl...]
5702 LOC: Config.rangeOffsetLimit
5705 usage: (size) [units] [[!]aclname]
5707 Sets an upper limit on how far (number of bytes) into the file
5708 a Range request may be to cause Squid to prefetch the whole file.
5709 If beyond this limit, Squid forwards the Range request as it is and
5710 the result is NOT cached.
5712 This is to stop a far ahead range request (lets say start at 17MB)
5713 from making Squid fetch the whole object up to that point before
5714 sending anything to the client.
5716 Multiple range_offset_limit lines may be specified, and they will
5717 be searched from top to bottom on each request until a match is found.
5718 The first match found will be used. If no line matches a request, the
5719 default limit of 0 bytes will be used.
5721 'size' is the limit specified as a number of units.
5723 'units' specifies whether to use bytes, KB, MB, etc.
5724 If no units are specified bytes are assumed.
5726 A size of 0 causes Squid to never fetch more than the
5727 client requested. (default)
5729 A size of 'none' causes Squid to always fetch the object from the
5730 beginning so it may cache the result. (2.0 style)
5732 'aclname' is the name of a defined ACL.
5734 NP: Using 'none' as the byte value here will override any quick_abort settings
5735 that may otherwise apply to the range request. The range request will
5736 be fully fetched from start to finish regardless of the client
5737 actions. This affects bandwidth usage.
5740 NAME: minimum_expiry_time
5743 LOC: Config.minimum_expiry_time
5746 The minimum caching time according to (Expires - Date)
5747 headers Squid honors if the object can't be revalidated.
5748 The default is 60 seconds.
5750 In reverse proxy environments it might be desirable to honor
5751 shorter object lifetimes. It is most likely better to make
5752 your server return a meaningful Last-Modified header however.
5754 In ESI environments where page fragments often have short
5755 lifetimes, this will often be best set to 0.
5758 NAME: store_avg_object_size
5762 LOC: Config.Store.avgObjectSize
5764 Average object size, used to estimate number of objects your
5765 cache can hold. The default is 13 KB.
5767 This is used to pre-seed the cache index memory allocation to
5768 reduce expensive reallocate operations while handling clients
5769 traffic. Too-large values may result in memory allocation during
5770 peak traffic, too-small values will result in wasted memory.
5772 Check the cache manager 'info' report metrics for the real
5773 object sizes seen by your Squid before tuning this.
5776 NAME: store_objects_per_bucket
5779 LOC: Config.Store.objectsPerBucket
5781 Target number of objects per bucket in the store hash table.
5782 Lowering this value increases the total number of buckets and
5783 also the storage maintenance rate. The default is 20.
5788 -----------------------------------------------------------------------------
5791 NAME: request_header_max_size
5795 LOC: Config.maxRequestHeaderSize
5797 This specifies the maximum size for HTTP headers in a request.
5798 Request headers are usually relatively small (about 512 bytes).
5799 Placing a limit on the request header size will catch certain
5800 bugs (for example with persistent connections) and possibly
5801 buffer-overflow or denial-of-service attacks.
5804 NAME: reply_header_max_size
5808 LOC: Config.maxReplyHeaderSize
5810 This specifies the maximum size for HTTP headers in a reply.
5811 Reply headers are usually relatively small (about 512 bytes).
5812 Placing a limit on the reply header size will catch certain
5813 bugs (for example with persistent connections) and possibly
5814 buffer-overflow or denial-of-service attacks.
5817 NAME: request_body_max_size
5821 DEFAULT_DOC: No limit.
5822 LOC: Config.maxRequestBodySize
5824 This specifies the maximum size for an HTTP request body.
5825 In other words, the maximum size of a PUT/POST request.
5826 A user who attempts to send a request with a body larger
5827 than this limit receives an "Invalid Request" error message.
5828 If you set this parameter to a zero (the default), there will
5829 be no limit imposed.
5831 See also client_request_buffer_max_size for an alternative
5832 limitation on client uploads which can be configured.
5835 NAME: client_request_buffer_max_size
5839 LOC: Config.maxRequestBufferSize
5841 This specifies the maximum buffer size of a client request.
5842 It prevents squid eating too much memory when somebody uploads
5847 IFDEF: USE_HTTP_VIOLATIONS
5850 DEFAULT_DOC: Obey RFC 2616.
5851 LOC: Config.accessList.brokenPosts
5853 A list of ACL elements which, if matched, causes Squid to send
5854 an extra CRLF pair after the body of a PUT/POST request.
5856 Some HTTP servers has broken implementations of PUT/POST,
5857 and rely on an extra CRLF pair sent by some WWW clients.
5859 Quote from RFC2616 section 4.1 on this matter:
5861 Note: certain buggy HTTP/1.0 client implementations generate an
5862 extra CRLF's after a POST request. To restate what is explicitly
5863 forbidden by the BNF, an HTTP/1.1 client must not preface or follow
5864 a request with an extra CRLF.
5866 This clause only supports fast acl types.
5867 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
5870 acl buggy_server url_regex ^http://....
5871 broken_posts allow buggy_server
5874 NAME: adaptation_uses_indirect_client icap_uses_indirect_client
5877 IFDEF: FOLLOW_X_FORWARDED_FOR&&USE_ADAPTATION
5879 LOC: Adaptation::Config::use_indirect_client
5881 Controls whether the indirect client IP address (instead of the direct
5882 client IP address) is passed to adaptation services.
5884 See also: follow_x_forwarded_for adaptation_send_client_ip
5888 IFDEF: USE_HTTP_VIOLATIONS
5892 LOC: Config.onoff.via
5894 If set (default), Squid will include a Via header in requests and
5895 replies as required by RFC2616.
5898 NAME: vary_ignore_expire
5901 LOC: Config.onoff.vary_ignore_expire
5904 Many HTTP servers supporting Vary gives such objects
5905 immediate expiry time with no cache-control header
5906 when requested by a HTTP/1.0 client. This option
5907 enables Squid to ignore such expiry times until
5908 HTTP/1.1 is fully implemented.
5910 WARNING: If turned on this may eventually cause some
5911 varying objects not intended for caching to get cached.
5914 NAME: request_entities
5916 LOC: Config.onoff.request_entities
5919 Squid defaults to deny GET and HEAD requests with request entities,
5920 as the meaning of such requests are undefined in the HTTP standard
5921 even if not explicitly forbidden.
5923 Set this directive to on if you have clients which insists
5924 on sending request entities in GET or HEAD requests. But be warned
5925 that there is server software (both proxies and web servers) which
5926 can fail to properly process this kind of request which may make you
5927 vulnerable to cache pollution attacks if enabled.
5930 NAME: request_header_access
5931 IFDEF: USE_HTTP_VIOLATIONS
5932 TYPE: http_header_access
5933 LOC: Config.request_header_access
5935 DEFAULT_DOC: No limits.
5937 Usage: request_header_access header_name allow|deny [!]aclname ...
5939 WARNING: Doing this VIOLATES the HTTP standard. Enabling
5940 this feature could make you liable for problems which it
5943 This option replaces the old 'anonymize_headers' and the
5944 older 'http_anonymizer' option with something that is much
5945 more configurable. A list of ACLs for each header name allows
5946 removal of specific header fields under specific conditions.
5948 This option only applies to outgoing HTTP request headers (i.e.,
5949 headers sent by Squid to the next HTTP hop such as a cache peer
5950 or an origin server). The option has no effect during cache hit
5951 detection. The equivalent adaptation vectoring point in ICAP
5952 terminology is post-cache REQMOD.
5954 The option is applied to individual outgoing request header
5955 fields. For each request header field F, Squid uses the first
5956 qualifying sets of request_header_access rules:
5958 1. Rules with header_name equal to F's name.
5959 2. Rules with header_name 'Other', provided F's name is not
5960 on the hard-coded list of commonly used HTTP header names.
5961 3. Rules with header_name 'All'.
5963 Within that qualifying rule set, rule ACLs are checked as usual.
5964 If ACLs of an "allow" rule match, the header field is allowed to
5965 go through as is. If ACLs of a "deny" rule match, the header is
5966 removed and request_header_replace is then checked to identify
5967 if the removed header has a replacement. If no rules within the
5968 set have matching ACLs, the header field is left as is.
5970 For example, to achieve the same behavior as the old
5971 'http_anonymizer standard' option, you should use:
5973 request_header_access From deny all
5974 request_header_access Referer deny all
5975 request_header_access User-Agent deny all
5977 Or, to reproduce the old 'http_anonymizer paranoid' feature
5980 request_header_access Authorization allow all
5981 request_header_access Proxy-Authorization allow all
5982 request_header_access Cache-Control allow all
5983 request_header_access Content-Length allow all
5984 request_header_access Content-Type allow all
5985 request_header_access Date allow all
5986 request_header_access Host allow all
5987 request_header_access If-Modified-Since allow all
5988 request_header_access Pragma allow all
5989 request_header_access Accept allow all
5990 request_header_access Accept-Charset allow all
5991 request_header_access Accept-Encoding allow all
5992 request_header_access Accept-Language allow all
5993 request_header_access Connection allow all
5994 request_header_access All deny all
5996 HTTP reply headers are controlled with the reply_header_access directive.
5998 By default, all headers are allowed (no anonymizing is performed).
6001 NAME: reply_header_access
6002 IFDEF: USE_HTTP_VIOLATIONS
6003 TYPE: http_header_access
6004 LOC: Config.reply_header_access
6006 DEFAULT_DOC: No limits.
6008 Usage: reply_header_access header_name allow|deny [!]aclname ...
6010 WARNING: Doing this VIOLATES the HTTP standard. Enabling
6011 this feature could make you liable for problems which it
6014 This option only applies to reply headers, i.e., from the
6015 server to the client.
6017 This is the same as request_header_access, but in the other
6018 direction. Please see request_header_access for detailed
6021 For example, to achieve the same behavior as the old
6022 'http_anonymizer standard' option, you should use:
6024 reply_header_access Server deny all
6025 reply_header_access WWW-Authenticate deny all
6026 reply_header_access Link deny all
6028 Or, to reproduce the old 'http_anonymizer paranoid' feature
6031 reply_header_access Allow allow all
6032 reply_header_access WWW-Authenticate allow all
6033 reply_header_access Proxy-Authenticate allow all
6034 reply_header_access Cache-Control allow all
6035 reply_header_access Content-Encoding allow all
6036 reply_header_access Content-Length allow all
6037 reply_header_access Content-Type allow all
6038 reply_header_access Date allow all
6039 reply_header_access Expires allow all
6040 reply_header_access Last-Modified allow all
6041 reply_header_access Location allow all
6042 reply_header_access Pragma allow all
6043 reply_header_access Content-Language allow all
6044 reply_header_access Retry-After allow all
6045 reply_header_access Title allow all
6046 reply_header_access Content-Disposition allow all
6047 reply_header_access Connection allow all
6048 reply_header_access All deny all
6050 HTTP request headers are controlled with the request_header_access directive.
6052 By default, all headers are allowed (no anonymizing is
6056 NAME: request_header_replace header_replace
6057 IFDEF: USE_HTTP_VIOLATIONS
6058 TYPE: http_header_replace
6059 LOC: Config.request_header_access
6062 Usage: request_header_replace header_name message
6063 Example: request_header_replace User-Agent Nutscrape/1.0 (CP/M; 8-bit)
6065 This option allows you to change the contents of headers
6066 denied with request_header_access above, by replacing them
6067 with some fixed string.
6069 This only applies to request headers, not reply headers.
6071 By default, headers are removed if denied.
6074 NAME: reply_header_replace
6075 IFDEF: USE_HTTP_VIOLATIONS
6076 TYPE: http_header_replace
6077 LOC: Config.reply_header_access
6080 Usage: reply_header_replace header_name message
6081 Example: reply_header_replace Server Foo/1.0
6083 This option allows you to change the contents of headers
6084 denied with reply_header_access above, by replacing them
6085 with some fixed string.
6087 This only applies to reply headers, not request headers.
6089 By default, headers are removed if denied.
6092 NAME: request_header_add
6093 TYPE: HeaderWithAclList
6094 LOC: Config.request_header_add
6097 Usage: request_header_add field-name field-value [ acl ... ]
6098 Example: request_header_add X-Client-CA "CA=%ssl::>cert_issuer" all
6100 This option adds header fields to outgoing HTTP requests (i.e.,
6101 request headers sent by Squid to the next HTTP hop such as a
6102 cache peer or an origin server). The option has no effect during
6103 cache hit detection. The equivalent adaptation vectoring point
6104 in ICAP terminology is post-cache REQMOD.
6106 Field-name is a token specifying an HTTP header name. If a
6107 standard HTTP header name is used, Squid does not check whether
6108 the new header conflicts with any existing headers or violates
6109 HTTP rules. If the request to be modified already contains a
6110 field with the same name, the old field is preserved but the
6111 header field values are not merged.
6113 Field-value is either a token or a quoted string. If quoted
6114 string format is used, then the surrounding quotes are removed
6115 while escape sequences and %macros are processed.
6117 One or more Squid ACLs may be specified to restrict header
6118 injection to matching requests. As always in squid.conf, all
6119 ACLs in the ACL list must be satisfied for the insertion to
6120 happen. The request_header_add supports fast ACLs only.
6122 See also: reply_header_add.
6125 NAME: reply_header_add
6126 TYPE: HeaderWithAclList
6127 LOC: Config.reply_header_add
6130 Usage: reply_header_add field-name field-value [ acl ... ]
6131 Example: reply_header_add X-Client-CA "CA=%ssl::>cert_issuer" all
6133 This option adds header fields to outgoing HTTP responses (i.e., response
6134 headers delivered by Squid to the client). This option has no effect on
6135 cache hit detection. The equivalent adaptation vectoring point in
6136 ICAP terminology is post-cache RESPMOD. This option does not apply to
6137 successful CONNECT replies.
6139 Field-name is a token specifying an HTTP header name. If a
6140 standard HTTP header name is used, Squid does not check whether
6141 the new header conflicts with any existing headers or violates
6142 HTTP rules. If the response to be modified already contains a
6143 field with the same name, the old field is preserved but the
6144 header field values are not merged.
6146 Field-value is either a token or a quoted string. If quoted
6147 string format is used, then the surrounding quotes are removed
6148 while escape sequences and %macros are processed.
6150 One or more Squid ACLs may be specified to restrict header
6151 injection to matching responses. As always in squid.conf, all
6152 ACLs in the ACL list must be satisfied for the insertion to
6153 happen. The reply_header_add option supports fast ACLs only.
6155 See also: request_header_add.
6163 This option used to log custom information about the master
6164 transaction. For example, an admin may configure Squid to log
6165 which "user group" the transaction belongs to, where "user group"
6166 will be determined based on a set of ACLs and not [just]
6167 authentication information.
6168 Values of key/value pairs can be logged using %{key}note macros:
6170 note key value acl ...
6171 logformat myFormat ... %{key}note ...
6174 NAME: relaxed_header_parser
6175 COMMENT: on|off|warn
6177 LOC: Config.onoff.relaxed_header_parser
6180 In the default "on" setting Squid accepts certain forms
6181 of non-compliant HTTP messages where it is unambiguous
6182 what the sending application intended even if the message
6183 is not correctly formatted. The messages is then normalized
6184 to the correct form when forwarded by Squid.
6186 If set to "warn" then a warning will be emitted in cache.log
6187 each time such HTTP error is encountered.
6189 If set to "off" then such HTTP errors will cause the request
6190 or response to be rejected.
6193 NAME: collapsed_forwarding
6196 LOC: Config.onoff.collapsed_forwarding
6199 This option controls whether Squid is allowed to merge multiple
6200 potentially cachable requests for the same URI before Squid knows
6201 whether the response is going to be cachable.
6203 When enabled, instead of forwarding each concurrent request for
6204 the same URL, Squid just sends the first of them. The other, so
6205 called "collapsed" requests, wait for the response to the first
6206 request and, if it happens to be cachable, use that response.
6207 Here, "concurrent requests" means "received after the first
6208 request headers were parsed and before the corresponding response
6209 headers were parsed".
6211 This feature is disabled by default: enabling collapsed
6212 forwarding needlessly delays forwarding requests that look
6213 cachable (when they are collapsed) but then need to be forwarded
6214 individually anyway because they end up being for uncachable
6215 content. However, in some cases, such as acceleration of highly
6216 cachable content with periodic or grouped expiration times, the
6217 gains from collapsing [large volumes of simultaneous refresh
6218 requests] outweigh losses from such delays.
6220 Squid collapses two kinds of requests: regular client requests
6221 received on one of the listening ports and internal "cache
6222 revalidation" requests which are triggered by those regular
6223 requests hitting a stale cached object. Revalidation collapsing
6224 is currently disabled for Squid instances containing SMP-aware
6225 disk or memory caches and for Vary-controlled cached objects.
6228 NAME: collapsed_forwarding_shared_entries_limit
6229 COMMENT: (number of entries)
6231 LOC: Config.collapsed_forwarding_shared_entries_limit
6234 This limits the size of a table used for sharing information
6235 about collapsible entries among SMP workers. Limiting sharing
6236 too much results in cache content duplication and missed
6237 collapsing opportunities. Using excessively large values
6238 wastes shared memory.
6240 The limit should be significantly larger then the number of
6241 concurrent collapsible entries one wants to share. For a cache
6242 that handles less than 5000 concurrent requests, the default
6243 setting of 16384 should be plenty.
6245 If the limit is set to zero, it disables sharing of collapsed
6246 forwarding between SMP workers.
6251 -----------------------------------------------------------------------------
6254 NAME: forward_timeout
6257 LOC: Config.Timeout.forward
6260 This parameter specifies how long Squid should at most attempt in
6261 finding a forwarding path for the request before giving up.
6264 NAME: connect_timeout
6267 LOC: Config.Timeout.connect
6270 This parameter specifies how long to wait for the TCP connect to
6271 the requested server or peer to complete before Squid should
6272 attempt to find another path where to forward the request.
6275 NAME: peer_connect_timeout
6278 LOC: Config.Timeout.peer_connect
6281 This parameter specifies how long to wait for a pending TCP
6282 connection to a peer cache. The default is 30 seconds. You
6283 may also set different timeout values for individual neighbors
6284 with the 'connect-timeout' option on a 'cache_peer' line.
6290 LOC: Config.Timeout.read
6293 Applied on peer server connections.
6295 After each successful read(), the timeout will be extended by this
6296 amount. If no data is read again after this amount of time,
6297 the request is aborted and logged with ERR_READ_TIMEOUT.
6299 The default is 15 minutes.
6305 LOC: Config.Timeout.write
6308 This timeout is tracked for all connections that have data
6309 available for writing and are waiting for the socket to become
6310 ready. After each successful write, the timeout is extended by
6311 the configured amount. If Squid has data to write but the
6312 connection is not ready for the configured duration, the
6313 transaction associated with the connection is terminated. The
6314 default is 15 minutes.
6317 NAME: request_timeout
6319 LOC: Config.Timeout.request
6322 How long to wait for complete HTTP request headers after initial
6323 connection establishment.
6326 NAME: request_start_timeout
6328 LOC: Config.Timeout.request_start_timeout
6331 How long to wait for the first request byte after initial
6332 connection establishment.
6335 NAME: client_idle_pconn_timeout persistent_request_timeout
6337 LOC: Config.Timeout.clientIdlePconn
6340 How long to wait for the next HTTP request on a persistent
6341 client connection after the previous request completes.
6344 NAME: ftp_client_idle_timeout
6346 LOC: Config.Timeout.ftpClientIdle
6349 How long to wait for an FTP request on a connection to Squid ftp_port.
6350 Many FTP clients do not deal with idle connection closures well,
6351 necessitating a longer default timeout than client_idle_pconn_timeout
6352 used for incoming HTTP requests.
6355 NAME: client_lifetime
6358 LOC: Config.Timeout.lifetime
6361 The maximum amount of time a client (browser) is allowed to
6362 remain connected to the cache process. This protects the Cache
6363 from having a lot of sockets (and hence file descriptors) tied up
6364 in a CLOSE_WAIT state from remote clients that go away without
6365 properly shutting down (either because of a network failure or
6366 because of a poor client implementation). The default is one
6369 NOTE: The default value is intended to be much larger than any
6370 client would ever need to be connected to your cache. You
6371 should probably change client_lifetime only as a last resort.
6372 If you seem to have many client connections tying up
6373 filedescriptors, we recommend first tuning the read_timeout,
6374 request_timeout, persistent_request_timeout and quick_abort values.
6377 NAME: pconn_lifetime
6380 LOC: Config.Timeout.pconnLifetime
6383 Desired maximum lifetime of a persistent connection.
6384 When set, Squid will close a now-idle persistent connection that
6385 exceeded configured lifetime instead of moving the connection into
6386 the idle connection pool (or equivalent). No effect on ongoing/active
6387 transactions. Connection lifetime is the time period from the
6388 connection acceptance or opening time until "now".
6390 This limit is useful in environments with long-lived connections
6391 where Squid configuration or environmental factors change during a
6392 single connection lifetime. If unrestricted, some connections may
6393 last for hours and even days, ignoring those changes that should
6394 have affected their behavior or their existence.
6396 Currently, a new lifetime value supplied via Squid reconfiguration
6397 has no effect on already idle connections unless they become busy.
6399 When set to '0' this limit is not used.
6402 NAME: half_closed_clients
6404 LOC: Config.onoff.half_closed_clients
6407 Some clients may shutdown the sending side of their TCP
6408 connections, while leaving their receiving sides open. Sometimes,
6409 Squid can not tell the difference between a half-closed and a
6410 fully-closed TCP connection.
6412 By default, Squid will immediately close client connections when
6413 read(2) returns "no more data to read."
6415 Change this option to 'on' and Squid will keep open connections
6416 until a read(2) or write(2) on the socket returns an error.
6417 This may show some benefits for reverse proxies. But if not
6418 it is recommended to leave OFF.
6421 NAME: server_idle_pconn_timeout pconn_timeout
6423 LOC: Config.Timeout.serverIdlePconn
6426 Timeout for idle persistent connections to servers and other
6433 LOC: Ident::TheConfig.timeout
6436 Maximum time to wait for IDENT lookups to complete.
6438 If this is too high, and you enabled IDENT lookups from untrusted
6439 users, you might be susceptible to denial-of-service by having
6440 many ident requests going at once.
6443 NAME: shutdown_lifetime
6446 LOC: Config.shutdownLifetime
6449 When SIGTERM or SIGHUP is received, the cache is put into
6450 "shutdown pending" mode until all active sockets are closed.
6451 This value is the lifetime to set for all open descriptors
6452 during shutdown mode. Any active clients after this many
6453 seconds will receive a 'timeout' message.
6457 ADMINISTRATIVE PARAMETERS
6458 -----------------------------------------------------------------------------
6464 LOC: Config.adminEmail
6466 Email-address of local cache manager who will receive
6467 mail if the cache dies. The default is "webmaster".
6473 LOC: Config.EmailFrom
6475 From: email-address for mail sent when the cache dies.
6476 The default is to use 'squid@unique_hostname'.
6478 See also: unique_hostname directive.
6484 LOC: Config.EmailProgram
6486 Email program used to send mail if the cache dies.
6487 The default is "mail". The specified program must comply
6488 with the standard Unix mail syntax:
6489 mail-program recipient < mailfile
6491 Optional command line options can be specified.
6494 NAME: cache_effective_user
6496 DEFAULT: @DEFAULT_CACHE_EFFECTIVE_USER@
6497 LOC: Config.effectiveUser
6499 If you start Squid as root, it will change its effective/real
6500 UID/GID to the user specified below. The default is to change
6501 to UID of @DEFAULT_CACHE_EFFECTIVE_USER@.
6502 see also; cache_effective_group
6505 NAME: cache_effective_group
6508 DEFAULT_DOC: Use system group memberships of the cache_effective_user account
6509 LOC: Config.effectiveGroup
6511 Squid sets the GID to the effective user's default group ID
6512 (taken from the password file) and supplementary group list
6513 from the groups membership.
6515 If you want Squid to run with a specific GID regardless of
6516 the group memberships of the effective user then set this
6517 to the group (or GID) you want Squid to run as. When set
6518 all other group privileges of the effective user are ignored
6519 and only this GID is effective. If Squid is not started as
6520 root the user starting Squid MUST be member of the specified
6523 This option is not recommended by the Squid Team.
6524 Our preference is for administrators to configure a secure
6525 user account for squid with UID/GID matching system policies.
6528 NAME: httpd_suppress_version_string
6532 LOC: Config.onoff.httpd_suppress_version_string
6534 Suppress Squid version string info in HTTP headers and HTML error pages.
6537 NAME: visible_hostname
6539 LOC: Config.visibleHostname
6541 DEFAULT_DOC: Automatically detect the system host name
6543 If you want to present a special hostname in error messages, etc,
6544 define this. Otherwise, the return value of gethostname()
6545 will be used. If you have multiple caches in a cluster and
6546 get errors about IP-forwarding you must set them to have individual
6547 names with this setting.
6550 NAME: unique_hostname
6552 LOC: Config.uniqueHostname
6554 DEFAULT_DOC: Copy the value from visible_hostname
6556 If you want to have multiple machines with the same
6557 'visible_hostname' you must give each machine a different
6558 'unique_hostname' so forwarding loops can be detected.
6561 NAME: hostname_aliases
6563 LOC: Config.hostnameAliases
6566 A list of other DNS names your cache has.
6574 Minimum umask which should be enforced while the proxy
6575 is running, in addition to the umask set at startup.
6577 For a traditional octal representation of umasks, start
6582 OPTIONS FOR THE CACHE REGISTRATION SERVICE
6583 -----------------------------------------------------------------------------
6585 This section contains parameters for the (optional) cache
6586 announcement service. This service is provided to help
6587 cache administrators locate one another in order to join or
6588 create cache hierarchies.
6590 An 'announcement' message is sent (via UDP) to the registration
6591 service by Squid. By default, the announcement message is NOT
6592 SENT unless you enable it with 'announce_period' below.
6594 The announcement message includes your hostname, plus the
6595 following information from this configuration file:
6601 All current information is processed regularly and made
6602 available on the Web at http://www.ircache.net/Cache/Tracker/.
6605 NAME: announce_period
6607 LOC: Config.Announce.period
6609 DEFAULT_DOC: Announcement messages disabled.
6611 This is how frequently to send cache announcements.
6613 To enable announcing your cache, just set an announce period.
6616 announce_period 1 day
6621 DEFAULT: tracker.ircache.net
6622 LOC: Config.Announce.host
6624 Set the hostname where announce registration messages will be sent.
6626 See also announce_port and announce_file
6632 LOC: Config.Announce.file
6634 The contents of this file will be included in the announce
6635 registration messages.
6641 LOC: Config.Announce.port
6643 Set the port where announce registration messages will be sent.
6645 See also announce_host and announce_file
6649 HTTPD-ACCELERATOR OPTIONS
6650 -----------------------------------------------------------------------------
6653 NAME: httpd_accel_surrogate_id
6656 DEFAULT_DOC: visible_hostname is used if no specific ID is set.
6657 LOC: Config.Accel.surrogate_id
6659 Surrogates (http://www.esi.org/architecture_spec_1.0.html)
6660 need an identification token to allow control targeting. Because
6661 a farm of surrogates may all perform the same tasks, they may share
6662 an identification token.
6665 NAME: http_accel_surrogate_remote
6669 LOC: Config.onoff.surrogate_is_remote
6671 Remote surrogates (such as those in a CDN) honour the header
6672 "Surrogate-Control: no-store-remote".
6674 Set this to on to have squid behave as a remote surrogate.
6678 IFDEF: USE_SQUID_ESI
6679 COMMENT: libxml2|expat|custom
6681 LOC: ESIParser::Type
6684 ESI markup is not strictly XML compatible. The custom ESI parser
6685 will give higher performance, but cannot handle non ASCII character
6690 DELAY POOL PARAMETERS
6691 -----------------------------------------------------------------------------
6695 TYPE: delay_pool_count
6697 IFDEF: USE_DELAY_POOLS
6700 This represents the number of delay pools to be used. For example,
6701 if you have one class 2 delay pool and one class 3 delays pool, you
6702 have a total of 2 delay pools.
6704 See also delay_parameters, delay_class, delay_access for pool
6705 configuration details.
6709 TYPE: delay_pool_class
6711 IFDEF: USE_DELAY_POOLS
6714 This defines the class of each delay pool. There must be exactly one
6715 delay_class line for each delay pool. For example, to define two
6716 delay pools, one of class 2 and one of class 3, the settings above
6720 delay_pools 4 # 4 delay pools
6721 delay_class 1 2 # pool 1 is a class 2 pool
6722 delay_class 2 3 # pool 2 is a class 3 pool
6723 delay_class 3 4 # pool 3 is a class 4 pool
6724 delay_class 4 5 # pool 4 is a class 5 pool
6726 The delay pool classes are:
6728 class 1 Everything is limited by a single aggregate
6731 class 2 Everything is limited by a single aggregate
6732 bucket as well as an "individual" bucket chosen
6733 from bits 25 through 32 of the IPv4 address.
6735 class 3 Everything is limited by a single aggregate
6736 bucket as well as a "network" bucket chosen
6737 from bits 17 through 24 of the IP address and a
6738 "individual" bucket chosen from bits 17 through
6739 32 of the IPv4 address.
6741 class 4 Everything in a class 3 delay pool, with an
6742 additional limit on a per user basis. This
6743 only takes effect if the username is established
6744 in advance - by forcing authentication in your
6747 class 5 Requests are grouped according their tag (see
6748 external_acl's tag= reply).
6751 Each pool also requires a delay_parameters directive to configure the pool size
6752 and speed limits used whenever the pool is applied to a request. Along with
6753 a set of delay_access directives to determine when it is used.
6755 NOTE: If an IP address is a.b.c.d
6756 -> bits 25 through 32 are "d"
6757 -> bits 17 through 24 are "c"
6758 -> bits 17 through 32 are "c * 256 + d"
6760 NOTE-2: Due to the use of bitmasks in class 2,3,4 pools they only apply to
6761 IPv4 traffic. Class 1 and 5 pools may be used with IPv6 traffic.
6763 This clause only supports fast acl types.
6764 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
6766 See also delay_parameters and delay_access.
6770 TYPE: delay_pool_access
6772 DEFAULT_DOC: Deny using the pool, unless allow rules exist in squid.conf for the pool.
6773 IFDEF: USE_DELAY_POOLS
6776 This is used to determine which delay pool a request falls into.
6778 delay_access is sorted per pool and the matching starts with pool 1,
6779 then pool 2, ..., and finally pool N. The first delay pool where the
6780 request is allowed is selected for the request. If it does not allow
6781 the request to any pool then the request is not delayed (default).
6783 For example, if you want some_big_clients in delay
6784 pool 1 and lotsa_little_clients in delay pool 2:
6786 delay_access 1 allow some_big_clients
6787 delay_access 1 deny all
6788 delay_access 2 allow lotsa_little_clients
6789 delay_access 2 deny all
6790 delay_access 3 allow authenticated_clients
6792 See also delay_parameters and delay_class.
6796 NAME: delay_parameters
6797 TYPE: delay_pool_rates
6799 IFDEF: USE_DELAY_POOLS
6802 This defines the parameters for a delay pool. Each delay pool has
6803 a number of "buckets" associated with it, as explained in the
6804 description of delay_class.
6806 For a class 1 delay pool, the syntax is:
6808 delay_parameters pool aggregate
6810 For a class 2 delay pool:
6812 delay_parameters pool aggregate individual
6814 For a class 3 delay pool:
6816 delay_parameters pool aggregate network individual
6818 For a class 4 delay pool:
6820 delay_parameters pool aggregate network individual user
6822 For a class 5 delay pool:
6824 delay_parameters pool tagrate
6826 The option variables are:
6828 pool a pool number - ie, a number between 1 and the
6829 number specified in delay_pools as used in
6832 aggregate the speed limit parameters for the aggregate bucket
6835 individual the speed limit parameters for the individual
6836 buckets (class 2, 3).
6838 network the speed limit parameters for the network buckets
6841 user the speed limit parameters for the user buckets
6844 tagrate the speed limit parameters for the tag buckets
6847 A pair of delay parameters is written restore/maximum, where restore is
6848 the number of bytes (not bits - modem and network speeds are usually
6849 quoted in bits) per second placed into the bucket, and maximum is the
6850 maximum number of bytes which can be in the bucket at any time.
6852 There must be one delay_parameters line for each delay pool.
6855 For example, if delay pool number 1 is a class 2 delay pool as in the
6856 above example, and is being used to strictly limit each host to 64Kbit/sec
6857 (plus overheads), with no overall limit, the line is:
6859 delay_parameters 1 none 8000/8000
6861 Note that 8 x 8K Byte/sec -> 64K bit/sec.
6863 Note that the word 'none' is used to represent no limit.
6866 And, if delay pool number 2 is a class 3 delay pool as in the above
6867 example, and you want to limit it to a total of 256Kbit/sec (strict limit)
6868 with each 8-bit network permitted 64Kbit/sec (strict limit) and each
6869 individual host permitted 4800bit/sec with a bucket maximum size of 64Kbits
6870 to permit a decent web page to be downloaded at a decent speed
6871 (if the network is not being limited due to overuse) but slow down
6872 large downloads more significantly:
6874 delay_parameters 2 32000/32000 8000/8000 600/8000
6876 Note that 8 x 32K Byte/sec -> 256K bit/sec.
6877 8 x 8K Byte/sec -> 64K bit/sec.
6878 8 x 600 Byte/sec -> 4800 bit/sec.
6881 Finally, for a class 4 delay pool as in the example - each user will
6882 be limited to 128Kbits/sec no matter how many workstations they are logged into.:
6884 delay_parameters 4 32000/32000 8000/8000 600/64000 16000/16000
6887 See also delay_class and delay_access.
6891 NAME: delay_initial_bucket_level
6892 COMMENT: (percent, 0-100)
6895 IFDEF: USE_DELAY_POOLS
6896 LOC: Config.Delay.initial
6898 The initial bucket percentage is used to determine how much is put
6899 in each bucket when squid starts, is reconfigured, or first notices
6900 a host accessing it (in class 2 and class 3, individual hosts and
6901 networks only have buckets associated with them once they have been
6906 CLIENT DELAY POOL PARAMETERS
6907 -----------------------------------------------------------------------------
6910 NAME: client_delay_pools
6911 TYPE: client_delay_pool_count
6913 IFDEF: USE_DELAY_POOLS
6914 LOC: Config.ClientDelay
6916 This option specifies the number of client delay pools used. It must
6917 preceed other client_delay_* options.
6920 client_delay_pools 2
6922 See also client_delay_parameters and client_delay_access.
6925 NAME: client_delay_initial_bucket_level
6926 COMMENT: (percent, 0-no_limit)
6929 IFDEF: USE_DELAY_POOLS
6930 LOC: Config.ClientDelay.initial
6932 This option determines the initial bucket size as a percentage of
6933 max_bucket_size from client_delay_parameters. Buckets are created
6934 at the time of the "first" connection from the matching IP. Idle
6935 buckets are periodically deleted up.
6937 You can specify more than 100 percent but note that such "oversized"
6938 buckets are not refilled until their size goes down to max_bucket_size
6939 from client_delay_parameters.
6942 client_delay_initial_bucket_level 50
6945 NAME: client_delay_parameters
6946 TYPE: client_delay_pool_rates
6948 IFDEF: USE_DELAY_POOLS
6949 LOC: Config.ClientDelay
6952 This option configures client-side bandwidth limits using the
6955 client_delay_parameters pool speed_limit max_bucket_size
6957 pool is an integer ID used for client_delay_access matching.
6959 speed_limit is bytes added to the bucket per second.
6961 max_bucket_size is the maximum size of a bucket, enforced after any
6962 speed_limit additions.
6964 Please see the delay_parameters option for more information and
6968 client_delay_parameters 1 1024 2048
6969 client_delay_parameters 2 51200 16384
6971 See also client_delay_access.
6975 NAME: client_delay_access
6976 TYPE: client_delay_pool_access
6978 DEFAULT_DOC: Deny use of the pool, unless allow rules exist in squid.conf for the pool.
6979 IFDEF: USE_DELAY_POOLS
6980 LOC: Config.ClientDelay
6982 This option determines the client-side delay pool for the
6985 client_delay_access pool_ID allow|deny acl_name
6987 All client_delay_access options are checked in their pool ID
6988 order, starting with pool 1. The first checked pool with allowed
6989 request is selected for the request. If no ACL matches or there
6990 are no client_delay_access options, the request bandwidth is not
6993 The ACL-selected pool is then used to find the
6994 client_delay_parameters for the request. Client-side pools are
6995 not used to aggregate clients. Clients are always aggregated
6996 based on their source IP addresses (one bucket per source IP).
6998 This clause only supports fast acl types.
6999 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
7000 Additionally, only the client TCP connection details are available.
7001 ACLs testing HTTP properties will not work.
7003 Please see delay_access for more examples.
7006 client_delay_access 1 allow low_rate_network
7007 client_delay_access 2 allow vips_network
7010 See also client_delay_parameters and client_delay_pools.
7014 WCCPv1 AND WCCPv2 CONFIGURATION OPTIONS
7015 -----------------------------------------------------------------------------
7020 LOC: Config.Wccp.router
7022 DEFAULT_DOC: WCCP disabled.
7025 Use this option to define your WCCP ``home'' router for
7028 wccp_router supports a single WCCP(v1) router
7030 wccp2_router supports multiple WCCPv2 routers
7032 only one of the two may be used at the same time and defines
7033 which version of WCCP to use.
7037 TYPE: IpAddress_list
7038 LOC: Config.Wccp2.router
7040 DEFAULT_DOC: WCCPv2 disabled.
7043 Use this option to define your WCCP ``home'' router for
7046 wccp_router supports a single WCCP(v1) router
7048 wccp2_router supports multiple WCCPv2 routers
7050 only one of the two may be used at the same time and defines
7051 which version of WCCP to use.
7056 LOC: Config.Wccp.version
7060 This directive is only relevant if you need to set up WCCP(v1)
7061 to some very old and end-of-life Cisco routers. In all other
7062 setups it must be left unset or at the default setting.
7063 It defines an internal version in the WCCP(v1) protocol,
7064 with version 4 being the officially documented protocol.
7066 According to some users, Cisco IOS 11.2 and earlier only
7067 support WCCP version 3. If you're using that or an earlier
7068 version of IOS, you may need to change this value to 3, otherwise
7069 do not specify this parameter.
7072 NAME: wccp2_rebuild_wait
7074 LOC: Config.Wccp2.rebuildwait
7078 If this is enabled Squid will wait for the cache dir rebuild to finish
7079 before sending the first wccp2 HereIAm packet
7082 NAME: wccp2_forwarding_method
7084 LOC: Config.Wccp2.forwarding_method
7088 WCCP2 allows the setting of forwarding methods between the
7089 router/switch and the cache. Valid values are as follows:
7091 gre - GRE encapsulation (forward the packet in a GRE/WCCP tunnel)
7092 l2 - L2 redirect (forward the packet using Layer 2/MAC rewriting)
7094 Currently (as of IOS 12.4) cisco routers only support GRE.
7095 Cisco switches only support the L2 redirect assignment method.
7098 NAME: wccp2_return_method
7100 LOC: Config.Wccp2.return_method
7104 WCCP2 allows the setting of return methods between the
7105 router/switch and the cache for packets that the cache
7106 decides not to handle. Valid values are as follows:
7108 gre - GRE encapsulation (forward the packet in a GRE/WCCP tunnel)
7109 l2 - L2 redirect (forward the packet using Layer 2/MAC rewriting)
7111 Currently (as of IOS 12.4) cisco routers only support GRE.
7112 Cisco switches only support the L2 redirect assignment.
7114 If the "ip wccp redirect exclude in" command has been
7115 enabled on the cache interface, then it is still safe for
7116 the proxy server to use a l2 redirect method even if this
7117 option is set to GRE.
7120 NAME: wccp2_assignment_method
7122 LOC: Config.Wccp2.assignment_method
7126 WCCP2 allows the setting of methods to assign the WCCP hash
7127 Valid values are as follows:
7129 hash - Hash assignment
7130 mask - Mask assignment
7132 As a general rule, cisco routers support the hash assignment method
7133 and cisco switches support the mask assignment method.
7138 LOC: Config.Wccp2.info
7139 DEFAULT_IF_NONE: standard 0
7140 DEFAULT_DOC: Use the 'web-cache' standard service.
7143 WCCP2 allows for multiple traffic services. There are two
7144 types: "standard" and "dynamic". The standard type defines
7145 one service id - http (id 0). The dynamic service ids can be from
7146 51 to 255 inclusive. In order to use a dynamic service id
7147 one must define the type of traffic to be redirected; this is done
7148 using the wccp2_service_info option.
7150 The "standard" type does not require a wccp2_service_info option,
7151 just specifying the service id will suffice.
7153 MD5 service authentication can be enabled by adding
7154 "password=<password>" to the end of this service declaration.
7158 wccp2_service standard 0 # for the 'web-cache' standard service
7159 wccp2_service dynamic 80 # a dynamic service type which will be
7160 # fleshed out with subsequent options.
7161 wccp2_service standard 0 password=foo
7164 NAME: wccp2_service_info
7165 TYPE: wccp2_service_info
7166 LOC: Config.Wccp2.info
7170 Dynamic WCCPv2 services require further information to define the
7171 traffic you wish to have diverted.
7175 wccp2_service_info <id> protocol=<protocol> flags=<flag>,<flag>..
7176 priority=<priority> ports=<port>,<port>..
7178 The relevant WCCPv2 flags:
7179 + src_ip_hash, dst_ip_hash
7180 + source_port_hash, dst_port_hash
7181 + src_ip_alt_hash, dst_ip_alt_hash
7182 + src_port_alt_hash, dst_port_alt_hash
7185 The port list can be one to eight entries.
7189 wccp2_service_info 80 protocol=tcp flags=src_ip_hash,ports_source
7190 priority=240 ports=80
7192 Note: the service id must have been defined by a previous
7193 'wccp2_service dynamic <id>' entry.
7198 LOC: Config.Wccp2.weight
7202 Each cache server gets assigned a set of the destination
7203 hash proportional to their weight.
7208 LOC: Config.Wccp.address
7210 DEFAULT_DOC: Address selected by the operating system.
7213 Use this option if you require WCCPv2 to use a specific
7216 The default behavior is to not bind to any specific address.
7221 LOC: Config.Wccp2.address
7223 DEFAULT_DOC: Address selected by the operating system.
7226 Use this option if you require WCCP to use a specific
7229 The default behavior is to not bind to any specific address.
7233 PERSISTENT CONNECTION HANDLING
7234 -----------------------------------------------------------------------------
7236 Also see "pconn_timeout" in the TIMEOUTS section
7239 NAME: client_persistent_connections
7241 LOC: Config.onoff.client_pconns
7244 Persistent connection support for clients.
7245 Squid uses persistent connections (when allowed). You can use
7246 this option to disable persistent connections with clients.
7249 NAME: server_persistent_connections
7251 LOC: Config.onoff.server_pconns
7254 Persistent connection support for servers.
7255 Squid uses persistent connections (when allowed). You can use
7256 this option to disable persistent connections with servers.
7259 NAME: persistent_connection_after_error
7261 LOC: Config.onoff.error_pconns
7264 With this directive the use of persistent connections after
7265 HTTP errors can be disabled. Useful if you have clients
7266 who fail to handle errors on persistent connections proper.
7269 NAME: detect_broken_pconn
7271 LOC: Config.onoff.detect_broken_server_pconns
7274 Some servers have been found to incorrectly signal the use
7275 of HTTP/1.0 persistent connections even on replies not
7276 compatible, causing significant delays. This server problem
7277 has mostly been seen on redirects.
7279 By enabling this directive Squid attempts to detect such
7280 broken replies and automatically assume the reply is finished
7281 after 10 seconds timeout.
7285 CACHE DIGEST OPTIONS
7286 -----------------------------------------------------------------------------
7289 NAME: digest_generation
7290 IFDEF: USE_CACHE_DIGESTS
7292 LOC: Config.onoff.digest_generation
7295 This controls whether the server will generate a Cache Digest
7296 of its contents. By default, Cache Digest generation is
7297 enabled if Squid is compiled with --enable-cache-digests defined.
7300 NAME: digest_bits_per_entry
7301 IFDEF: USE_CACHE_DIGESTS
7303 LOC: Config.digest.bits_per_entry
7306 This is the number of bits of the server's Cache Digest which
7307 will be associated with the Digest entry for a given HTTP
7308 Method and URL (public key) combination. The default is 5.
7311 NAME: digest_rebuild_period
7312 IFDEF: USE_CACHE_DIGESTS
7315 LOC: Config.digest.rebuild_period
7318 This is the wait time between Cache Digest rebuilds.
7321 NAME: digest_rewrite_period
7323 IFDEF: USE_CACHE_DIGESTS
7325 LOC: Config.digest.rewrite_period
7328 This is the wait time between Cache Digest writes to
7332 NAME: digest_swapout_chunk_size
7335 IFDEF: USE_CACHE_DIGESTS
7336 LOC: Config.digest.swapout_chunk_size
7339 This is the number of bytes of the Cache Digest to write to
7340 disk at a time. It defaults to 4096 bytes (4KB), the Squid
7344 NAME: digest_rebuild_chunk_percentage
7345 COMMENT: (percent, 0-100)
7346 IFDEF: USE_CACHE_DIGESTS
7348 LOC: Config.digest.rebuild_chunk_percentage
7351 This is the percentage of the Cache Digest to be scanned at a
7352 time. By default it is set to 10% of the Cache Digest.
7357 -----------------------------------------------------------------------------
7362 LOC: Config.Port.snmp
7364 DEFAULT_DOC: SNMP disabled.
7367 The port number where Squid listens for SNMP requests. To enable
7368 SNMP support set this to a suitable port number. Port number
7369 3401 is often used for the Squid SNMP agent. By default it's
7370 set to "0" (disabled)
7378 LOC: Config.accessList.snmp
7380 DEFAULT_DOC: Deny, unless rules exist in squid.conf.
7383 Allowing or denying access to the SNMP port.
7385 All access to the agent is denied by default.
7388 snmp_access allow|deny [!]aclname ...
7390 This clause only supports fast acl types.
7391 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
7394 snmp_access allow snmppublic localhost
7395 snmp_access deny all
7398 NAME: snmp_incoming_address
7400 LOC: Config.Addrs.snmp_incoming
7402 DEFAULT_DOC: Accept SNMP packets from all machine interfaces.
7405 Just like 'udp_incoming_address', but for the SNMP port.
7407 snmp_incoming_address is used for the SNMP socket receiving
7408 messages from SNMP agents.
7410 The default snmp_incoming_address is to listen on all
7411 available network interfaces.
7414 NAME: snmp_outgoing_address
7416 LOC: Config.Addrs.snmp_outgoing
7418 DEFAULT_DOC: Use snmp_incoming_address or an address selected by the operating system.
7421 Just like 'udp_outgoing_address', but for the SNMP port.
7423 snmp_outgoing_address is used for SNMP packets returned to SNMP
7426 If snmp_outgoing_address is not set it will use the same socket
7427 as snmp_incoming_address. Only change this if you want to have
7428 SNMP replies sent using another address than where this Squid
7429 listens for SNMP queries.
7431 NOTE, snmp_incoming_address and snmp_outgoing_address can not have
7432 the same value since they both use the same port.
7437 -----------------------------------------------------------------------------
7440 NAME: icp_port udp_port
7443 DEFAULT_DOC: ICP disabled.
7444 LOC: Config.Port.icp
7446 The port number where Squid sends and receives ICP queries to
7447 and from neighbor caches. The standard UDP port for ICP is 3130.
7450 icp_port @DEFAULT_ICP_PORT@
7457 DEFAULT_DOC: HTCP disabled.
7458 LOC: Config.Port.htcp
7460 The port number where Squid sends and receives HTCP queries to
7461 and from neighbor caches. To turn it on you want to set it to
7468 NAME: log_icp_queries
7472 LOC: Config.onoff.log_udp
7474 If set, ICP queries are logged to access.log. You may wish
7475 do disable this if your ICP load is VERY high to speed things
7476 up or to simplify log analysis.
7479 NAME: udp_incoming_address
7481 LOC:Config.Addrs.udp_incoming
7483 DEFAULT_DOC: Accept packets from all machine interfaces.
7485 udp_incoming_address is used for UDP packets received from other
7488 The default behavior is to not bind to any specific address.
7490 Only change this if you want to have all UDP queries received on
7491 a specific interface/address.
7493 NOTE: udp_incoming_address is used by the ICP, HTCP, and DNS
7494 modules. Altering it will affect all of them in the same manner.
7496 see also; udp_outgoing_address
7498 NOTE, udp_incoming_address and udp_outgoing_address can not
7499 have the same value since they both use the same port.
7502 NAME: udp_outgoing_address
7504 LOC: Config.Addrs.udp_outgoing
7506 DEFAULT_DOC: Use udp_incoming_address or an address selected by the operating system.
7508 udp_outgoing_address is used for UDP packets sent out to other
7511 The default behavior is to not bind to any specific address.
7513 Instead it will use the same socket as udp_incoming_address.
7514 Only change this if you want to have UDP queries sent using another
7515 address than where this Squid listens for UDP queries from other
7518 NOTE: udp_outgoing_address is used by the ICP, HTCP, and DNS
7519 modules. Altering it will affect all of them in the same manner.
7521 see also; udp_incoming_address
7523 NOTE, udp_incoming_address and udp_outgoing_address can not
7524 have the same value since they both use the same port.
7531 LOC: Config.onoff.icp_hit_stale
7533 If you want to return ICP_HIT for stale cache objects, set this
7534 option to 'on'. If you have sibling relationships with caches
7535 in other administrative domains, this should be 'off'. If you only
7536 have sibling relationships with caches under your control,
7537 it is probably okay to set this to 'on'.
7538 If set to 'on', your siblings should use the option "allow-miss"
7539 on their cache_peer lines for connecting to you.
7542 NAME: minimum_direct_hops
7545 LOC: Config.minDirectHops
7547 If using the ICMP pinging stuff, do direct fetches for sites
7548 which are no more than this many hops away.
7551 NAME: minimum_direct_rtt
7555 LOC: Config.minDirectRtt
7557 If using the ICMP pinging stuff, do direct fetches for sites
7558 which are no more than this many rtt milliseconds away.
7564 LOC: Config.Netdb.low
7566 The low water mark for the ICMP measurement database.
7568 Note: high watermark controlled by netdb_high directive.
7570 These watermarks are counts, not percents. The defaults are
7571 (low) 900 and (high) 1000. When the high water mark is
7572 reached, database entries will be deleted until the low
7579 LOC: Config.Netdb.high
7581 The high water mark for the ICMP measurement database.
7583 Note: low watermark controlled by netdb_low directive.
7585 These watermarks are counts, not percents. The defaults are
7586 (low) 900 and (high) 1000. When the high water mark is
7587 reached, database entries will be deleted until the low
7591 NAME: netdb_ping_period
7593 LOC: Config.Netdb.period
7596 The minimum period for measuring a site. There will be at
7597 least this much delay between successive pings to the same
7598 network. The default is five minutes.
7605 LOC: Config.onoff.query_icmp
7607 If you want to ask your peers to include ICMP data in their ICP
7608 replies, enable this option.
7610 If your peer has configured Squid (during compilation) with
7611 '--enable-icmp' that peer will send ICMP pings to origin server
7612 sites of the URLs it receives. If you enable this option the
7613 ICP replies from that peer will include the ICMP data (if available).
7614 Then, when choosing a parent cache, Squid will choose the parent with
7615 the minimal RTT to the origin server. When this happens, the
7616 hierarchy field of the access.log will be
7617 "CLOSEST_PARENT_MISS". This option is off by default.
7620 NAME: test_reachability
7624 LOC: Config.onoff.test_reachability
7626 When this is 'on', ICP MISS replies will be ICP_MISS_NOFETCH
7627 instead of ICP_MISS if the target host is NOT in the ICMP
7628 database, or has a zero RTT.
7631 NAME: icp_query_timeout
7634 DEFAULT_DOC: Dynamic detection.
7636 LOC: Config.Timeout.icp_query
7638 Normally Squid will automatically determine an optimal ICP
7639 query timeout value based on the round-trip-time of recent ICP
7640 queries. If you want to override the value determined by
7641 Squid, set this 'icp_query_timeout' to a non-zero value. This
7642 value is specified in MILLISECONDS, so, to use a 2-second
7643 timeout (the old default), you would write:
7645 icp_query_timeout 2000
7648 NAME: maximum_icp_query_timeout
7652 LOC: Config.Timeout.icp_query_max
7654 Normally the ICP query timeout is determined dynamically. But
7655 sometimes it can lead to very large values (say 5 seconds).
7656 Use this option to put an upper limit on the dynamic timeout
7657 value. Do NOT use this option to always use a fixed (instead
7658 of a dynamic) timeout value. To set a fixed timeout see the
7659 'icp_query_timeout' directive.
7662 NAME: minimum_icp_query_timeout
7666 LOC: Config.Timeout.icp_query_min
7668 Normally the ICP query timeout is determined dynamically. But
7669 sometimes it can lead to very small timeouts, even lower than
7670 the normal latency variance on your link due to traffic.
7671 Use this option to put an lower limit on the dynamic timeout
7672 value. Do NOT use this option to always use a fixed (instead
7673 of a dynamic) timeout value. To set a fixed timeout see the
7674 'icp_query_timeout' directive.
7677 NAME: background_ping_rate
7681 LOC: Config.backgroundPingRate
7683 Controls how often the ICP pings are sent to siblings that
7684 have background-ping set.
7688 MULTICAST ICP OPTIONS
7689 -----------------------------------------------------------------------------
7694 LOC: Config.mcast_group_list
7697 This tag specifies a list of multicast groups which your server
7698 should join to receive multicasted ICP queries.
7700 NOTE! Be very careful what you put here! Be sure you
7701 understand the difference between an ICP _query_ and an ICP
7702 _reply_. This option is to be set only if you want to RECEIVE
7703 multicast queries. Do NOT set this option to SEND multicast
7704 ICP (use cache_peer for that). ICP replies are always sent via
7705 unicast, so this option does not affect whether or not you will
7706 receive replies from multicast group members.
7708 You must be very careful to NOT use a multicast address which
7709 is already in use by another group of caches.
7711 If you are unsure about multicast, please read the Multicast
7712 chapter in the Squid FAQ (http://www.squid-cache.org/FAQ/).
7714 Usage: mcast_groups 239.128.16.128 224.0.1.20
7716 By default, Squid doesn't listen on any multicast groups.
7719 NAME: mcast_miss_addr
7720 IFDEF: MULTICAST_MISS_STREAM
7722 LOC: Config.mcast_miss.addr
7724 DEFAULT_DOC: disabled.
7726 If you enable this option, every "cache miss" URL will
7727 be sent out on the specified multicast address.
7729 Do not enable this option unless you are are absolutely
7730 certain you understand what you are doing.
7733 NAME: mcast_miss_ttl
7734 IFDEF: MULTICAST_MISS_STREAM
7736 LOC: Config.mcast_miss.ttl
7739 This is the time-to-live value for packets multicasted
7740 when multicasting off cache miss URLs is enabled. By
7741 default this is set to 'site scope', i.e. 16.
7744 NAME: mcast_miss_port
7745 IFDEF: MULTICAST_MISS_STREAM
7747 LOC: Config.mcast_miss.port
7750 This is the port number to be used in conjunction with
7754 NAME: mcast_miss_encode_key
7755 IFDEF: MULTICAST_MISS_STREAM
7757 LOC: Config.mcast_miss.encode_key
7758 DEFAULT: XXXXXXXXXXXXXXXX
7760 The URLs that are sent in the multicast miss stream are
7761 encrypted. This is the encryption key.
7764 NAME: mcast_icp_query_timeout
7768 LOC: Config.Timeout.mcast_icp_query
7770 For multicast peers, Squid regularly sends out ICP "probes" to
7771 count how many other peers are listening on the given multicast
7772 address. This value specifies how long Squid should wait to
7773 count all the replies. The default is 2000 msec, or 2
7778 INTERNAL ICON OPTIONS
7779 -----------------------------------------------------------------------------
7782 NAME: icon_directory
7784 LOC: Config.icons.directory
7785 DEFAULT: @DEFAULT_ICON_DIR@
7787 Where the icons are stored. These are normally kept in
7791 NAME: global_internal_static
7793 LOC: Config.onoff.global_internal_static
7796 This directive controls is Squid should intercept all requests for
7797 /squid-internal-static/ no matter which host the URL is requesting
7798 (default on setting), or if nothing special should be done for
7799 such URLs (off setting). The purpose of this directive is to make
7800 icons etc work better in complex cache hierarchies where it may
7801 not always be possible for all corners in the cache mesh to reach
7802 the server generating a directory listing.
7805 NAME: short_icon_urls
7807 LOC: Config.icons.use_short_names
7810 If this is enabled Squid will use short URLs for icons.
7811 If disabled it will revert to the old behavior of including
7812 it's own name and port in the URL.
7814 If you run a complex cache hierarchy with a mix of Squid and
7815 other proxies you may need to disable this directive.
7820 -----------------------------------------------------------------------------
7823 NAME: error_directory
7825 LOC: Config.errorDirectory
7827 DEFAULT_DOC: Send error pages in the clients preferred language
7829 If you wish to create your own versions of the default
7830 error files to customize them to suit your company copy
7831 the error/template files to another directory and point
7834 WARNING: This option will disable multi-language support
7835 on error pages if used.
7837 The squid developers are interested in making squid available in
7838 a wide variety of languages. If you are making translations for a
7839 language that Squid does not currently provide please consider
7840 contributing your translation back to the project.
7841 http://wiki.squid-cache.org/Translations
7843 The squid developers working on translations are happy to supply drop-in
7844 translated error files in exchange for any new language contributions.
7847 NAME: error_default_language
7848 IFDEF: USE_ERR_LOCALES
7850 LOC: Config.errorDefaultLanguage
7852 DEFAULT_DOC: Generate English language pages.
7854 Set the default language which squid will send error pages in
7855 if no existing translation matches the clients language
7858 If unset (default) generic English will be used.
7860 The squid developers are interested in making squid available in
7861 a wide variety of languages. If you are interested in making
7862 translations for any language see the squid wiki for details.
7863 http://wiki.squid-cache.org/Translations
7866 NAME: error_log_languages
7867 IFDEF: USE_ERR_LOCALES
7869 LOC: Config.errorLogMissingLanguages
7872 Log to cache.log what languages users are attempting to
7873 auto-negotiate for translations.
7875 Successful negotiations are not logged. Only failures
7876 have meaning to indicate that Squid may need an upgrade
7877 of its error page translations.
7880 NAME: err_page_stylesheet
7882 LOC: Config.errorStylesheet
7883 DEFAULT: @DEFAULT_CONFIG_DIR@/errorpage.css
7885 CSS Stylesheet to pattern the display of Squid default error pages.
7887 For information on CSS see http://www.w3.org/Style/CSS/
7892 LOC: Config.errHtmlText
7895 HTML text to include in error messages. Make this a "mailto"
7896 URL to your admin address, or maybe just a link to your
7897 organizations Web page.
7899 To include this in your error messages, you must rewrite
7900 the error template files (found in the "errors" directory).
7901 Wherever you want the 'err_html_text' line to appear,
7902 insert a %L tag in the error template file.
7905 NAME: email_err_data
7908 LOC: Config.onoff.emailErrData
7911 If enabled, information about the occurred error will be
7912 included in the mailto links of the ERR pages (if %W is set)
7913 so that the email body contains the data.
7914 Syntax is <A HREF="mailto:%w%W">%w</A>
7919 LOC: Config.denyInfoList
7922 Usage: deny_info err_page_name acl
7923 or deny_info http://... acl
7924 or deny_info TCP_RESET acl
7926 This can be used to return a ERR_ page for requests which
7927 do not pass the 'http_access' rules. Squid remembers the last
7928 acl it evaluated in http_access, and if a 'deny_info' line exists
7929 for that ACL Squid returns a corresponding error page.
7931 The acl is typically the last acl on the http_access deny line which
7932 denied access. The exceptions to this rule are:
7933 - When Squid needs to request authentication credentials. It's then
7934 the first authentication related acl encountered
7935 - When none of the http_access lines matches. It's then the last
7936 acl processed on the last http_access line.
7937 - When the decision to deny access was made by an adaptation service,
7938 the acl name is the corresponding eCAP or ICAP service_name.
7940 NP: If providing your own custom error pages with error_directory
7941 you may also specify them by your custom file name:
7942 Example: deny_info ERR_CUSTOM_ACCESS_DENIED bad_guys
7944 By defaut Squid will send "403 Forbidden". A different 4xx or 5xx
7945 may be specified by prefixing the file name with the code and a colon.
7946 e.g. 404:ERR_CUSTOM_ACCESS_DENIED
7948 Alternatively you can tell Squid to reset the TCP connection
7949 by specifying TCP_RESET.
7951 Or you can specify an error URL or URL pattern. The browsers will
7952 get redirected to the specified URL after formatting tags have
7953 been replaced. Redirect will be done with 302 or 307 according to
7954 HTTP/1.1 specs. A different 3xx code may be specified by prefixing
7955 the URL. e.g. 303:http://example.com/
7958 %a - username (if available. Password NOT included)
7961 %E - Error description
7963 %H - Request domain name
7964 %i - Client IP Address
7966 %O - Unescaped message result from external ACL helper
7967 %o - Message result from external ACL helper
7968 %p - Request Port number
7969 %P - Request Protocol name
7970 %R - Request URL path
7971 %T - Timestamp in RFC 1123 format
7972 %U - Full canonical URL from client
7973 (HTTPS URLs terminate with *)
7974 %u - Full canonical URL from client
7975 %w - Admin email from squid.conf
7977 %% - Literal percent (%) code
7982 OPTIONS INFLUENCING REQUEST FORWARDING
7983 -----------------------------------------------------------------------------
7986 NAME: nonhierarchical_direct
7988 LOC: Config.onoff.nonhierarchical_direct
7991 By default, Squid will send any non-hierarchical requests
7992 (not cacheable request type) direct to origin servers.
7994 When this is set to "off", Squid will prefer to send these
7995 requests to parents.
7997 Note that in most configurations, by turning this off you will only
7998 add latency to these request without any improvement in global hit
8001 This option only sets a preference. If the parent is unavailable a
8002 direct connection to the origin server may still be attempted. To
8003 completely prevent direct connections use never_direct.
8008 LOC: Config.onoff.prefer_direct
8011 Normally Squid tries to use parents for most requests. If you for some
8012 reason like it to first try going direct and only use a parent if
8013 going direct fails set this to on.
8015 By combining nonhierarchical_direct off and prefer_direct on you
8016 can set up Squid to use a parent as a backup path if going direct
8019 Note: If you want Squid to use parents for all requests see
8020 the never_direct directive. prefer_direct only modifies how Squid
8021 acts on cacheable requests.
8024 NAME: cache_miss_revalidate
8028 LOC: Config.onoff.cache_miss_revalidate
8030 RFC 7232 defines a conditional request mechanism to prevent
8031 response objects being unnecessarily transferred over the network.
8032 If that mechanism is used by the client and a cache MISS occurs
8033 it can prevent new cache entries being created.
8035 This option determines whether Squid on cache MISS will pass the
8036 client revalidation request to the server or tries to fetch new
8037 content for caching. It can be useful while the cache is mostly
8038 empty to more quickly have the cache populated by generating
8039 non-conditional GETs.
8041 When set to 'on' (default), Squid will pass all client If-* headers
8042 to the server. This permits server responses without a cacheable
8043 payload to be delivered and on MISS no new cache entry is created.
8045 When set to 'off' and if the request is cacheable, Squid will
8046 remove the clients If-Modified-Since and If-None-Match headers from
8047 the request sent to the server. This requests a 200 status response
8048 from the server to create a new cache entry with.
8053 LOC: Config.accessList.AlwaysDirect
8055 DEFAULT_DOC: Prevent any cache_peer being used for this request.
8057 Usage: always_direct allow|deny [!]aclname ...
8059 Here you can use ACL elements to specify requests which should
8060 ALWAYS be forwarded by Squid to the origin servers without using
8061 any peers. For example, to always directly forward requests for
8062 local servers ignoring any parents or siblings you may have use
8065 acl local-servers dstdomain my.domain.net
8066 always_direct allow local-servers
8068 To always forward FTP requests directly, use
8071 always_direct allow FTP
8073 NOTE: There is a similar, but opposite option named
8074 'never_direct'. You need to be aware that "always_direct deny
8075 foo" is NOT the same thing as "never_direct allow foo". You
8076 may need to use a deny rule to exclude a more-specific case of
8077 some other rule. Example:
8079 acl local-external dstdomain external.foo.net
8080 acl local-servers dstdomain .foo.net
8081 always_direct deny local-external
8082 always_direct allow local-servers
8084 NOTE: If your goal is to make the client forward the request
8085 directly to the origin server bypassing Squid then this needs
8086 to be done in the client configuration. Squid configuration
8087 can only tell Squid how Squid should fetch the object.
8089 NOTE: This directive is not related to caching. The replies
8090 is cached as usual even if you use always_direct. To not cache
8091 the replies see the 'cache' directive.
8093 This clause supports both fast and slow acl types.
8094 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
8099 LOC: Config.accessList.NeverDirect
8101 DEFAULT_DOC: Allow DNS results to be used for this request.
8103 Usage: never_direct allow|deny [!]aclname ...
8105 never_direct is the opposite of always_direct. Please read
8106 the description for always_direct if you have not already.
8108 With 'never_direct' you can use ACL elements to specify
8109 requests which should NEVER be forwarded directly to origin
8110 servers. For example, to force the use of a proxy for all
8111 requests, except those in your local domain use something like:
8113 acl local-servers dstdomain .foo.net
8114 never_direct deny local-servers
8115 never_direct allow all
8117 or if Squid is inside a firewall and there are local intranet
8118 servers inside the firewall use something like:
8120 acl local-intranet dstdomain .foo.net
8121 acl local-external dstdomain external.foo.net
8122 always_direct deny local-external
8123 always_direct allow local-intranet
8124 never_direct allow all
8126 This clause supports both fast and slow acl types.
8127 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
8131 ADVANCED NETWORKING OPTIONS
8132 -----------------------------------------------------------------------------
8135 NAME: incoming_udp_average incoming_icp_average
8138 LOC: Config.comm_incoming.udp.average
8140 Heavy voodoo here. I can't even believe you are reading this.
8141 Are you crazy? Don't even think about adjusting these unless
8142 you understand the algorithms in comm_select.c first!
8145 NAME: incoming_tcp_average incoming_http_average
8148 LOC: Config.comm_incoming.tcp.average
8150 Heavy voodoo here. I can't even believe you are reading this.
8151 Are you crazy? Don't even think about adjusting these unless
8152 you understand the algorithms in comm_select.c first!
8155 NAME: incoming_dns_average
8158 LOC: Config.comm_incoming.dns.average
8160 Heavy voodoo here. I can't even believe you are reading this.
8161 Are you crazy? Don't even think about adjusting these unless
8162 you understand the algorithms in comm_select.c first!
8165 NAME: min_udp_poll_cnt min_icp_poll_cnt
8168 LOC: Config.comm_incoming.udp.min_poll
8170 Heavy voodoo here. I can't even believe you are reading this.
8171 Are you crazy? Don't even think about adjusting these unless
8172 you understand the algorithms in comm_select.c first!
8175 NAME: min_dns_poll_cnt
8178 LOC: Config.comm_incoming.dns.min_poll
8180 Heavy voodoo here. I can't even believe you are reading this.
8181 Are you crazy? Don't even think about adjusting these unless
8182 you understand the algorithms in comm_select.c first!
8185 NAME: min_tcp_poll_cnt min_http_poll_cnt
8188 LOC: Config.comm_incoming.tcp.min_poll
8190 Heavy voodoo here. I can't even believe you are reading this.
8191 Are you crazy? Don't even think about adjusting these unless
8192 you understand the algorithms in comm_select.c first!
8198 LOC: Config.accept_filter
8202 The name of an accept(2) filter to install on Squid's
8203 listen socket(s). This feature is perhaps specific to
8204 FreeBSD and requires support in the kernel.
8206 The 'httpready' filter delays delivering new connections
8207 to Squid until a full HTTP request has been received.
8208 See the accf_http(9) man page for details.
8210 The 'dataready' filter delays delivering new connections
8211 to Squid until there is some data to process.
8212 See the accf_dataready(9) man page for details.
8216 The 'data' filter delays delivering of new connections
8217 to Squid until there is some data to process by TCP_ACCEPT_DEFER.
8218 You may optionally specify a number of seconds to wait by
8219 'data=N' where N is the number of seconds. Defaults to 30
8220 if not specified. See the tcp(7) man page for details.
8223 accept_filter httpready
8228 NAME: client_ip_max_connections
8230 LOC: Config.client_ip_max_connections
8232 DEFAULT_DOC: No limit.
8234 Set an absolute limit on the number of connections a single
8235 client IP can use. Any more than this and Squid will begin to drop
8236 new connections from the client until it closes some links.
8238 Note that this is a global limit. It affects all HTTP, HTCP, Gopher and FTP
8239 connections from the client. For finer control use the ACL access controls.
8241 Requires client_db to be enabled (the default).
8243 WARNING: This may noticably slow down traffic received via external proxies
8244 or NAT devices and cause them to rebound error messages back to their clients.
8247 NAME: tcp_recv_bufsize
8251 DEFAULT_DOC: Use operating system TCP defaults.
8252 LOC: Config.tcpRcvBufsz
8254 Size of receive buffer to set for TCP sockets. Probably just
8255 as easy to change your kernel's default.
8256 Omit from squid.conf to use the default buffer size.
8261 -----------------------------------------------------------------------------
8268 LOC: Adaptation::Icap::TheConfig.onoff
8271 If you want to enable the ICAP module support, set this to on.
8274 NAME: icap_connect_timeout
8277 LOC: Adaptation::Icap::TheConfig.connect_timeout_raw
8280 This parameter specifies how long to wait for the TCP connect to
8281 the requested ICAP server to complete before giving up and either
8282 terminating the HTTP transaction or bypassing the failure.
8284 The default for optional services is peer_connect_timeout.
8285 The default for essential services is connect_timeout.
8286 If this option is explicitly set, its value applies to all services.
8289 NAME: icap_io_timeout
8293 DEFAULT_DOC: Use read_timeout.
8294 LOC: Adaptation::Icap::TheConfig.io_timeout_raw
8297 This parameter specifies how long to wait for an I/O activity on
8298 an established, active ICAP connection before giving up and
8299 either terminating the HTTP transaction or bypassing the
8303 NAME: icap_service_failure_limit
8304 COMMENT: limit [in memory-depth time-units]
8305 TYPE: icap_service_failure_limit
8307 LOC: Adaptation::Icap::TheConfig
8310 The limit specifies the number of failures that Squid tolerates
8311 when establishing a new TCP connection with an ICAP service. If
8312 the number of failures exceeds the limit, the ICAP service is
8313 not used for new ICAP requests until it is time to refresh its
8316 A negative value disables the limit. Without the limit, an ICAP
8317 service will not be considered down due to connectivity failures
8318 between ICAP OPTIONS requests.
8320 Squid forgets ICAP service failures older than the specified
8321 value of memory-depth. The memory fading algorithm
8322 is approximate because Squid does not remember individual
8323 errors but groups them instead, splitting the option
8324 value into ten time slots of equal length.
8326 When memory-depth is 0 and by default this option has no
8327 effect on service failure expiration.
8329 Squid always forgets failures when updating service settings
8330 using an ICAP OPTIONS transaction, regardless of this option
8334 # suspend service usage after 10 failures in 5 seconds:
8335 icap_service_failure_limit 10 in 5 seconds
8338 NAME: icap_service_revival_delay
8341 LOC: Adaptation::Icap::TheConfig.service_revival_delay
8344 The delay specifies the number of seconds to wait after an ICAP
8345 OPTIONS request failure before requesting the options again. The
8346 failed ICAP service is considered "down" until fresh OPTIONS are
8349 The actual delay cannot be smaller than the hardcoded minimum
8350 delay of 30 seconds.
8353 NAME: icap_preview_enable
8357 LOC: Adaptation::Icap::TheConfig.preview_enable
8360 The ICAP Preview feature allows the ICAP server to handle the
8361 HTTP message by looking only at the beginning of the message body
8362 or even without receiving the body at all. In some environments,
8363 previews greatly speedup ICAP processing.
8365 During an ICAP OPTIONS transaction, the server may tell Squid what
8366 HTTP messages should be previewed and how big the preview should be.
8367 Squid will not use Preview if the server did not request one.
8369 To disable ICAP Preview for all ICAP services, regardless of
8370 individual ICAP server OPTIONS responses, set this option to "off".
8372 icap_preview_enable off
8375 NAME: icap_preview_size
8378 LOC: Adaptation::Icap::TheConfig.preview_size
8380 DEFAULT_DOC: No preview sent.
8382 The default size of preview data to be sent to the ICAP server.
8383 This value might be overwritten on a per server basis by OPTIONS requests.
8386 NAME: icap_206_enable
8390 LOC: Adaptation::Icap::TheConfig.allow206_enable
8393 206 (Partial Content) responses is an ICAP extension that allows the
8394 ICAP agents to optionally combine adapted and original HTTP message
8395 content. The decision to combine is postponed until the end of the
8396 ICAP response. Squid supports Partial Content extension by default.
8398 Activation of the Partial Content extension is negotiated with each
8399 ICAP service during OPTIONS exchange. Most ICAP servers should handle
8400 negotation correctly even if they do not support the extension, but
8401 some might fail. To disable Partial Content support for all ICAP
8402 services and to avoid any negotiation, set this option to "off".
8408 NAME: icap_default_options_ttl
8411 LOC: Adaptation::Icap::TheConfig.default_options_ttl
8414 The default TTL value for ICAP OPTIONS responses that don't have
8415 an Options-TTL header.
8418 NAME: icap_persistent_connections
8422 LOC: Adaptation::Icap::TheConfig.reuse_connections
8425 Whether or not Squid should use persistent connections to
8429 NAME: adaptation_send_client_ip icap_send_client_ip
8431 IFDEF: USE_ADAPTATION
8433 LOC: Adaptation::Config::send_client_ip
8436 If enabled, Squid shares HTTP client IP information with adaptation
8437 services. For ICAP, Squid adds the X-Client-IP header to ICAP requests.
8438 For eCAP, Squid sets the libecap::metaClientIp transaction option.
8440 See also: adaptation_uses_indirect_client
8443 NAME: adaptation_send_username icap_send_client_username
8445 IFDEF: USE_ADAPTATION
8447 LOC: Adaptation::Config::send_username
8450 This sends authenticated HTTP client username (if available) to
8451 the adaptation service.
8453 For ICAP, the username value is encoded based on the
8454 icap_client_username_encode option and is sent using the header
8455 specified by the icap_client_username_header option.
8458 NAME: icap_client_username_header
8461 LOC: Adaptation::Icap::TheConfig.client_username_header
8462 DEFAULT: X-Client-Username
8464 ICAP request header name to use for adaptation_send_username.
8467 NAME: icap_client_username_encode
8471 LOC: Adaptation::Icap::TheConfig.client_username_encode
8474 Whether to base64 encode the authenticated client username.
8478 TYPE: icap_service_type
8480 LOC: Adaptation::Icap::TheConfig
8483 Defines a single ICAP service using the following format:
8485 icap_service id vectoring_point uri [option ...]
8488 an opaque identifier or name which is used to direct traffic to
8489 this specific service. Must be unique among all adaptation
8490 services in squid.conf.
8492 vectoring_point: reqmod_precache|reqmod_postcache|respmod_precache|respmod_postcache
8493 This specifies at which point of transaction processing the
8494 ICAP service should be activated. *_postcache vectoring points
8495 are not yet supported.
8497 uri: icap://servername:port/servicepath
8498 ICAP server and service location.
8499 icaps://servername:port/servicepath
8500 The "icap:" URI scheme is used for traditional ICAP server and
8501 service location (default port is 1344, connections are not
8502 encrypted). The "icaps:" URI scheme is for Secure ICAP
8503 services that use SSL/TLS-encrypted ICAP connections (by
8504 default, on port 11344).
8506 ICAP does not allow a single service to handle both REQMOD and RESPMOD
8507 transactions. Squid does not enforce that requirement. You can specify
8508 services with the same service_url and different vectoring_points. You
8509 can even specify multiple identical services as long as their
8510 service_names differ.
8512 To activate a service, use the adaptation_access directive. To group
8513 services, use adaptation_service_chain and adaptation_service_set.
8515 Service options are separated by white space. ICAP services support
8516 the following name=value options:
8519 If set to 'on' or '1', the ICAP service is treated as
8520 optional. If the service cannot be reached or malfunctions,
8521 Squid will try to ignore any errors and process the message as
8522 if the service was not enabled. No all ICAP errors can be
8523 bypassed. If set to 0, the ICAP service is treated as
8524 essential and all ICAP errors will result in an error page
8525 returned to the HTTP client.
8527 Bypass is off by default: services are treated as essential.
8530 If set to 'on' or '1', the ICAP service is allowed to
8531 dynamically change the current message adaptation plan by
8532 returning a chain of services to be used next. The services
8533 are specified using the X-Next-Services ICAP response header
8534 value, formatted as a comma-separated list of service names.
8535 Each named service should be configured in squid.conf. Other
8536 services are ignored. An empty X-Next-Services value results
8537 in an empty plan which ends the current adaptation.
8539 Dynamic adaptation plan may cross or cover multiple supported
8540 vectoring points in their natural processing order.
8542 Routing is not allowed by default: the ICAP X-Next-Services
8543 response header is ignored.
8546 Only has effect on split-stack systems. The default on those systems
8547 is to use IPv4-only connections. When set to 'on' this option will
8548 make Squid use IPv6-only connections to contact this ICAP service.
8550 on-overload=block|bypass|wait|force
8551 If the service Max-Connections limit has been reached, do
8552 one of the following for each new ICAP transaction:
8553 * block: send an HTTP error response to the client
8554 * bypass: ignore the "over-connected" ICAP service
8555 * wait: wait (in a FIFO queue) for an ICAP connection slot
8556 * force: proceed, ignoring the Max-Connections limit
8558 In SMP mode with N workers, each worker assumes the service
8559 connection limit is Max-Connections/N, even though not all
8560 workers may use a given service.
8562 The default value is "bypass" if service is bypassable,
8563 otherwise it is set to "wait".
8567 Use the given number as the Max-Connections limit, regardless
8568 of the Max-Connections value given by the service, if any.
8570 connection-encryption=on|off
8571 Determines the ICAP service effect on the connections_encrypted
8574 The default is "on" for Secure ICAP services (i.e., those
8575 with the icaps:// service URIs scheme) and "off" for plain ICAP
8578 Does not affect ICAP connections (e.g., does not turn Secure
8581 ==== ICAPS / TLS OPTIONS ====
8583 These options are used for Secure ICAP (icaps://....) services only.
8585 tls-cert=/path/to/ssl/certificate
8586 A client SSL certificate to use when connecting to
8589 tls-key=/path/to/ssl/key
8590 The private TLS/SSL key corresponding to sslcert above.
8591 If 'tls-key' is not specified 'tls-cert' is assumed to
8592 reference a combined PEM format file containing both the
8593 certificate and the key.
8595 tls-cipher=... The list of valid TLS/SSL ciphers to use when connecting
8596 to this icap server.
8599 The minimum TLS protocol version to permit. To control
8600 SSLv3 use the ssloptions= parameter.
8601 Supported Values: 1.0 (default), 1.1, 1.2
8603 tls-options=... Specify various OpenSSL library options:
8605 NO_SSLv3 Disallow the use of SSLv3
8607 NO_TLSv1 Disallow the use of TLSv1.0
8608 NO_TLSv1_1 Disallow the use of TLSv1.1
8609 NO_TLSv1_2 Disallow the use of TLSv1.2
8612 Always create a new key when using
8613 temporary/ephemeral DH key exchanges
8615 ALL Enable various bug workarounds
8616 suggested as "harmless" by OpenSSL
8617 Be warned that this reduces SSL/TLS
8618 strength to some attacks.
8620 See the OpenSSL SSL_CTX_set_options documentation for a
8621 more complete list. Options relevant only to SSLv2 are
8624 tls-cafile= PEM file containing CA certificates to use when verifying
8625 the icap server certificate.
8626 Use to specify intermediate CA certificate(s) if not sent
8627 by the server. Or the full CA chain for the server when
8628 using the tls-default-ca=off flag.
8629 May be repeated to load multiple files.
8631 tls-capath=... A directory containing additional CA certificates to
8632 use when verifying the icap server certificate.
8633 Requires OpenSSL or LibreSSL.
8635 tls-crlfile=... A certificate revocation list file to use when
8636 verifying the icap server certificate.
8638 tls-flags=... Specify various flags modifying the Squid TLS implementation:
8641 Accept certificates even if they fail to
8644 Don't verify the icap server certificate
8645 matches the server name
8647 tls-default-ca[=off]
8648 Whether to use the system Trusted CAs. Default is ON.
8650 tls-domain= The icap server name as advertised in it's certificate.
8651 Used for verifying the correctness of the received icap
8652 server certificate. If not specified the icap server
8653 hostname extracted from ICAP URI will be used.
8655 Older icap_service format without optional named parameters is
8656 deprecated but supported for backward compatibility.
8659 icap_service svcBlocker reqmod_precache icap://icap1.mydomain.net:1344/reqmod bypass=0
8660 icap_service svcLogger reqmod_precache icaps://icap2.mydomain.net:11344/reqmod routing=on
8664 TYPE: icap_class_type
8669 This deprecated option was documented to define an ICAP service
8670 chain, even though it actually defined a set of similar, redundant
8671 services, and the chains were not supported.
8673 To define a set of redundant services, please use the
8674 adaptation_service_set directive. For service chains, use
8675 adaptation_service_chain.
8679 TYPE: icap_access_type
8684 This option is deprecated. Please use adaptation_access, which
8685 has the same ICAP functionality, but comes with better
8686 documentation, and eCAP support.
8691 -----------------------------------------------------------------------------
8698 LOC: Adaptation::Ecap::TheConfig.onoff
8701 Controls whether eCAP support is enabled.
8705 TYPE: ecap_service_type
8707 LOC: Adaptation::Ecap::TheConfig
8710 Defines a single eCAP service
8712 ecap_service id vectoring_point uri [option ...]
8715 an opaque identifier or name which is used to direct traffic to
8716 this specific service. Must be unique among all adaptation
8717 services in squid.conf.
8719 vectoring_point: reqmod_precache|reqmod_postcache|respmod_precache|respmod_postcache
8720 This specifies at which point of transaction processing the
8721 eCAP service should be activated. *_postcache vectoring points
8722 are not yet supported.
8724 uri: ecap://vendor/service_name?custom&cgi=style¶meters=optional
8725 Squid uses the eCAP service URI to match this configuration
8726 line with one of the dynamically loaded services. Each loaded
8727 eCAP service must have a unique URI. Obtain the right URI from
8728 the service provider.
8730 To activate a service, use the adaptation_access directive. To group
8731 services, use adaptation_service_chain and adaptation_service_set.
8733 Service options are separated by white space. eCAP services support
8734 the following name=value options:
8737 If set to 'on' or '1', the eCAP service is treated as optional.
8738 If the service cannot be reached or malfunctions, Squid will try
8739 to ignore any errors and process the message as if the service
8740 was not enabled. No all eCAP errors can be bypassed.
8741 If set to 'off' or '0', the eCAP service is treated as essential
8742 and all eCAP errors will result in an error page returned to the
8745 Bypass is off by default: services are treated as essential.
8748 If set to 'on' or '1', the eCAP service is allowed to
8749 dynamically change the current message adaptation plan by
8750 returning a chain of services to be used next.
8752 Dynamic adaptation plan may cross or cover multiple supported
8753 vectoring points in their natural processing order.
8755 Routing is not allowed by default.
8757 connection-encryption=on|off
8758 Determines the eCAP service effect on the connections_encrypted
8761 Defaults to "on", which does not taint the master transaction
8764 Does not affect eCAP API calls.
8766 Older ecap_service format without optional named parameters is
8767 deprecated but supported for backward compatibility.
8771 ecap_service s1 reqmod_precache ecap://filters.R.us/leakDetector?on_error=block bypass=off
8772 ecap_service s2 respmod_precache ecap://filters.R.us/virusFilter config=/etc/vf.cfg bypass=on
8775 NAME: loadable_modules
8777 IFDEF: USE_LOADABLE_MODULES
8778 LOC: Config.loadable_module_names
8781 Instructs Squid to load the specified dynamic module(s) or activate
8782 preloaded module(s).
8784 loadable_modules @DEFAULT_PREFIX@/lib/MinimalAdapter.so
8788 MESSAGE ADAPTATION OPTIONS
8789 -----------------------------------------------------------------------------
8792 NAME: adaptation_service_set
8793 TYPE: adaptation_service_set_type
8794 IFDEF: USE_ADAPTATION
8799 Configures an ordered set of similar, redundant services. This is
8800 useful when hot standby or backup adaptation servers are available.
8802 adaptation_service_set set_name service_name1 service_name2 ...
8804 The named services are used in the set declaration order. The first
8805 applicable adaptation service from the set is used first. The next
8806 applicable service is tried if and only if the transaction with the
8807 previous service fails and the message waiting to be adapted is still
8810 When adaptation starts, broken services are ignored as if they were
8811 not a part of the set. A broken service is a down optional service.
8813 The services in a set must be attached to the same vectoring point
8814 (e.g., pre-cache) and use the same adaptation method (e.g., REQMOD).
8816 If all services in a set are optional then adaptation failures are
8817 bypassable. If all services in the set are essential, then a
8818 transaction failure with one service may still be retried using
8819 another service from the set, but when all services fail, the master
8820 transaction fails as well.
8822 A set may contain a mix of optional and essential services, but that
8823 is likely to lead to surprising results because broken services become
8824 ignored (see above), making previously bypassable failures fatal.
8825 Technically, it is the bypassability of the last failed service that
8828 See also: adaptation_access adaptation_service_chain
8831 adaptation_service_set svcBlocker urlFilterPrimary urlFilterBackup
8832 adaptation service_set svcLogger loggerLocal loggerRemote
8835 NAME: adaptation_service_chain
8836 TYPE: adaptation_service_chain_type
8837 IFDEF: USE_ADAPTATION
8842 Configures a list of complementary services that will be applied
8843 one-by-one, forming an adaptation chain or pipeline. This is useful
8844 when Squid must perform different adaptations on the same message.
8846 adaptation_service_chain chain_name service_name1 svc_name2 ...
8848 The named services are used in the chain declaration order. The first
8849 applicable adaptation service from the chain is used first. The next
8850 applicable service is applied to the successful adaptation results of
8851 the previous service in the chain.
8853 When adaptation starts, broken services are ignored as if they were
8854 not a part of the chain. A broken service is a down optional service.
8856 Request satisfaction terminates the adaptation chain because Squid
8857 does not currently allow declaration of RESPMOD services at the
8858 "reqmod_precache" vectoring point (see icap_service or ecap_service).
8860 The services in a chain must be attached to the same vectoring point
8861 (e.g., pre-cache) and use the same adaptation method (e.g., REQMOD).
8863 A chain may contain a mix of optional and essential services. If an
8864 essential adaptation fails (or the failure cannot be bypassed for
8865 other reasons), the master transaction fails. Otherwise, the failure
8866 is bypassed as if the failed adaptation service was not in the chain.
8868 See also: adaptation_access adaptation_service_set
8871 adaptation_service_chain svcRequest requestLogger urlFilter leakDetector
8874 NAME: adaptation_access
8875 TYPE: adaptation_access_type
8876 IFDEF: USE_ADAPTATION
8879 DEFAULT_DOC: Allow, unless rules exist in squid.conf.
8881 Sends an HTTP transaction to an ICAP or eCAP adaptation service.
8883 adaptation_access service_name allow|deny [!]aclname...
8884 adaptation_access set_name allow|deny [!]aclname...
8886 At each supported vectoring point, the adaptation_access
8887 statements are processed in the order they appear in this
8888 configuration file. Statements pointing to the following services
8889 are ignored (i.e., skipped without checking their ACL):
8891 - services serving different vectoring points
8892 - "broken-but-bypassable" services
8893 - "up" services configured to ignore such transactions
8894 (e.g., based on the ICAP Transfer-Ignore header).
8896 When a set_name is used, all services in the set are checked
8897 using the same rules, to find the first applicable one. See
8898 adaptation_service_set for details.
8900 If an access list is checked and there is a match, the
8901 processing stops: For an "allow" rule, the corresponding
8902 adaptation service is used for the transaction. For a "deny"
8903 rule, no adaptation service is activated.
8905 It is currently not possible to apply more than one adaptation
8906 service at the same vectoring point to the same HTTP transaction.
8908 See also: icap_service and ecap_service
8911 adaptation_access service_1 allow all
8914 NAME: adaptation_service_iteration_limit
8916 IFDEF: USE_ADAPTATION
8917 LOC: Adaptation::Config::service_iteration_limit
8920 Limits the number of iterations allowed when applying adaptation
8921 services to a message. If your longest adaptation set or chain
8922 may have more than 16 services, increase the limit beyond its
8923 default value of 16. If detecting infinite iteration loops sooner
8924 is critical, make the iteration limit match the actual number
8925 of services in your longest adaptation set or chain.
8927 Infinite adaptation loops are most likely with routing services.
8929 See also: icap_service routing=1
8932 NAME: adaptation_masterx_shared_names
8934 IFDEF: USE_ADAPTATION
8935 LOC: Adaptation::Config::masterx_shared_name
8938 For each master transaction (i.e., the HTTP request and response
8939 sequence, including all related ICAP and eCAP exchanges), Squid
8940 maintains a table of metadata. The table entries are (name, value)
8941 pairs shared among eCAP and ICAP exchanges. The table is destroyed
8942 with the master transaction.
8944 This option specifies the table entry names that Squid must accept
8945 from and forward to the adaptation transactions.
8947 An ICAP REQMOD or RESPMOD transaction may set an entry in the
8948 shared table by returning an ICAP header field with a name
8949 specified in adaptation_masterx_shared_names.
8951 An eCAP REQMOD or RESPMOD transaction may set an entry in the
8952 shared table by implementing the libecap::visitEachOption() API
8953 to provide an option with a name specified in
8954 adaptation_masterx_shared_names.
8956 Squid will store and forward the set entry to subsequent adaptation
8957 transactions within the same master transaction scope.
8959 Only one shared entry name is supported at this time.
8962 # share authentication information among ICAP services
8963 adaptation_masterx_shared_names X-Subscriber-ID
8966 NAME: adaptation_meta
8968 IFDEF: USE_ADAPTATION
8969 LOC: Adaptation::Config::metaHeaders
8972 This option allows Squid administrator to add custom ICAP request
8973 headers or eCAP options to Squid ICAP requests or eCAP transactions.
8974 Use it to pass custom authentication tokens and other
8975 transaction-state related meta information to an ICAP/eCAP service.
8977 The addition of a meta header is ACL-driven:
8978 adaptation_meta name value [!]aclname ...
8980 Processing for a given header name stops after the first ACL list match.
8981 Thus, it is impossible to add two headers with the same name. If no ACL
8982 lists match for a given header name, no such header is added. For
8985 # do not debug transactions except for those that need debugging
8986 adaptation_meta X-Debug 1 needs_debugging
8988 # log all transactions except for those that must remain secret
8989 adaptation_meta X-Log 1 !keep_secret
8991 # mark transactions from users in the "G 1" group
8992 adaptation_meta X-Authenticated-Groups "G 1" authed_as_G1
8994 The "value" parameter may be a regular squid.conf token or a "double
8995 quoted string". Within the quoted string, use backslash (\) to escape
8996 any character, which is currently only useful for escaping backslashes
8997 and double quotes. For example,
8998 "this string has one backslash (\\) and two \"quotes\""
9000 Used adaptation_meta header values may be logged via %note
9001 logformat code. If multiple adaptation_meta headers with the same name
9002 are used during master transaction lifetime, the header values are
9003 logged in the order they were used and duplicate values are ignored
9004 (only the first repeated value will be logged).
9010 LOC: Adaptation::Icap::TheConfig.repeat
9011 DEFAULT_IF_NONE: deny all
9013 This ACL determines which retriable ICAP transactions are
9014 retried. Transactions that received a complete ICAP response
9015 and did not have to consume or produce HTTP bodies to receive
9016 that response are usually retriable.
9018 icap_retry allow|deny [!]aclname ...
9020 Squid automatically retries some ICAP I/O timeouts and errors
9021 due to persistent connection race conditions.
9023 See also: icap_retry_limit
9026 NAME: icap_retry_limit
9029 LOC: Adaptation::Icap::TheConfig.repeat_limit
9031 DEFAULT_DOC: No retries are allowed.
9033 Limits the number of retries allowed.
9035 Communication errors due to persistent connection race
9036 conditions are unavoidable, automatically retried, and do not
9037 count against this limit.
9039 See also: icap_retry
9045 -----------------------------------------------------------------------------
9048 NAME: check_hostnames
9051 LOC: Config.onoff.check_hostnames
9053 For security and stability reasons Squid can check
9054 hostnames for Internet standard RFC compliance. If you want
9055 Squid to perform these checks turn this directive on.
9058 NAME: allow_underscore
9061 LOC: Config.onoff.allow_underscore
9063 Underscore characters is not strictly allowed in Internet hostnames
9064 but nevertheless used by many sites. Set this to off if you want
9065 Squid to be strict about the standard.
9066 This check is performed only when check_hostnames is set to on.
9069 NAME: dns_retransmit_interval
9072 LOC: Config.Timeout.idns_retransmit
9074 Initial retransmit interval for DNS queries. The interval is
9075 doubled each time all configured DNS servers have been tried.
9081 LOC: Config.Timeout.idns_query
9083 DNS Query timeout. If no response is received to a DNS query
9084 within this time all DNS servers for the queried domain
9085 are assumed to be unavailable.
9088 NAME: dns_packet_max
9090 DEFAULT_DOC: EDNS disabled
9092 LOC: Config.dns.packet_max
9094 Maximum number of bytes packet size to advertise via EDNS.
9095 Set to "none" to disable EDNS large packet support.
9097 For legacy reasons DNS UDP replies will default to 512 bytes which
9098 is too small for many responses. EDNS provides a means for Squid to
9099 negotiate receiving larger responses back immediately without having
9100 to failover with repeat requests. Responses larger than this limit
9101 will retain the old behaviour of failover to TCP DNS.
9103 Squid has no real fixed limit internally, but allowing packet sizes
9104 over 1500 bytes requires network jumbogram support and is usually not
9107 WARNING: The RFC also indicates that some older resolvers will reply
9108 with failure of the whole request if the extension is added. Some
9109 resolvers have already been identified which will reply with mangled
9110 EDNS response on occasion. Usually in response to many-KB jumbogram
9111 sizes being advertised by Squid.
9112 Squid will currently treat these both as an unable-to-resolve domain
9113 even if it would be resolvable without EDNS.
9120 DEFAULT_DOC: Search for single-label domain names is disabled.
9121 LOC: Config.onoff.res_defnames
9123 Normally the RES_DEFNAMES resolver option is disabled
9124 (see res_init(3)). This prevents caches in a hierarchy
9125 from interpreting single-component hostnames locally. To allow
9126 Squid to handle single-component names, enable this option.
9129 NAME: dns_multicast_local
9133 DEFAULT_DOC: Search for .local and .arpa names is disabled.
9134 LOC: Config.onoff.dns_mdns
9136 When set to on, Squid sends multicast DNS lookups on the local
9137 network for domains ending in .local and .arpa.
9138 This enables local servers and devices to be contacted in an
9139 ad-hoc or zero-configuration network environment.
9142 NAME: dns_nameservers
9145 DEFAULT_DOC: Use operating system definitions
9146 LOC: Config.dns_nameservers
9148 Use this if you want to specify a list of DNS name servers
9149 (IP addresses) to use instead of those given in your
9150 /etc/resolv.conf file.
9152 On Windows platforms, if no value is specified here or in
9153 the /etc/resolv.conf file, the list of DNS name servers are
9154 taken from the Windows registry, both static and dynamic DHCP
9155 configurations are supported.
9157 Example: dns_nameservers 10.0.0.1 192.172.0.4
9162 DEFAULT: @DEFAULT_HOSTS@
9163 LOC: Config.etcHostsPath
9165 Location of the host-local IP name-address associations
9166 database. Most Operating Systems have such a file on different
9168 - Un*X & Linux: /etc/hosts
9169 - Windows NT/2000: %SystemRoot%\system32\drivers\etc\hosts
9170 (%SystemRoot% value install default is c:\winnt)
9171 - Windows XP/2003: %SystemRoot%\system32\drivers\etc\hosts
9172 (%SystemRoot% value install default is c:\windows)
9173 - Windows 9x/Me: %windir%\hosts
9174 (%windir% value is usually c:\windows)
9175 - Cygwin: /etc/hosts
9177 The file contains newline-separated definitions, in the
9178 form ip_address_in_dotted_form name [name ...] names are
9179 whitespace-separated. Lines beginning with an hash (#)
9180 character are comments.
9182 The file is checked at startup and upon configuration.
9183 If set to 'none', it won't be checked.
9184 If append_domain is used, that domain will be added to
9185 domain-local (i.e. not containing any dot character) host
9191 LOC: Config.appendDomain
9193 DEFAULT_DOC: Use operating system definitions
9195 Appends local domain name to hostnames without any dots in
9196 them. append_domain must begin with a period.
9198 Be warned there are now Internet names with no dots in
9199 them using only top-domain names, so setting this may
9200 cause some Internet sites to become unavailable.
9203 append_domain .yourdomain.com
9206 NAME: ignore_unknown_nameservers
9208 LOC: Config.onoff.ignore_unknown_nameservers
9211 By default Squid checks that DNS responses are received
9212 from the same IP addresses they are sent to. If they
9213 don't match, Squid ignores the response and writes a warning
9214 message to cache.log. You can allow responses from unknown
9215 nameservers by setting this option to 'off'.
9221 LOC: Config.dns.v4_first
9223 With the IPv6 Internet being as fast or faster than IPv4 Internet
9224 for most networks Squid prefers to contact websites over IPv6.
9226 This option reverses the order of preference to make Squid contact
9227 dual-stack websites over IPv4 first. Squid will still perform both
9228 IPv6 and IPv4 DNS lookups before connecting.
9231 This option will restrict the situations under which IPv6
9232 connectivity is used (and tested). Hiding network problems
9233 which would otherwise be detected and warned about.
9237 COMMENT: (number of entries)
9240 LOC: Config.ipcache.size
9242 Maximum number of DNS IP cache entries.
9249 LOC: Config.ipcache.low
9256 LOC: Config.ipcache.high
9258 The size, low-, and high-water marks for the IP cache.
9261 NAME: fqdncache_size
9262 COMMENT: (number of entries)
9265 LOC: Config.fqdncache.size
9267 Maximum number of FQDN cache entries.
9272 -----------------------------------------------------------------------------
9275 NAME: configuration_includes_quoted_values
9277 TYPE: configuration_includes_quoted_values
9279 LOC: ConfigParser::RecognizeQuotedValues
9281 If set, Squid will recognize each "quoted string" after a configuration
9282 directive as a single parameter. The quotes are stripped before the
9283 parameter value is interpreted or used.
9284 See "Values with spaces, quotes, and other special characters"
9285 section for more details.
9292 LOC: Config.onoff.mem_pools
9294 If set, Squid will keep pools of allocated (but unused) memory
9295 available for future use. If memory is a premium on your
9296 system and you believe your malloc library outperforms Squid
9297 routines, disable this.
9300 NAME: memory_pools_limit
9304 LOC: Config.MemPools.limit
9306 Used only with memory_pools on:
9307 memory_pools_limit 50 MB
9309 If set to a non-zero value, Squid will keep at most the specified
9310 limit of allocated (but unused) memory in memory pools. All free()
9311 requests that exceed this limit will be handled by your malloc
9312 library. Squid does not pre-allocate any memory, just safe-keeps
9313 objects that otherwise would be free()d. Thus, it is safe to set
9314 memory_pools_limit to a reasonably high value even if your
9315 configuration will use less memory.
9317 If set to none, Squid will keep all memory it can. That is, there
9318 will be no limit on the total amount of memory used for safe-keeping.
9320 To disable memory allocation optimization, do not set
9321 memory_pools_limit to 0 or none. Set memory_pools to "off" instead.
9323 An overhead for maintaining memory pools is not taken into account
9324 when the limit is checked. This overhead is close to four bytes per
9325 object kept. However, pools may actually _save_ memory because of
9326 reduced memory thrashing in your malloc library.
9330 COMMENT: on|off|transparent|truncate|delete
9333 LOC: opt_forwarded_for
9335 If set to "on", Squid will append your client's IP address
9336 in the HTTP requests it forwards. By default it looks like:
9338 X-Forwarded-For: 192.1.2.3
9340 If set to "off", it will appear as
9342 X-Forwarded-For: unknown
9344 If set to "transparent", Squid will not alter the
9345 X-Forwarded-For header in any way.
9347 If set to "delete", Squid will delete the entire
9348 X-Forwarded-For header.
9350 If set to "truncate", Squid will remove all existing
9351 X-Forwarded-For entries, and place the client IP as the sole entry.
9354 NAME: cachemgr_passwd
9355 TYPE: cachemgrpasswd
9357 DEFAULT_DOC: No password. Actions which require password are denied.
9358 LOC: Config.passwd_list
9360 Specify passwords for cachemgr operations.
9362 Usage: cachemgr_passwd password action action ...
9364 Some valid actions are (see cache manager menu for a full list):
9404 * Indicates actions which will not be performed without a
9405 valid password, others can be performed if not listed here.
9407 To disable an action, set the password to "disable".
9408 To allow performing an action without a password, set the
9411 Use the keyword "all" to set the same password for all actions.
9414 cachemgr_passwd secret shutdown
9415 cachemgr_passwd lesssssssecret info stats/objects
9416 cachemgr_passwd disable all
9423 LOC: Config.onoff.client_db
9425 If you want to disable collecting per-client statistics,
9426 turn off client_db here.
9429 NAME: refresh_all_ims
9433 LOC: Config.onoff.refresh_all_ims
9435 When you enable this option, squid will always check
9436 the origin server for an update when a client sends an
9437 If-Modified-Since request. Many browsers use IMS
9438 requests when the user requests a reload, and this
9439 ensures those clients receive the latest version.
9441 By default (off), squid may return a Not Modified response
9442 based on the age of the cached version.
9445 NAME: reload_into_ims
9446 IFDEF: USE_HTTP_VIOLATIONS
9450 LOC: Config.onoff.reload_into_ims
9452 When you enable this option, client no-cache or ``reload''
9453 requests will be changed to If-Modified-Since requests.
9454 Doing this VIOLATES the HTTP standard. Enabling this
9455 feature could make you liable for problems which it
9458 see also refresh_pattern for a more selective approach.
9461 NAME: connect_retries
9463 LOC: Config.connect_retries
9465 DEFAULT_DOC: Do not retry failed connections.
9467 This sets the maximum number of connection attempts made for each
9468 TCP connection. The connect_retries attempts must all still
9469 complete within the connection timeout period.
9471 The default is not to re-try if the first connection attempt fails.
9472 The (not recommended) maximum is 10 tries.
9474 A warning message will be generated if it is set to a too-high
9475 value and the configured value will be over-ridden.
9477 Note: These re-tries are in addition to forward_max_tries
9478 which limit how many different addresses may be tried to find
9482 NAME: retry_on_error
9484 LOC: Config.retry.onerror
9487 If set to ON Squid will automatically retry requests when
9488 receiving an error response with status 403 (Forbidden),
9489 500 (Internal Error), 501 or 503 (Service not available).
9490 Status 502 and 504 (Gateway errors) are always retried.
9492 This is mainly useful if you are in a complex cache hierarchy to
9493 work around access control errors.
9495 NOTE: This retry will attempt to find another working destination.
9496 Which is different from the server which just failed.
9499 NAME: as_whois_server
9501 LOC: Config.as_whois_server
9502 DEFAULT: whois.ra.net
9504 WHOIS server to query for AS numbers. NOTE: AS numbers are
9505 queried only when Squid starts up, not for every request.
9510 LOC: Config.onoff.offline
9513 Enable this option and Squid will never try to validate cached
9517 NAME: uri_whitespace
9518 TYPE: uri_whitespace
9519 LOC: Config.uri_whitespace
9522 What to do with requests that have whitespace characters in the
9525 strip: The whitespace characters are stripped out of the URL.
9526 This is the behavior recommended by RFC2396 and RFC3986
9527 for tolerant handling of generic URI.
9528 NOTE: This is one difference between generic URI and HTTP URLs.
9530 deny: The request is denied. The user receives an "Invalid
9532 This is the behaviour recommended by RFC2616 for safe
9533 handling of HTTP request URL.
9535 allow: The request is allowed and the URI is not changed. The
9536 whitespace characters remain in the URI. Note the
9537 whitespace is passed to redirector processes if they
9539 Note this may be considered a violation of RFC2616
9540 request parsing where whitespace is prohibited in the
9543 encode: The request is allowed and the whitespace characters are
9544 encoded according to RFC1738.
9546 chop: The request is allowed and the URI is chopped at the
9550 NOTE the current Squid implementation of encode and chop violates
9551 RFC2616 by not using a 301 redirect after altering the URL.
9556 LOC: Config.chroot_dir
9559 Specifies a directory where Squid should do a chroot() while
9560 initializing. This also causes Squid to fully drop root
9561 privileges after initializing. This means, for example, if you
9562 use a HTTP port less than 1024 and try to reconfigure, you may
9563 get an error saying that Squid can not open the port.
9566 NAME: balance_on_multiple_ip
9568 LOC: Config.onoff.balance_on_multiple_ip
9571 Modern IP resolvers in squid sort lookup results by preferred access.
9572 By default squid will use these IP in order and only rotates to
9573 the next listed when the most preffered fails.
9575 Some load balancing servers based on round robin DNS have been
9576 found not to preserve user session state across requests
9577 to different IP addresses.
9579 Enabling this directive Squid rotates IP's per request.
9582 NAME: pipeline_prefetch
9583 TYPE: pipelinePrefetch
9584 LOC: Config.pipeline_max_prefetch
9586 DEFAULT_DOC: Do not pre-parse pipelined requests.
9588 HTTP clients may send a pipeline of 1+N requests to Squid using a
9589 single connection, without waiting for Squid to respond to the first
9590 of those requests. This option limits the number of concurrent
9591 requests Squid will try to handle in parallel. If set to N, Squid
9592 will try to receive and process up to 1+N requests on the same
9593 connection concurrently.
9595 Defaults to 0 (off) for bandwidth management and access logging
9598 NOTE: pipelining requires persistent connections to clients.
9600 WARNING: pipelining breaks NTLM and Negotiate/Kerberos authentication.
9603 NAME: high_response_time_warning
9606 LOC: Config.warnings.high_rptm
9608 DEFAULT_DOC: disabled.
9610 If the one-minute median response time exceeds this value,
9611 Squid prints a WARNING with debug level 0 to get the
9612 administrators attention. The value is in milliseconds.
9615 NAME: high_page_fault_warning
9617 LOC: Config.warnings.high_pf
9619 DEFAULT_DOC: disabled.
9621 If the one-minute average page fault rate exceeds this
9622 value, Squid prints a WARNING with debug level 0 to get
9623 the administrators attention. The value is in page faults
9627 NAME: high_memory_warning
9629 LOC: Config.warnings.high_memory
9630 IFDEF: HAVE_MSTATS&&HAVE_GNUMALLOC_H
9632 DEFAULT_DOC: disabled.
9634 If the memory usage (as determined by gnumalloc, if available and used)
9635 exceeds this amount, Squid prints a WARNING with debug level 0 to get
9636 the administrators attention.
9638 # TODO: link high_memory_warning to mempools?
9640 NAME: sleep_after_fork
9641 COMMENT: (microseconds)
9643 LOC: Config.sleep_after_fork
9646 When this is set to a non-zero value, the main Squid process
9647 sleeps the specified number of microseconds after a fork()
9648 system call. This sleep may help the situation where your
9649 system reports fork() failures due to lack of (virtual)
9650 memory. Note, however, if you have a lot of child
9651 processes, these sleep delays will add up and your
9652 Squid will not service requests for some amount of time
9653 until all the child processes have been started.
9654 On Windows value less then 1000 (1 milliseconds) are
9658 NAME: windows_ipaddrchangemonitor
9659 IFDEF: _SQUID_WINDOWS_
9663 LOC: Config.onoff.WIN32_IpAddrChangeMonitor
9665 On Windows Squid by default will monitor IP address changes and will
9666 reconfigure itself after any detected event. This is very useful for
9667 proxies connected to internet with dial-up interfaces.
9668 In some cases (a Proxy server acting as VPN gateway is one) it could be
9669 desiderable to disable this behaviour setting this to 'off'.
9670 Note: after changing this, Squid service must be restarted.
9675 IFDEF: USE_SQUID_EUI
9677 LOC: Eui::TheConfig.euiLookup
9679 Whether to lookup the EUI or MAC address of a connected client.
9682 NAME: max_filedescriptors max_filedesc
9685 DEFAULT_DOC: Use operating system limits set by ulimit.
9686 LOC: Config.max_filedescriptors
9688 Reduce the maximum number of filedescriptors supported below
9689 the usual operating system defaults.
9691 Remove from squid.conf to inherit the current ulimit setting.
9693 Note: Changing this requires a restart of Squid. Also
9694 not all I/O types supports large values (eg on Windows).
9697 NAME: force_request_body_continuation
9699 LOC: Config.accessList.forceRequestBodyContinuation
9701 DEFAULT_DOC: Deny, unless rules exist in squid.conf.
9703 This option controls how Squid handles data upload requests from HTTP
9704 and FTP agents that require a "Please Continue" control message response
9705 to actually send the request body to Squid. It is mostly useful in
9706 adaptation environments.
9708 When Squid receives an HTTP request with an "Expect: 100-continue"
9709 header or an FTP upload command (e.g., STOR), Squid normally sends the
9710 request headers or FTP command information to an adaptation service (or
9711 peer) and waits for a response. Most adaptation services (and some
9712 broken peers) may not respond to Squid at that stage because they may
9713 decide to wait for the HTTP request body or FTP data transfer. However,
9714 that request body or data transfer may never come because Squid has not
9715 responded with the HTTP 100 or FTP 150 (Please Continue) control message
9716 to the request sender yet!
9718 An allow match tells Squid to respond with the HTTP 100 or FTP 150
9719 (Please Continue) control message on its own, before forwarding the
9720 request to an adaptation service or peer. Such a response usually forces
9721 the request sender to proceed with sending the body. A deny match tells
9722 Squid to delay that control response until the origin server confirms
9723 that the request body is needed. Delaying is the default behavior.
9726 NAME: server_pconn_for_nonretriable
9729 DEFAULT_DOC: Open new connections for forwarding requests Squid cannot retry safely.
9730 LOC: Config.accessList.serverPconnForNonretriable
9732 This option provides fine-grained control over persistent connection
9733 reuse when forwarding HTTP requests that Squid cannot retry. It is useful
9734 in environments where opening new connections is very expensive
9735 (e.g., all connections are secured with TLS with complex client and server
9736 certificate validation) and race conditions associated with persistent
9737 connections are very rare and/or only cause minor problems.
9739 HTTP prohibits retrying unsafe and non-idempotent requests (e.g., POST).
9740 Squid limitations also prohibit retrying all requests with bodies (e.g., PUT).
9741 By default, when forwarding such "risky" requests, Squid opens a new
9742 connection to the server or cache_peer, even if there is an idle persistent
9743 connection available. When Squid is configured to risk sending a non-retriable
9744 request on a previously used persistent connection, and the server closes
9745 the connection before seeing that risky request, the user gets an error response
9746 from Squid. In most cases, that error response will be HTTP 502 (Bad Gateway)
9747 with ERR_ZERO_SIZE_OBJECT or ERR_WRITE_ERROR (peer connection reset) error detail.
9749 If an allow rule matches, Squid reuses an available idle persistent connection
9750 (if any) for the request that Squid cannot retry. If a deny rule matches, then
9751 Squid opens a new connection for the request that Squid cannot retry.
9753 This option does not affect requests that Squid can retry. They will reuse idle
9754 persistent connections (if any).
9756 This clause only supports fast acl types.
9757 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
9760 acl SpeedIsWorthTheRisk method POST
9761 server_pconn_for_nonretriable allow SpeedIsWorthTheRisk
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