2 # SQUID Web Proxy Cache http://www.squid-cache.org/
3 # ----------------------------------------------------------
5 # Squid is the result of efforts by numerous individuals from
6 # the Internet community; see the CONTRIBUTORS file for full
7 # details. Many organizations have provided support for Squid's
8 # development; see the SPONSORS file for full details. Squid is
9 # Copyrighted (C) 2000 by the Regents of the University of
10 # California; see the COPYRIGHT file for full details. Squid
11 # incorporates software developed and/or copyrighted by other
12 # sources; see the CREDITS file for full details.
14 # This program is free software; you can redistribute it and/or modify
15 # it under the terms of the GNU General Public License as published by
16 # the Free Software Foundation; either version 2 of the License, or
17 # (at your option) any later version.
19 # This program is distributed in the hope that it will be useful,
20 # but WITHOUT ANY WARRANTY; without even the implied warranty of
21 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
22 # GNU General Public License for more details.
24 # You should have received a copy of the GNU General Public License
25 # along with this program; if not, write to the Free Software
26 # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, USA.
31 ----------------------------
33 This is the documentation for the Squid configuration file.
34 This documentation can also be found online at:
35 http://www.squid-cache.org/Doc/config/
37 You may wish to look at the Squid home page and wiki for the
38 FAQ and other documentation:
39 http://www.squid-cache.org/
40 http://wiki.squid-cache.org/SquidFaq
41 http://wiki.squid-cache.org/ConfigExamples
43 This documentation shows what the defaults for various directives
44 happen to be. If you don't need to change the default, you should
45 leave the line out of your squid.conf in most cases.
47 In some cases "none" refers to no default setting at all,
48 while in other cases it refers to the value of the option
49 - the comments for that keyword indicate if this is the case.
54 Configuration options can be included using the "include" directive.
55 Include takes a list of files to include. Quoting and wildcards are
60 include /path/to/included/file/squid.acl.config
62 Includes can be nested up to a hard-coded depth of 16 levels.
63 This arbitrary restriction is to prevent recursive include references
64 from causing Squid entering an infinite loop whilst trying to load
67 Values with byte units
69 Squid accepts size units on some size related directives. All
70 such directives are documented with a default value displaying
73 Units accepted by Squid are:
75 KB - Kilobyte (1024 bytes)
79 Values with spaces, quotes, and other special characters
81 Squid supports directive parameters with spaces, quotes, and other
82 special characters. Surround such parameters with "double quotes". Use
83 the configuration_includes_quoted_values directive to enable or
86 Squid supports reading configuration option parameters from external
87 files using the syntax:
88 parameters("/path/filename")
90 acl whitelist dstdomain parameters("/etc/squid/whitelist.txt")
92 Conditional configuration
94 If-statements can be used to make configuration directives
98 ... regular configuration directives ...
100 ... regular configuration directives ...]
103 The else part is optional. The keywords "if", "else", and "endif"
104 must be typed on their own lines, as if they were regular
105 configuration directives.
107 NOTE: An else-if condition is not supported.
109 These individual conditions types are supported:
112 Always evaluates to true.
114 Always evaluates to false.
115 <integer> = <integer>
116 Equality comparison of two integer numbers.
121 The following SMP-related preprocessor macros can be used.
123 ${process_name} expands to the current Squid process "name"
124 (e.g., squid1, squid2, or cache1).
126 ${process_number} expands to the current Squid process
127 identifier, which is an integer number (e.g., 1, 2, 3) unique
128 across all Squid processes of the current service instance.
130 ${service_name} expands into the current Squid service instance
131 name identifier which is provided by -n on the command line.
135 # options still not yet ported from 2.7 to 3.x
136 NAME: broken_vary_encoding
139 This option is not yet supported by Squid-3.
145 This option is not yet supported by Squid-3.
151 This option is not yet supported by Squid-3.
154 NAME: external_refresh_check
157 This option is not yet supported by Squid-3.
160 NAME: location_rewrite_program location_rewrite_access location_rewrite_children location_rewrite_concurrency
163 This option is not yet supported by Squid-3.
166 NAME: refresh_stale_hit
169 This option is not yet supported by Squid-3.
172 # Options Removed in 3.3
173 NAME: ignore_ims_on_miss
176 Remove this line. The HTTP/1.1 feature is now fully supported by default.
179 # Options Removed in 3.2
180 NAME: ignore_expect_100
183 Remove this line. The HTTP/1.1 feature is now fully supported by default.
186 NAME: dns_v4_fallback
189 Remove this line. Squid performs a 'Happy Eyeballs' algorithm, the 'fallback' algorithm is no longer relevant.
195 Remove this line. Configure FTP page display using the CSS controls in errorpages.css instead.
198 NAME: maximum_single_addr_tries
201 Replaced by connect_retries. The behaviour has changed, please read the documentation before altering.
207 Remove this line. The feature is supported by default in storage types where update is implemented.
210 NAME: url_rewrite_concurrency
213 Remove this line. Set the 'concurrency=' option of url_rewrite_children instead.
216 # Options Removed in 3.1
220 Remove this line. DNS is no longer tested on startup.
223 NAME: extension_methods
226 Remove this line. All valid methods for HTTP are accepted by default.
229 # 2.7 Options Removed/Replaced in 3.2
234 # 2.7 Options Removed/Replaced in 3.1
242 Remove this line. HTTP/1.1 is supported by default.
245 NAME: upgrade_http0.9
248 Remove this line. ICY/1.0 streaming protocol is supported by default.
251 NAME: zph_local zph_mode zph_option zph_parent zph_sibling
254 Alter these entries. Use the qos_flows directive instead.
257 # Options Removed in 3.0
261 Since squid-3.0 replace with request_header_access or reply_header_access
262 depending on whether you wish to match client requests or server replies.
265 NAME: httpd_accel_no_pmtu_disc
268 Since squid-3.0 use the 'disable-pmtu-discovery' flag on http_port instead.
271 NAME: wais_relay_host
274 Replace this line with 'cache_peer' configuration.
277 NAME: wais_relay_port
280 Replace this line with 'cache_peer' configuration.
284 OPTIONS FOR AUTHENTICATION
285 -----------------------------------------------------------------------------
294 This is used to define parameters for the various authentication
295 schemes supported by Squid.
297 format: auth_param scheme parameter [setting]
299 The order in which authentication schemes are presented to the client is
300 dependent on the order the scheme first appears in config file. IE
301 has a bug (it's not RFC 2617 compliant) in that it will use the basic
302 scheme if basic is the first entry presented, even if more secure
303 schemes are presented. For now use the order in the recommended
304 settings section below. If other browsers have difficulties (don't
305 recognize the schemes offered even if you are using basic) either
306 put basic first, or disable the other schemes (by commenting out their
309 Once an authentication scheme is fully configured, it can only be
310 shutdown by shutting squid down and restarting. Changes can be made on
311 the fly and activated with a reconfigure. I.E. You can change to a
312 different helper, but not unconfigure the helper completely.
314 Please note that while this directive defines how Squid processes
315 authentication it does not automatically activate authentication.
316 To use authentication you must in addition make use of ACLs based
317 on login name in http_access (proxy_auth, proxy_auth_regex or
318 external with %LOGIN used in the format tag). The browser will be
319 challenged for authentication on the first such acl encountered
320 in http_access processing and will also be re-challenged for new
321 login credentials if the request is being denied by a proxy_auth
324 WARNING: authentication can't be used in a transparently intercepting
325 proxy as the client then thinks it is talking to an origin server and
326 not the proxy. This is a limitation of bending the TCP/IP protocol to
327 transparently intercepting port 80, not a limitation in Squid.
328 Ports flagged 'transparent', 'intercept', or 'tproxy' have
329 authentication disabled.
331 === Parameters common to all schemes. ===
334 Specifies the command for the external authenticator.
336 By default, each authentication scheme is not used unless a
337 program is specified.
339 See http://wiki.squid-cache.org/Features/AddonHelpers for
340 more details on helper operations and creating your own.
343 Specifies a string to be append to request line format for
344 the authentication helper. "Quoted" format values may contain
345 spaces and logformat %macros. In theory, any logformat %macro
346 can be used. In practice, a %macro expands as a dash (-) if
347 the helper request is sent before the required macro
348 information is available to Squid.
350 By default, Squid uses request formats provided in
351 scheme-specific examples below (search for %credentials).
353 The expanded key_extras value is added to the Squid credentials
354 cache and, hence, will affect authentication. It can be used to
355 autenticate different users with identical user names (e.g.,
356 when user authentication depends on http_port).
358 Avoid adding frequently changing information to key_extras. For
359 example, if you add user source IP, and it changes frequently
360 in your environment, then max_user_ip ACL is going to treat
361 every user+IP combination as a unique "user", breaking the ACL
362 and wasting a lot of memory on those user records. It will also
363 force users to authenticate from scratch whenever their IP
367 Specifies the protection scope (aka realm name) which is to be
368 reported to the client for the authentication scheme. It is
369 commonly part of the text the user will see when prompted for
370 their username and password.
372 For Basic the default is "Squid proxy-caching web server".
373 For Digest there is no default, this parameter is mandatory.
374 For NTLM and Negotiate this parameter is ignored.
376 "children" numberofchildren [startup=N] [idle=N] [concurrency=N]
378 The maximum number of authenticator processes to spawn. If
379 you start too few Squid will have to wait for them to process
380 a backlog of credential verifications, slowing it down. When
381 password verifications are done via a (slow) network you are
382 likely to need lots of authenticator processes.
384 The startup= and idle= options permit some skew in the exact
385 amount run. A minimum of startup=N will begin during startup
386 and reconfigure. Squid will start more in groups of up to
387 idle=N in an attempt to meet traffic needs and to keep idle=N
388 free above those traffic needs up to the maximum.
390 The concurrency= option sets the number of concurrent requests
391 the helper can process. The default of 0 is used for helpers
392 who only supports one request at a time. Setting this to a
393 number greater than 0 changes the protocol used to include a
394 channel ID field first on the request/response line, allowing
395 multiple requests to be sent to the same helper in parallel
396 without waiting for the response.
398 Concurrency must not be set unless it's known the helper
399 supports the input format with channel-ID fields.
401 NOTE: NTLM and Negotiate schemes do not support concurrency
402 in the Squid code module even though some helpers can.
405 IF HAVE_AUTH_MODULE_BASIC
406 === Basic authentication parameters ===
409 HTTP uses iso-latin-1 as character set, while some
410 authentication backends such as LDAP expects UTF-8. If this is
411 set to on Squid will translate the HTTP iso-latin-1 charset to
412 UTF-8 before sending the username and password to the helper.
414 "credentialsttl" timetolive
415 Specifies how long squid assumes an externally validated
416 username:password pair is valid for - in other words how
417 often the helper program is called for that user. Set this
418 low to force revalidation with short lived passwords.
420 NOTE: setting this high does not impact your susceptibility
421 to replay attacks unless you are using an one-time password
422 system (such as SecureID). If you are using such a system,
423 you will be vulnerable to replay attacks unless you also
424 use the max_user_ip ACL in an http_access rule.
426 "casesensitive" on|off
427 Specifies if usernames are case sensitive. Most user databases
428 are case insensitive allowing the same username to be spelled
429 using both lower and upper case letters, but some are case
430 sensitive. This makes a big difference for user_max_ip ACL
431 processing and similar.
434 IF HAVE_AUTH_MODULE_DIGEST
435 === Digest authentication parameters ===
438 HTTP uses iso-latin-1 as character set, while some
439 authentication backends such as LDAP expects UTF-8. If this is
440 set to on Squid will translate the HTTP iso-latin-1 charset to
441 UTF-8 before sending the username and password to the helper.
443 "nonce_garbage_interval" timeinterval
444 Specifies the interval that nonces that have been issued
445 to client_agent's are checked for validity.
447 "nonce_max_duration" timeinterval
448 Specifies the maximum length of time a given nonce will be
451 "nonce_max_count" number
452 Specifies the maximum number of times a given nonce can be
455 "nonce_strictness" on|off
456 Determines if squid requires strict increment-by-1 behavior
457 for nonce counts, or just incrementing (off - for use when
458 user agents generate nonce counts that occasionally miss 1
459 (ie, 1,2,4,6)). Default off.
461 "check_nonce_count" on|off
462 This directive if set to off can disable the nonce count check
463 completely to work around buggy digest qop implementations in
464 certain mainstream browser versions. Default on to check the
465 nonce count to protect from authentication replay attacks.
467 "post_workaround" on|off
468 This is a workaround to certain buggy browsers who send an
469 incorrect request digest in POST requests when reusing the
470 same nonce as acquired earlier on a GET request.
473 IF HAVE_AUTH_MODULE_NEGOTIATE
474 === Negotiate authentication parameters ===
477 If you experience problems with PUT/POST requests when using
478 the this authentication scheme then you can try setting this
479 to off. This will cause Squid to forcibly close the connection
480 on the initial request where the browser asks which schemes
481 are supported by the proxy.
484 IF HAVE_AUTH_MODULE_NTLM
485 === NTLM authentication parameters ===
488 If you experience problems with PUT/POST requests when using
489 the this authentication scheme then you can try setting this
490 to off. This will cause Squid to forcibly close the connection
491 on the initial request where the browser asks which schemes
492 are supported by the proxy.
495 === Example Configuration ===
497 This configuration displays the recommended authentication scheme
498 order from most to least secure with recommended minimum configuration
499 settings for each scheme:
501 #auth_param negotiate program <uncomment and complete this line to activate>
502 #auth_param negotiate children 20 startup=0 idle=1
503 #auth_param negotiate keep_alive on
505 #auth_param digest program <uncomment and complete this line to activate>
506 #auth_param digest children 20 startup=0 idle=1
507 #auth_param digest realm Squid proxy-caching web server
508 #auth_param digest nonce_garbage_interval 5 minutes
509 #auth_param digest nonce_max_duration 30 minutes
510 #auth_param digest nonce_max_count 50
512 #auth_param ntlm program <uncomment and complete this line to activate>
513 #auth_param ntlm children 20 startup=0 idle=1
514 #auth_param ntlm keep_alive on
516 #auth_param basic program <uncomment and complete this line>
517 #auth_param basic children 5 startup=5 idle=1
518 #auth_param basic realm Squid proxy-caching web server
519 #auth_param basic credentialsttl 2 hours
522 NAME: authenticate_cache_garbage_interval
525 LOC: Config.authenticateGCInterval
527 The time period between garbage collection across the username cache.
528 This is a trade-off between memory utilization (long intervals - say
529 2 days) and CPU (short intervals - say 1 minute). Only change if you
533 NAME: authenticate_ttl
536 LOC: Config.authenticateTTL
538 The time a user & their credentials stay in the logged in
539 user cache since their last request. When the garbage
540 interval passes, all user credentials that have passed their
541 TTL are removed from memory.
544 NAME: authenticate_ip_ttl
546 LOC: Config.authenticateIpTTL
549 If you use proxy authentication and the 'max_user_ip' ACL,
550 this directive controls how long Squid remembers the IP
551 addresses associated with each user. Use a small value
552 (e.g., 60 seconds) if your users might change addresses
553 quickly, as is the case with dialup. You might be safe
554 using a larger value (e.g., 2 hours) in a corporate LAN
555 environment with relatively static address assignments.
560 -----------------------------------------------------------------------------
563 NAME: external_acl_type
564 TYPE: externalAclHelper
565 LOC: Config.externalAclHelperList
568 This option defines external acl classes using a helper program
569 to look up the status
571 external_acl_type name [options] FORMAT.. /path/to/helper [helper arguments..]
575 ttl=n TTL in seconds for cached results (defaults to 3600
578 TTL for cached negative lookups (default same
581 Maximum number of acl helper processes spawned to service
582 external acl lookups of this type. (default 20)
584 Minimum number of acl helper processes to spawn during
585 startup and reconfigure to service external acl lookups
586 of this type. (default 0)
588 Number of acl helper processes to keep ahead of traffic
589 loads. Squid will spawn this many at once whenever load
590 rises above the capabilities of existing processes.
591 Up to the value of children-max. (default 1)
592 concurrency=n concurrency level per process. Only used with helpers
593 capable of processing more than one query at a time.
594 cache=n limit the result cache size, default is 262144.
595 grace=n Percentage remaining of TTL where a refresh of a
596 cached entry should be initiated without needing to
597 wait for a new reply. (default is for no grace period)
598 protocol=2.5 Compatibility mode for Squid-2.5 external acl helpers
599 ipv4 / ipv6 IP protocol used to communicate with this helper.
600 The default is to auto-detect IPv6 and use it when available.
602 FORMAT specifications
604 %LOGIN Authenticated user login name
605 %EXT_USER Username from previous external acl
606 %EXT_LOG Log details from previous external acl
607 %EXT_TAG Tag from previous external acl
608 %IDENT Ident user name
610 %SRCPORT Client source port
613 %PROTO Requested URL scheme
615 %PATH Requested URL path
616 %METHOD Request method
617 %MYADDR Squid interface address
618 %MYPORT Squid http_port number
619 %PATH Requested URL-path (including query-string if any)
620 %USER_CERT SSL User certificate in PEM format
621 %USER_CERTCHAIN SSL User certificate chain in PEM format
622 %USER_CERT_xx SSL User certificate subject attribute xx
623 %USER_CA_xx SSL User certificate issuer attribute xx
625 %>{Header} HTTP request header "Header"
627 HTTP request header "Hdr" list member "member"
629 HTTP request header list member using ; as
630 list separator. ; can be any non-alphanumeric
633 %<{Header} HTTP reply header "Header"
635 HTTP reply header "Hdr" list member "member"
637 HTTP reply header list member using ; as
638 list separator. ; can be any non-alphanumeric
641 %ACL The name of the ACL being tested.
642 %DATA The ACL arguments. If not used then any arguments
643 is automatically added at the end of the line
645 NOTE: this will encode the arguments as one token,
646 whereas the default will pass each separately.
648 %% The percent sign. Useful for helpers which need
649 an unchanging input format.
652 General request syntax:
654 [channel-ID] FORMAT-values [acl-values ...]
657 FORMAT-values consists of transaction details expanded with
658 whitespace separation per the config file FORMAT specification
659 using the FORMAT macros listed above.
661 acl-values consists of any string specified in the referencing
662 config 'acl ... external' line. see the "acl external" directive.
664 Request values sent to the helper are URL escaped to protect
665 each value in requests against whitespaces.
667 If using protocol=2.5 then the request sent to the helper is not
668 URL escaped to protect against whitespace.
670 NOTE: protocol=3.0 is deprecated as no longer necessary.
672 When using the concurrency= option the protocol is changed by
673 introducing a query channel tag in front of the request/response.
674 The query channel tag is a number between 0 and concurrency-1.
675 This value must be echoed back unchanged to Squid as the first part
676 of the response relating to its request.
679 The helper receives lines expanded per the above format specification
680 and for each input line returns 1 line starting with OK/ERR/BH result
681 code and optionally followed by additional keywords with more details.
684 General result syntax:
686 [channel-ID] result keyword=value ...
688 Result consists of one of the codes:
691 the ACL test produced a match.
694 the ACL test does not produce a match.
697 An internal error occurred in the helper, preventing
698 a result being identified.
700 The meaning of 'a match' is determined by your squid.conf
701 access control configuration. See the Squid wiki for details.
705 user= The users name (login)
707 password= The users password (for login= cache_peer option)
709 message= Message describing the reason for this response.
710 Available as %o in error pages.
711 Useful on (ERR and BH results).
713 tag= Apply a tag to a request. Only sets a tag once,
714 does not alter existing tags.
716 log= String to be logged in access.log. Available as
717 %ea in logformat specifications.
719 Any keywords may be sent on any response whether OK, ERR or BH.
721 All response keyword values need to be a single token with URL
722 escaping, or enclosed in double quotes (") and escaped using \ on
723 any double quotes or \ characters within the value. The wrapping
724 double quotes are removed before the value is interpreted by Squid.
725 \r and \n are also replace by CR and LF.
727 Some example key values:
731 user="J. \"Bob\" Smith"
738 DEFAULT: ssl::certHasExpired ssl_error X509_V_ERR_CERT_HAS_EXPIRED
739 DEFAULT: ssl::certNotYetValid ssl_error X509_V_ERR_CERT_NOT_YET_VALID
740 DEFAULT: ssl::certDomainMismatch ssl_error SQUID_X509_V_ERR_DOMAIN_MISMATCH
741 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
742 DEFAULT: ssl::certSelfSigned ssl_error X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT
745 DEFAULT: manager url_regex -i ^cache_object:// +i ^https?://[^/]+/squid-internal-mgr/
746 DEFAULT: localhost src 127.0.0.1/32 ::1
747 DEFAULT: to_localhost dst 127.0.0.0/8 0.0.0.0/32 ::1
748 DEFAULT_DOC: ACLs all, manager, localhost, and to_localhost are predefined.
750 Defining an Access List
752 Every access list definition must begin with an aclname and acltype,
753 followed by either type-specific arguments or a quoted filename that
756 acl aclname acltype argument ...
757 acl aclname acltype "file" ...
759 When using "file", the file should contain one item per line.
761 Some acl types supports options which changes their default behaviour.
762 The available options are:
764 -i,+i By default, regular expressions are CASE-SENSITIVE. To make them
765 case-insensitive, use the -i option. To return case-sensitive
766 use the +i option between patterns, or make a new ACL line
769 -n Disable lookups and address type conversions. If lookup or
770 conversion is required because the parameter type (IP or
771 domain name) does not match the message address type (domain
772 name or IP), then the ACL would immediately declare a mismatch
773 without any warnings or lookups.
775 -- Used to stop processing all options, in the case the first acl
776 value has '-' character as first character (for example the '-'
777 is a valid domain name)
779 Some acl types require suspending the current request in order
780 to access some external data source.
781 Those which do are marked with the tag [slow], those which
782 don't are marked as [fast].
783 See http://wiki.squid-cache.org/SquidFaq/SquidAcl
784 for further information
786 ***** ACL TYPES AVAILABLE *****
788 acl aclname src ip-address/mask ... # clients IP address [fast]
789 acl aclname src addr1-addr2/mask ... # range of addresses [fast]
790 acl aclname dst [-n] ip-address/mask ... # URL host's IP address [slow]
791 acl aclname localip ip-address/mask ... # IP address the client connected to [fast]
793 acl aclname arp mac-address ... (xx:xx:xx:xx:xx:xx notation)
794 # The arp ACL requires the special configure option --enable-arp-acl.
795 # Furthermore, the ARP ACL code is not portable to all operating systems.
796 # It works on Linux, Solaris, Windows, FreeBSD, and some
797 # other *BSD variants.
800 # NOTE: Squid can only determine the MAC address for clients that are on
801 # the same subnet. If the client is on a different subnet,
802 # then Squid cannot find out its MAC address.
804 acl aclname srcdomain .foo.com ...
805 # reverse lookup, from client IP [slow]
806 acl aclname dstdomain [-n] .foo.com ...
807 # Destination server from URL [fast]
808 acl aclname srcdom_regex [-i] \.foo\.com ...
809 # regex matching client name [slow]
810 acl aclname dstdom_regex [-n] [-i] \.foo\.com ...
811 # regex matching server [fast]
813 # For dstdomain and dstdom_regex a reverse lookup is tried if a IP
814 # based URL is used and no match is found. The name "none" is used
815 # if the reverse lookup fails.
817 acl aclname src_as number ...
818 acl aclname dst_as number ...
820 # Except for access control, AS numbers can be used for
821 # routing of requests to specific caches. Here's an
822 # example for routing all requests for AS#1241 and only
823 # those to mycache.mydomain.net:
824 # acl asexample dst_as 1241
825 # cache_peer_access mycache.mydomain.net allow asexample
826 # cache_peer_access mycache_mydomain.net deny all
828 acl aclname peername myPeer ...
830 # match against a named cache_peer entry
831 # set unique name= on cache_peer lines for reliable use.
833 acl aclname time [day-abbrevs] [h1:m1-h2:m2]
843 # h1:m1 must be less than h2:m2
845 acl aclname url_regex [-i] ^http:// ...
846 # regex matching on whole URL [fast]
847 acl aclname urllogin [-i] [^a-zA-Z0-9] ...
848 # regex matching on URL login field
849 acl aclname urlpath_regex [-i] \.gif$ ...
850 # regex matching on URL path [fast]
852 acl aclname port 80 70 21 0-1024... # destination TCP port [fast]
854 acl aclname localport 3128 ... # TCP port the client connected to [fast]
855 # NP: for interception mode this is usually '80'
857 acl aclname myportname 3128 ... # http(s)_port name [fast]
859 acl aclname proto HTTP FTP ... # request protocol [fast]
861 acl aclname method GET POST ... # HTTP request method [fast]
863 acl aclname http_status 200 301 500- 400-403 ...
864 # status code in reply [fast]
866 acl aclname browser [-i] regexp ...
867 # pattern match on User-Agent header (see also req_header below) [fast]
869 acl aclname referer_regex [-i] regexp ...
870 # pattern match on Referer header [fast]
871 # Referer is highly unreliable, so use with care
873 acl aclname ident username ...
874 acl aclname ident_regex [-i] pattern ...
875 # string match on ident output [slow]
876 # use REQUIRED to accept any non-null ident.
878 acl aclname proxy_auth [-i] username ...
879 acl aclname proxy_auth_regex [-i] pattern ...
880 # perform http authentication challenge to the client and match against
881 # supplied credentials [slow]
883 # takes a list of allowed usernames.
884 # use REQUIRED to accept any valid username.
886 # Will use proxy authentication in forward-proxy scenarios, and plain
887 # http authenticaiton in reverse-proxy scenarios
889 # NOTE: when a Proxy-Authentication header is sent but it is not
890 # needed during ACL checking the username is NOT logged
893 # NOTE: proxy_auth requires a EXTERNAL authentication program
894 # to check username/password combinations (see
895 # auth_param directive).
897 # NOTE: proxy_auth can't be used in a transparent/intercepting proxy
898 # as the browser needs to be configured for using a proxy in order
899 # to respond to proxy authentication.
901 acl aclname snmp_community string ...
902 # A community string to limit access to your SNMP Agent [fast]
905 # acl snmppublic snmp_community public
907 acl aclname maxconn number
908 # This will be matched when the client's IP address has
909 # more than <number> TCP connections established. [fast]
910 # NOTE: This only measures direct TCP links so X-Forwarded-For
911 # indirect clients are not counted.
913 acl aclname max_user_ip [-s] number
914 # This will be matched when the user attempts to log in from more
915 # than <number> different ip addresses. The authenticate_ip_ttl
916 # parameter controls the timeout on the ip entries. [fast]
917 # If -s is specified the limit is strict, denying browsing
918 # from any further IP addresses until the ttl has expired. Without
919 # -s Squid will just annoy the user by "randomly" denying requests.
920 # (the counter is reset each time the limit is reached and a
922 # NOTE: in acceleration mode or where there is mesh of child proxies,
923 # clients may appear to come from multiple addresses if they are
924 # going through proxy farms, so a limit of 1 may cause user problems.
926 acl aclname random probability
927 # Pseudo-randomly match requests. Based on the probability given.
928 # Probability may be written as a decimal (0.333), fraction (1/3)
929 # or ratio of matches:non-matches (3:5).
931 acl aclname req_mime_type [-i] mime-type ...
932 # regex match against the mime type of the request generated
933 # by the client. Can be used to detect file upload or some
934 # types HTTP tunneling requests [fast]
935 # NOTE: This does NOT match the reply. You cannot use this
936 # to match the returned file type.
938 acl aclname req_header header-name [-i] any\.regex\.here
939 # regex match against any of the known request headers. May be
940 # thought of as a superset of "browser", "referer" and "mime-type"
943 acl aclname rep_mime_type [-i] mime-type ...
944 # regex match against the mime type of the reply received by
945 # squid. Can be used to detect file download or some
946 # types HTTP tunneling requests. [fast]
947 # NOTE: This has no effect in http_access rules. It only has
948 # effect in rules that affect the reply data stream such as
951 acl aclname rep_header header-name [-i] any\.regex\.here
952 # regex match against any of the known reply headers. May be
953 # thought of as a superset of "browser", "referer" and "mime-type"
956 acl aclname external class_name [arguments...]
957 # external ACL lookup via a helper class defined by the
958 # external_acl_type directive [slow]
960 acl aclname user_cert attribute values...
961 # match against attributes in a user SSL certificate
962 # attribute is one of DN/C/O/CN/L/ST [fast]
964 acl aclname ca_cert attribute values...
965 # match against attributes a users issuing CA SSL certificate
966 # attribute is one of DN/C/O/CN/L/ST [fast]
968 acl aclname ext_user username ...
969 acl aclname ext_user_regex [-i] pattern ...
970 # string match on username returned by external acl helper [slow]
971 # use REQUIRED to accept any non-null user name.
973 acl aclname tag tagvalue ...
974 # string match on tag returned by external acl helper [slow]
976 acl aclname hier_code codename ...
977 # string match against squid hierarchy code(s); [fast]
978 # e.g., DIRECT, PARENT_HIT, NONE, etc.
980 # NOTE: This has no effect in http_access rules. It only has
981 # effect in rules that affect the reply data stream such as
984 acl aclname note name [value ...]
985 # match transaction annotation [fast]
986 # Without values, matches any annotation with a given name.
987 # With value(s), matches any annotation with a given name that
988 # also has one of the given values.
989 # Names and values are compared using a string equality test.
990 # Annotation sources include note and adaptation_meta directives
991 # as well as helper and eCAP responses.
993 acl aclname adaptation_service service ...
994 # Matches the name of any icap_service, ecap_service,
995 # adaptation_service_set, or adaptation_service_chain that Squid
996 # has used (or attempted to use) for the master transaction.
997 # This ACL must be defined after the corresponding adaptation
998 # service is named in squid.conf. This ACL is usable with
999 # adaptation_meta because it starts matching immediately after
1000 # the service has been selected for adaptation.
1003 acl aclname ssl_error errorname
1004 # match against SSL certificate validation error [fast]
1006 # For valid error names see in @DEFAULT_ERROR_DIR@/templates/error-details.txt
1009 # The following can be used as shortcuts for certificate properties:
1010 # [ssl::]certHasExpired: the "not after" field is in the past
1011 # [ssl::]certNotYetValid: the "not before" field is in the future
1012 # [ssl::]certUntrusted: The certificate issuer is not to be trusted.
1013 # [ssl::]certSelfSigned: The certificate is self signed.
1014 # [ssl::]certDomainMismatch: The certificate CN domain does not
1015 # match the name the name of the host we are connecting to.
1017 # The ssl::certHasExpired, ssl::certNotYetValid, ssl::certDomainMismatch,
1018 # ssl::certUntrusted, and ssl::certSelfSigned can also be used as
1019 # predefined ACLs, just like the 'all' ACL.
1021 # NOTE: The ssl_error ACL is only supported with sslproxy_cert_error,
1022 # sslproxy_cert_sign, and sslproxy_cert_adapt options.
1024 acl aclname server_cert_fingerprint [-sha1] fingerprint
1025 # match against server SSL certificate fingerprint [fast]
1027 # The fingerprint is the digest of the DER encoded version
1028 # of the whole certificate. The user should use the form: XX:XX:...
1029 # Optional argument specifies the digest algorithm to use.
1030 # The SHA1 digest algorithm is the default and is currently
1031 # the only algorithm supported (-sha1).
1033 acl aclname any-of acl1 acl2 ...
1034 # match any one of the acls [fast or slow]
1035 # The first matching ACL stops further ACL evaluation.
1037 # ACLs from multiple any-of lines with the same name are ORed.
1038 # For example, A = (a1 or a2) or (a3 or a4) can be written as
1039 # acl A any-of a1 a2
1040 # acl A any-of a3 a4
1042 # This group ACL is fast if all evaluated ACLs in the group are fast
1043 # and slow otherwise.
1045 acl aclname all-of acl1 acl2 ...
1046 # match all of the acls [fast or slow]
1047 # The first mismatching ACL stops further ACL evaluation.
1049 # ACLs from multiple all-of lines with the same name are ORed.
1050 # For example, B = (b1 and b2) or (b3 and b4) can be written as
1051 # acl B all-of b1 b2
1052 # acl B all-of b3 b4
1054 # This group ACL is fast if all evaluated ACLs in the group are fast
1055 # and slow otherwise.
1058 acl macaddress arp 09:00:2b:23:45:67
1059 acl myexample dst_as 1241
1060 acl password proxy_auth REQUIRED
1061 acl fileupload req_mime_type -i ^multipart/form-data$
1062 acl javascript rep_mime_type -i ^application/x-javascript$
1066 # Recommended minimum configuration:
1069 # Example rule allowing access from your local networks.
1070 # Adapt to list your (internal) IP networks from where browsing
1072 acl localnet src 10.0.0.0/8 # RFC1918 possible internal network
1073 acl localnet src 172.16.0.0/12 # RFC1918 possible internal network
1074 acl localnet src 192.168.0.0/16 # RFC1918 possible internal network
1075 acl localnet src fc00::/7 # RFC 4193 local private network range
1076 acl localnet src fe80::/10 # RFC 4291 link-local (directly plugged) machines
1078 acl SSL_ports port 443
1079 acl Safe_ports port 80 # http
1080 acl Safe_ports port 21 # ftp
1081 acl Safe_ports port 443 # https
1082 acl Safe_ports port 70 # gopher
1083 acl Safe_ports port 210 # wais
1084 acl Safe_ports port 1025-65535 # unregistered ports
1085 acl Safe_ports port 280 # http-mgmt
1086 acl Safe_ports port 488 # gss-http
1087 acl Safe_ports port 591 # filemaker
1088 acl Safe_ports port 777 # multiling http
1089 acl CONNECT method CONNECT
1093 NAME: proxy_forwarded_access follow_x_forwarded_for
1095 LOC: Config.accessList.followXFF
1096 DEFAULT_IF_NONE: deny all
1097 DEFAULT_DOC: indirect client IP will not be accepted.
1099 Determine which client proxies can be trusted to provide correct
1100 information regarding real client IP address.
1102 The original source details can be relayed in:
1103 HTTP message Forwarded header, or
1104 HTTP message X-Forwarded-For header, or
1105 PROXY protocol connection header.
1107 Allowing or Denying the X-Forwarded-For or Forwarded headers to
1108 be followed to find the original source of a request. Or permitting
1109 a client proxy to connect using PROXY protocol.
1111 Requests may pass through a chain of several other proxies
1112 before reaching us. The X-Forwarded-For header will contain a
1113 comma-separated list of the IP addresses in the chain, with the
1114 rightmost address being the most recent.
1116 If a request reaches us from a source that is allowed by this
1117 configuration item, then we consult the X-Forwarded-For header
1118 to see where that host received the request from. If the
1119 X-Forwarded-For header contains multiple addresses, we continue
1120 backtracking until we reach an address for which we are not allowed
1121 to follow the X-Forwarded-For header, or until we reach the first
1122 address in the list. For the purpose of ACL used in the
1123 follow_x_forwarded_for directive the src ACL type always matches
1124 the address we are testing and srcdomain matches its rDNS.
1126 The end result of this process is an IP address that we will
1127 refer to as the indirect client address. This address may
1128 be treated as the client address for access control, ICAP, delay
1129 pools and logging, depending on the acl_uses_indirect_client,
1130 icap_uses_indirect_client, delay_pool_uses_indirect_client,
1131 log_uses_indirect_client and tproxy_uses_indirect_client options.
1133 This clause only supports fast acl types.
1134 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
1136 SECURITY CONSIDERATIONS:
1138 Any host for which we follow the X-Forwarded-For header
1139 can place incorrect information in the header, and Squid
1140 will use the incorrect information as if it were the
1141 source address of the request. This may enable remote
1142 hosts to bypass any access control restrictions that are
1143 based on the client's source addresses.
1147 acl localhost src 127.0.0.1
1148 acl my_other_proxy srcdomain .proxy.example.com
1149 follow_x_forwarded_for allow localhost
1150 follow_x_forwarded_for allow my_other_proxy
1153 NAME: acl_uses_indirect_client
1156 IFDEF: FOLLOW_X_FORWARDED_FOR
1158 LOC: Config.onoff.acl_uses_indirect_client
1160 Controls whether the indirect client address
1161 (see follow_x_forwarded_for) is used instead of the
1162 direct client address in acl matching.
1164 NOTE: maxconn ACL considers direct TCP links and indirect
1165 clients will always have zero. So no match.
1168 NAME: delay_pool_uses_indirect_client
1171 IFDEF: FOLLOW_X_FORWARDED_FOR&&USE_DELAY_POOLS
1173 LOC: Config.onoff.delay_pool_uses_indirect_client
1175 Controls whether the indirect client address
1176 (see follow_x_forwarded_for) is used instead of the
1177 direct client address in delay pools.
1180 NAME: log_uses_indirect_client
1183 IFDEF: FOLLOW_X_FORWARDED_FOR
1185 LOC: Config.onoff.log_uses_indirect_client
1187 Controls whether the indirect client address
1188 (see follow_x_forwarded_for) is used instead of the
1189 direct client address in the access log.
1192 NAME: tproxy_uses_indirect_client
1195 IFDEF: FOLLOW_X_FORWARDED_FOR&&LINUX_NETFILTER
1197 LOC: Config.onoff.tproxy_uses_indirect_client
1199 Controls whether the indirect client address
1200 (see follow_x_forwarded_for) is used instead of the
1201 direct client address when spoofing the outgoing client.
1203 This has no effect on requests arriving in non-tproxy
1206 SECURITY WARNING: Usage of this option is dangerous
1207 and should not be used trivially. Correct configuration
1208 of follow_x_forewarded_for with a limited set of trusted
1209 sources is required to prevent abuse of your proxy.
1212 NAME: spoof_client_ip
1214 LOC: Config.accessList.spoof_client_ip
1216 DEFAULT_DOC: Allow spoofing on all TPROXY traffic.
1218 Control client IP address spoofing of TPROXY traffic based on
1219 defined access lists.
1221 spoof_client_ip allow|deny [!]aclname ...
1223 If there are no "spoof_client_ip" lines present, the default
1224 is to "allow" spoofing of any suitable request.
1226 Note that the cache_peer "no-tproxy" option overrides this ACL.
1228 This clause supports fast acl types.
1229 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
1234 LOC: Config.accessList.http
1235 DEFAULT_IF_NONE: deny all
1236 DEFAULT_DOC: Deny, unless rules exist in squid.conf.
1238 Allowing or Denying access based on defined access lists
1240 Access to the HTTP port:
1241 http_access allow|deny [!]aclname ...
1243 NOTE on default values:
1245 If there are no "access" lines present, the default is to deny
1248 If none of the "access" lines cause a match, the default is the
1249 opposite of the last line in the list. If the last line was
1250 deny, the default is allow. Conversely, if the last line
1251 is allow, the default will be deny. For these reasons, it is a
1252 good idea to have an "deny all" entry at the end of your access
1253 lists to avoid potential confusion.
1255 This clause supports both fast and slow acl types.
1256 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
1261 # Recommended minimum Access Permission configuration:
1263 # Deny requests to certain unsafe ports
1264 http_access deny !Safe_ports
1266 # Deny CONNECT to other than secure SSL ports
1267 http_access deny CONNECT !SSL_ports
1269 # Only allow cachemgr access from localhost
1270 http_access allow localhost manager
1271 http_access deny manager
1273 # We strongly recommend the following be uncommented to protect innocent
1274 # web applications running on the proxy server who think the only
1275 # one who can access services on "localhost" is a local user
1276 #http_access deny to_localhost
1279 # INSERT YOUR OWN RULE(S) HERE TO ALLOW ACCESS FROM YOUR CLIENTS
1282 # Example rule allowing access from your local networks.
1283 # Adapt localnet in the ACL section to list your (internal) IP networks
1284 # from where browsing should be allowed
1285 http_access allow localnet
1286 http_access allow localhost
1288 # And finally deny all other access to this proxy
1289 http_access deny all
1293 NAME: adapted_http_access http_access2
1295 LOC: Config.accessList.adapted_http
1297 DEFAULT_DOC: Allow, unless rules exist in squid.conf.
1299 Allowing or Denying access based on defined access lists
1301 Essentially identical to http_access, but runs after redirectors
1302 and ICAP/eCAP adaptation. Allowing access control based on their
1305 If not set then only http_access is used.
1308 NAME: http_reply_access
1310 LOC: Config.accessList.reply
1312 DEFAULT_DOC: Allow, unless rules exist in squid.conf.
1314 Allow replies to client requests. This is complementary to http_access.
1316 http_reply_access allow|deny [!] aclname ...
1318 NOTE: if there are no access lines present, the default is to allow
1321 If none of the access lines cause a match the opposite of the
1322 last line will apply. Thus it is good practice to end the rules
1323 with an "allow all" or "deny all" entry.
1325 This clause supports both fast and slow acl types.
1326 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
1331 LOC: Config.accessList.icp
1333 DEFAULT_DOC: Deny, unless rules exist in squid.conf.
1335 Allowing or Denying access to the ICP port based on defined
1338 icp_access allow|deny [!]aclname ...
1340 NOTE: The default if no icp_access lines are present is to
1341 deny all traffic. This default may cause problems with peers
1344 This clause only supports fast acl types.
1345 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
1347 # Allow ICP queries from local networks only
1348 #icp_access allow localnet
1349 #icp_access deny all
1355 LOC: Config.accessList.htcp
1357 DEFAULT_DOC: Deny, unless rules exist in squid.conf.
1359 Allowing or Denying access to the HTCP port based on defined
1362 htcp_access allow|deny [!]aclname ...
1364 See also htcp_clr_access for details on access control for
1365 cache purge (CLR) HTCP messages.
1367 NOTE: The default if no htcp_access lines are present is to
1368 deny all traffic. This default may cause problems with peers
1369 using the htcp option.
1371 This clause only supports fast acl types.
1372 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
1374 # Allow HTCP queries from local networks only
1375 #htcp_access allow localnet
1376 #htcp_access deny all
1379 NAME: htcp_clr_access
1382 LOC: Config.accessList.htcp_clr
1384 DEFAULT_DOC: Deny, unless rules exist in squid.conf.
1386 Allowing or Denying access to purge content using HTCP based
1387 on defined access lists.
1388 See htcp_access for details on general HTCP access control.
1390 htcp_clr_access allow|deny [!]aclname ...
1392 This clause only supports fast acl types.
1393 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
1395 # Allow HTCP CLR requests from trusted peers
1396 acl htcp_clr_peer src 192.0.2.2 2001:DB8::2
1397 htcp_clr_access allow htcp_clr_peer
1398 htcp_clr_access deny all
1403 LOC: Config.accessList.miss
1405 DEFAULT_DOC: Allow, unless rules exist in squid.conf.
1407 Determins whether network access is permitted when satisfying a request.
1410 to force your neighbors to use you as a sibling instead of
1413 acl localclients src 192.0.2.0/24 2001:DB8::a:0/64
1414 miss_access deny !localclients
1415 miss_access allow all
1417 This means only your local clients are allowed to fetch relayed/MISS
1418 replies from the network and all other clients can only fetch cached
1421 The default for this setting allows all clients who passed the
1422 http_access rules to relay via this proxy.
1424 This clause only supports fast acl types.
1425 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
1428 NAME: ident_lookup_access
1432 DEFAULT_DOC: Unless rules exist in squid.conf, IDENT is not fetched.
1433 LOC: Ident::TheConfig.identLookup
1435 A list of ACL elements which, if matched, cause an ident
1436 (RFC 931) lookup to be performed for this request. For
1437 example, you might choose to always perform ident lookups
1438 for your main multi-user Unix boxes, but not for your Macs
1439 and PCs. By default, ident lookups are not performed for
1442 To enable ident lookups for specific client addresses, you
1443 can follow this example:
1445 acl ident_aware_hosts src 198.168.1.0/24
1446 ident_lookup_access allow ident_aware_hosts
1447 ident_lookup_access deny all
1449 Only src type ACL checks are fully supported. A srcdomain
1450 ACL might work at times, but it will not always provide
1453 This clause only supports fast acl types.
1454 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
1457 NAME: reply_body_max_size
1458 COMMENT: size [acl acl...]
1461 DEFAULT_DOC: No limit is applied.
1462 LOC: Config.ReplyBodySize
1464 This option specifies the maximum size of a reply body. It can be
1465 used to prevent users from downloading very large files, such as
1466 MP3's and movies. When the reply headers are received, the
1467 reply_body_max_size lines are processed, and the first line where
1468 all (if any) listed ACLs are true is used as the maximum body size
1471 This size is checked twice. First when we get the reply headers,
1472 we check the content-length value. If the content length value exists
1473 and is larger than the allowed size, the request is denied and the
1474 user receives an error message that says "the request or reply
1475 is too large." If there is no content-length, and the reply
1476 size exceeds this limit, the client's connection is just closed
1477 and they will receive a partial reply.
1479 WARNING: downstream caches probably can not detect a partial reply
1480 if there is no content-length header, so they will cache
1481 partial responses and give them out as hits. You should NOT
1482 use this option if you have downstream caches.
1484 WARNING: A maximum size smaller than the size of squid's error messages
1485 will cause an infinite loop and crash squid. Ensure that the smallest
1486 non-zero value you use is greater that the maximum header size plus
1487 the size of your largest error page.
1489 If you set this parameter none (the default), there will be
1492 Configuration Format is:
1493 reply_body_max_size SIZE UNITS [acl ...]
1495 reply_body_max_size 10 MB
1501 -----------------------------------------------------------------------------
1504 NAME: http_port ascii_port
1507 LOC: Config.Sockaddr.http
1509 Usage: port [mode] [options]
1510 hostname:port [mode] [options]
1511 1.2.3.4:port [mode] [options]
1513 The socket addresses where Squid will listen for HTTP client
1514 requests. You may specify multiple socket addresses.
1515 There are three forms: port alone, hostname with port, and
1516 IP address with port. If you specify a hostname or IP
1517 address, Squid binds the socket to that specific
1518 address. Most likely, you do not need to bind to a specific
1519 address, so you can use the port number alone.
1521 If you are running Squid in accelerator mode, you
1522 probably want to listen on port 80 also, or instead.
1524 The -a command line option may be used to specify additional
1525 port(s) where Squid listens for proxy request. Such ports will
1526 be plain proxy ports with no options.
1528 You may specify multiple socket addresses on multiple lines.
1532 intercept Support for IP-Layer interception of
1533 outgoing requests without browser settings.
1534 NP: disables authentication and IPv6 on the port.
1536 tproxy Support Linux TPROXY for spoofing outgoing
1537 connections using the client IP address.
1538 NP: disables authentication and maybe IPv6 on the port.
1540 accel Accelerator / reverse proxy mode
1543 Support for PROXY protocol version 1 or 2 connections.
1544 The proxy_forwarded_access is required to whitelist
1545 downstream proxies which can be trusted.
1547 ssl-bump For each CONNECT request allowed by ssl_bump ACLs,
1548 establish secure connection with the client and with
1549 the server, decrypt HTTPS messages as they pass through
1550 Squid, and treat them as unencrypted HTTP messages,
1551 becoming the man-in-the-middle.
1553 The ssl_bump option is required to fully enable
1554 bumping of CONNECT requests.
1556 Omitting the mode flag causes default forward proxy mode to be used.
1559 Accelerator Mode Options:
1561 defaultsite=domainname
1562 What to use for the Host: header if it is not present
1563 in a request. Determines what site (not origin server)
1564 accelerators should consider the default.
1566 no-vhost Disable using HTTP/1.1 Host header for virtual domain support.
1568 protocol= Protocol to reconstruct accelerated and intercepted
1569 requests with. Defaults to HTTP/1.1 for http_port and
1570 HTTPS/1.1 for https_port.
1571 When an unsupported value is configured Squid will
1572 produce a FATAL error.
1573 Values: HTTP or HTTP/1.1, HTTPS or HTTPS/1.1
1575 vport Virtual host port support. Using the http_port number
1576 instead of the port passed on Host: headers.
1578 vport=NN Virtual host port support. Using the specified port
1579 number instead of the port passed on Host: headers.
1582 Act as if this Squid is the origin server.
1583 This currently means generate new Date: and Expires:
1584 headers on HIT instead of adding Age:.
1586 ignore-cc Ignore request Cache-Control headers.
1588 WARNING: This option violates HTTP specifications if
1589 used in non-accelerator setups.
1591 allow-direct Allow direct forwarding in accelerator mode. Normally
1592 accelerated requests are denied direct forwarding as if
1593 never_direct was used.
1595 WARNING: this option opens accelerator mode to security
1596 vulnerabilities usually only affecting in interception
1597 mode. Make sure to protect forwarding with suitable
1598 http_access rules when using this.
1601 SSL Bump Mode Options:
1602 In addition to these options ssl-bump requires TLS/SSL options.
1604 generate-host-certificates[=<on|off>]
1605 Dynamically create SSL server certificates for the
1606 destination hosts of bumped CONNECT requests.When
1607 enabled, the cert and key options are used to sign
1608 generated certificates. Otherwise generated
1609 certificate will be selfsigned.
1610 If there is a CA certificate lifetime of the generated
1611 certificate equals lifetime of the CA certificate. If
1612 generated certificate is selfsigned lifetime is three
1614 This option is enabled by default when ssl-bump is used.
1615 See the ssl-bump option above for more information.
1617 dynamic_cert_mem_cache_size=SIZE
1618 Approximate total RAM size spent on cached generated
1619 certificates. If set to zero, caching is disabled. The
1620 default value is 4MB.
1624 cert= Path to SSL certificate (PEM format).
1626 key= Path to SSL private key file (PEM format)
1627 if not specified, the certificate file is
1628 assumed to be a combined certificate and
1631 version= The version of SSL/TLS supported
1632 1 automatic (default)
1639 cipher= Colon separated list of supported ciphers.
1640 NOTE: some ciphers such as EDH ciphers depend on
1641 additional settings. If those settings are
1642 omitted the ciphers may be silently ignored
1643 by the OpenSSL library.
1645 options= Various SSL implementation options. The most important
1647 NO_SSLv2 Disallow the use of SSLv2
1648 NO_SSLv3 Disallow the use of SSLv3
1649 NO_TLSv1 Disallow the use of TLSv1.0
1650 NO_TLSv1_1 Disallow the use of TLSv1.1
1651 NO_TLSv1_2 Disallow the use of TLSv1.2
1652 SINGLE_DH_USE Always create a new key when using
1653 temporary/ephemeral DH key exchanges
1654 ALL Enable various bug workarounds
1655 suggested as "harmless" by OpenSSL
1656 Be warned that this reduces SSL/TLS
1657 strength to some attacks.
1658 See OpenSSL SSL_CTX_set_options documentation for a
1659 complete list of options.
1661 clientca= File containing the list of CAs to use when
1662 requesting a client certificate.
1664 cafile= File containing additional CA certificates to
1665 use when verifying client certificates. If unset
1666 clientca will be used.
1668 capath= Directory containing additional CA certificates
1669 and CRL lists to use when verifying client certificates.
1671 crlfile= File of additional CRL lists to use when verifying
1672 the client certificate, in addition to CRLs stored in
1673 the capath. Implies VERIFY_CRL flag below.
1675 dhparams= File containing DH parameters for temporary/ephemeral
1676 DH key exchanges. See OpenSSL documentation for details
1677 on how to create this file.
1678 WARNING: EDH ciphers will be silently disabled if this
1681 sslflags= Various flags modifying the use of SSL:
1683 Don't request client certificates
1684 immediately, but wait until acl processing
1685 requires a certificate (not yet implemented).
1687 Don't use the default CA lists built in
1690 Don't allow for session reuse. Each connection
1691 will result in a new SSL session.
1693 Verify CRL lists when accepting client
1696 Verify CRL lists for all certificates in the
1697 client certificate chain.
1699 sslcontext= SSL session ID context identifier.
1703 connection-auth[=on|off]
1704 use connection-auth=off to tell Squid to prevent
1705 forwarding Microsoft connection oriented authentication
1706 (NTLM, Negotiate and Kerberos)
1708 disable-pmtu-discovery=
1709 Control Path-MTU discovery usage:
1710 off lets OS decide on what to do (default).
1711 transparent disable PMTU discovery when transparent
1713 always disable always PMTU discovery.
1715 In many setups of transparently intercepting proxies
1716 Path-MTU discovery can not work on traffic towards the
1717 clients. This is the case when the intercepting device
1718 does not fully track connections and fails to forward
1719 ICMP must fragment messages to the cache server. If you
1720 have such setup and experience that certain clients
1721 sporadically hang or never complete requests set
1722 disable-pmtu-discovery option to 'transparent'.
1724 name= Specifies a internal name for the port. Defaults to
1725 the port specification (port or addr:port)
1727 tcpkeepalive[=idle,interval,timeout]
1728 Enable TCP keepalive probes of idle connections.
1729 In seconds; idle is the initial time before TCP starts
1730 probing the connection, interval how often to probe, and
1731 timeout the time before giving up.
1733 If you run Squid on a dual-homed machine with an internal
1734 and an external interface we recommend you to specify the
1735 internal address:port in http_port. This way Squid will only be
1736 visible on the internal address.
1740 # Squid normally listens to port 3128
1741 http_port @DEFAULT_HTTP_PORT@
1749 LOC: Config.Sockaddr.https
1751 Usage: [ip:]port cert=certificate.pem [key=key.pem] [mode] [options...]
1753 The socket address where Squid will listen for client requests made
1754 over TLS or SSL connections. Commonly referred to as HTTPS.
1756 This is most useful for situations where you are running squid in
1757 accelerator mode and you want to do the SSL work at the accelerator level.
1759 You may specify multiple socket addresses on multiple lines,
1760 each with their own SSL certificate and/or options.
1764 accel Accelerator / reverse proxy mode
1766 intercept Support for IP-Layer interception of
1767 outgoing requests without browser settings.
1768 NP: disables authentication and IPv6 on the port.
1770 tproxy Support Linux TPROXY for spoofing outgoing
1771 connections using the client IP address.
1772 NP: disables authentication and maybe IPv6 on the port.
1774 ssl-bump For each intercepted connection allowed by ssl_bump
1775 ACLs, establish a secure connection with the client and with
1776 the server, decrypt HTTPS messages as they pass through
1777 Squid, and treat them as unencrypted HTTP messages,
1778 becoming the man-in-the-middle.
1780 An "ssl_bump server-first" match is required to
1781 fully enable bumping of intercepted SSL connections.
1783 Requires tproxy or intercept.
1785 Omitting the mode flag causes default forward proxy mode to be used.
1788 See http_port for a list of generic options
1793 cert= Path to SSL certificate (PEM format).
1795 key= Path to SSL private key file (PEM format)
1796 if not specified, the certificate file is
1797 assumed to be a combined certificate and
1800 version= The version of SSL/TLS supported
1801 1 automatic (default)
1806 cipher= Colon separated list of supported ciphers.
1808 options= Various SSL engine options. The most important
1810 NO_SSLv2 Disallow the use of SSLv2
1811 NO_SSLv3 Disallow the use of SSLv3
1812 NO_TLSv1 Disallow the use of TLSv1
1813 SINGLE_DH_USE Always create a new key when using
1814 temporary/ephemeral DH key exchanges
1815 See src/ssl_support.c or OpenSSL SSL_CTX_set_options
1816 documentation for a complete list of options.
1818 clientca= File containing the list of CAs to use when
1819 requesting a client certificate.
1821 cafile= File containing additional CA certificates to
1822 use when verifying client certificates. If unset
1823 clientca will be used.
1825 capath= Directory containing additional CA certificates
1826 and CRL lists to use when verifying client certificates.
1828 crlfile= File of additional CRL lists to use when verifying
1829 the client certificate, in addition to CRLs stored in
1830 the capath. Implies VERIFY_CRL flag below.
1832 dhparams= File containing DH parameters for temporary/ephemeral
1835 sslflags= Various flags modifying the use of SSL:
1837 Don't request client certificates
1838 immediately, but wait until acl processing
1839 requires a certificate (not yet implemented).
1841 Don't use the default CA lists built in
1844 Don't allow for session reuse. Each connection
1845 will result in a new SSL session.
1847 Verify CRL lists when accepting client
1850 Verify CRL lists for all certificates in the
1851 client certificate chain.
1853 sslcontext= SSL session ID context identifier.
1855 generate-host-certificates[=<on|off>]
1856 Dynamically create SSL server certificates for the
1857 destination hosts of bumped SSL requests.When
1858 enabled, the cert and key options are used to sign
1859 generated certificates. Otherwise generated
1860 certificate will be selfsigned.
1861 If there is CA certificate life time of generated
1862 certificate equals lifetime of CA certificate. If
1863 generated certificate is selfsigned lifetime is three
1865 This option is enabled by default when SslBump is used.
1866 See the sslBump option above for more information.
1868 dynamic_cert_mem_cache_size=SIZE
1869 Approximate total RAM size spent on cached generated
1870 certificates. If set to zero, caching is disabled. The
1871 default value is 4MB.
1873 See http_port for a list of available options.
1876 NAME: tcp_outgoing_tos tcp_outgoing_ds tcp_outgoing_dscp
1879 LOC: Ip::Qos::TheConfig.tosToServer
1881 Allows you to select a TOS/Diffserv value for packets outgoing
1882 on the server side, based on an ACL.
1884 tcp_outgoing_tos ds-field [!]aclname ...
1886 Example where normal_service_net uses the TOS value 0x00
1887 and good_service_net uses 0x20
1889 acl normal_service_net src 10.0.0.0/24
1890 acl good_service_net src 10.0.1.0/24
1891 tcp_outgoing_tos 0x00 normal_service_net
1892 tcp_outgoing_tos 0x20 good_service_net
1894 TOS/DSCP values really only have local significance - so you should
1895 know what you're specifying. For more information, see RFC2474,
1896 RFC2475, and RFC3260.
1898 The TOS/DSCP byte must be exactly that - a octet value 0 - 255, or
1899 "default" to use whatever default your host has. Note that in
1900 practice often only multiples of 4 is usable as the two rightmost bits
1901 have been redefined for use by ECN (RFC 3168 section 23.1).
1903 Processing proceeds in the order specified, and stops at first fully
1907 NAME: clientside_tos
1910 LOC: Ip::Qos::TheConfig.tosToClient
1912 Allows you to select a TOS/Diffserv value for packets being transmitted
1913 on the client-side, based on an ACL.
1915 clientside_tos ds-field [!]aclname ...
1917 Example where normal_service_net uses the TOS value 0x00
1918 and good_service_net uses 0x20
1920 acl normal_service_net src 10.0.0.0/24
1921 acl good_service_net src 10.0.1.0/24
1922 clientside_tos 0x00 normal_service_net
1923 clientside_tos 0x20 good_service_net
1925 Note: This feature is incompatible with qos_flows. Any TOS values set here
1926 will be overwritten by TOS values in qos_flows.
1929 NAME: tcp_outgoing_mark
1931 IFDEF: SO_MARK&&USE_LIBCAP
1933 LOC: Ip::Qos::TheConfig.nfmarkToServer
1935 Allows you to apply a Netfilter mark value to outgoing packets
1936 on the server side, based on an ACL.
1938 tcp_outgoing_mark mark-value [!]aclname ...
1940 Example where normal_service_net uses the mark value 0x00
1941 and good_service_net uses 0x20
1943 acl normal_service_net src 10.0.0.0/24
1944 acl good_service_net src 10.0.1.0/24
1945 tcp_outgoing_mark 0x00 normal_service_net
1946 tcp_outgoing_mark 0x20 good_service_net
1949 NAME: clientside_mark
1951 IFDEF: SO_MARK&&USE_LIBCAP
1953 LOC: Ip::Qos::TheConfig.nfmarkToClient
1955 Allows you to apply a Netfilter mark value to packets being transmitted
1956 on the client-side, based on an ACL.
1958 clientside_mark mark-value [!]aclname ...
1960 Example where normal_service_net uses the mark value 0x00
1961 and good_service_net uses 0x20
1963 acl normal_service_net src 10.0.0.0/24
1964 acl good_service_net src 10.0.1.0/24
1965 clientside_mark 0x00 normal_service_net
1966 clientside_mark 0x20 good_service_net
1968 Note: This feature is incompatible with qos_flows. Any mark values set here
1969 will be overwritten by mark values in qos_flows.
1976 LOC: Ip::Qos::TheConfig
1978 Allows you to select a TOS/DSCP value to mark outgoing
1979 connections to the client, based on where the reply was sourced.
1980 For platforms using netfilter, allows you to set a netfilter mark
1981 value instead of, or in addition to, a TOS value.
1983 By default this functionality is disabled. To enable it with the default
1984 settings simply use "qos_flows mark" or "qos_flows tos". Default
1985 settings will result in the netfilter mark or TOS value being copied
1986 from the upstream connection to the client. Note that it is the connection
1987 CONNMARK value not the packet MARK value that is copied.
1989 It is not currently possible to copy the mark or TOS value from the
1990 client to the upstream connection request.
1992 TOS values really only have local significance - so you should
1993 know what you're specifying. For more information, see RFC2474,
1994 RFC2475, and RFC3260.
1996 The TOS/DSCP byte must be exactly that - a octet value 0 - 255. Note that
1997 in practice often only multiples of 4 is usable as the two rightmost bits
1998 have been redefined for use by ECN (RFC 3168 section 23.1).
2000 Mark values can be any unsigned 32-bit integer value.
2002 This setting is configured by setting the following values:
2004 tos|mark Whether to set TOS or netfilter mark values
2006 local-hit=0xFF Value to mark local cache hits.
2008 sibling-hit=0xFF Value to mark hits from sibling peers.
2010 parent-hit=0xFF Value to mark hits from parent peers.
2012 miss=0xFF[/mask] Value to mark cache misses. Takes precedence
2013 over the preserve-miss feature (see below), unless
2014 mask is specified, in which case only the bits
2015 specified in the mask are written.
2017 The TOS variant of the following features are only possible on Linux
2018 and require your kernel to be patched with the TOS preserving ZPH
2019 patch, available from http://zph.bratcheda.org
2020 No patch is needed to preserve the netfilter mark, which will work
2021 with all variants of netfilter.
2023 disable-preserve-miss
2024 This option disables the preservation of the TOS or netfilter
2025 mark. By default, the existing TOS or netfilter mark value of
2026 the response coming from the remote server will be retained
2027 and masked with miss-mark.
2028 NOTE: in the case of a netfilter mark, the mark must be set on
2029 the connection (using the CONNMARK target) not on the packet
2033 Allows you to mask certain bits in the TOS or mark value
2034 received from the remote server, before copying the value to
2035 the TOS sent towards clients.
2036 Default for tos: 0xFF (TOS from server is not changed).
2037 Default for mark: 0xFFFFFFFF (mark from server is not changed).
2039 All of these features require the --enable-zph-qos compilation flag
2040 (enabled by default). Netfilter marking also requires the
2041 libnetfilter_conntrack libraries (--with-netfilter-conntrack) and
2042 libcap 2.09+ (--with-libcap).
2046 NAME: tcp_outgoing_address
2049 DEFAULT_DOC: Address selection is performed by the operating system.
2050 LOC: Config.accessList.outgoing_address
2052 Allows you to map requests to different outgoing IP addresses
2053 based on the username or source address of the user making
2056 tcp_outgoing_address ipaddr [[!]aclname] ...
2059 Forwarding clients with dedicated IPs for certain subnets.
2061 acl normal_service_net src 10.0.0.0/24
2062 acl good_service_net src 10.0.2.0/24
2064 tcp_outgoing_address 2001:db8::c001 good_service_net
2065 tcp_outgoing_address 10.1.0.2 good_service_net
2067 tcp_outgoing_address 2001:db8::beef normal_service_net
2068 tcp_outgoing_address 10.1.0.1 normal_service_net
2070 tcp_outgoing_address 2001:db8::1
2071 tcp_outgoing_address 10.1.0.3
2073 Processing proceeds in the order specified, and stops at first fully
2076 Squid will add an implicit IP version test to each line.
2077 Requests going to IPv4 websites will use the outgoing 10.1.0.* addresses.
2078 Requests going to IPv6 websites will use the outgoing 2001:db8:* addresses.
2081 NOTE: The use of this directive using client dependent ACLs is
2082 incompatible with the use of server side persistent connections. To
2083 ensure correct results it is best to set server_persistent_connections
2084 to off when using this directive in such configurations.
2086 NOTE: The use of this directive to set a local IP on outgoing TCP links
2087 is incompatible with using TPROXY to set client IP out outbound TCP links.
2088 When needing to contact peers use the no-tproxy cache_peer option and the
2089 client_dst_passthru directive re-enable normal forwarding such as this.
2093 NAME: host_verify_strict
2096 LOC: Config.onoff.hostStrictVerify
2098 Regardless of this option setting, when dealing with intercepted
2099 traffic, Squid always verifies that the destination IP address matches
2100 the Host header domain or IP (called 'authority form URL').
2102 This enforcement is performed to satisfy a MUST-level requirement in
2103 RFC 2616 section 14.23: "The Host field value MUST represent the naming
2104 authority of the origin server or gateway given by the original URL".
2107 Squid always responds with an HTTP 409 (Conflict) error
2108 page and logs a security warning if there is no match.
2110 Squid verifies that the destination IP address matches
2111 the Host header for forward-proxy and reverse-proxy traffic
2112 as well. For those traffic types, Squid also enables the
2113 following checks, comparing the corresponding Host header
2114 and Request-URI components:
2116 * The host names (domain or IP) must be identical,
2117 but valueless or missing Host header disables all checks.
2118 For the two host names to match, both must be either IP
2121 * Port numbers must be identical, but if a port is missing
2122 the scheme-default port is assumed.
2125 When set to OFF (the default):
2126 Squid allows suspicious requests to continue but logs a
2127 security warning and blocks caching of the response.
2129 * Forward-proxy traffic is not checked at all.
2131 * Reverse-proxy traffic is not checked at all.
2133 * Intercepted traffic which passes verification is handled
2134 according to client_dst_passthru.
2136 * Intercepted requests which fail verification are sent
2137 to the client original destination instead of DIRECT.
2138 This overrides 'client_dst_passthru off'.
2140 For now suspicious intercepted CONNECT requests are always
2141 responded to with an HTTP 409 (Conflict) error page.
2146 As described in CVE-2009-0801 when the Host: header alone is used
2147 to determine the destination of a request it becomes trivial for
2148 malicious scripts on remote websites to bypass browser same-origin
2149 security policy and sandboxing protections.
2151 The cause of this is that such applets are allowed to perform their
2152 own HTTP stack, in which case the same-origin policy of the browser
2153 sandbox only verifies that the applet tries to contact the same IP
2154 as from where it was loaded at the IP level. The Host: header may
2155 be different from the connected IP and approved origin.
2159 NAME: client_dst_passthru
2162 LOC: Config.onoff.client_dst_passthru
2164 With NAT or TPROXY intercepted traffic Squid may pass the request
2165 directly to the original client destination IP or seek a faster
2166 source using the HTTP Host header.
2168 Using Host to locate alternative servers can provide faster
2169 connectivity with a range of failure recovery options.
2170 But can also lead to connectivity trouble when the client and
2171 server are attempting stateful interactions unaware of the proxy.
2173 This option (on by default) prevents alternative DNS entries being
2174 located to send intercepted traffic DIRECT to an origin server.
2175 The clients original destination IP and port will be used instead.
2177 Regardless of this option setting, when dealing with intercepted
2178 traffic Squid will verify the Host: header and any traffic which
2179 fails Host verification will be treated as if this option were ON.
2181 see host_verify_strict for details on the verification process.
2186 -----------------------------------------------------------------------------
2189 NAME: ssl_unclean_shutdown
2193 LOC: Config.SSL.unclean_shutdown
2195 Some browsers (especially MSIE) bugs out on SSL shutdown
2202 LOC: Config.SSL.ssl_engine
2205 The OpenSSL engine to use. You will need to set this if you
2206 would like to use hardware SSL acceleration for example.
2209 NAME: sslproxy_client_certificate
2212 LOC: Config.ssl_client.cert
2215 Client SSL Certificate to use when proxying https:// URLs
2218 NAME: sslproxy_client_key
2221 LOC: Config.ssl_client.key
2224 Client SSL Key to use when proxying https:// URLs
2227 NAME: sslproxy_version
2230 DEFAULT_DOC: automatic SSL/TLS version negotiation
2231 LOC: Config.ssl_client.version
2234 SSL version level to use when proxying https:// URLs
2236 The versions of SSL/TLS supported:
2238 1 automatic (default)
2246 NAME: sslproxy_options
2249 LOC: Config.ssl_client.options
2252 SSL implementation options to use when proxying https:// URLs
2254 The most important being:
2256 NO_SSLv2 Disallow the use of SSLv2
2257 NO_SSLv3 Disallow the use of SSLv3
2258 NO_TLSv1 Disallow the use of TLSv1.0
2259 NO_TLSv1_1 Disallow the use of TLSv1.1
2260 NO_TLSv1_2 Disallow the use of TLSv1.2
2262 Always create a new key when using temporary/ephemeral
2265 Disable use of RFC5077 session tickets. Some servers
2266 may have problems understanding the TLS extension due
2267 to ambiguous specification in RFC4507.
2268 ALL Enable various bug workarounds suggested as "harmless"
2269 by OpenSSL. Be warned that this may reduce SSL/TLS
2270 strength to some attacks.
2272 See the OpenSSL SSL_CTX_set_options documentation for a
2273 complete list of possible options.
2276 NAME: sslproxy_cipher
2279 LOC: Config.ssl_client.cipher
2282 SSL cipher list to use when proxying https:// URLs
2284 Colon separated list of supported ciphers.
2287 NAME: sslproxy_cafile
2290 LOC: Config.ssl_client.cafile
2293 file containing CA certificates to use when verifying server
2294 certificates while proxying https:// URLs
2297 NAME: sslproxy_capath
2300 LOC: Config.ssl_client.capath
2303 directory containing CA certificates to use when verifying
2304 server certificates while proxying https:// URLs
2307 NAME: sslproxy_session_ttl
2310 LOC: Config.SSL.session_ttl
2313 Sets the timeout value for SSL sessions
2316 NAME: sslproxy_session_cache_size
2319 LOC: Config.SSL.sessionCacheSize
2322 Sets the cache size to use for ssl session
2327 TYPE: sslproxy_ssl_bump
2328 LOC: Config.accessList.ssl_bump
2329 DEFAULT_DOC: Does not bump unless rules are present in squid.conf
2332 This option is consulted when a CONNECT request is received on
2333 an http_port (or a new connection is intercepted at an
2334 https_port), provided that port was configured with an ssl-bump
2335 flag. The subsequent data on the connection is either treated as
2336 HTTPS and decrypted OR tunneled at TCP level without decryption,
2337 depending on the first bumping "mode" which ACLs match.
2339 ssl_bump <mode> [!]acl ...
2341 The following bumping modes are supported:
2344 Allow bumping of the connection. Establish a secure connection
2345 with the client first, then connect to the server. This old mode
2346 does not allow Squid to mimic server SSL certificate and does
2347 not work with intercepted SSL connections.
2350 Allow bumping of the connection. Establish a secure connection
2351 with the server first, then establish a secure connection with
2352 the client, using a mimicked server certificate. Works with both
2353 CONNECT requests and intercepted SSL connections.
2356 Become a TCP tunnel without decoding the connection.
2357 Works with both CONNECT requests and intercepted SSL
2358 connections. This is the default behavior when no
2359 ssl_bump option is given or no ssl_bump ACLs match.
2361 By default, no connections are bumped.
2363 The first matching ssl_bump option wins. If no ACLs match, the
2364 connection is not bumped. Unlike most allow/deny ACL lists, ssl_bump
2365 does not have an implicit "negate the last given option" rule. You
2366 must make that rule explicit if you convert old ssl_bump allow/deny
2367 rules that rely on such an implicit rule.
2369 This clause supports both fast and slow acl types.
2370 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
2372 See also: http_port ssl-bump, https_port ssl-bump
2375 # Example: Bump all requests except those originating from
2376 # localhost or those going to example.com.
2378 acl broken_sites dstdomain .example.com
2379 ssl_bump none localhost
2380 ssl_bump none broken_sites
2381 ssl_bump server-first all
2384 NAME: sslproxy_flags
2387 LOC: Config.ssl_client.flags
2390 Various flags modifying the use of SSL while proxying https:// URLs:
2391 DONT_VERIFY_PEER Accept certificates that fail verification.
2392 For refined control, see sslproxy_cert_error.
2393 NO_DEFAULT_CA Don't use the default CA list built in
2397 NAME: sslproxy_cert_error
2400 DEFAULT_DOC: Server certificate errors terminate the transaction.
2401 LOC: Config.ssl_client.cert_error
2404 Use this ACL to bypass server certificate validation errors.
2406 For example, the following lines will bypass all validation errors
2407 when talking to servers for example.com. All other
2408 validation errors will result in ERR_SECURE_CONNECT_FAIL error.
2410 acl BrokenButTrustedServers dstdomain example.com
2411 sslproxy_cert_error allow BrokenButTrustedServers
2412 sslproxy_cert_error deny all
2414 This clause only supports fast acl types.
2415 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
2416 Using slow acl types may result in server crashes
2418 Without this option, all server certificate validation errors
2419 terminate the transaction to protect Squid and the client.
2421 SQUID_X509_V_ERR_INFINITE_VALIDATION error cannot be bypassed
2422 but should not happen unless your OpenSSL library is buggy.
2425 Bypassing validation errors is dangerous because an
2426 error usually implies that the server cannot be trusted
2427 and the connection may be insecure.
2429 See also: sslproxy_flags and DONT_VERIFY_PEER.
2432 NAME: sslproxy_cert_sign
2435 POSTSCRIPTUM: signUntrusted ssl::certUntrusted
2436 POSTSCRIPTUM: signSelf ssl::certSelfSigned
2437 POSTSCRIPTUM: signTrusted all
2438 TYPE: sslproxy_cert_sign
2439 LOC: Config.ssl_client.cert_sign
2442 sslproxy_cert_sign <signing algorithm> acl ...
2444 The following certificate signing algorithms are supported:
2447 Sign using the configured CA certificate which is usually
2448 placed in and trusted by end-user browsers. This is the
2449 default for trusted origin server certificates.
2452 Sign to guarantee an X509_V_ERR_CERT_UNTRUSTED browser error.
2453 This is the default for untrusted origin server certificates
2454 that are not self-signed (see ssl::certUntrusted).
2457 Sign using a self-signed certificate with the right CN to
2458 generate a X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT error in the
2459 browser. This is the default for self-signed origin server
2460 certificates (see ssl::certSelfSigned).
2462 This clause only supports fast acl types.
2464 When sslproxy_cert_sign acl(s) match, Squid uses the corresponding
2465 signing algorithm to generate the certificate and ignores all
2466 subsequent sslproxy_cert_sign options (the first match wins). If no
2467 acl(s) match, the default signing algorithm is determined by errors
2468 detected when obtaining and validating the origin server certificate.
2470 WARNING: SQUID_X509_V_ERR_DOMAIN_MISMATCH and ssl:certDomainMismatch can
2471 be used with sslproxy_cert_adapt, but if and only if Squid is bumping a
2472 CONNECT request that carries a domain name. In all other cases (CONNECT
2473 to an IP address or an intercepted SSL connection), Squid cannot detect
2474 the domain mismatch at certificate generation time when
2475 bump-server-first is used.
2478 NAME: sslproxy_cert_adapt
2481 TYPE: sslproxy_cert_adapt
2482 LOC: Config.ssl_client.cert_adapt
2485 sslproxy_cert_adapt <adaptation algorithm> acl ...
2487 The following certificate adaptation algorithms are supported:
2490 Sets the "Not After" property to the "Not After" property of
2491 the CA certificate used to sign generated certificates.
2494 Sets the "Not Before" property to the "Not Before" property of
2495 the CA certificate used to sign generated certificates.
2497 setCommonName or setCommonName{CN}
2498 Sets Subject.CN property to the host name specified as a
2499 CN parameter or, if no explicit CN parameter was specified,
2500 extracted from the CONNECT request. It is a misconfiguration
2501 to use setCommonName without an explicit parameter for
2502 intercepted or tproxied SSL connections.
2504 This clause only supports fast acl types.
2506 Squid first groups sslproxy_cert_adapt options by adaptation algorithm.
2507 Within a group, when sslproxy_cert_adapt acl(s) match, Squid uses the
2508 corresponding adaptation algorithm to generate the certificate and
2509 ignores all subsequent sslproxy_cert_adapt options in that algorithm's
2510 group (i.e., the first match wins within each algorithm group). If no
2511 acl(s) match, the default mimicking action takes place.
2513 WARNING: SQUID_X509_V_ERR_DOMAIN_MISMATCH and ssl:certDomainMismatch can
2514 be used with sslproxy_cert_adapt, but if and only if Squid is bumping a
2515 CONNECT request that carries a domain name. In all other cases (CONNECT
2516 to an IP address or an intercepted SSL connection), Squid cannot detect
2517 the domain mismatch at certificate generation time when
2518 bump-server-first is used.
2521 NAME: sslpassword_program
2524 LOC: Config.Program.ssl_password
2527 Specify a program used for entering SSL key passphrases
2528 when using encrypted SSL certificate keys. If not specified
2529 keys must either be unencrypted, or Squid started with the -N
2530 option to allow it to query interactively for the passphrase.
2532 The key file name is given as argument to the program allowing
2533 selection of the right password if you have multiple encrypted
2538 OPTIONS RELATING TO EXTERNAL SSL_CRTD
2539 -----------------------------------------------------------------------------
2542 NAME: sslcrtd_program
2545 DEFAULT: @DEFAULT_SSL_CRTD@ -s @DEFAULT_SSL_DB_DIR@ -M 4MB
2546 LOC: Ssl::TheConfig.ssl_crtd
2548 Specify the location and options of the executable for ssl_crtd process.
2549 @DEFAULT_SSL_CRTD@ program requires -s and -M parameters
2550 For more information use:
2551 @DEFAULT_SSL_CRTD@ -h
2554 NAME: sslcrtd_children
2555 TYPE: HelperChildConfig
2557 DEFAULT: 32 startup=5 idle=1
2558 LOC: Ssl::TheConfig.ssl_crtdChildren
2560 The maximum number of processes spawn to service ssl server.
2561 The maximum this may be safely set to is 32.
2563 The startup= and idle= options allow some measure of skew in your
2568 Sets the minimum number of processes to spawn when Squid
2569 starts or reconfigures. When set to zero the first request will
2570 cause spawning of the first child process to handle it.
2572 Starting too few children temporary slows Squid under load while it
2573 tries to spawn enough additional processes to cope with traffic.
2577 Sets a minimum of how many processes Squid is to try and keep available
2578 at all times. When traffic begins to rise above what the existing
2579 processes can handle this many more will be spawned up to the maximum
2580 configured. A minimum setting of 1 is required.
2582 You must have at least one ssl_crtd process.
2585 NAME: sslcrtvalidator_program
2589 LOC: Ssl::TheConfig.ssl_crt_validator
2591 Specify the location and options of the executable for ssl_crt_validator
2594 Usage: sslcrtvalidator_program [ttl=n] [cache=n] path ...
2597 ttl=n TTL in seconds for cached results. The default is 60 secs
2598 cache=n limit the result cache size. The default value is 2048
2601 NAME: sslcrtvalidator_children
2602 TYPE: HelperChildConfig
2604 DEFAULT: 32 startup=5 idle=1 concurrency=1
2605 LOC: Ssl::TheConfig.ssl_crt_validator_Children
2607 The maximum number of processes spawn to service SSL server.
2608 The maximum this may be safely set to is 32.
2610 The startup= and idle= options allow some measure of skew in your
2615 Sets the minimum number of processes to spawn when Squid
2616 starts or reconfigures. When set to zero the first request will
2617 cause spawning of the first child process to handle it.
2619 Starting too few children temporary slows Squid under load while it
2620 tries to spawn enough additional processes to cope with traffic.
2624 Sets a minimum of how many processes Squid is to try and keep available
2625 at all times. When traffic begins to rise above what the existing
2626 processes can handle this many more will be spawned up to the maximum
2627 configured. A minimum setting of 1 is required.
2631 The number of requests each certificate validator helper can handle in
2632 parallel. A value of 0 indicates the certficate validator does not
2633 support concurrency. Defaults to 1.
2635 When this directive is set to a value >= 1 then the protocol
2636 used to communicate with the helper is modified to include
2637 a request ID in front of the request/response. The request
2638 ID from the request must be echoed back with the response
2641 You must have at least one ssl_crt_validator process.
2645 OPTIONS WHICH AFFECT THE NEIGHBOR SELECTION ALGORITHM
2646 -----------------------------------------------------------------------------
2654 To specify other caches in a hierarchy, use the format:
2656 cache_peer hostname type http-port icp-port [options]
2661 # hostname type port port options
2662 # -------------------- -------- ----- ----- -----------
2663 cache_peer parent.foo.net parent 3128 3130 default
2664 cache_peer sib1.foo.net sibling 3128 3130 proxy-only
2665 cache_peer sib2.foo.net sibling 3128 3130 proxy-only
2666 cache_peer example.com parent 80 0 default
2667 cache_peer cdn.example.com sibling 3128 0
2669 type: either 'parent', 'sibling', or 'multicast'.
2671 proxy-port: The port number where the peer accept HTTP requests.
2672 For other Squid proxies this is usually 3128
2673 For web servers this is usually 80
2675 icp-port: Used for querying neighbor caches about objects.
2676 Set to 0 if the peer does not support ICP or HTCP.
2677 See ICP and HTCP options below for additional details.
2680 ==== ICP OPTIONS ====
2682 You MUST also set icp_port and icp_access explicitly when using these options.
2683 The defaults will prevent peer traffic using ICP.
2686 no-query Disable ICP queries to this neighbor.
2689 Indicates the named peer is a member of a multicast group.
2690 ICP queries will not be sent directly to the peer, but ICP
2691 replies will be accepted from it.
2693 closest-only Indicates that, for ICP_OP_MISS replies, we'll only forward
2694 CLOSEST_PARENT_MISSes and never FIRST_PARENT_MISSes.
2697 To only send ICP queries to this neighbor infrequently.
2698 This is used to keep the neighbor round trip time updated
2699 and is usually used in conjunction with weighted-round-robin.
2702 ==== HTCP OPTIONS ====
2704 You MUST also set htcp_port and htcp_access explicitly when using these options.
2705 The defaults will prevent peer traffic using HTCP.
2708 htcp Send HTCP, instead of ICP, queries to the neighbor.
2709 You probably also want to set the "icp-port" to 4827
2710 instead of 3130. This directive accepts a comma separated
2711 list of options described below.
2713 htcp=oldsquid Send HTCP to old Squid versions (2.5 or earlier).
2715 htcp=no-clr Send HTCP to the neighbor but without
2716 sending any CLR requests. This cannot be used with
2719 htcp=only-clr Send HTCP to the neighbor but ONLY CLR requests.
2720 This cannot be used with no-clr.
2723 Send HTCP to the neighbor including CLRs but only when
2724 they do not result from PURGE requests.
2727 Forward any HTCP CLR requests this proxy receives to the peer.
2730 ==== PEER SELECTION METHODS ====
2732 The default peer selection method is ICP, with the first responding peer
2733 being used as source. These options can be used for better load balancing.
2736 default This is a parent cache which can be used as a "last-resort"
2737 if a peer cannot be located by any of the peer-selection methods.
2738 If specified more than once, only the first is used.
2740 round-robin Load-Balance parents which should be used in a round-robin
2741 fashion in the absence of any ICP queries.
2742 weight=N can be used to add bias.
2744 weighted-round-robin
2745 Load-Balance parents which should be used in a round-robin
2746 fashion with the frequency of each parent being based on the
2747 round trip time. Closer parents are used more often.
2748 Usually used for background-ping parents.
2749 weight=N can be used to add bias.
2751 carp Load-Balance parents which should be used as a CARP array.
2752 The requests will be distributed among the parents based on the
2753 CARP load balancing hash function based on their weight.
2755 userhash Load-balance parents based on the client proxy_auth or ident username.
2757 sourcehash Load-balance parents based on the client source IP.
2760 To be used only for cache peers of type "multicast".
2761 ALL members of this multicast group have "sibling"
2762 relationship with it, not "parent". This is to a multicast
2763 group when the requested object would be fetched only from
2764 a "parent" cache, anyway. It's useful, e.g., when
2765 configuring a pool of redundant Squid proxies, being
2766 members of the same multicast group.
2769 ==== PEER SELECTION OPTIONS ====
2771 weight=N use to affect the selection of a peer during any weighted
2772 peer-selection mechanisms.
2773 The weight must be an integer; default is 1,
2774 larger weights are favored more.
2775 This option does not affect parent selection if a peering
2776 protocol is not in use.
2778 basetime=N Specify a base amount to be subtracted from round trip
2780 It is subtracted before division by weight in calculating
2781 which parent to fectch from. If the rtt is less than the
2782 base time the rtt is set to a minimal value.
2784 ttl=N Specify a TTL to use when sending multicast ICP queries
2786 Only useful when sending to a multicast group.
2787 Because we don't accept ICP replies from random
2788 hosts, you must configure other group members as
2789 peers with the 'multicast-responder' option.
2791 no-delay To prevent access to this neighbor from influencing the
2794 digest-url=URL Tell Squid to fetch the cache digest (if digests are
2795 enabled) for this host from the specified URL rather
2796 than the Squid default location.
2799 ==== CARP OPTIONS ====
2801 carp-key=key-specification
2802 use a different key than the full URL to hash against the peer.
2803 the key-specification is a comma-separated list of the keywords
2804 scheme, host, port, path, params
2805 Order is not important.
2807 ==== ACCELERATOR / REVERSE-PROXY OPTIONS ====
2809 originserver Causes this parent to be contacted as an origin server.
2810 Meant to be used in accelerator setups when the peer
2814 Set the Host header of requests forwarded to this peer.
2815 Useful in accelerator setups where the server (peer)
2816 expects a certain domain name but clients may request
2817 others. ie example.com or www.example.com
2819 no-digest Disable request of cache digests.
2822 Disables requesting ICMP RTT database (NetDB).
2825 ==== AUTHENTICATION OPTIONS ====
2828 If this is a personal/workgroup proxy and your parent
2829 requires proxy authentication.
2831 Note: The string can include URL escapes (i.e. %20 for
2832 spaces). This also means % must be written as %%.
2835 Send login details received from client to this peer.
2836 Both Proxy- and WWW-Authorization headers are passed
2837 without alteration to the peer.
2838 Authentication is not required by Squid for this to work.
2840 Note: This will pass any form of authentication but
2841 only Basic auth will work through a proxy unless the
2842 connection-auth options are also used.
2844 login=PASS Send login details received from client to this peer.
2845 Authentication is not required by this option.
2847 If there are no client-provided authentication headers
2848 to pass on, but username and password are available
2849 from an external ACL user= and password= result tags
2850 they may be sent instead.
2852 Note: To combine this with proxy_auth both proxies must
2853 share the same user database as HTTP only allows for
2854 a single login (one for proxy, one for origin server).
2855 Also be warned this will expose your users proxy
2856 password to the peer. USE WITH CAUTION
2859 Send the username to the upstream cache, but with a
2860 fixed password. This is meant to be used when the peer
2861 is in another administrative domain, but it is still
2862 needed to identify each user.
2863 The star can optionally be followed by some extra
2864 information which is added to the username. This can
2865 be used to identify this proxy to the peer, similar to
2866 the login=username:password option above.
2869 If this is a personal/workgroup proxy and your parent
2870 requires a secure proxy authentication.
2871 The first principal from the default keytab or defined by
2872 the environment variable KRB5_KTNAME will be used.
2874 WARNING: The connection may transmit requests from multiple
2875 clients. Negotiate often assumes end-to-end authentication
2876 and a single-client. Which is not strictly true here.
2878 login=NEGOTIATE:principal_name
2879 If this is a personal/workgroup proxy and your parent
2880 requires a secure proxy authentication.
2881 The principal principal_name from the default keytab or
2882 defined by the environment variable KRB5_KTNAME will be
2885 WARNING: The connection may transmit requests from multiple
2886 clients. Negotiate often assumes end-to-end authentication
2887 and a single-client. Which is not strictly true here.
2889 connection-auth=on|off
2890 Tell Squid that this peer does or not support Microsoft
2891 connection oriented authentication, and any such
2892 challenges received from there should be ignored.
2893 Default is auto to automatically determine the status
2897 ==== SSL / HTTPS / TLS OPTIONS ====
2899 ssl Encrypt connections to this peer with SSL/TLS.
2901 sslcert=/path/to/ssl/certificate
2902 A client SSL certificate to use when connecting to
2905 sslkey=/path/to/ssl/key
2906 The private SSL key corresponding to sslcert above.
2907 If 'sslkey' is not specified 'sslcert' is assumed to
2908 reference a combined file containing both the
2909 certificate and the key.
2911 sslversion=1|2|3|4|5|6
2912 The SSL version to use when connecting to this peer
2913 1 = automatic (default)
2920 sslcipher=... The list of valid SSL ciphers to use when connecting
2923 ssloptions=... Specify various SSL implementation options:
2925 NO_SSLv2 Disallow the use of SSLv2
2926 NO_SSLv3 Disallow the use of SSLv3
2927 NO_TLSv1 Disallow the use of TLSv1.0
2928 NO_TLSv1_1 Disallow the use of TLSv1.1
2929 NO_TLSv1_2 Disallow the use of TLSv1.2
2931 Always create a new key when using
2932 temporary/ephemeral DH key exchanges
2933 ALL Enable various bug workarounds
2934 suggested as "harmless" by OpenSSL
2935 Be warned that this reduces SSL/TLS
2936 strength to some attacks.
2938 See the OpenSSL SSL_CTX_set_options documentation for a
2941 sslcafile=... A file containing additional CA certificates to use
2942 when verifying the peer certificate.
2944 sslcapath=... A directory containing additional CA certificates to
2945 use when verifying the peer certificate.
2947 sslcrlfile=... A certificate revocation list file to use when
2948 verifying the peer certificate.
2950 sslflags=... Specify various flags modifying the SSL implementation:
2953 Accept certificates even if they fail to
2956 Don't use the default CA list built in
2959 Don't verify the peer certificate
2960 matches the server name
2962 ssldomain= The peer name as advertised in it's certificate.
2963 Used for verifying the correctness of the received peer
2964 certificate. If not specified the peer hostname will be
2968 Enable the "Front-End-Https: On" header needed when
2969 using Squid as a SSL frontend in front of Microsoft OWA.
2970 See MS KB document Q307347 for details on this header.
2971 If set to auto the header will only be added if the
2972 request is forwarded as a https:// URL.
2975 ==== GENERAL OPTIONS ====
2978 A peer-specific connect timeout.
2979 Also see the peer_connect_timeout directive.
2981 connect-fail-limit=N
2982 How many times connecting to a peer must fail before
2983 it is marked as down. Standby connection failures
2984 count towards this limit. Default is 10.
2986 allow-miss Disable Squid's use of only-if-cached when forwarding
2987 requests to siblings. This is primarily useful when
2988 icp_hit_stale is used by the sibling. To extensive use
2989 of this option may result in forwarding loops, and you
2990 should avoid having two-way peerings with this option.
2991 For example to deny peer usage on requests from peer
2992 by denying cache_peer_access if the source is a peer.
2994 max-conn=N Limit the number of concurrent connections the Squid
2995 may open to this peer, including already opened idle
2996 and standby connections. There is no peer-specific
2997 connection limit by default.
2999 A peer exceeding the limit is not used for new
3000 requests unless a standby connection is available.
3002 max-conn currently works poorly with idle persistent
3003 connections: When a peer reaches its max-conn limit,
3004 and there are idle persistent connections to the peer,
3005 the peer may not be selected because the limiting code
3006 does not know whether Squid can reuse those idle
3009 standby=N Maintain a pool of N "hot standby" connections to an
3010 UP peer, available for requests when no idle
3011 persistent connection is available (or safe) to use.
3012 By default and with zero N, no such pool is maintained.
3013 N must not exceed the max-conn limit (if any).
3015 At start or after reconfiguration, Squid opens new TCP
3016 standby connections until there are N connections
3017 available and then replenishes the standby pool as
3018 opened connections are used up for requests. A used
3019 connection never goes back to the standby pool, but
3020 may go to the regular idle persistent connection pool
3021 shared by all peers and origin servers.
3023 Squid never opens multiple new standby connections
3024 concurrently. This one-at-a-time approach minimizes
3025 flooding-like effect on peers. Furthermore, just a few
3026 standby connections should be sufficient in most cases
3027 to supply most new requests with a ready-to-use
3030 Standby connections obey server_idle_pconn_timeout.
3031 For the feature to work as intended, the peer must be
3032 configured to accept and keep them open longer than
3033 the idle timeout at the connecting Squid, to minimize
3034 race conditions typical to idle used persistent
3035 connections. Default request_timeout and
3036 server_idle_pconn_timeout values ensure such a
3039 name=xxx Unique name for the peer.
3040 Required if you have multiple peers on the same host
3041 but different ports.
3042 This name can be used in cache_peer_access and similar
3043 directives to dentify the peer.
3044 Can be used by outgoing access controls through the
3047 no-tproxy Do not use the client-spoof TPROXY support when forwarding
3048 requests to this peer. Use normal address selection instead.
3049 This overrides the spoof_client_ip ACL.
3051 proxy-only objects fetched from the peer will not be stored locally.
3055 NAME: cache_peer_domain cache_host_domain
3060 Use to limit the domains for which a neighbor cache will be
3064 cache_peer_domain cache-host domain [domain ...]
3065 cache_peer_domain cache-host !domain
3067 For example, specifying
3069 cache_peer_domain parent.foo.net .edu
3071 has the effect such that UDP query packets are sent to
3072 'bigserver' only when the requested object exists on a
3073 server in the .edu domain. Prefixing the domainname
3074 with '!' means the cache will be queried for objects
3077 NOTE: * Any number of domains may be given for a cache-host,
3078 either on the same or separate lines.
3079 * When multiple domains are given for a particular
3080 cache-host, the first matched domain is applied.
3081 * Cache hosts with no domain restrictions are queried
3083 * There are no defaults.
3084 * There is also a 'cache_peer_access' tag in the ACL
3088 NAME: cache_peer_access
3093 Similar to 'cache_peer_domain' but provides more flexibility by
3097 cache_peer_access cache-host allow|deny [!]aclname ...
3099 The syntax is identical to 'http_access' and the other lists of
3100 ACL elements. See the comments for 'http_access' below, or
3101 the Squid FAQ (http://wiki.squid-cache.org/SquidFaq/SquidAcl).
3104 NAME: neighbor_type_domain
3105 TYPE: hostdomaintype
3107 DEFAULT_DOC: The peer type from cache_peer directive is used for all requests to that peer.
3110 Modify the cache_peer neighbor type when passing requests
3111 about specific domains to the peer.
3114 neighbor_type_domain neighbor parent|sibling domain domain ...
3117 cache_peer foo.example.com parent 3128 3130
3118 neighbor_type_domain foo.example.com sibling .au .de
3120 The above configuration treats all requests to foo.example.com as a
3121 parent proxy unless the request is for a .au or .de ccTLD domain name.
3124 NAME: dead_peer_timeout
3128 LOC: Config.Timeout.deadPeer
3130 This controls how long Squid waits to declare a peer cache
3131 as "dead." If there are no ICP replies received in this
3132 amount of time, Squid will declare the peer dead and not
3133 expect to receive any further ICP replies. However, it
3134 continues to send ICP queries, and will mark the peer as
3135 alive upon receipt of the first subsequent ICP reply.
3137 This timeout also affects when Squid expects to receive ICP
3138 replies from peers. If more than 'dead_peer' seconds have
3139 passed since the last ICP reply was received, Squid will not
3140 expect to receive an ICP reply on the next query. Thus, if
3141 your time between requests is greater than this timeout, you
3142 will see a lot of requests sent DIRECT to origin servers
3143 instead of to your parents.
3146 NAME: forward_max_tries
3149 LOC: Config.forward_max_tries
3151 Controls how many different forward paths Squid will try
3152 before giving up. See also forward_timeout.
3154 NOTE: connect_retries (default: none) can make each of these
3155 possible forwarding paths be tried multiple times.
3158 NAME: hierarchy_stoplist
3161 LOC: Config.hierarchy_stoplist
3163 A list of words which, if found in a URL, cause the object to
3164 be handled directly by this cache. In other words, use this
3165 to not query neighbor caches for certain objects. You may
3166 list this option multiple times.
3169 hierarchy_stoplist cgi-bin ?
3171 Note: never_direct overrides this option.
3175 MEMORY CACHE OPTIONS
3176 -----------------------------------------------------------------------------
3183 LOC: Config.memMaxSize
3185 NOTE: THIS PARAMETER DOES NOT SPECIFY THE MAXIMUM PROCESS SIZE.
3186 IT ONLY PLACES A LIMIT ON HOW MUCH ADDITIONAL MEMORY SQUID WILL
3187 USE AS A MEMORY CACHE OF OBJECTS. SQUID USES MEMORY FOR OTHER
3188 THINGS AS WELL. SEE THE SQUID FAQ SECTION 8 FOR DETAILS.
3190 'cache_mem' specifies the ideal amount of memory to be used
3192 * In-Transit objects
3194 * Negative-Cached objects
3196 Data for these objects are stored in 4 KB blocks. This
3197 parameter specifies the ideal upper limit on the total size of
3198 4 KB blocks allocated. In-Transit objects take the highest
3201 In-transit objects have priority over the others. When
3202 additional space is needed for incoming data, negative-cached
3203 and hot objects will be released. In other words, the
3204 negative-cached and hot objects will fill up any unused space
3205 not needed for in-transit objects.
3207 If circumstances require, this limit will be exceeded.
3208 Specifically, if your incoming request rate requires more than
3209 'cache_mem' of memory to hold in-transit objects, Squid will
3210 exceed this limit to satisfy the new requests. When the load
3211 decreases, blocks will be freed until the high-water mark is
3212 reached. Thereafter, blocks will be used to store hot
3215 If shared memory caching is enabled, Squid does not use the shared
3216 cache space for in-transit objects, but they still consume as much
3217 local memory as they need. For more details about the shared memory
3218 cache, see memory_cache_shared.
3221 NAME: maximum_object_size_in_memory
3225 LOC: Config.Store.maxInMemObjSize
3227 Objects greater than this size will not be attempted to kept in
3228 the memory cache. This should be set high enough to keep objects
3229 accessed frequently in memory to improve performance whilst low
3230 enough to keep larger objects from hoarding cache_mem.
3233 NAME: memory_cache_shared
3236 LOC: Config.memShared
3238 DEFAULT_DOC: "on" where supported if doing memory caching with multiple SMP workers.
3240 Controls whether the memory cache is shared among SMP workers.
3242 The shared memory cache is meant to occupy cache_mem bytes and replace
3243 the non-shared memory cache, although some entities may still be
3244 cached locally by workers for now (e.g., internal and in-transit
3245 objects may be served from a local memory cache even if shared memory
3246 caching is enabled).
3248 By default, the memory cache is shared if and only if all of the
3249 following conditions are satisfied: Squid runs in SMP mode with
3250 multiple workers, cache_mem is positive, and Squid environment
3251 supports required IPC primitives (e.g., POSIX shared memory segments
3252 and GCC-style atomic operations).
3254 To avoid blocking locks, shared memory uses opportunistic algorithms
3255 that do not guarantee that every cachable entity that could have been
3256 shared among SMP workers will actually be shared.
3258 Currently, entities exceeding 32KB in size cannot be shared.
3261 NAME: memory_cache_mode
3265 DEFAULT_DOC: Keep the most recently fetched objects in memory
3267 Controls which objects to keep in the memory cache (cache_mem)
3269 always Keep most recently fetched objects in memory (default)
3271 disk Only disk cache hits are kept in memory, which means
3272 an object must first be cached on disk and then hit
3273 a second time before cached in memory.
3275 network Only objects fetched from network is kept in memory
3278 NAME: memory_replacement_policy
3280 LOC: Config.memPolicy
3283 The memory replacement policy parameter determines which
3284 objects are purged from memory when memory space is needed.
3286 See cache_replacement_policy for details on algorithms.
3291 -----------------------------------------------------------------------------
3294 NAME: cache_replacement_policy
3296 LOC: Config.replPolicy
3299 The cache replacement policy parameter determines which
3300 objects are evicted (replaced) when disk space is needed.
3302 lru : Squid's original list based LRU policy
3303 heap GDSF : Greedy-Dual Size Frequency
3304 heap LFUDA: Least Frequently Used with Dynamic Aging
3305 heap LRU : LRU policy implemented using a heap
3307 Applies to any cache_dir lines listed below this directive.
3309 The LRU policies keeps recently referenced objects.
3311 The heap GDSF policy optimizes object hit rate by keeping smaller
3312 popular objects in cache so it has a better chance of getting a
3313 hit. It achieves a lower byte hit rate than LFUDA though since
3314 it evicts larger (possibly popular) objects.
3316 The heap LFUDA policy keeps popular objects in cache regardless of
3317 their size and thus optimizes byte hit rate at the expense of
3318 hit rate since one large, popular object will prevent many
3319 smaller, slightly less popular objects from being cached.
3321 Both policies utilize a dynamic aging mechanism that prevents
3322 cache pollution that can otherwise occur with frequency-based
3323 replacement policies.
3325 NOTE: if using the LFUDA replacement policy you should increase
3326 the value of maximum_object_size above its default of 4 MB to
3327 to maximize the potential byte hit rate improvement of LFUDA.
3329 For more information about the GDSF and LFUDA cache replacement
3330 policies see http://www.hpl.hp.com/techreports/1999/HPL-1999-69.html
3331 and http://fog.hpl.external.hp.com/techreports/98/HPL-98-173.html.
3334 NAME: minimum_object_size
3338 DEFAULT_DOC: no limit
3339 LOC: Config.Store.minObjectSize
3341 Objects smaller than this size will NOT be saved on disk. The
3342 value is specified in bytes, and the default is 0 KB, which
3343 means all responses can be stored.
3346 NAME: maximum_object_size
3350 LOC: Config.Store.maxObjectSize
3352 Set the default value for max-size parameter on any cache_dir.
3353 The value is specified in bytes, and the default is 4 MB.
3355 If you wish to get a high BYTES hit ratio, you should probably
3356 increase this (one 32 MB object hit counts for 3200 10KB
3359 If you wish to increase hit ratio more than you want to
3360 save bandwidth you should leave this low.
3362 NOTE: if using the LFUDA replacement policy you should increase
3363 this value to maximize the byte hit rate improvement of LFUDA!
3364 See cache_replacement_policy for a discussion of this policy.
3370 DEFAULT_DOC: No disk cache. Store cache ojects only in memory.
3371 LOC: Config.cacheSwap
3374 cache_dir Type Directory-Name Fs-specific-data [options]
3376 You can specify multiple cache_dir lines to spread the
3377 cache among different disk partitions.
3379 Type specifies the kind of storage system to use. Only "ufs"
3380 is built by default. To enable any of the other storage systems
3381 see the --enable-storeio configure option.
3383 'Directory' is a top-level directory where cache swap
3384 files will be stored. If you want to use an entire disk
3385 for caching, this can be the mount-point directory.
3386 The directory must exist and be writable by the Squid
3387 process. Squid will NOT create this directory for you.
3389 In SMP configurations, cache_dir must not precede the workers option
3390 and should use configuration macros or conditionals to give each
3391 worker interested in disk caching a dedicated cache directory.
3394 ==== The ufs store type ====
3396 "ufs" is the old well-known Squid storage format that has always
3400 cache_dir ufs Directory-Name Mbytes L1 L2 [options]
3402 'Mbytes' is the amount of disk space (MB) to use under this
3403 directory. The default is 100 MB. Change this to suit your
3404 configuration. Do NOT put the size of your disk drive here.
3405 Instead, if you want Squid to use the entire disk drive,
3406 subtract 20% and use that value.
3408 'L1' is the number of first-level subdirectories which
3409 will be created under the 'Directory'. The default is 16.
3411 'L2' is the number of second-level subdirectories which
3412 will be created under each first-level directory. The default
3416 ==== The aufs store type ====
3418 "aufs" uses the same storage format as "ufs", utilizing
3419 POSIX-threads to avoid blocking the main Squid process on
3420 disk-I/O. This was formerly known in Squid as async-io.
3423 cache_dir aufs Directory-Name Mbytes L1 L2 [options]
3425 see argument descriptions under ufs above
3428 ==== The diskd store type ====
3430 "diskd" uses the same storage format as "ufs", utilizing a
3431 separate process to avoid blocking the main Squid process on
3435 cache_dir diskd Directory-Name Mbytes L1 L2 [options] [Q1=n] [Q2=n]
3437 see argument descriptions under ufs above
3439 Q1 specifies the number of unacknowledged I/O requests when Squid
3440 stops opening new files. If this many messages are in the queues,
3441 Squid won't open new files. Default is 64
3443 Q2 specifies the number of unacknowledged messages when Squid
3444 starts blocking. If this many messages are in the queues,
3445 Squid blocks until it receives some replies. Default is 72
3447 When Q1 < Q2 (the default), the cache directory is optimized
3448 for lower response time at the expense of a decrease in hit
3449 ratio. If Q1 > Q2, the cache directory is optimized for
3450 higher hit ratio at the expense of an increase in response
3454 ==== The rock store type ====
3457 cache_dir rock Directory-Name Mbytes [options]
3459 The Rock Store type is a database-style storage. All cached
3460 entries are stored in a "database" file, using fixed-size slots.
3461 A single entry occupies one or more slots.
3463 If possible, Squid using Rock Store creates a dedicated kid
3464 process called "disker" to avoid blocking Squid worker(s) on disk
3465 I/O. One disker kid is created for each rock cache_dir. Diskers
3466 are created only when Squid, running in daemon mode, has support
3467 for the IpcIo disk I/O module.
3469 swap-timeout=msec: Squid will not start writing a miss to or
3470 reading a hit from disk if it estimates that the swap operation
3471 will take more than the specified number of milliseconds. By
3472 default and when set to zero, disables the disk I/O time limit
3473 enforcement. Ignored when using blocking I/O module because
3474 blocking synchronous I/O does not allow Squid to estimate the
3475 expected swap wait time.
3477 max-swap-rate=swaps/sec: Artificially limits disk access using
3478 the specified I/O rate limit. Swap out requests that
3479 would cause the average I/O rate to exceed the limit are
3480 delayed. Individual swap in requests (i.e., hits or reads) are
3481 not delayed, but they do contribute to measured swap rate and
3482 since they are placed in the same FIFO queue as swap out
3483 requests, they may wait longer if max-swap-rate is smaller.
3484 This is necessary on file systems that buffer "too
3485 many" writes and then start blocking Squid and other processes
3486 while committing those writes to disk. Usually used together
3487 with swap-timeout to avoid excessive delays and queue overflows
3488 when disk demand exceeds available disk "bandwidth". By default
3489 and when set to zero, disables the disk I/O rate limit
3490 enforcement. Currently supported by IpcIo module only.
3492 slot-size=bytes: The size of a database "record" used for
3493 storing cached responses. A cached response occupies at least
3494 one slot and all database I/O is done using individual slots so
3495 increasing this parameter leads to more disk space waste while
3496 decreasing it leads to more disk I/O overheads. Should be a
3497 multiple of your operating system I/O page size. Defaults to
3498 16KBytes. A housekeeping header is stored with each slot and
3499 smaller slot-sizes will be rejected. The header is smaller than
3503 ==== COMMON OPTIONS ====
3505 no-store no new objects should be stored to this cache_dir.
3507 min-size=n the minimum object size in bytes this cache_dir
3508 will accept. It's used to restrict a cache_dir
3509 to only store large objects (e.g. AUFS) while
3510 other stores are optimized for smaller objects
3514 max-size=n the maximum object size in bytes this cache_dir
3516 The value in maximum_object_size directive sets
3517 the default unless more specific details are
3518 available (ie a small store capacity).
3520 Note: To make optimal use of the max-size limits you should order
3521 the cache_dir lines with the smallest max-size value first.
3525 # Uncomment and adjust the following to add a disk cache directory.
3526 #cache_dir ufs @DEFAULT_SWAP_DIR@ 100 16 256
3530 NAME: store_dir_select_algorithm
3532 LOC: Config.store_dir_select_algorithm
3535 How Squid selects which cache_dir to use when the response
3536 object will fit into more than one.
3538 Regardless of which algorithm is used the cache_dir min-size
3539 and max-size parameters are obeyed. As such they can affect
3540 the selection algorithm by limiting the set of considered
3547 This algorithm is suited to caches with similar cache_dir
3548 sizes and disk speeds.
3550 The disk with the least I/O pending is selected.
3551 When there are multiple disks with the same I/O load ranking
3552 the cache_dir with most available capacity is selected.
3554 When a mix of cache_dir sizes are configured the faster disks
3555 have a naturally lower I/O loading and larger disks have more
3556 capacity. So space used to store objects and data throughput
3557 may be very unbalanced towards larger disks.
3562 This algorithm is suited to caches with unequal cache_dir
3565 Each cache_dir is selected in a rotation. The next suitable
3568 Available cache_dir capacity is only considered in relation
3569 to whether the object will fit and meets the min-size and
3570 max-size parameters.
3572 Disk I/O loading is only considered to prevent overload on slow
3573 disks. This algorithm does not spread objects by size, so any
3574 I/O loading per-disk may appear very unbalanced and volatile.
3578 NAME: max_open_disk_fds
3580 LOC: Config.max_open_disk_fds
3582 DEFAULT_DOC: no limit
3584 To avoid having disk as the I/O bottleneck Squid can optionally
3585 bypass the on-disk cache if more than this amount of disk file
3586 descriptors are open.
3588 A value of 0 indicates no limit.
3591 NAME: cache_swap_low
3592 COMMENT: (percent, 0-100)
3595 LOC: Config.Swap.lowWaterMark
3597 The low-water mark for cache object replacement.
3598 Replacement begins when the swap (disk) usage is above the
3599 low-water mark and attempts to maintain utilization near the
3600 low-water mark. As swap utilization gets close to high-water
3601 mark object eviction becomes more aggressive. If utilization is
3602 close to the low-water mark less replacement is done each time.
3604 Defaults are 90% and 95%. If you have a large cache, 5% could be
3605 hundreds of MB. If this is the case you may wish to set these
3606 numbers closer together.
3608 See also cache_swap_high
3611 NAME: cache_swap_high
3612 COMMENT: (percent, 0-100)
3615 LOC: Config.Swap.highWaterMark
3617 The high-water mark for cache object replacement.
3618 Replacement begins when the swap (disk) usage is above the
3619 low-water mark and attempts to maintain utilization near the
3620 low-water mark. As swap utilization gets close to high-water
3621 mark object eviction becomes more aggressive. If utilization is
3622 close to the low-water mark less replacement is done each time.
3624 Defaults are 90% and 95%. If you have a large cache, 5% could be
3625 hundreds of MB. If this is the case you may wish to set these
3626 numbers closer together.
3628 See also cache_swap_low
3633 -----------------------------------------------------------------------------
3640 DEFAULT_DOC: The format definitions squid, common, combined, referrer, useragent are built in.
3644 logformat <name> <format specification>
3646 Defines an access log format.
3648 The <format specification> is a string with embedded % format codes
3650 % format codes all follow the same basic structure where all but
3651 the formatcode is optional. Output strings are automatically escaped
3652 as required according to their context and the output format
3653 modifiers are usually not needed, but can be specified if an explicit
3654 output format is desired.
3656 % ["|[|'|#] [-] [[0]width] [{argument}] formatcode
3658 " output in quoted string format
3659 [ output in squid text log format as used by log_mime_hdrs
3660 # output in URL quoted format
3665 width minimum and/or maximum field width:
3666 [width_min][.width_max]
3667 When minimum starts with 0, the field is zero-padded.
3668 String values exceeding maximum width are truncated.
3670 {arg} argument such as header name etc
3674 % a literal % character
3675 sn Unique sequence number per log line entry
3676 err_code The ID of an error response served by Squid or
3677 a similar internal error identifier.
3678 err_detail Additional err_code-dependent error information.
3679 note The annotation specified by the argument. Also
3680 logs the adaptation meta headers set by the
3681 adaptation_meta configuration parameter.
3682 If no argument given all annotations logged.
3683 The argument may include a separator to use with
3686 By default, multiple note values are separated with ","
3687 and multiple notes are separated with "\r\n".
3688 When logging named notes with %{name}note, the
3689 explicitly configured separator is used between note
3690 values. When logging all notes with %note, the
3691 explicitly configured separator is used between
3692 individual notes. There is currently no way to
3693 specify both value and notes separators when logging
3694 all notes with %note.
3696 Connection related format codes:
3698 >a Client source IP address
3700 >p Client source port
3701 >eui Client source EUI (MAC address, EUI-48 or EUI-64 identifier)
3702 >la Local IP address the client connected to
3703 >lp Local port number the client connected to
3704 >qos Client connection TOS/DSCP value set by Squid
3705 >nfmark Client connection netfilter mark set by Squid
3707 la Local listening IP address the client connection was connected to.
3708 lp Local listening port number the client connection was connected to.
3710 <a Server IP address of the last server or peer connection
3711 <A Server FQDN or peer name
3712 <p Server port number of the last server or peer connection
3713 <la Local IP address of the last server or peer connection
3714 <lp Local port number of the last server or peer connection
3715 <qos Server connection TOS/DSCP value set by Squid
3716 <nfmark Server connection netfilter mark set by Squid
3718 Time related format codes:
3720 ts Seconds since epoch
3721 tu subsecond time (milliseconds)
3722 tl Local time. Optional strftime format argument
3723 default %d/%b/%Y:%H:%M:%S %z
3724 tg GMT time. Optional strftime format argument
3725 default %d/%b/%Y:%H:%M:%S %z
3726 tr Response time (milliseconds)
3727 dt Total time spent making DNS lookups (milliseconds)
3728 tS Approximate master transaction start time in
3729 <full seconds since epoch>.<fractional seconds> format.
3730 Currently, Squid considers the master transaction
3731 started when a complete HTTP request header initiating
3732 the transaction is received from the client. This is
3733 the same value that Squid uses to calculate transaction
3734 response time when logging %tr to access.log. Currently,
3735 Squid uses millisecond resolution for %tS values,
3736 similar to the default access.log "current time" field
3739 Access Control related format codes:
3741 et Tag returned by external acl
3742 ea Log string returned by external acl
3743 un User name (any available)
3744 ul User name from authentication
3745 ue User name from external acl helper
3746 ui User name from ident
3747 us User name from SSL
3748 credentials Client credentials. The exact meaning depends on
3749 the authentication scheme: For Basic authentication,
3750 it is the password; for Digest, the realm sent by the
3751 client; for NTLM and Negotiate, the client challenge
3752 or client credentials prefixed with "YR " or "KK ".
3754 HTTP related format codes:
3758 [http::]rm Request method (GET/POST etc)
3759 [http::]>rm Request method from client
3760 [http::]<rm Request method sent to server or peer
3761 [http::]ru Request URL from client (historic, filtered for logging)
3762 [http::]>ru Request URL from client
3763 [http::]<ru Request URL sent to server or peer
3764 [http::]>rs Request URL scheme from client
3765 [http::]<rs Request URL scheme sent to server or peer
3766 [http::]>rd Request URL domain from client
3767 [http::]>rd Request URL domain sent to server or peer
3768 [http::]>rP Request URL port from client
3769 [http::]<rP Request URL port sent to server or peer
3770 [http::]rp Request URL path excluding hostname
3771 [http::]>rp Request URL path excluding hostname from client
3772 [http::]<rp Request URL path excluding hostname sent to server or peer
3773 [http::]rv Request protocol version
3774 [http::]>rv Request protocol version from client
3775 [http::]<rv Request protocol version sent to server or peer
3777 [http::]>h Original received request header.
3778 Usually differs from the request header sent by
3779 Squid, although most fields are often preserved.
3780 Accepts optional header field name/value filter
3781 argument using name[:[separator]element] format.
3782 [http::]>ha Received request header after adaptation and
3783 redirection (pre-cache REQMOD vectoring point).
3784 Usually differs from the request header sent by
3785 Squid, although most fields are often preserved.
3786 Optional header name argument as for >h
3791 [http::]<Hs HTTP status code received from the next hop
3792 [http::]>Hs HTTP status code sent to the client
3794 [http::]<h Reply header. Optional header name argument
3797 [http::]mt MIME content type
3802 [http::]st Total size of request + reply traffic with client
3803 [http::]>st Total size of request received from client.
3804 Excluding chunked encoding bytes.
3805 [http::]<st Total size of reply sent to client (after adaptation)
3807 [http::]>sh Size of request headers received from client
3808 [http::]<sh Size of reply headers sent to client (after adaptation)
3810 [http::]<sH Reply high offset sent
3811 [http::]<sS Upstream object size
3813 [http::]<bs Number of HTTP-equivalent message body bytes
3814 received from the next hop, excluding chunked
3815 transfer encoding and control messages.
3816 Generated FTP/Gopher listings are treated as
3822 [http::]<pt Peer response time in milliseconds. The timer starts
3823 when the last request byte is sent to the next hop
3824 and stops when the last response byte is received.
3825 [http::]<tt Total server-side time in milliseconds. The timer
3826 starts with the first connect request (or write I/O)
3827 sent to the first selected peer. The timer stops
3828 with the last I/O with the last peer.
3830 Squid handling related format codes:
3832 Ss Squid request status (TCP_MISS etc)
3833 Sh Squid hierarchy status (DEFAULT_PARENT etc)
3835 SSL-related format codes:
3837 ssl::bump_mode SslBump decision for the transaction:
3839 For CONNECT requests that initiated bumping of
3840 a connection and for any request received on
3841 an already bumped connection, Squid logs the
3842 corresponding SslBump mode ("server-first" or
3843 "client-first"). See the ssl_bump option for
3844 more information about these modes.
3846 A "none" token is logged for requests that
3847 triggered "ssl_bump" ACL evaluation matching
3848 either a "none" rule or no rules at all.
3850 In all other cases, a single dash ("-") is
3853 If ICAP is enabled, the following code becomes available (as
3854 well as ICAP log codes documented with the icap_log option):
3856 icap::tt Total ICAP processing time for the HTTP
3857 transaction. The timer ticks when ICAP
3858 ACLs are checked and when ICAP
3859 transaction is in progress.
3861 If adaptation is enabled the following three codes become available:
3863 adapt::<last_h The header of the last ICAP response or
3864 meta-information from the last eCAP
3865 transaction related to the HTTP transaction.
3866 Like <h, accepts an optional header name
3869 adapt::sum_trs Summed adaptation transaction response
3870 times recorded as a comma-separated list in
3871 the order of transaction start time. Each time
3872 value is recorded as an integer number,
3873 representing response time of one or more
3874 adaptation (ICAP or eCAP) transaction in
3875 milliseconds. When a failed transaction is
3876 being retried or repeated, its time is not
3877 logged individually but added to the
3878 replacement (next) transaction. See also:
3881 adapt::all_trs All adaptation transaction response times.
3882 Same as adaptation_strs but response times of
3883 individual transactions are never added
3884 together. Instead, all transaction response
3885 times are recorded individually.
3887 You can prefix adapt::*_trs format codes with adaptation
3888 service name in curly braces to record response time(s) specific
3889 to that service. For example: %{my_service}adapt::sum_trs
3891 If SSL is enabled, the following formating codes become available:
3893 %ssl::>cert_subject The Subject field of the received client
3894 SSL certificate or a dash ('-') if Squid has
3895 received an invalid/malformed certificate or
3896 no certificate at all. Consider encoding the
3897 logged value because Subject often has spaces.
3899 %ssl::>cert_issuer The Issuer field of the received client
3900 SSL certificate or a dash ('-') if Squid has
3901 received an invalid/malformed certificate or
3902 no certificate at all. Consider encoding the
3903 logged value because Issuer often has spaces.
3905 The default formats available (which do not need re-defining) are:
3907 logformat squid %ts.%03tu %6tr %>a %Ss/%03>Hs %<st %rm %ru %[un %Sh/%<a %mt
3908 logformat common %>a %[ui %[un [%tl] "%rm %ru HTTP/%rv" %>Hs %<st %Ss:%Sh
3909 logformat combined %>a %[ui %[un [%tl] "%rm %ru HTTP/%rv" %>Hs %<st "%{Referer}>h" "%{User-Agent}>h" %Ss:%Sh
3910 logformat referrer %ts.%03tu %>a %{Referer}>h %ru
3911 logformat useragent %>a [%tl] "%{User-Agent}>h"
3913 NOTE: When the log_mime_hdrs directive is set to ON.
3914 The squid, common and combined formats have a safely encoded copy
3915 of the mime headers appended to each line within a pair of brackets.
3917 NOTE: The common and combined formats are not quite true to the Apache definition.
3918 The logs from Squid contain an extra status and hierarchy code appended.
3922 NAME: access_log cache_access_log
3924 LOC: Config.Log.accesslogs
3925 DEFAULT_IF_NONE: daemon:@DEFAULT_ACCESS_LOG@ squid
3927 Configures whether and how Squid logs HTTP and ICP transactions.
3928 If access logging is enabled, a single line is logged for every
3929 matching HTTP or ICP request. The recommended directive formats are:
3931 access_log <module>:<place> [option ...] [acl acl ...]
3932 access_log none [acl acl ...]
3934 The following directive format is accepted but may be deprecated:
3935 access_log <module>:<place> [<logformat name> [acl acl ...]]
3937 In most cases, the first ACL name must not contain the '=' character
3938 and should not be equal to an existing logformat name. You can always
3939 start with an 'all' ACL to work around those restrictions.
3941 Will log to the specified module:place using the specified format (which
3942 must be defined in a logformat directive) those entries which match
3943 ALL the acl's specified (which must be defined in acl clauses).
3944 If no acl is specified, all requests will be logged to this destination.
3946 ===== Available options for the recommended directive format =====
3948 logformat=name Names log line format (either built-in or
3949 defined by a logformat directive). Defaults
3952 buffer-size=64KB Defines approximate buffering limit for log
3953 records (see buffered_logs). Squid should not
3954 keep more than the specified size and, hence,
3955 should flush records before the buffer becomes
3956 full to avoid overflows under normal
3957 conditions (the exact flushing algorithm is
3958 module-dependent though). The on-error option
3959 controls overflow handling.
3961 on-error=die|drop Defines action on unrecoverable errors. The
3962 'drop' action ignores (i.e., does not log)
3963 affected log records. The default 'die' action
3964 kills the affected worker. The drop action
3965 support has not been tested for modules other
3968 ===== Modules Currently available =====
3970 none Do not log any requests matching these ACL.
3971 Do not specify Place or logformat name.
3973 stdio Write each log line to disk immediately at the completion of
3975 Place: the filename and path to be written.
3977 daemon Very similar to stdio. But instead of writing to disk the log
3978 line is passed to a daemon helper for asychronous handling instead.
3979 Place: varies depending on the daemon.
3981 log_file_daemon Place: the file name and path to be written.
3983 syslog To log each request via syslog facility.
3984 Place: The syslog facility and priority level for these entries.
3985 Place Format: facility.priority
3987 where facility could be any of:
3988 authpriv, daemon, local0 ... local7 or user.
3990 And priority could be any of:
3991 err, warning, notice, info, debug.
3993 udp To send each log line as text data to a UDP receiver.
3994 Place: The destination host name or IP and port.
3995 Place Format: //host:port
3997 tcp To send each log line as text data to a TCP receiver.
3998 Lines may be accumulated before sending (see buffered_logs).
3999 Place: The destination host name or IP and port.
4000 Place Format: //host:port
4003 access_log daemon:@DEFAULT_ACCESS_LOG@ squid
4009 LOC: Config.Log.icaplogs
4012 ICAP log files record ICAP transaction summaries, one line per
4015 The icap_log option format is:
4016 icap_log <filepath> [<logformat name> [acl acl ...]]
4017 icap_log none [acl acl ...]]
4019 Please see access_log option documentation for details. The two
4020 kinds of logs share the overall configuration approach and many
4023 ICAP processing of a single HTTP message or transaction may
4024 require multiple ICAP transactions. In such cases, multiple
4025 ICAP transaction log lines will correspond to a single access
4028 ICAP log uses logformat codes that make sense for an ICAP
4029 transaction. Header-related codes are applied to the HTTP header
4030 embedded in an ICAP server response, with the following caveats:
4031 For REQMOD, there is no HTTP response header unless the ICAP
4032 server performed request satisfaction. For RESPMOD, the HTTP
4033 request header is the header sent to the ICAP server. For
4034 OPTIONS, there are no HTTP headers.
4036 The following format codes are also available for ICAP logs:
4038 icap::<A ICAP server IP address. Similar to <A.
4040 icap::<service_name ICAP service name from the icap_service
4041 option in Squid configuration file.
4043 icap::ru ICAP Request-URI. Similar to ru.
4045 icap::rm ICAP request method (REQMOD, RESPMOD, or
4046 OPTIONS). Similar to existing rm.
4048 icap::>st Bytes sent to the ICAP server (TCP payload
4049 only; i.e., what Squid writes to the socket).
4051 icap::<st Bytes received from the ICAP server (TCP
4052 payload only; i.e., what Squid reads from
4055 icap::<bs Number of message body bytes received from the
4056 ICAP server. ICAP message body, if any, usually
4057 includes encapsulated HTTP message headers and
4058 possibly encapsulated HTTP message body. The
4059 HTTP body part is dechunked before its size is
4062 icap::tr Transaction response time (in
4063 milliseconds). The timer starts when
4064 the ICAP transaction is created and
4065 stops when the transaction is completed.
4068 icap::tio Transaction I/O time (in milliseconds). The
4069 timer starts when the first ICAP request
4070 byte is scheduled for sending. The timers
4071 stops when the last byte of the ICAP response
4074 icap::to Transaction outcome: ICAP_ERR* for all
4075 transaction errors, ICAP_OPT for OPTION
4076 transactions, ICAP_ECHO for 204
4077 responses, ICAP_MOD for message
4078 modification, and ICAP_SAT for request
4079 satisfaction. Similar to Ss.
4081 icap::Hs ICAP response status code. Similar to Hs.
4083 icap::>h ICAP request header(s). Similar to >h.
4085 icap::<h ICAP response header(s). Similar to <h.
4087 The default ICAP log format, which can be used without an explicit
4088 definition, is called icap_squid:
4090 logformat icap_squid %ts.%03tu %6icap::tr %>a %icap::to/%03icap::Hs %icap::<size %icap::rm %icap::ru% %un -/%icap::<A -
4092 See also: logformat, log_icap, and %adapt::<last_h
4095 NAME: logfile_daemon
4097 DEFAULT: @DEFAULT_LOGFILED@
4098 LOC: Log::TheConfig.logfile_daemon
4100 Specify the path to the logfile-writing daemon. This daemon is
4101 used to write the access and store logs, if configured.
4103 Squid sends a number of commands to the log daemon:
4104 L<data>\n - logfile data
4109 r<n>\n - set rotate count to <n>
4110 b<n>\n - 1 = buffer output, 0 = don't buffer output
4112 No responses is expected.
4118 Remove this line. Use acls with access_log directives to control access logging
4124 Remove this line. Use acls with icap_log directives to control icap logging
4127 NAME: stats_collection
4129 LOC: Config.accessList.stats_collection
4131 DEFAULT_DOC: Allow logging for all transactions.
4132 COMMENT: allow|deny acl acl...
4134 This options allows you to control which requests gets accounted
4135 in performance counters.
4137 This clause only supports fast acl types.
4138 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
4141 NAME: cache_store_log
4144 LOC: Config.Log.store
4146 Logs the activities of the storage manager. Shows which
4147 objects are ejected from the cache, and which objects are
4148 saved and for how long.
4149 There are not really utilities to analyze this data, so you can safely
4150 disable it (the default).
4152 Store log uses modular logging outputs. See access_log for the list
4153 of modules supported.
4156 cache_store_log stdio:@DEFAULT_STORE_LOG@
4157 cache_store_log daemon:@DEFAULT_STORE_LOG@
4160 NAME: cache_swap_state cache_swap_log
4162 LOC: Config.Log.swap
4164 DEFAULT_DOC: Store the journal inside its cache_dir
4166 Location for the cache "swap.state" file. This index file holds
4167 the metadata of objects saved on disk. It is used to rebuild
4168 the cache during startup. Normally this file resides in each
4169 'cache_dir' directory, but you may specify an alternate
4170 pathname here. Note you must give a full filename, not just
4171 a directory. Since this is the index for the whole object
4172 list you CANNOT periodically rotate it!
4174 If %s can be used in the file name it will be replaced with a
4175 a representation of the cache_dir name where each / is replaced
4176 with '.'. This is needed to allow adding/removing cache_dir
4177 lines when cache_swap_log is being used.
4179 If have more than one 'cache_dir', and %s is not used in the name
4180 these swap logs will have names such as:
4186 The numbered extension (which is added automatically)
4187 corresponds to the order of the 'cache_dir' lines in this
4188 configuration file. If you change the order of the 'cache_dir'
4189 lines in this file, these index files will NOT correspond to
4190 the correct 'cache_dir' entry (unless you manually rename
4191 them). We recommend you do NOT use this option. It is
4192 better to keep these index files in each 'cache_dir' directory.
4195 NAME: logfile_rotate
4198 LOC: Config.Log.rotateNumber
4200 Specifies the number of logfile rotations to make when you
4201 type 'squid -k rotate'. The default is 10, which will rotate
4202 with extensions 0 through 9. Setting logfile_rotate to 0 will
4203 disable the file name rotation, but the logfiles are still closed
4204 and re-opened. This will enable you to rename the logfiles
4205 yourself just before sending the rotate signal.
4207 Note, the 'squid -k rotate' command normally sends a USR1
4208 signal to the running squid process. In certain situations
4209 (e.g. on Linux with Async I/O), USR1 is used for other
4210 purposes, so -k rotate uses another signal. It is best to get
4211 in the habit of using 'squid -k rotate' instead of 'kill -USR1
4214 Note, from Squid-3.1 this option is only a default for cache.log,
4215 that log can be rotated separately by using debug_options.
4218 NAME: emulate_httpd_log
4221 Replace this with an access_log directive using the format 'common' or 'combined'.
4224 NAME: log_ip_on_direct
4227 Remove this option from your config. To log server or peer names use %<A in the log format.
4232 DEFAULT: @DEFAULT_MIME_TABLE@
4233 LOC: Config.mimeTablePathname
4235 Path to Squid's icon configuration file.
4237 You shouldn't need to change this, but the default file contains
4238 examples and formatting information if you do.
4244 LOC: Config.onoff.log_mime_hdrs
4247 The Cache can record both the request and the response MIME
4248 headers for each HTTP transaction. The headers are encoded
4249 safely and will appear as two bracketed fields at the end of
4250 the access log (for either the native or httpd-emulated log
4251 formats). To enable this logging set log_mime_hdrs to 'on'.
4257 Replace this with an access_log directive using the format 'useragent'.
4260 NAME: referer_log referrer_log
4263 Replace this with an access_log directive using the format 'referrer'.
4268 DEFAULT: @DEFAULT_PID_FILE@
4269 LOC: Config.pidFilename
4271 A filename to write the process-id to. To disable, enter "none".
4277 Remove this option from your config. To log FQDN use %>A in the log format.
4280 NAME: client_netmask
4282 LOC: Config.Addrs.client_netmask
4284 DEFAULT_DOC: Log full client IP address
4286 A netmask for client addresses in logfiles and cachemgr output.
4287 Change this to protect the privacy of your cache clients.
4288 A netmask of 255.255.255.0 will log all IP's in that range with
4289 the last digit set to '0'.
4295 Use a regular access.log with ACL limiting it to MISS events.
4298 NAME: strip_query_terms
4300 LOC: Config.onoff.strip_query_terms
4303 By default, Squid strips query terms from requested URLs before
4304 logging. This protects your user's privacy and reduces log size.
4306 When investigating HIT/MISS or other caching behaviour you
4307 will need to disable this to see the full URL used by Squid.
4314 LOC: Config.onoff.buffered_logs
4316 Whether to write/send access_log records ASAP or accumulate them and
4317 then write/send them in larger chunks. Buffering may improve
4318 performance because it decreases the number of I/Os. However,
4319 buffering increases the delay before log records become available to
4320 the final recipient (e.g., a disk file or logging daemon) and,
4321 hence, increases the risk of log records loss.
4323 Note that even when buffered_logs are off, Squid may have to buffer
4324 records if it cannot write/send them immediately due to pending I/Os
4325 (e.g., the I/O writing the previous log record) or connectivity loss.
4327 Currently honored by 'daemon' and 'tcp' access_log modules only.
4330 NAME: netdb_filename
4332 DEFAULT: stdio:@DEFAULT_NETDB_FILE@
4333 LOC: Config.netdbFilename
4336 Where Squid stores it's netdb journal.
4337 When enabled this journal preserves netdb state between restarts.
4339 To disable, enter "none".
4343 OPTIONS FOR TROUBLESHOOTING
4344 -----------------------------------------------------------------------------
4349 DEFAULT_IF_NONE: @DEFAULT_CACHE_LOG@
4350 LOC: Debug::cache_log
4352 Squid administrative logging file.
4354 This is where general information about Squid behavior goes. You can
4355 increase the amount of data logged to this file and how often it is
4356 rotated with "debug_options"
4362 DEFAULT_DOC: Log all critical and important messages.
4363 LOC: Debug::debugOptions
4365 Logging options are set as section,level where each source file
4366 is assigned a unique section. Lower levels result in less
4367 output, Full debugging (level 9) can result in a very large
4368 log file, so be careful.
4370 The magic word "ALL" sets debugging levels for all sections.
4371 The default is to run with "ALL,1" to record important warnings.
4373 The rotate=N option can be used to keep more or less of these logs
4374 than would otherwise be kept by logfile_rotate.
4375 For most uses a single log should be enough to monitor current
4376 events affecting Squid.
4381 LOC: Config.coredump_dir
4382 DEFAULT_IF_NONE: none
4383 DEFAULT_DOC: Use the directory from where Squid was started.
4385 By default Squid leaves core files in the directory from where
4386 it was started. If you set 'coredump_dir' to a directory
4387 that exists, Squid will chdir() to that directory at startup
4388 and coredump files will be left there.
4392 # Leave coredumps in the first cache dir
4393 coredump_dir @DEFAULT_SWAP_DIR@
4399 OPTIONS FOR FTP GATEWAYING
4400 -----------------------------------------------------------------------------
4406 LOC: Config.Ftp.anon_user
4408 If you want the anonymous login password to be more informative
4409 (and enable the use of picky FTP servers), set this to something
4410 reasonable for your domain, like wwwuser@somewhere.net
4412 The reason why this is domainless by default is the
4413 request can be made on the behalf of a user in any domain,
4414 depending on how the cache is used.
4415 Some FTP server also validate the email address is valid
4416 (for example perl.com).
4422 LOC: Config.Ftp.passive
4424 If your firewall does not allow Squid to use passive
4425 connections, turn off this option.
4427 Use of ftp_epsv_all option requires this to be ON.
4433 LOC: Config.Ftp.epsv_all
4435 FTP Protocol extensions permit the use of a special "EPSV ALL" command.
4437 NATs may be able to put the connection on a "fast path" through the
4438 translator, as the EPRT command will never be used and therefore,
4439 translation of the data portion of the segments will never be needed.
4441 When a client only expects to do two-way FTP transfers this may be
4443 If squid finds that it must do a three-way FTP transfer after issuing
4444 an EPSV ALL command, the FTP session will fail.
4446 If you have any doubts about this option do not use it.
4447 Squid will nicely attempt all other connection methods.
4449 Requires ftp_passive to be ON (default) for any effect.
4455 LOC: Config.accessList.ftp_epsv
4457 FTP Protocol extensions permit the use of a special "EPSV" command.
4459 NATs may be able to put the connection on a "fast path" through the
4460 translator using EPSV, as the EPRT command will never be used
4461 and therefore, translation of the data portion of the segments
4462 will never be needed.
4464 EPSV is often required to interoperate with FTP servers on IPv6
4465 networks. On the other hand, it may break some IPv4 servers.
4467 By default, EPSV may try EPSV with any FTP server. To fine tune
4468 that decision, you may restrict EPSV to certain clients or servers
4471 ftp_epsv allow|deny al1 acl2 ...
4473 WARNING: Disabling EPSV may cause problems with external NAT and IPv6.
4475 Only fast ACLs are supported.
4476 Requires ftp_passive to be ON (default) for any effect.
4482 LOC: Config.Ftp.eprt
4484 FTP Protocol extensions permit the use of a special "EPRT" command.
4486 This extension provides a protocol neutral alternative to the
4487 IPv4-only PORT command. When supported it enables active FTP data
4488 channels over IPv6 and efficient NAT handling.
4490 Turning this OFF will prevent EPRT being attempted and will skip
4491 straight to using PORT for IPv4 servers.
4493 Some devices are known to not handle this extension correctly and
4494 may result in crashes. Devices which suport EPRT enough to fail
4495 cleanly will result in Squid attempting PORT anyway. This directive
4496 should only be disabled when EPRT results in device failures.
4498 WARNING: Doing so will convert Squid back to the old behavior with all
4499 the related problems with external NAT devices/layers and IPv4-only FTP.
4502 NAME: ftp_sanitycheck
4505 LOC: Config.Ftp.sanitycheck
4507 For security and data integrity reasons Squid by default performs
4508 sanity checks of the addresses of FTP data connections ensure the
4509 data connection is to the requested server. If you need to allow
4510 FTP connections to servers using another IP address for the data
4511 connection turn this off.
4514 NAME: ftp_telnet_protocol
4517 LOC: Config.Ftp.telnet
4519 The FTP protocol is officially defined to use the telnet protocol
4520 as transport channel for the control connection. However, many
4521 implementations are broken and does not respect this aspect of
4524 If you have trouble accessing files with ASCII code 255 in the
4525 path or similar problems involving this ASCII code you can
4526 try setting this directive to off. If that helps, report to the
4527 operator of the FTP server in question that their FTP server
4528 is broken and does not follow the FTP standard.
4532 OPTIONS FOR EXTERNAL SUPPORT PROGRAMS
4533 -----------------------------------------------------------------------------
4538 DEFAULT: @DEFAULT_DISKD@
4539 LOC: Config.Program.diskd
4541 Specify the location of the diskd executable.
4542 Note this is only useful if you have compiled in
4543 diskd as one of the store io modules.
4546 NAME: unlinkd_program
4549 DEFAULT: @DEFAULT_UNLINKD@
4550 LOC: Config.Program.unlinkd
4552 Specify the location of the executable for file deletion process.
4555 NAME: pinger_program
4557 DEFAULT: @DEFAULT_PINGER@
4558 LOC: Config.pinger.program
4561 Specify the location of the executable for the pinger process.
4567 LOC: Config.pinger.enable
4570 Control whether the pinger is active at run-time.
4571 Enables turning ICMP pinger on and off with a simple
4572 squid -k reconfigure.
4577 OPTIONS FOR URL REWRITING
4578 -----------------------------------------------------------------------------
4581 NAME: url_rewrite_program redirect_program
4583 LOC: Config.Program.redirect
4586 Specify the location of the executable URL rewriter to use.
4587 Since they can perform almost any function there isn't one included.
4589 For each requested URL, the rewriter will receive on line with the format
4591 [channel-ID <SP>] URL [<SP> extras]<NL>
4594 After processing the request the helper must reply using the following format:
4596 [channel-ID <SP>] result [<SP> kv-pairs]
4598 The result code can be:
4600 OK status=30N url="..."
4601 Redirect the URL to the one supplied in 'url='.
4602 'status=' is optional and contains the status code to send
4603 the client in Squids HTTP response. It must be one of the
4604 HTTP redirect status codes: 301, 302, 303, 307, 308.
4605 When no status is given Squid will use 302.
4607 OK rewrite-url="..."
4608 Rewrite the URL to the one supplied in 'rewrite-url='.
4609 The new URL is fetched directly by Squid and returned to
4610 the client as the response to its request.
4613 When neither of url= and rewrite-url= are sent Squid does
4617 Do not change the URL.
4620 An internal error occurred in the helper, preventing
4621 a result being identified. The 'message=' key name is
4622 reserved for delivering a log message.
4625 In the future, the interface protocol will be extended with
4626 key=value pairs ("kv-pairs" shown above). Helper programs
4627 should be prepared to receive and possibly ignore additional
4628 whitespace-separated tokens on each input line.
4630 When using the concurrency= option the protocol is changed by
4631 introducing a query channel tag in front of the request/response.
4632 The query channel tag is a number between 0 and concurrency-1.
4633 This value must be echoed back unchanged to Squid as the first part
4634 of the response relating to its request.
4636 WARNING: URL re-writing ability should be avoided whenever possible.
4637 Use the URL redirect form of response instead.
4639 Re-write creates a difference in the state held by the client
4640 and server. Possibly causing confusion when the server response
4641 contains snippets of its view state. Embeded URLs, response
4642 and content Location headers, etc. are not re-written by this
4645 By default, a URL rewriter is not used.
4648 NAME: url_rewrite_children redirect_children
4649 TYPE: HelperChildConfig
4650 DEFAULT: 20 startup=0 idle=1 concurrency=0
4651 LOC: Config.redirectChildren
4653 The maximum number of redirector processes to spawn. If you limit
4654 it too few Squid will have to wait for them to process a backlog of
4655 URLs, slowing it down. If you allow too many they will use RAM
4656 and other system resources noticably.
4658 The startup= and idle= options allow some measure of skew in your
4663 Sets a minimum of how many processes are to be spawned when Squid
4664 starts or reconfigures. When set to zero the first request will
4665 cause spawning of the first child process to handle it.
4667 Starting too few will cause an initial slowdown in traffic as Squid
4668 attempts to simultaneously spawn enough processes to cope.
4672 Sets a minimum of how many processes Squid is to try and keep available
4673 at all times. When traffic begins to rise above what the existing
4674 processes can handle this many more will be spawned up to the maximum
4675 configured. A minimum setting of 1 is required.
4679 The number of requests each redirector helper can handle in
4680 parallel. Defaults to 0 which indicates the redirector
4681 is a old-style single threaded redirector.
4683 When this directive is set to a value >= 1 then the protocol
4684 used to communicate with the helper is modified to include
4685 an ID in front of the request/response. The ID from the request
4686 must be echoed back with the response to that request.
4689 NAME: url_rewrite_host_header redirect_rewrites_host_header
4692 LOC: Config.onoff.redir_rewrites_host
4694 To preserve same-origin security policies in browsers and
4695 prevent Host: header forgery by redirectors Squid rewrites
4696 any Host: header in redirected requests.
4698 If you are running an accelerator this may not be a wanted
4699 effect of a redirector. This directive enables you disable
4700 Host: alteration in reverse-proxy traffic.
4702 WARNING: Entries are cached on the result of the URL rewriting
4703 process, so be careful if you have domain-virtual hosts.
4705 WARNING: Squid and other software verifies the URL and Host
4706 are matching, so be careful not to relay through other proxies
4707 or inspecting firewalls with this disabled.
4710 NAME: url_rewrite_access redirector_access
4713 DEFAULT_DOC: Allow, unless rules exist in squid.conf.
4714 LOC: Config.accessList.redirector
4716 If defined, this access list specifies which requests are
4717 sent to the redirector processes.
4719 This clause supports both fast and slow acl types.
4720 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
4723 NAME: url_rewrite_bypass redirector_bypass
4725 LOC: Config.onoff.redirector_bypass
4728 When this is 'on', a request will not go through the
4729 redirector if all the helpers are busy. If this is 'off'
4730 and the redirector queue grows too large, Squid will exit
4731 with a FATAL error and ask you to increase the number of
4732 redirectors. You should only enable this if the redirectors
4733 are not critical to your caching system. If you use
4734 redirectors for access control, and you enable this option,
4735 users may have access to pages they should not
4736 be allowed to request.
4739 NAME: url_rewrite_extras
4740 TYPE: TokenOrQuotedString
4741 LOC: Config.redirector_extras
4742 DEFAULT: "%>a/%>A %un %>rm myip=%la myport=%lp"
4744 Specifies a string to be append to request line format for the
4745 rewriter helper. "Quoted" format values may contain spaces and
4746 logformat %macros. In theory, any logformat %macro can be used.
4747 In practice, a %macro expands as a dash (-) if the helper request is
4748 sent before the required macro information is available to Squid.
4752 OPTIONS FOR STORE ID
4753 -----------------------------------------------------------------------------
4756 NAME: store_id_program storeurl_rewrite_program
4758 LOC: Config.Program.store_id
4761 Specify the location of the executable StoreID helper to use.
4762 Since they can perform almost any function there isn't one included.
4764 For each requested URL, the helper will receive one line with the format
4766 [channel-ID <SP>] URL [<SP> extras]<NL>
4769 After processing the request the helper must reply using the following format:
4771 [channel-ID <SP>] result [<SP> kv-pairs]
4773 The result code can be:
4776 Use the StoreID supplied in 'store-id='.
4779 The default is to use HTTP request URL as the store ID.
4782 An internal error occured in the helper, preventing
4783 a result being identified.
4786 Helper programs should be prepared to receive and possibly ignore
4787 additional whitespace-separated tokens on each input line.
4789 When using the concurrency= option the protocol is changed by
4790 introducing a query channel tag in front of the request/response.
4791 The query channel tag is a number between 0 and concurrency-1.
4792 This value must be echoed back unchanged to Squid as the first part
4793 of the response relating to its request.
4795 NOTE: when using StoreID refresh_pattern will apply to the StoreID
4796 returned from the helper and not the URL.
4798 WARNING: Wrong StoreID value returned by a careless helper may result
4799 in the wrong cached response returned to the user.
4801 By default, a StoreID helper is not used.
4804 NAME: store_id_extras
4805 TYPE: TokenOrQuotedString
4806 LOC: Config.storeId_extras
4807 DEFAULT: "%>a/%>A %un %>rm myip=%la myport=%lp"
4809 Specifies a string to be append to request line format for the
4810 StoreId helper. "Quoted" format values may contain spaces and
4811 logformat %macros. In theory, any logformat %macro can be used.
4812 In practice, a %macro expands as a dash (-) if the helper request is
4813 sent before the required macro information is available to Squid.
4816 NAME: store_id_children storeurl_rewrite_children
4817 TYPE: HelperChildConfig
4818 DEFAULT: 20 startup=0 idle=1 concurrency=0
4819 LOC: Config.storeIdChildren
4821 The maximum number of StoreID helper processes to spawn. If you limit
4822 it too few Squid will have to wait for them to process a backlog of
4823 requests, slowing it down. If you allow too many they will use RAM
4824 and other system resources noticably.
4826 The startup= and idle= options allow some measure of skew in your
4831 Sets a minimum of how many processes are to be spawned when Squid
4832 starts or reconfigures. When set to zero the first request will
4833 cause spawning of the first child process to handle it.
4835 Starting too few will cause an initial slowdown in traffic as Squid
4836 attempts to simultaneously spawn enough processes to cope.
4840 Sets a minimum of how many processes Squid is to try and keep available
4841 at all times. When traffic begins to rise above what the existing
4842 processes can handle this many more will be spawned up to the maximum
4843 configured. A minimum setting of 1 is required.
4847 The number of requests each storeID helper can handle in
4848 parallel. Defaults to 0 which indicates the helper
4849 is a old-style single threaded program.
4851 When this directive is set to a value >= 1 then the protocol
4852 used to communicate with the helper is modified to include
4853 an ID in front of the request/response. The ID from the request
4854 must be echoed back with the response to that request.
4857 NAME: store_id_access storeurl_rewrite_access
4860 DEFAULT_DOC: Allow, unless rules exist in squid.conf.
4861 LOC: Config.accessList.store_id
4863 If defined, this access list specifies which requests are
4864 sent to the StoreID processes. By default all requests
4867 This clause supports both fast and slow acl types.
4868 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
4871 NAME: store_id_bypass storeurl_rewrite_bypass
4873 LOC: Config.onoff.store_id_bypass
4876 When this is 'on', a request will not go through the
4877 helper if all helpers are busy. If this is 'off'
4878 and the helper queue grows too large, Squid will exit
4879 with a FATAL error and ask you to increase the number of
4880 helpers. You should only enable this if the helperss
4881 are not critical to your caching system. If you use
4882 helpers for critical caching components, and you enable this
4883 option, users may not get objects from cache.
4887 OPTIONS FOR TUNING THE CACHE
4888 -----------------------------------------------------------------------------
4891 NAME: cache no_cache
4894 DEFAULT_DOC: By default, this directive is unused and has no effect.
4895 LOC: Config.accessList.noCache
4897 Requests denied by this directive will not be served from the cache
4898 and their responses will not be stored in the cache. This directive
4899 has no effect on other transactions and on already cached responses.
4901 This clause supports both fast and slow acl types.
4902 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
4904 This and the two other similar caching directives listed below are
4905 checked at different transaction processing stages, have different
4906 access to response information, affect different cache operations,
4907 and differ in slow ACLs support:
4909 * cache: Checked before Squid makes a hit/miss determination.
4910 No access to reply information!
4911 Denies both serving a hit and storing a miss.
4912 Supports both fast and slow ACLs.
4913 * send_hit: Checked after a hit was detected.
4914 Has access to reply (hit) information.
4915 Denies serving a hit only.
4916 Supports fast ACLs only.
4917 * store_miss: Checked before storing a cachable miss.
4918 Has access to reply (miss) information.
4919 Denies storing a miss only.
4920 Supports fast ACLs only.
4922 If you are not sure which of the three directives to use, apply the
4923 following decision logic:
4925 * If your ACL(s) are of slow type _and_ need response info, redesign.
4926 Squid does not support that particular combination at this time.
4928 * If your directive ACL(s) are of slow type, use "cache"; and/or
4929 * if your directive ACL(s) need no response info, use "cache".
4931 * If you do not want the response cached, use store_miss; and/or
4932 * if you do not want a hit on a cached response, use send_hit.
4938 DEFAULT_DOC: By default, this directive is unused and has no effect.
4939 LOC: Config.accessList.sendHit
4941 Responses denied by this directive will not be served from the cache
4942 (but may still be cached, see store_miss). This directive has no
4943 effect on the responses it allows and on the cached objects.
4945 Please see the "cache" directive for a summary of differences among
4946 store_miss, send_hit, and cache directives.
4948 Unlike the "cache" directive, send_hit only supports fast acl
4949 types. See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
4953 # apply custom Store ID mapping to some URLs
4954 acl MapMe dstdomain .c.example.com
4955 store_id_program ...
4956 store_id_access allow MapMe
4958 # but prevent caching of special responses
4959 # such as 302 redirects that cause StoreID loops
4960 acl Ordinary http_status 200-299
4961 store_miss deny MapMe !Ordinary
4963 # and do not serve any previously stored special responses
4964 # from the cache (in case they were already cached before
4965 # the above store_miss rule was in effect).
4966 send_hit deny MapMe !Ordinary
4972 DEFAULT_DOC: By default, this directive is unused and has no effect.
4973 LOC: Config.accessList.storeMiss
4975 Responses denied by this directive will not be cached (but may still
4976 be served from the cache, see send_hit). This directive has no
4977 effect on the responses it allows and on the already cached responses.
4979 Please see the "cache" directive for a summary of differences among
4980 store_miss, send_hit, and cache directives. See the
4981 send_hit directive for a usage example.
4983 Unlike the "cache" directive, store_miss only supports fast acl
4984 types. See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
4990 LOC: Config.maxStale
4993 This option puts an upper limit on how stale content Squid
4994 will serve from the cache if cache validation fails.
4995 Can be overriden by the refresh_pattern max-stale option.
4998 NAME: refresh_pattern
4999 TYPE: refreshpattern
5003 usage: refresh_pattern [-i] regex min percent max [options]
5005 By default, regular expressions are CASE-SENSITIVE. To make
5006 them case-insensitive, use the -i option.
5008 'Min' is the time (in minutes) an object without an explicit
5009 expiry time should be considered fresh. The recommended
5010 value is 0, any higher values may cause dynamic applications
5011 to be erroneously cached unless the application designer
5012 has taken the appropriate actions.
5014 'Percent' is a percentage of the objects age (time since last
5015 modification age) an object without explicit expiry time
5016 will be considered fresh.
5018 'Max' is an upper limit on how long objects without an explicit
5019 expiry time will be considered fresh.
5021 options: override-expire
5026 ignore-must-revalidate
5033 override-expire enforces min age even if the server
5034 sent an explicit expiry time (e.g., with the
5035 Expires: header or Cache-Control: max-age). Doing this
5036 VIOLATES the HTTP standard. Enabling this feature
5037 could make you liable for problems which it causes.
5039 Note: override-expire does not enforce staleness - it only extends
5040 freshness / min. If the server returns a Expires time which
5041 is longer than your max time, Squid will still consider
5042 the object fresh for that period of time.
5044 override-lastmod enforces min age even on objects
5045 that were modified recently.
5047 reload-into-ims changes a client no-cache or ``reload''
5048 request for a cached entry into a conditional request using
5049 If-Modified-Since and/or If-None-Match headers, provided the
5050 cached entry has a Last-Modified and/or a strong ETag header.
5051 Doing this VIOLATES the HTTP standard. Enabling this feature
5052 could make you liable for problems which it causes.
5054 ignore-reload ignores a client no-cache or ``reload''
5055 header. Doing this VIOLATES the HTTP standard. Enabling
5056 this feature could make you liable for problems which
5059 ignore-no-store ignores any ``Cache-control: no-store''
5060 headers received from a server. Doing this VIOLATES
5061 the HTTP standard. Enabling this feature could make you
5062 liable for problems which it causes.
5064 ignore-must-revalidate ignores any ``Cache-Control: must-revalidate``
5065 headers received from a server. Doing this VIOLATES
5066 the HTTP standard. Enabling this feature could make you
5067 liable for problems which it causes.
5069 ignore-private ignores any ``Cache-control: private''
5070 headers received from a server. Doing this VIOLATES
5071 the HTTP standard. Enabling this feature could make you
5072 liable for problems which it causes.
5074 ignore-auth caches responses to requests with authorization,
5075 as if the originserver had sent ``Cache-control: public''
5076 in the response header. Doing this VIOLATES the HTTP standard.
5077 Enabling this feature could make you liable for problems which
5080 refresh-ims causes squid to contact the origin server
5081 when a client issues an If-Modified-Since request. This
5082 ensures that the client will receive an updated version
5083 if one is available.
5085 store-stale stores responses even if they don't have explicit
5086 freshness or a validator (i.e., Last-Modified or an ETag)
5087 present, or if they're already stale. By default, Squid will
5088 not cache such responses because they usually can't be
5089 reused. Note that such responses will be stale by default.
5091 max-stale=NN provide a maximum staleness factor. Squid won't
5092 serve objects more stale than this even if it failed to
5093 validate the object. Default: use the max_stale global limit.
5095 Basically a cached object is:
5097 FRESH if expires < now, else STALE
5099 FRESH if lm-factor < percent, else STALE
5103 The refresh_pattern lines are checked in the order listed here.
5104 The first entry which matches is used. If none of the entries
5105 match the default will be used.
5107 Note, you must uncomment all the default lines if you want
5108 to change one. The default setting is only active if none is
5114 # Add any of your own refresh_pattern entries above these.
5116 refresh_pattern ^ftp: 1440 20% 10080
5117 refresh_pattern ^gopher: 1440 0% 1440
5118 refresh_pattern -i (/cgi-bin/|\?) 0 0% 0
5119 refresh_pattern . 0 20% 4320
5123 NAME: quick_abort_min
5127 LOC: Config.quickAbort.min
5130 NAME: quick_abort_max
5134 LOC: Config.quickAbort.max
5137 NAME: quick_abort_pct
5141 LOC: Config.quickAbort.pct
5143 The cache by default continues downloading aborted requests
5144 which are almost completed (less than 16 KB remaining). This
5145 may be undesirable on slow (e.g. SLIP) links and/or very busy
5146 caches. Impatient users may tie up file descriptors and
5147 bandwidth by repeatedly requesting and immediately aborting
5150 When the user aborts a request, Squid will check the
5151 quick_abort values to the amount of data transfered until
5154 If the transfer has less than 'quick_abort_min' KB remaining,
5155 it will finish the retrieval.
5157 If the transfer has more than 'quick_abort_max' KB remaining,
5158 it will abort the retrieval.
5160 If more than 'quick_abort_pct' of the transfer has completed,
5161 it will finish the retrieval.
5163 If you do not want any retrieval to continue after the client
5164 has aborted, set both 'quick_abort_min' and 'quick_abort_max'
5167 If you want retrievals to always continue if they are being
5168 cached set 'quick_abort_min' to '-1 KB'.
5171 NAME: read_ahead_gap
5172 COMMENT: buffer-size
5174 LOC: Config.readAheadGap
5177 The amount of data the cache will buffer ahead of what has been
5178 sent to the client when retrieving an object from another server.
5182 IFDEF: USE_HTTP_VIOLATIONS
5185 LOC: Config.negativeTtl
5188 Set the Default Time-to-Live (TTL) for failed requests.
5189 Certain types of failures (such as "connection refused" and
5190 "404 Not Found") are able to be negatively-cached for a short time.
5191 Modern web servers should provide Expires: header, however if they
5192 do not this can provide a minimum TTL.
5193 The default is not to cache errors with unknown expiry details.
5195 Note that this is different from negative caching of DNS lookups.
5197 WARNING: Doing this VIOLATES the HTTP standard. Enabling
5198 this feature could make you liable for problems which it
5202 NAME: positive_dns_ttl
5205 LOC: Config.positiveDnsTtl
5208 Upper limit on how long Squid will cache positive DNS responses.
5209 Default is 6 hours (360 minutes). This directive must be set
5210 larger than negative_dns_ttl.
5213 NAME: negative_dns_ttl
5216 LOC: Config.negativeDnsTtl
5219 Time-to-Live (TTL) for negative caching of failed DNS lookups.
5220 This also sets the lower cache limit on positive lookups.
5221 Minimum value is 1 second, and it is not recommendable to go
5222 much below 10 seconds.
5225 NAME: range_offset_limit
5226 COMMENT: size [acl acl...]
5228 LOC: Config.rangeOffsetLimit
5231 usage: (size) [units] [[!]aclname]
5233 Sets an upper limit on how far (number of bytes) into the file
5234 a Range request may be to cause Squid to prefetch the whole file.
5235 If beyond this limit, Squid forwards the Range request as it is and
5236 the result is NOT cached.
5238 This is to stop a far ahead range request (lets say start at 17MB)
5239 from making Squid fetch the whole object up to that point before
5240 sending anything to the client.
5242 Multiple range_offset_limit lines may be specified, and they will
5243 be searched from top to bottom on each request until a match is found.
5244 The first match found will be used. If no line matches a request, the
5245 default limit of 0 bytes will be used.
5247 'size' is the limit specified as a number of units.
5249 'units' specifies whether to use bytes, KB, MB, etc.
5250 If no units are specified bytes are assumed.
5252 A size of 0 causes Squid to never fetch more than the
5253 client requested. (default)
5255 A size of 'none' causes Squid to always fetch the object from the
5256 beginning so it may cache the result. (2.0 style)
5258 'aclname' is the name of a defined ACL.
5260 NP: Using 'none' as the byte value here will override any quick_abort settings
5261 that may otherwise apply to the range request. The range request will
5262 be fully fetched from start to finish regardless of the client
5263 actions. This affects bandwidth usage.
5266 NAME: minimum_expiry_time
5269 LOC: Config.minimum_expiry_time
5272 The minimum caching time according to (Expires - Date)
5273 headers Squid honors if the object can't be revalidated.
5274 The default is 60 seconds.
5276 In reverse proxy environments it might be desirable to honor
5277 shorter object lifetimes. It is most likely better to make
5278 your server return a meaningful Last-Modified header however.
5280 In ESI environments where page fragments often have short
5281 lifetimes, this will often be best set to 0.
5284 NAME: store_avg_object_size
5288 LOC: Config.Store.avgObjectSize
5290 Average object size, used to estimate number of objects your
5291 cache can hold. The default is 13 KB.
5293 This is used to pre-seed the cache index memory allocation to
5294 reduce expensive reallocate operations while handling clients
5295 traffic. Too-large values may result in memory allocation during
5296 peak traffic, too-small values will result in wasted memory.
5298 Check the cache manager 'info' report metrics for the real
5299 object sizes seen by your Squid before tuning this.
5302 NAME: store_objects_per_bucket
5305 LOC: Config.Store.objectsPerBucket
5307 Target number of objects per bucket in the store hash table.
5308 Lowering this value increases the total number of buckets and
5309 also the storage maintenance rate. The default is 20.
5314 -----------------------------------------------------------------------------
5317 NAME: request_header_max_size
5321 LOC: Config.maxRequestHeaderSize
5323 This specifies the maximum size for HTTP headers in a request.
5324 Request headers are usually relatively small (about 512 bytes).
5325 Placing a limit on the request header size will catch certain
5326 bugs (for example with persistent connections) and possibly
5327 buffer-overflow or denial-of-service attacks.
5330 NAME: reply_header_max_size
5334 LOC: Config.maxReplyHeaderSize
5336 This specifies the maximum size for HTTP headers in a reply.
5337 Reply headers are usually relatively small (about 512 bytes).
5338 Placing a limit on the reply header size will catch certain
5339 bugs (for example with persistent connections) and possibly
5340 buffer-overflow or denial-of-service attacks.
5343 NAME: request_body_max_size
5347 DEFAULT_DOC: No limit.
5348 LOC: Config.maxRequestBodySize
5350 This specifies the maximum size for an HTTP request body.
5351 In other words, the maximum size of a PUT/POST request.
5352 A user who attempts to send a request with a body larger
5353 than this limit receives an "Invalid Request" error message.
5354 If you set this parameter to a zero (the default), there will
5355 be no limit imposed.
5357 See also client_request_buffer_max_size for an alternative
5358 limitation on client uploads which can be configured.
5361 NAME: client_request_buffer_max_size
5365 LOC: Config.maxRequestBufferSize
5367 This specifies the maximum buffer size of a client request.
5368 It prevents squid eating too much memory when somebody uploads
5372 NAME: chunked_request_body_max_size
5376 LOC: Config.maxChunkedRequestBodySize
5378 A broken or confused HTTP/1.1 client may send a chunked HTTP
5379 request to Squid. Squid does not have full support for that
5380 feature yet. To cope with such requests, Squid buffers the
5381 entire request and then dechunks request body to create a
5382 plain HTTP/1.0 request with a known content length. The plain
5383 request is then used by the rest of Squid code as usual.
5385 The option value specifies the maximum size of the buffer used
5386 to hold the request before the conversion. If the chunked
5387 request size exceeds the specified limit, the conversion
5388 fails, and the client receives an "unsupported request" error,
5389 as if dechunking was disabled.
5391 Dechunking is enabled by default. To disable conversion of
5392 chunked requests, set the maximum to zero.
5394 Request dechunking feature and this option in particular are a
5395 temporary hack. When chunking requests and responses are fully
5396 supported, there will be no need to buffer a chunked request.
5400 IFDEF: USE_HTTP_VIOLATIONS
5403 DEFAULT_DOC: Obey RFC 2616.
5404 LOC: Config.accessList.brokenPosts
5406 A list of ACL elements which, if matched, causes Squid to send
5407 an extra CRLF pair after the body of a PUT/POST request.
5409 Some HTTP servers has broken implementations of PUT/POST,
5410 and rely on an extra CRLF pair sent by some WWW clients.
5412 Quote from RFC2616 section 4.1 on this matter:
5414 Note: certain buggy HTTP/1.0 client implementations generate an
5415 extra CRLF's after a POST request. To restate what is explicitly
5416 forbidden by the BNF, an HTTP/1.1 client must not preface or follow
5417 a request with an extra CRLF.
5419 This clause only supports fast acl types.
5420 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
5423 acl buggy_server url_regex ^http://....
5424 broken_posts allow buggy_server
5427 NAME: adaptation_uses_indirect_client icap_uses_indirect_client
5430 IFDEF: FOLLOW_X_FORWARDED_FOR&&USE_ADAPTATION
5432 LOC: Adaptation::Config::use_indirect_client
5434 Controls whether the indirect client IP address (instead of the direct
5435 client IP address) is passed to adaptation services.
5437 See also: follow_x_forwarded_for adaptation_send_client_ip
5441 IFDEF: USE_HTTP_VIOLATIONS
5445 LOC: Config.onoff.via
5447 If set (default), Squid will include a Via header in requests and
5448 replies as required by RFC2616.
5454 LOC: Config.onoff.ie_refresh
5457 Microsoft Internet Explorer up until version 5.5 Service
5458 Pack 1 has an issue with transparent proxies, wherein it
5459 is impossible to force a refresh. Turning this on provides
5460 a partial fix to the problem, by causing all IMS-REFRESH
5461 requests from older IE versions to check the origin server
5462 for fresh content. This reduces hit ratio by some amount
5463 (~10% in my experience), but allows users to actually get
5464 fresh content when they want it. Note because Squid
5465 cannot tell if the user is using 5.5 or 5.5SP1, the behavior
5466 of 5.5 is unchanged from old versions of Squid (i.e. a
5467 forced refresh is impossible). Newer versions of IE will,
5468 hopefully, continue to have the new behavior and will be
5469 handled based on that assumption. This option defaults to
5470 the old Squid behavior, which is better for hit ratios but
5471 worse for clients using IE, if they need to be able to
5472 force fresh content.
5475 NAME: vary_ignore_expire
5478 LOC: Config.onoff.vary_ignore_expire
5481 Many HTTP servers supporting Vary gives such objects
5482 immediate expiry time with no cache-control header
5483 when requested by a HTTP/1.0 client. This option
5484 enables Squid to ignore such expiry times until
5485 HTTP/1.1 is fully implemented.
5487 WARNING: If turned on this may eventually cause some
5488 varying objects not intended for caching to get cached.
5491 NAME: request_entities
5493 LOC: Config.onoff.request_entities
5496 Squid defaults to deny GET and HEAD requests with request entities,
5497 as the meaning of such requests are undefined in the HTTP standard
5498 even if not explicitly forbidden.
5500 Set this directive to on if you have clients which insists
5501 on sending request entities in GET or HEAD requests. But be warned
5502 that there is server software (both proxies and web servers) which
5503 can fail to properly process this kind of request which may make you
5504 vulnerable to cache pollution attacks if enabled.
5507 NAME: request_header_access
5508 IFDEF: USE_HTTP_VIOLATIONS
5509 TYPE: http_header_access
5510 LOC: Config.request_header_access
5512 DEFAULT_DOC: No limits.
5514 Usage: request_header_access header_name allow|deny [!]aclname ...
5516 WARNING: Doing this VIOLATES the HTTP standard. Enabling
5517 this feature could make you liable for problems which it
5520 This option replaces the old 'anonymize_headers' and the
5521 older 'http_anonymizer' option with something that is much
5522 more configurable. A list of ACLs for each header name allows
5523 removal of specific header fields under specific conditions.
5525 This option only applies to outgoing HTTP request headers (i.e.,
5526 headers sent by Squid to the next HTTP hop such as a cache peer
5527 or an origin server). The option has no effect during cache hit
5528 detection. The equivalent adaptation vectoring point in ICAP
5529 terminology is post-cache REQMOD.
5531 The option is applied to individual outgoing request header
5532 fields. For each request header field F, Squid uses the first
5533 qualifying sets of request_header_access rules:
5535 1. Rules with header_name equal to F's name.
5536 2. Rules with header_name 'Other', provided F's name is not
5537 on the hard-coded list of commonly used HTTP header names.
5538 3. Rules with header_name 'All'.
5540 Within that qualifying rule set, rule ACLs are checked as usual.
5541 If ACLs of an "allow" rule match, the header field is allowed to
5542 go through as is. If ACLs of a "deny" rule match, the header is
5543 removed and request_header_replace is then checked to identify
5544 if the removed header has a replacement. If no rules within the
5545 set have matching ACLs, the header field is left as is.
5547 For example, to achieve the same behavior as the old
5548 'http_anonymizer standard' option, you should use:
5550 request_header_access From deny all
5551 request_header_access Referer deny all
5552 request_header_access User-Agent deny all
5554 Or, to reproduce the old 'http_anonymizer paranoid' feature
5557 request_header_access Authorization allow all
5558 request_header_access Proxy-Authorization allow all
5559 request_header_access Cache-Control allow all
5560 request_header_access Content-Length allow all
5561 request_header_access Content-Type allow all
5562 request_header_access Date allow all
5563 request_header_access Host allow all
5564 request_header_access If-Modified-Since allow all
5565 request_header_access Pragma allow all
5566 request_header_access Accept allow all
5567 request_header_access Accept-Charset allow all
5568 request_header_access Accept-Encoding allow all
5569 request_header_access Accept-Language allow all
5570 request_header_access Connection allow all
5571 request_header_access All deny all
5573 HTTP reply headers are controlled with the reply_header_access directive.
5575 By default, all headers are allowed (no anonymizing is performed).
5578 NAME: reply_header_access
5579 IFDEF: USE_HTTP_VIOLATIONS
5580 TYPE: http_header_access
5581 LOC: Config.reply_header_access
5583 DEFAULT_DOC: No limits.
5585 Usage: reply_header_access header_name allow|deny [!]aclname ...
5587 WARNING: Doing this VIOLATES the HTTP standard. Enabling
5588 this feature could make you liable for problems which it
5591 This option only applies to reply headers, i.e., from the
5592 server to the client.
5594 This is the same as request_header_access, but in the other
5595 direction. Please see request_header_access for detailed
5598 For example, to achieve the same behavior as the old
5599 'http_anonymizer standard' option, you should use:
5601 reply_header_access Server deny all
5602 reply_header_access WWW-Authenticate deny all
5603 reply_header_access Link deny all
5605 Or, to reproduce the old 'http_anonymizer paranoid' feature
5608 reply_header_access Allow allow all
5609 reply_header_access WWW-Authenticate allow all
5610 reply_header_access Proxy-Authenticate allow all
5611 reply_header_access Cache-Control allow all
5612 reply_header_access Content-Encoding allow all
5613 reply_header_access Content-Length allow all
5614 reply_header_access Content-Type allow all
5615 reply_header_access Date allow all
5616 reply_header_access Expires allow all
5617 reply_header_access Last-Modified allow all
5618 reply_header_access Location allow all
5619 reply_header_access Pragma allow all
5620 reply_header_access Content-Language allow all
5621 reply_header_access Retry-After allow all
5622 reply_header_access Title allow all
5623 reply_header_access Content-Disposition allow all
5624 reply_header_access Connection allow all
5625 reply_header_access All deny all
5627 HTTP request headers are controlled with the request_header_access directive.
5629 By default, all headers are allowed (no anonymizing is
5633 NAME: request_header_replace header_replace
5634 IFDEF: USE_HTTP_VIOLATIONS
5635 TYPE: http_header_replace
5636 LOC: Config.request_header_access
5639 Usage: request_header_replace header_name message
5640 Example: request_header_replace User-Agent Nutscrape/1.0 (CP/M; 8-bit)
5642 This option allows you to change the contents of headers
5643 denied with request_header_access above, by replacing them
5644 with some fixed string.
5646 This only applies to request headers, not reply headers.
5648 By default, headers are removed if denied.
5651 NAME: reply_header_replace
5652 IFDEF: USE_HTTP_VIOLATIONS
5653 TYPE: http_header_replace
5654 LOC: Config.reply_header_access
5657 Usage: reply_header_replace header_name message
5658 Example: reply_header_replace Server Foo/1.0
5660 This option allows you to change the contents of headers
5661 denied with reply_header_access above, by replacing them
5662 with some fixed string.
5664 This only applies to reply headers, not request headers.
5666 By default, headers are removed if denied.
5669 NAME: request_header_add
5670 TYPE: HeaderWithAclList
5671 LOC: Config.request_header_add
5674 Usage: request_header_add field-name field-value acl1 [acl2] ...
5675 Example: request_header_add X-Client-CA "CA=%ssl::>cert_issuer" all
5677 This option adds header fields to outgoing HTTP requests (i.e.,
5678 request headers sent by Squid to the next HTTP hop such as a
5679 cache peer or an origin server). The option has no effect during
5680 cache hit detection. The equivalent adaptation vectoring point
5681 in ICAP terminology is post-cache REQMOD.
5683 Field-name is a token specifying an HTTP header name. If a
5684 standard HTTP header name is used, Squid does not check whether
5685 the new header conflicts with any existing headers or violates
5686 HTTP rules. If the request to be modified already contains a
5687 field with the same name, the old field is preserved but the
5688 header field values are not merged.
5690 Field-value is either a token or a quoted string. If quoted
5691 string format is used, then the surrounding quotes are removed
5692 while escape sequences and %macros are processed.
5694 In theory, all of the logformat codes can be used as %macros.
5695 However, unlike logging (which happens at the very end of
5696 transaction lifetime), the transaction may not yet have enough
5697 information to expand a macro when the new header value is needed.
5698 And some information may already be available to Squid but not yet
5699 committed where the macro expansion code can access it (report
5700 such instances!). The macro will be expanded into a single dash
5701 ('-') in such cases. Not all macros have been tested.
5703 One or more Squid ACLs may be specified to restrict header
5704 injection to matching requests. As always in squid.conf, all
5705 ACLs in an option ACL list must be satisfied for the insertion
5706 to happen. The request_header_add option supports fast ACLs
5715 This option used to log custom information about the master
5716 transaction. For example, an admin may configure Squid to log
5717 which "user group" the transaction belongs to, where "user group"
5718 will be determined based on a set of ACLs and not [just]
5719 authentication information.
5720 Values of key/value pairs can be logged using %{key}note macros:
5722 note key value acl ...
5723 logformat myFormat ... %{key}note ...
5726 NAME: relaxed_header_parser
5727 COMMENT: on|off|warn
5729 LOC: Config.onoff.relaxed_header_parser
5732 In the default "on" setting Squid accepts certain forms
5733 of non-compliant HTTP messages where it is unambiguous
5734 what the sending application intended even if the message
5735 is not correctly formatted. The messages is then normalized
5736 to the correct form when forwarded by Squid.
5738 If set to "warn" then a warning will be emitted in cache.log
5739 each time such HTTP error is encountered.
5741 If set to "off" then such HTTP errors will cause the request
5742 or response to be rejected.
5745 NAME: collapsed_forwarding
5748 LOC: Config.onoff.collapsed_forwarding
5751 This option controls whether Squid is allowed to merge multiple
5752 potentially cachable requests for the same URI before Squid knows
5753 whether the response is going to be cachable.
5755 This feature is disabled by default: Enabling collapsed forwarding
5756 needlessly delays forwarding requests that look cachable (when they are
5757 collapsed) but then need to be forwarded individually anyway because
5758 they end up being for uncachable content. However, in some cases, such
5759 as accelleration of highly cachable content with periodic or groupped
5760 expiration times, the gains from collapsing [large volumes of
5761 simultenous refresh requests] outweigh losses from such delays.
5766 -----------------------------------------------------------------------------
5769 NAME: forward_timeout
5772 LOC: Config.Timeout.forward
5775 This parameter specifies how long Squid should at most attempt in
5776 finding a forwarding path for the request before giving up.
5779 NAME: connect_timeout
5782 LOC: Config.Timeout.connect
5785 This parameter specifies how long to wait for the TCP connect to
5786 the requested server or peer to complete before Squid should
5787 attempt to find another path where to forward the request.
5790 NAME: peer_connect_timeout
5793 LOC: Config.Timeout.peer_connect
5796 This parameter specifies how long to wait for a pending TCP
5797 connection to a peer cache. The default is 30 seconds. You
5798 may also set different timeout values for individual neighbors
5799 with the 'connect-timeout' option on a 'cache_peer' line.
5805 LOC: Config.Timeout.read
5808 The read_timeout is applied on server-side connections. After
5809 each successful read(), the timeout will be extended by this
5810 amount. If no data is read again after this amount of time,
5811 the request is aborted and logged with ERR_READ_TIMEOUT. The
5812 default is 15 minutes.
5818 LOC: Config.Timeout.write
5821 This timeout is tracked for all connections that have data
5822 available for writing and are waiting for the socket to become
5823 ready. After each successful write, the timeout is extended by
5824 the configured amount. If Squid has data to write but the
5825 connection is not ready for the configured duration, the
5826 transaction associated with the connection is terminated. The
5827 default is 15 minutes.
5830 NAME: request_timeout
5832 LOC: Config.Timeout.request
5835 How long to wait for complete HTTP request headers after initial
5836 connection establishment.
5839 NAME: client_idle_pconn_timeout persistent_request_timeout
5841 LOC: Config.Timeout.clientIdlePconn
5844 How long to wait for the next HTTP request on a persistent
5845 client connection after the previous request completes.
5848 NAME: client_lifetime
5851 LOC: Config.Timeout.lifetime
5854 The maximum amount of time a client (browser) is allowed to
5855 remain connected to the cache process. This protects the Cache
5856 from having a lot of sockets (and hence file descriptors) tied up
5857 in a CLOSE_WAIT state from remote clients that go away without
5858 properly shutting down (either because of a network failure or
5859 because of a poor client implementation). The default is one
5862 NOTE: The default value is intended to be much larger than any
5863 client would ever need to be connected to your cache. You
5864 should probably change client_lifetime only as a last resort.
5865 If you seem to have many client connections tying up
5866 filedescriptors, we recommend first tuning the read_timeout,
5867 request_timeout, persistent_request_timeout and quick_abort values.
5870 NAME: half_closed_clients
5872 LOC: Config.onoff.half_closed_clients
5875 Some clients may shutdown the sending side of their TCP
5876 connections, while leaving their receiving sides open. Sometimes,
5877 Squid can not tell the difference between a half-closed and a
5878 fully-closed TCP connection.
5880 By default, Squid will immediately close client connections when
5881 read(2) returns "no more data to read."
5883 Change this option to 'on' and Squid will keep open connections
5884 until a read(2) or write(2) on the socket returns an error.
5885 This may show some benefits for reverse proxies. But if not
5886 it is recommended to leave OFF.
5889 NAME: server_idle_pconn_timeout pconn_timeout
5891 LOC: Config.Timeout.serverIdlePconn
5894 Timeout for idle persistent connections to servers and other
5901 LOC: Ident::TheConfig.timeout
5904 Maximum time to wait for IDENT lookups to complete.
5906 If this is too high, and you enabled IDENT lookups from untrusted
5907 users, you might be susceptible to denial-of-service by having
5908 many ident requests going at once.
5911 NAME: shutdown_lifetime
5914 LOC: Config.shutdownLifetime
5917 When SIGTERM or SIGHUP is received, the cache is put into
5918 "shutdown pending" mode until all active sockets are closed.
5919 This value is the lifetime to set for all open descriptors
5920 during shutdown mode. Any active clients after this many
5921 seconds will receive a 'timeout' message.
5925 ADMINISTRATIVE PARAMETERS
5926 -----------------------------------------------------------------------------
5932 LOC: Config.adminEmail
5934 Email-address of local cache manager who will receive
5935 mail if the cache dies. The default is "webmaster".
5941 LOC: Config.EmailFrom
5943 From: email-address for mail sent when the cache dies.
5944 The default is to use 'squid@unique_hostname'.
5946 See also: unique_hostname directive.
5952 LOC: Config.EmailProgram
5954 Email program used to send mail if the cache dies.
5955 The default is "mail". The specified program must comply
5956 with the standard Unix mail syntax:
5957 mail-program recipient < mailfile
5959 Optional command line options can be specified.
5962 NAME: cache_effective_user
5964 DEFAULT: @DEFAULT_CACHE_EFFECTIVE_USER@
5965 LOC: Config.effectiveUser
5967 If you start Squid as root, it will change its effective/real
5968 UID/GID to the user specified below. The default is to change
5969 to UID of @DEFAULT_CACHE_EFFECTIVE_USER@.
5970 see also; cache_effective_group
5973 NAME: cache_effective_group
5976 DEFAULT_DOC: Use system group memberships of the cache_effective_user account
5977 LOC: Config.effectiveGroup
5979 Squid sets the GID to the effective user's default group ID
5980 (taken from the password file) and supplementary group list
5981 from the groups membership.
5983 If you want Squid to run with a specific GID regardless of
5984 the group memberships of the effective user then set this
5985 to the group (or GID) you want Squid to run as. When set
5986 all other group privileges of the effective user are ignored
5987 and only this GID is effective. If Squid is not started as
5988 root the user starting Squid MUST be member of the specified
5991 This option is not recommended by the Squid Team.
5992 Our preference is for administrators to configure a secure
5993 user account for squid with UID/GID matching system policies.
5996 NAME: httpd_suppress_version_string
6000 LOC: Config.onoff.httpd_suppress_version_string
6002 Suppress Squid version string info in HTTP headers and HTML error pages.
6005 NAME: visible_hostname
6007 LOC: Config.visibleHostname
6009 DEFAULT_DOC: Automatically detect the system host name
6011 If you want to present a special hostname in error messages, etc,
6012 define this. Otherwise, the return value of gethostname()
6013 will be used. If you have multiple caches in a cluster and
6014 get errors about IP-forwarding you must set them to have individual
6015 names with this setting.
6018 NAME: unique_hostname
6020 LOC: Config.uniqueHostname
6022 DEFAULT_DOC: Copy the value from visible_hostname
6024 If you want to have multiple machines with the same
6025 'visible_hostname' you must give each machine a different
6026 'unique_hostname' so forwarding loops can be detected.
6029 NAME: hostname_aliases
6031 LOC: Config.hostnameAliases
6034 A list of other DNS names your cache has.
6042 Minimum umask which should be enforced while the proxy
6043 is running, in addition to the umask set at startup.
6045 For a traditional octal representation of umasks, start
6050 OPTIONS FOR THE CACHE REGISTRATION SERVICE
6051 -----------------------------------------------------------------------------
6053 This section contains parameters for the (optional) cache
6054 announcement service. This service is provided to help
6055 cache administrators locate one another in order to join or
6056 create cache hierarchies.
6058 An 'announcement' message is sent (via UDP) to the registration
6059 service by Squid. By default, the announcement message is NOT
6060 SENT unless you enable it with 'announce_period' below.
6062 The announcement message includes your hostname, plus the
6063 following information from this configuration file:
6069 All current information is processed regularly and made
6070 available on the Web at http://www.ircache.net/Cache/Tracker/.
6073 NAME: announce_period
6075 LOC: Config.Announce.period
6077 DEFAULT_DOC: Announcement messages disabled.
6079 This is how frequently to send cache announcements.
6081 To enable announcing your cache, just set an announce period.
6084 announce_period 1 day
6089 DEFAULT: tracker.ircache.net
6090 LOC: Config.Announce.host
6092 Set the hostname where announce registration messages will be sent.
6094 See also announce_port and announce_file
6100 LOC: Config.Announce.file
6102 The contents of this file will be included in the announce
6103 registration messages.
6109 LOC: Config.Announce.port
6111 Set the port where announce registration messages will be sent.
6113 See also announce_host and announce_file
6117 HTTPD-ACCELERATOR OPTIONS
6118 -----------------------------------------------------------------------------
6121 NAME: httpd_accel_surrogate_id
6124 DEFAULT_DOC: visible_hostname is used if no specific ID is set.
6125 LOC: Config.Accel.surrogate_id
6127 Surrogates (http://www.esi.org/architecture_spec_1.0.html)
6128 need an identification token to allow control targeting. Because
6129 a farm of surrogates may all perform the same tasks, they may share
6130 an identification token.
6133 NAME: http_accel_surrogate_remote
6137 LOC: Config.onoff.surrogate_is_remote
6139 Remote surrogates (such as those in a CDN) honour the header
6140 "Surrogate-Control: no-store-remote".
6142 Set this to on to have squid behave as a remote surrogate.
6146 IFDEF: USE_SQUID_ESI
6147 COMMENT: libxml2|expat|custom
6149 LOC: ESIParser::Type
6152 ESI markup is not strictly XML compatible. The custom ESI parser
6153 will give higher performance, but cannot handle non ASCII character
6158 DELAY POOL PARAMETERS
6159 -----------------------------------------------------------------------------
6163 TYPE: delay_pool_count
6165 IFDEF: USE_DELAY_POOLS
6168 This represents the number of delay pools to be used. For example,
6169 if you have one class 2 delay pool and one class 3 delays pool, you
6170 have a total of 2 delay pools.
6172 See also delay_parameters, delay_class, delay_access for pool
6173 configuration details.
6177 TYPE: delay_pool_class
6179 IFDEF: USE_DELAY_POOLS
6182 This defines the class of each delay pool. There must be exactly one
6183 delay_class line for each delay pool. For example, to define two
6184 delay pools, one of class 2 and one of class 3, the settings above
6188 delay_pools 4 # 4 delay pools
6189 delay_class 1 2 # pool 1 is a class 2 pool
6190 delay_class 2 3 # pool 2 is a class 3 pool
6191 delay_class 3 4 # pool 3 is a class 4 pool
6192 delay_class 4 5 # pool 4 is a class 5 pool
6194 The delay pool classes are:
6196 class 1 Everything is limited by a single aggregate
6199 class 2 Everything is limited by a single aggregate
6200 bucket as well as an "individual" bucket chosen
6201 from bits 25 through 32 of the IPv4 address.
6203 class 3 Everything is limited by a single aggregate
6204 bucket as well as a "network" bucket chosen
6205 from bits 17 through 24 of the IP address and a
6206 "individual" bucket chosen from bits 17 through
6207 32 of the IPv4 address.
6209 class 4 Everything in a class 3 delay pool, with an
6210 additional limit on a per user basis. This
6211 only takes effect if the username is established
6212 in advance - by forcing authentication in your
6215 class 5 Requests are grouped according their tag (see
6216 external_acl's tag= reply).
6219 Each pool also requires a delay_parameters directive to configure the pool size
6220 and speed limits used whenever the pool is applied to a request. Along with
6221 a set of delay_access directives to determine when it is used.
6223 NOTE: If an IP address is a.b.c.d
6224 -> bits 25 through 32 are "d"
6225 -> bits 17 through 24 are "c"
6226 -> bits 17 through 32 are "c * 256 + d"
6228 NOTE-2: Due to the use of bitmasks in class 2,3,4 pools they only apply to
6229 IPv4 traffic. Class 1 and 5 pools may be used with IPv6 traffic.
6231 This clause only supports fast acl types.
6232 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
6234 See also delay_parameters and delay_access.
6238 TYPE: delay_pool_access
6240 DEFAULT_DOC: Deny using the pool, unless allow rules exist in squid.conf for the pool.
6241 IFDEF: USE_DELAY_POOLS
6244 This is used to determine which delay pool a request falls into.
6246 delay_access is sorted per pool and the matching starts with pool 1,
6247 then pool 2, ..., and finally pool N. The first delay pool where the
6248 request is allowed is selected for the request. If it does not allow
6249 the request to any pool then the request is not delayed (default).
6251 For example, if you want some_big_clients in delay
6252 pool 1 and lotsa_little_clients in delay pool 2:
6254 delay_access 1 allow some_big_clients
6255 delay_access 1 deny all
6256 delay_access 2 allow lotsa_little_clients
6257 delay_access 2 deny all
6258 delay_access 3 allow authenticated_clients
6260 See also delay_parameters and delay_class.
6264 NAME: delay_parameters
6265 TYPE: delay_pool_rates
6267 IFDEF: USE_DELAY_POOLS
6270 This defines the parameters for a delay pool. Each delay pool has
6271 a number of "buckets" associated with it, as explained in the
6272 description of delay_class.
6274 For a class 1 delay pool, the syntax is:
6276 delay_parameters pool aggregate
6278 For a class 2 delay pool:
6280 delay_parameters pool aggregate individual
6282 For a class 3 delay pool:
6284 delay_parameters pool aggregate network individual
6286 For a class 4 delay pool:
6288 delay_parameters pool aggregate network individual user
6290 For a class 5 delay pool:
6292 delay_parameters pool tagrate
6294 The option variables are:
6296 pool a pool number - ie, a number between 1 and the
6297 number specified in delay_pools as used in
6300 aggregate the speed limit parameters for the aggregate bucket
6303 individual the speed limit parameters for the individual
6304 buckets (class 2, 3).
6306 network the speed limit parameters for the network buckets
6309 user the speed limit parameters for the user buckets
6312 tagrate the speed limit parameters for the tag buckets
6315 A pair of delay parameters is written restore/maximum, where restore is
6316 the number of bytes (not bits - modem and network speeds are usually
6317 quoted in bits) per second placed into the bucket, and maximum is the
6318 maximum number of bytes which can be in the bucket at any time.
6320 There must be one delay_parameters line for each delay pool.
6323 For example, if delay pool number 1 is a class 2 delay pool as in the
6324 above example, and is being used to strictly limit each host to 64Kbit/sec
6325 (plus overheads), with no overall limit, the line is:
6327 delay_parameters 1 -1/-1 8000/8000
6329 Note that 8 x 8000 KByte/sec -> 64Kbit/sec.
6331 Note that the figure -1 is used to represent "unlimited".
6334 And, if delay pool number 2 is a class 3 delay pool as in the above
6335 example, and you want to limit it to a total of 256Kbit/sec (strict limit)
6336 with each 8-bit network permitted 64Kbit/sec (strict limit) and each
6337 individual host permitted 4800bit/sec with a bucket maximum size of 64Kbits
6338 to permit a decent web page to be downloaded at a decent speed
6339 (if the network is not being limited due to overuse) but slow down
6340 large downloads more significantly:
6342 delay_parameters 2 32000/32000 8000/8000 600/8000
6344 Note that 8 x 32000 KByte/sec -> 256Kbit/sec.
6345 8 x 8000 KByte/sec -> 64Kbit/sec.
6346 8 x 600 Byte/sec -> 4800bit/sec.
6349 Finally, for a class 4 delay pool as in the example - each user will
6350 be limited to 128Kbits/sec no matter how many workstations they are logged into.:
6352 delay_parameters 4 32000/32000 8000/8000 600/64000 16000/16000
6355 See also delay_class and delay_access.
6359 NAME: delay_initial_bucket_level
6360 COMMENT: (percent, 0-100)
6363 IFDEF: USE_DELAY_POOLS
6364 LOC: Config.Delay.initial
6366 The initial bucket percentage is used to determine how much is put
6367 in each bucket when squid starts, is reconfigured, or first notices
6368 a host accessing it (in class 2 and class 3, individual hosts and
6369 networks only have buckets associated with them once they have been
6374 CLIENT DELAY POOL PARAMETERS
6375 -----------------------------------------------------------------------------
6378 NAME: client_delay_pools
6379 TYPE: client_delay_pool_count
6381 IFDEF: USE_DELAY_POOLS
6382 LOC: Config.ClientDelay
6384 This option specifies the number of client delay pools used. It must
6385 preceed other client_delay_* options.
6388 client_delay_pools 2
6390 See also client_delay_parameters and client_delay_access.
6393 NAME: client_delay_initial_bucket_level
6394 COMMENT: (percent, 0-no_limit)
6397 IFDEF: USE_DELAY_POOLS
6398 LOC: Config.ClientDelay.initial
6400 This option determines the initial bucket size as a percentage of
6401 max_bucket_size from client_delay_parameters. Buckets are created
6402 at the time of the "first" connection from the matching IP. Idle
6403 buckets are periodically deleted up.
6405 You can specify more than 100 percent but note that such "oversized"
6406 buckets are not refilled until their size goes down to max_bucket_size
6407 from client_delay_parameters.
6410 client_delay_initial_bucket_level 50
6413 NAME: client_delay_parameters
6414 TYPE: client_delay_pool_rates
6416 IFDEF: USE_DELAY_POOLS
6417 LOC: Config.ClientDelay
6420 This option configures client-side bandwidth limits using the
6423 client_delay_parameters pool speed_limit max_bucket_size
6425 pool is an integer ID used for client_delay_access matching.
6427 speed_limit is bytes added to the bucket per second.
6429 max_bucket_size is the maximum size of a bucket, enforced after any
6430 speed_limit additions.
6432 Please see the delay_parameters option for more information and
6436 client_delay_parameters 1 1024 2048
6437 client_delay_parameters 2 51200 16384
6439 See also client_delay_access.
6443 NAME: client_delay_access
6444 TYPE: client_delay_pool_access
6446 DEFAULT_DOC: Deny use of the pool, unless allow rules exist in squid.conf for the pool.
6447 IFDEF: USE_DELAY_POOLS
6448 LOC: Config.ClientDelay
6450 This option determines the client-side delay pool for the
6453 client_delay_access pool_ID allow|deny acl_name
6455 All client_delay_access options are checked in their pool ID
6456 order, starting with pool 1. The first checked pool with allowed
6457 request is selected for the request. If no ACL matches or there
6458 are no client_delay_access options, the request bandwidth is not
6461 The ACL-selected pool is then used to find the
6462 client_delay_parameters for the request. Client-side pools are
6463 not used to aggregate clients. Clients are always aggregated
6464 based on their source IP addresses (one bucket per source IP).
6466 This clause only supports fast acl types.
6467 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
6468 Additionally, only the client TCP connection details are available.
6469 ACLs testing HTTP properties will not work.
6471 Please see delay_access for more examples.
6474 client_delay_access 1 allow low_rate_network
6475 client_delay_access 2 allow vips_network
6478 See also client_delay_parameters and client_delay_pools.
6482 WCCPv1 AND WCCPv2 CONFIGURATION OPTIONS
6483 -----------------------------------------------------------------------------
6488 LOC: Config.Wccp.router
6490 DEFAULT_DOC: WCCP disabled.
6493 Use this option to define your WCCP ``home'' router for
6496 wccp_router supports a single WCCP(v1) router
6498 wccp2_router supports multiple WCCPv2 routers
6500 only one of the two may be used at the same time and defines
6501 which version of WCCP to use.
6505 TYPE: IpAddress_list
6506 LOC: Config.Wccp2.router
6508 DEFAULT_DOC: WCCPv2 disabled.
6511 Use this option to define your WCCP ``home'' router for
6514 wccp_router supports a single WCCP(v1) router
6516 wccp2_router supports multiple WCCPv2 routers
6518 only one of the two may be used at the same time and defines
6519 which version of WCCP to use.
6524 LOC: Config.Wccp.version
6528 This directive is only relevant if you need to set up WCCP(v1)
6529 to some very old and end-of-life Cisco routers. In all other
6530 setups it must be left unset or at the default setting.
6531 It defines an internal version in the WCCP(v1) protocol,
6532 with version 4 being the officially documented protocol.
6534 According to some users, Cisco IOS 11.2 and earlier only
6535 support WCCP version 3. If you're using that or an earlier
6536 version of IOS, you may need to change this value to 3, otherwise
6537 do not specify this parameter.
6540 NAME: wccp2_rebuild_wait
6542 LOC: Config.Wccp2.rebuildwait
6546 If this is enabled Squid will wait for the cache dir rebuild to finish
6547 before sending the first wccp2 HereIAm packet
6550 NAME: wccp2_forwarding_method
6552 LOC: Config.Wccp2.forwarding_method
6556 WCCP2 allows the setting of forwarding methods between the
6557 router/switch and the cache. Valid values are as follows:
6559 gre - GRE encapsulation (forward the packet in a GRE/WCCP tunnel)
6560 l2 - L2 redirect (forward the packet using Layer 2/MAC rewriting)
6562 Currently (as of IOS 12.4) cisco routers only support GRE.
6563 Cisco switches only support the L2 redirect assignment method.
6566 NAME: wccp2_return_method
6568 LOC: Config.Wccp2.return_method
6572 WCCP2 allows the setting of return methods between the
6573 router/switch and the cache for packets that the cache
6574 decides not to handle. Valid values are as follows:
6576 gre - GRE encapsulation (forward the packet in a GRE/WCCP tunnel)
6577 l2 - L2 redirect (forward the packet using Layer 2/MAC rewriting)
6579 Currently (as of IOS 12.4) cisco routers only support GRE.
6580 Cisco switches only support the L2 redirect assignment.
6582 If the "ip wccp redirect exclude in" command has been
6583 enabled on the cache interface, then it is still safe for
6584 the proxy server to use a l2 redirect method even if this
6585 option is set to GRE.
6588 NAME: wccp2_assignment_method
6590 LOC: Config.Wccp2.assignment_method
6594 WCCP2 allows the setting of methods to assign the WCCP hash
6595 Valid values are as follows:
6597 hash - Hash assignment
6598 mask - Mask assignment
6600 As a general rule, cisco routers support the hash assignment method
6601 and cisco switches support the mask assignment method.
6606 LOC: Config.Wccp2.info
6607 DEFAULT_IF_NONE: standard 0
6608 DEFAULT_DOC: Use the 'web-cache' standard service.
6611 WCCP2 allows for multiple traffic services. There are two
6612 types: "standard" and "dynamic". The standard type defines
6613 one service id - http (id 0). The dynamic service ids can be from
6614 51 to 255 inclusive. In order to use a dynamic service id
6615 one must define the type of traffic to be redirected; this is done
6616 using the wccp2_service_info option.
6618 The "standard" type does not require a wccp2_service_info option,
6619 just specifying the service id will suffice.
6621 MD5 service authentication can be enabled by adding
6622 "password=<password>" to the end of this service declaration.
6626 wccp2_service standard 0 # for the 'web-cache' standard service
6627 wccp2_service dynamic 80 # a dynamic service type which will be
6628 # fleshed out with subsequent options.
6629 wccp2_service standard 0 password=foo
6632 NAME: wccp2_service_info
6633 TYPE: wccp2_service_info
6634 LOC: Config.Wccp2.info
6638 Dynamic WCCPv2 services require further information to define the
6639 traffic you wish to have diverted.
6643 wccp2_service_info <id> protocol=<protocol> flags=<flag>,<flag>..
6644 priority=<priority> ports=<port>,<port>..
6646 The relevant WCCPv2 flags:
6647 + src_ip_hash, dst_ip_hash
6648 + source_port_hash, dst_port_hash
6649 + src_ip_alt_hash, dst_ip_alt_hash
6650 + src_port_alt_hash, dst_port_alt_hash
6653 The port list can be one to eight entries.
6657 wccp2_service_info 80 protocol=tcp flags=src_ip_hash,ports_source
6658 priority=240 ports=80
6660 Note: the service id must have been defined by a previous
6661 'wccp2_service dynamic <id>' entry.
6666 LOC: Config.Wccp2.weight
6670 Each cache server gets assigned a set of the destination
6671 hash proportional to their weight.
6676 LOC: Config.Wccp.address
6678 DEFAULT_DOC: Address selected by the operating system.
6681 Use this option if you require WCCPv2 to use a specific
6684 The default behavior is to not bind to any specific address.
6689 LOC: Config.Wccp2.address
6691 DEFAULT_DOC: Address selected by the operating system.
6694 Use this option if you require WCCP to use a specific
6697 The default behavior is to not bind to any specific address.
6701 PERSISTENT CONNECTION HANDLING
6702 -----------------------------------------------------------------------------
6704 Also see "pconn_timeout" in the TIMEOUTS section
6707 NAME: client_persistent_connections
6709 LOC: Config.onoff.client_pconns
6712 Persistent connection support for clients.
6713 Squid uses persistent connections (when allowed). You can use
6714 this option to disable persistent connections with clients.
6717 NAME: server_persistent_connections
6719 LOC: Config.onoff.server_pconns
6722 Persistent connection support for servers.
6723 Squid uses persistent connections (when allowed). You can use
6724 this option to disable persistent connections with servers.
6727 NAME: persistent_connection_after_error
6729 LOC: Config.onoff.error_pconns
6732 With this directive the use of persistent connections after
6733 HTTP errors can be disabled. Useful if you have clients
6734 who fail to handle errors on persistent connections proper.
6737 NAME: detect_broken_pconn
6739 LOC: Config.onoff.detect_broken_server_pconns
6742 Some servers have been found to incorrectly signal the use
6743 of HTTP/1.0 persistent connections even on replies not
6744 compatible, causing significant delays. This server problem
6745 has mostly been seen on redirects.
6747 By enabling this directive Squid attempts to detect such
6748 broken replies and automatically assume the reply is finished
6749 after 10 seconds timeout.
6753 CACHE DIGEST OPTIONS
6754 -----------------------------------------------------------------------------
6757 NAME: digest_generation
6758 IFDEF: USE_CACHE_DIGESTS
6760 LOC: Config.onoff.digest_generation
6763 This controls whether the server will generate a Cache Digest
6764 of its contents. By default, Cache Digest generation is
6765 enabled if Squid is compiled with --enable-cache-digests defined.
6768 NAME: digest_bits_per_entry
6769 IFDEF: USE_CACHE_DIGESTS
6771 LOC: Config.digest.bits_per_entry
6774 This is the number of bits of the server's Cache Digest which
6775 will be associated with the Digest entry for a given HTTP
6776 Method and URL (public key) combination. The default is 5.
6779 NAME: digest_rebuild_period
6780 IFDEF: USE_CACHE_DIGESTS
6783 LOC: Config.digest.rebuild_period
6786 This is the wait time between Cache Digest rebuilds.
6789 NAME: digest_rewrite_period
6791 IFDEF: USE_CACHE_DIGESTS
6793 LOC: Config.digest.rewrite_period
6796 This is the wait time between Cache Digest writes to
6800 NAME: digest_swapout_chunk_size
6803 IFDEF: USE_CACHE_DIGESTS
6804 LOC: Config.digest.swapout_chunk_size
6807 This is the number of bytes of the Cache Digest to write to
6808 disk at a time. It defaults to 4096 bytes (4KB), the Squid
6812 NAME: digest_rebuild_chunk_percentage
6813 COMMENT: (percent, 0-100)
6814 IFDEF: USE_CACHE_DIGESTS
6816 LOC: Config.digest.rebuild_chunk_percentage
6819 This is the percentage of the Cache Digest to be scanned at a
6820 time. By default it is set to 10% of the Cache Digest.
6825 -----------------------------------------------------------------------------
6830 LOC: Config.Port.snmp
6832 DEFAULT_DOC: SNMP disabled.
6835 The port number where Squid listens for SNMP requests. To enable
6836 SNMP support set this to a suitable port number. Port number
6837 3401 is often used for the Squid SNMP agent. By default it's
6838 set to "0" (disabled)
6846 LOC: Config.accessList.snmp
6848 DEFAULT_DOC: Deny, unless rules exist in squid.conf.
6851 Allowing or denying access to the SNMP port.
6853 All access to the agent is denied by default.
6856 snmp_access allow|deny [!]aclname ...
6858 This clause only supports fast acl types.
6859 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
6862 snmp_access allow snmppublic localhost
6863 snmp_access deny all
6866 NAME: snmp_incoming_address
6868 LOC: Config.Addrs.snmp_incoming
6870 DEFAULT_DOC: Accept SNMP packets from all machine interfaces.
6873 Just like 'udp_incoming_address', but for the SNMP port.
6875 snmp_incoming_address is used for the SNMP socket receiving
6876 messages from SNMP agents.
6878 The default snmp_incoming_address is to listen on all
6879 available network interfaces.
6882 NAME: snmp_outgoing_address
6884 LOC: Config.Addrs.snmp_outgoing
6886 DEFAULT_DOC: Use snmp_incoming_address or an address selected by the operating system.
6889 Just like 'udp_outgoing_address', but for the SNMP port.
6891 snmp_outgoing_address is used for SNMP packets returned to SNMP
6894 If snmp_outgoing_address is not set it will use the same socket
6895 as snmp_incoming_address. Only change this if you want to have
6896 SNMP replies sent using another address than where this Squid
6897 listens for SNMP queries.
6899 NOTE, snmp_incoming_address and snmp_outgoing_address can not have
6900 the same value since they both use the same port.
6905 -----------------------------------------------------------------------------
6908 NAME: icp_port udp_port
6911 DEFAULT_DOC: ICP disabled.
6912 LOC: Config.Port.icp
6914 The port number where Squid sends and receives ICP queries to
6915 and from neighbor caches. The standard UDP port for ICP is 3130.
6918 icp_port @DEFAULT_ICP_PORT@
6925 DEFAULT_DOC: HTCP disabled.
6926 LOC: Config.Port.htcp
6928 The port number where Squid sends and receives HTCP queries to
6929 and from neighbor caches. To turn it on you want to set it to
6936 NAME: log_icp_queries
6940 LOC: Config.onoff.log_udp
6942 If set, ICP queries are logged to access.log. You may wish
6943 do disable this if your ICP load is VERY high to speed things
6944 up or to simplify log analysis.
6947 NAME: udp_incoming_address
6949 LOC:Config.Addrs.udp_incoming
6951 DEFAULT_DOC: Accept packets from all machine interfaces.
6953 udp_incoming_address is used for UDP packets received from other
6956 The default behavior is to not bind to any specific address.
6958 Only change this if you want to have all UDP queries received on
6959 a specific interface/address.
6961 NOTE: udp_incoming_address is used by the ICP, HTCP, and DNS
6962 modules. Altering it will affect all of them in the same manner.
6964 see also; udp_outgoing_address
6966 NOTE, udp_incoming_address and udp_outgoing_address can not
6967 have the same value since they both use the same port.
6970 NAME: udp_outgoing_address
6972 LOC: Config.Addrs.udp_outgoing
6974 DEFAULT_DOC: Use udp_incoming_address or an address selected by the operating system.
6976 udp_outgoing_address is used for UDP packets sent out to other
6979 The default behavior is to not bind to any specific address.
6981 Instead it will use the same socket as udp_incoming_address.
6982 Only change this if you want to have UDP queries sent using another
6983 address than where this Squid listens for UDP queries from other
6986 NOTE: udp_outgoing_address is used by the ICP, HTCP, and DNS
6987 modules. Altering it will affect all of them in the same manner.
6989 see also; udp_incoming_address
6991 NOTE, udp_incoming_address and udp_outgoing_address can not
6992 have the same value since they both use the same port.
6999 LOC: Config.onoff.icp_hit_stale
7001 If you want to return ICP_HIT for stale cache objects, set this
7002 option to 'on'. If you have sibling relationships with caches
7003 in other administrative domains, this should be 'off'. If you only
7004 have sibling relationships with caches under your control,
7005 it is probably okay to set this to 'on'.
7006 If set to 'on', your siblings should use the option "allow-miss"
7007 on their cache_peer lines for connecting to you.
7010 NAME: minimum_direct_hops
7013 LOC: Config.minDirectHops
7015 If using the ICMP pinging stuff, do direct fetches for sites
7016 which are no more than this many hops away.
7019 NAME: minimum_direct_rtt
7023 LOC: Config.minDirectRtt
7025 If using the ICMP pinging stuff, do direct fetches for sites
7026 which are no more than this many rtt milliseconds away.
7032 LOC: Config.Netdb.low
7034 The low water mark for the ICMP measurement database.
7036 Note: high watermark controlled by netdb_high directive.
7038 These watermarks are counts, not percents. The defaults are
7039 (low) 900 and (high) 1000. When the high water mark is
7040 reached, database entries will be deleted until the low
7047 LOC: Config.Netdb.high
7049 The high water mark for the ICMP measurement database.
7051 Note: low watermark controlled by netdb_low directive.
7053 These watermarks are counts, not percents. The defaults are
7054 (low) 900 and (high) 1000. When the high water mark is
7055 reached, database entries will be deleted until the low
7059 NAME: netdb_ping_period
7061 LOC: Config.Netdb.period
7064 The minimum period for measuring a site. There will be at
7065 least this much delay between successive pings to the same
7066 network. The default is five minutes.
7073 LOC: Config.onoff.query_icmp
7075 If you want to ask your peers to include ICMP data in their ICP
7076 replies, enable this option.
7078 If your peer has configured Squid (during compilation) with
7079 '--enable-icmp' that peer will send ICMP pings to origin server
7080 sites of the URLs it receives. If you enable this option the
7081 ICP replies from that peer will include the ICMP data (if available).
7082 Then, when choosing a parent cache, Squid will choose the parent with
7083 the minimal RTT to the origin server. When this happens, the
7084 hierarchy field of the access.log will be
7085 "CLOSEST_PARENT_MISS". This option is off by default.
7088 NAME: test_reachability
7092 LOC: Config.onoff.test_reachability
7094 When this is 'on', ICP MISS replies will be ICP_MISS_NOFETCH
7095 instead of ICP_MISS if the target host is NOT in the ICMP
7096 database, or has a zero RTT.
7099 NAME: icp_query_timeout
7102 DEFAULT_DOC: Dynamic detection.
7104 LOC: Config.Timeout.icp_query
7106 Normally Squid will automatically determine an optimal ICP
7107 query timeout value based on the round-trip-time of recent ICP
7108 queries. If you want to override the value determined by
7109 Squid, set this 'icp_query_timeout' to a non-zero value. This
7110 value is specified in MILLISECONDS, so, to use a 2-second
7111 timeout (the old default), you would write:
7113 icp_query_timeout 2000
7116 NAME: maximum_icp_query_timeout
7120 LOC: Config.Timeout.icp_query_max
7122 Normally the ICP query timeout is determined dynamically. But
7123 sometimes it can lead to very large values (say 5 seconds).
7124 Use this option to put an upper limit on the dynamic timeout
7125 value. Do NOT use this option to always use a fixed (instead
7126 of a dynamic) timeout value. To set a fixed timeout see the
7127 'icp_query_timeout' directive.
7130 NAME: minimum_icp_query_timeout
7134 LOC: Config.Timeout.icp_query_min
7136 Normally the ICP query timeout is determined dynamically. But
7137 sometimes it can lead to very small timeouts, even lower than
7138 the normal latency variance on your link due to traffic.
7139 Use this option to put an lower limit on the dynamic timeout
7140 value. Do NOT use this option to always use a fixed (instead
7141 of a dynamic) timeout value. To set a fixed timeout see the
7142 'icp_query_timeout' directive.
7145 NAME: background_ping_rate
7149 LOC: Config.backgroundPingRate
7151 Controls how often the ICP pings are sent to siblings that
7152 have background-ping set.
7156 MULTICAST ICP OPTIONS
7157 -----------------------------------------------------------------------------
7162 LOC: Config.mcast_group_list
7165 This tag specifies a list of multicast groups which your server
7166 should join to receive multicasted ICP queries.
7168 NOTE! Be very careful what you put here! Be sure you
7169 understand the difference between an ICP _query_ and an ICP
7170 _reply_. This option is to be set only if you want to RECEIVE
7171 multicast queries. Do NOT set this option to SEND multicast
7172 ICP (use cache_peer for that). ICP replies are always sent via
7173 unicast, so this option does not affect whether or not you will
7174 receive replies from multicast group members.
7176 You must be very careful to NOT use a multicast address which
7177 is already in use by another group of caches.
7179 If you are unsure about multicast, please read the Multicast
7180 chapter in the Squid FAQ (http://www.squid-cache.org/FAQ/).
7182 Usage: mcast_groups 239.128.16.128 224.0.1.20
7184 By default, Squid doesn't listen on any multicast groups.
7187 NAME: mcast_miss_addr
7188 IFDEF: MULTICAST_MISS_STREAM
7190 LOC: Config.mcast_miss.addr
7192 DEFAULT_DOC: disabled.
7194 If you enable this option, every "cache miss" URL will
7195 be sent out on the specified multicast address.
7197 Do not enable this option unless you are are absolutely
7198 certain you understand what you are doing.
7201 NAME: mcast_miss_ttl
7202 IFDEF: MULTICAST_MISS_STREAM
7204 LOC: Config.mcast_miss.ttl
7207 This is the time-to-live value for packets multicasted
7208 when multicasting off cache miss URLs is enabled. By
7209 default this is set to 'site scope', i.e. 16.
7212 NAME: mcast_miss_port
7213 IFDEF: MULTICAST_MISS_STREAM
7215 LOC: Config.mcast_miss.port
7218 This is the port number to be used in conjunction with
7222 NAME: mcast_miss_encode_key
7223 IFDEF: MULTICAST_MISS_STREAM
7225 LOC: Config.mcast_miss.encode_key
7226 DEFAULT: XXXXXXXXXXXXXXXX
7228 The URLs that are sent in the multicast miss stream are
7229 encrypted. This is the encryption key.
7232 NAME: mcast_icp_query_timeout
7236 LOC: Config.Timeout.mcast_icp_query
7238 For multicast peers, Squid regularly sends out ICP "probes" to
7239 count how many other peers are listening on the given multicast
7240 address. This value specifies how long Squid should wait to
7241 count all the replies. The default is 2000 msec, or 2
7246 INTERNAL ICON OPTIONS
7247 -----------------------------------------------------------------------------
7250 NAME: icon_directory
7252 LOC: Config.icons.directory
7253 DEFAULT: @DEFAULT_ICON_DIR@
7255 Where the icons are stored. These are normally kept in
7259 NAME: global_internal_static
7261 LOC: Config.onoff.global_internal_static
7264 This directive controls is Squid should intercept all requests for
7265 /squid-internal-static/ no matter which host the URL is requesting
7266 (default on setting), or if nothing special should be done for
7267 such URLs (off setting). The purpose of this directive is to make
7268 icons etc work better in complex cache hierarchies where it may
7269 not always be possible for all corners in the cache mesh to reach
7270 the server generating a directory listing.
7273 NAME: short_icon_urls
7275 LOC: Config.icons.use_short_names
7278 If this is enabled Squid will use short URLs for icons.
7279 If disabled it will revert to the old behavior of including
7280 it's own name and port in the URL.
7282 If you run a complex cache hierarchy with a mix of Squid and
7283 other proxies you may need to disable this directive.
7288 -----------------------------------------------------------------------------
7291 NAME: error_directory
7293 LOC: Config.errorDirectory
7295 DEFAULT_DOC: Send error pages in the clients preferred language
7297 If you wish to create your own versions of the default
7298 error files to customize them to suit your company copy
7299 the error/template files to another directory and point
7302 WARNING: This option will disable multi-language support
7303 on error pages if used.
7305 The squid developers are interested in making squid available in
7306 a wide variety of languages. If you are making translations for a
7307 language that Squid does not currently provide please consider
7308 contributing your translation back to the project.
7309 http://wiki.squid-cache.org/Translations
7311 The squid developers working on translations are happy to supply drop-in
7312 translated error files in exchange for any new language contributions.
7315 NAME: error_default_language
7316 IFDEF: USE_ERR_LOCALES
7318 LOC: Config.errorDefaultLanguage
7320 DEFAULT_DOC: Generate English language pages.
7322 Set the default language which squid will send error pages in
7323 if no existing translation matches the clients language
7326 If unset (default) generic English will be used.
7328 The squid developers are interested in making squid available in
7329 a wide variety of languages. If you are interested in making
7330 translations for any language see the squid wiki for details.
7331 http://wiki.squid-cache.org/Translations
7334 NAME: error_log_languages
7335 IFDEF: USE_ERR_LOCALES
7337 LOC: Config.errorLogMissingLanguages
7340 Log to cache.log what languages users are attempting to
7341 auto-negotiate for translations.
7343 Successful negotiations are not logged. Only failures
7344 have meaning to indicate that Squid may need an upgrade
7345 of its error page translations.
7348 NAME: err_page_stylesheet
7350 LOC: Config.errorStylesheet
7351 DEFAULT: @DEFAULT_CONFIG_DIR@/errorpage.css
7353 CSS Stylesheet to pattern the display of Squid default error pages.
7355 For information on CSS see http://www.w3.org/Style/CSS/
7360 LOC: Config.errHtmlText
7363 HTML text to include in error messages. Make this a "mailto"
7364 URL to your admin address, or maybe just a link to your
7365 organizations Web page.
7367 To include this in your error messages, you must rewrite
7368 the error template files (found in the "errors" directory).
7369 Wherever you want the 'err_html_text' line to appear,
7370 insert a %L tag in the error template file.
7373 NAME: email_err_data
7376 LOC: Config.onoff.emailErrData
7379 If enabled, information about the occurred error will be
7380 included in the mailto links of the ERR pages (if %W is set)
7381 so that the email body contains the data.
7382 Syntax is <A HREF="mailto:%w%W">%w</A>
7387 LOC: Config.denyInfoList
7390 Usage: deny_info err_page_name acl
7391 or deny_info http://... acl
7392 or deny_info TCP_RESET acl
7394 This can be used to return a ERR_ page for requests which
7395 do not pass the 'http_access' rules. Squid remembers the last
7396 acl it evaluated in http_access, and if a 'deny_info' line exists
7397 for that ACL Squid returns a corresponding error page.
7399 The acl is typically the last acl on the http_access deny line which
7400 denied access. The exceptions to this rule are:
7401 - When Squid needs to request authentication credentials. It's then
7402 the first authentication related acl encountered
7403 - When none of the http_access lines matches. It's then the last
7404 acl processed on the last http_access line.
7405 - When the decision to deny access was made by an adaptation service,
7406 the acl name is the corresponding eCAP or ICAP service_name.
7408 NP: If providing your own custom error pages with error_directory
7409 you may also specify them by your custom file name:
7410 Example: deny_info ERR_CUSTOM_ACCESS_DENIED bad_guys
7412 By defaut Squid will send "403 Forbidden". A different 4xx or 5xx
7413 may be specified by prefixing the file name with the code and a colon.
7414 e.g. 404:ERR_CUSTOM_ACCESS_DENIED
7416 Alternatively you can tell Squid to reset the TCP connection
7417 by specifying TCP_RESET.
7419 Or you can specify an error URL or URL pattern. The browsers will
7420 get redirected to the specified URL after formatting tags have
7421 been replaced. Redirect will be done with 302 or 307 according to
7422 HTTP/1.1 specs. A different 3xx code may be specified by prefixing
7423 the URL. e.g. 303:http://example.com/
7426 %a - username (if available. Password NOT included)
7429 %E - Error description
7431 %H - Request domain name
7432 %i - Client IP Address
7434 %o - Message result from external ACL helper
7435 %p - Request Port number
7436 %P - Request Protocol name
7437 %R - Request URL path
7438 %T - Timestamp in RFC 1123 format
7439 %U - Full canonical URL from client
7440 (HTTPS URLs terminate with *)
7441 %u - Full canonical URL from client
7442 %w - Admin email from squid.conf
7444 %% - Literal percent (%) code
7449 OPTIONS INFLUENCING REQUEST FORWARDING
7450 -----------------------------------------------------------------------------
7453 NAME: nonhierarchical_direct
7455 LOC: Config.onoff.nonhierarchical_direct
7458 By default, Squid will send any non-hierarchical requests
7459 (matching hierarchy_stoplist or not cacheable request type) direct
7462 When this is set to "off", Squid will prefer to send these
7463 requests to parents.
7465 Note that in most configurations, by turning this off you will only
7466 add latency to these request without any improvement in global hit
7469 This option only sets a preference. If the parent is unavailable a
7470 direct connection to the origin server may still be attempted. To
7471 completely prevent direct connections use never_direct.
7476 LOC: Config.onoff.prefer_direct
7479 Normally Squid tries to use parents for most requests. If you for some
7480 reason like it to first try going direct and only use a parent if
7481 going direct fails set this to on.
7483 By combining nonhierarchical_direct off and prefer_direct on you
7484 can set up Squid to use a parent as a backup path if going direct
7487 Note: If you want Squid to use parents for all requests see
7488 the never_direct directive. prefer_direct only modifies how Squid
7489 acts on cacheable requests.
7492 NAME: cache_miss_revalidate
7496 LOC: Config.onoff.cache_miss_revalidate
7498 Whether Squid on cache MISS will pass client revalidation requests
7499 to the server or tries to fetch new content for caching.
7500 This is useful while the cache is mostly empty to more quickly
7501 have the cache populated.
7503 When set to 'on' (default), Squid will pass all client If-* headers
7506 When set to 'off' and if the request is cacheable, Squid will
7507 remove the clients If-Modified-Since and If-None-Match headers from
7508 the request sent to the server.
7513 LOC: Config.accessList.AlwaysDirect
7515 DEFAULT_DOC: Prevent any cache_peer being used for this request.
7517 Usage: always_direct allow|deny [!]aclname ...
7519 Here you can use ACL elements to specify requests which should
7520 ALWAYS be forwarded by Squid to the origin servers without using
7521 any peers. For example, to always directly forward requests for
7522 local servers ignoring any parents or siblings you may have use
7525 acl local-servers dstdomain my.domain.net
7526 always_direct allow local-servers
7528 To always forward FTP requests directly, use
7531 always_direct allow FTP
7533 NOTE: There is a similar, but opposite option named
7534 'never_direct'. You need to be aware that "always_direct deny
7535 foo" is NOT the same thing as "never_direct allow foo". You
7536 may need to use a deny rule to exclude a more-specific case of
7537 some other rule. Example:
7539 acl local-external dstdomain external.foo.net
7540 acl local-servers dstdomain .foo.net
7541 always_direct deny local-external
7542 always_direct allow local-servers
7544 NOTE: If your goal is to make the client forward the request
7545 directly to the origin server bypassing Squid then this needs
7546 to be done in the client configuration. Squid configuration
7547 can only tell Squid how Squid should fetch the object.
7549 NOTE: This directive is not related to caching. The replies
7550 is cached as usual even if you use always_direct. To not cache
7551 the replies see the 'cache' directive.
7553 This clause supports both fast and slow acl types.
7554 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
7559 LOC: Config.accessList.NeverDirect
7561 DEFAULT_DOC: Allow DNS results to be used for this request.
7563 Usage: never_direct allow|deny [!]aclname ...
7565 never_direct is the opposite of always_direct. Please read
7566 the description for always_direct if you have not already.
7568 With 'never_direct' you can use ACL elements to specify
7569 requests which should NEVER be forwarded directly to origin
7570 servers. For example, to force the use of a proxy for all
7571 requests, except those in your local domain use something like:
7573 acl local-servers dstdomain .foo.net
7574 never_direct deny local-servers
7575 never_direct allow all
7577 or if Squid is inside a firewall and there are local intranet
7578 servers inside the firewall use something like:
7580 acl local-intranet dstdomain .foo.net
7581 acl local-external dstdomain external.foo.net
7582 always_direct deny local-external
7583 always_direct allow local-intranet
7584 never_direct allow all
7586 This clause supports both fast and slow acl types.
7587 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
7591 ADVANCED NETWORKING OPTIONS
7592 -----------------------------------------------------------------------------
7595 NAME: incoming_udp_average incoming_icp_average
7598 LOC: Config.comm_incoming.udp.average
7600 Heavy voodoo here. I can't even believe you are reading this.
7601 Are you crazy? Don't even think about adjusting these unless
7602 you understand the algorithms in comm_select.c first!
7605 NAME: incoming_tcp_average incoming_http_average
7608 LOC: Config.comm_incoming.tcp.average
7610 Heavy voodoo here. I can't even believe you are reading this.
7611 Are you crazy? Don't even think about adjusting these unless
7612 you understand the algorithms in comm_select.c first!
7615 NAME: incoming_dns_average
7618 LOC: Config.comm_incoming.dns.average
7620 Heavy voodoo here. I can't even believe you are reading this.
7621 Are you crazy? Don't even think about adjusting these unless
7622 you understand the algorithms in comm_select.c first!
7625 NAME: min_udp_poll_cnt min_icp_poll_cnt
7628 LOC: Config.comm_incoming.udp.min_poll
7630 Heavy voodoo here. I can't even believe you are reading this.
7631 Are you crazy? Don't even think about adjusting these unless
7632 you understand the algorithms in comm_select.c first!
7635 NAME: min_dns_poll_cnt
7638 LOC: Config.comm_incoming.dns.min_poll
7640 Heavy voodoo here. I can't even believe you are reading this.
7641 Are you crazy? Don't even think about adjusting these unless
7642 you understand the algorithms in comm_select.c first!
7645 NAME: min_tcp_poll_cnt min_http_poll_cnt
7648 LOC: Config.comm_incoming.tcp.min_poll
7650 Heavy voodoo here. I can't even believe you are reading this.
7651 Are you crazy? Don't even think about adjusting these unless
7652 you understand the algorithms in comm_select.c first!
7658 LOC: Config.accept_filter
7662 The name of an accept(2) filter to install on Squid's
7663 listen socket(s). This feature is perhaps specific to
7664 FreeBSD and requires support in the kernel.
7666 The 'httpready' filter delays delivering new connections
7667 to Squid until a full HTTP request has been received.
7668 See the accf_http(9) man page for details.
7670 The 'dataready' filter delays delivering new connections
7671 to Squid until there is some data to process.
7672 See the accf_dataready(9) man page for details.
7676 The 'data' filter delays delivering of new connections
7677 to Squid until there is some data to process by TCP_ACCEPT_DEFER.
7678 You may optionally specify a number of seconds to wait by
7679 'data=N' where N is the number of seconds. Defaults to 30
7680 if not specified. See the tcp(7) man page for details.
7683 accept_filter httpready
7688 NAME: client_ip_max_connections
7690 LOC: Config.client_ip_max_connections
7692 DEFAULT_DOC: No limit.
7694 Set an absolute limit on the number of connections a single
7695 client IP can use. Any more than this and Squid will begin to drop
7696 new connections from the client until it closes some links.
7698 Note that this is a global limit. It affects all HTTP, HTCP, Gopher and FTP
7699 connections from the client. For finer control use the ACL access controls.
7701 Requires client_db to be enabled (the default).
7703 WARNING: This may noticably slow down traffic received via external proxies
7704 or NAT devices and cause them to rebound error messages back to their clients.
7707 NAME: tcp_recv_bufsize
7711 DEFAULT_DOC: Use operating system TCP defaults.
7712 LOC: Config.tcpRcvBufsz
7714 Size of receive buffer to set for TCP sockets. Probably just
7715 as easy to change your kernel's default.
7716 Omit from squid.conf to use the default buffer size.
7721 -----------------------------------------------------------------------------
7728 LOC: Adaptation::Icap::TheConfig.onoff
7731 If you want to enable the ICAP module support, set this to on.
7734 NAME: icap_connect_timeout
7737 LOC: Adaptation::Icap::TheConfig.connect_timeout_raw
7740 This parameter specifies how long to wait for the TCP connect to
7741 the requested ICAP server to complete before giving up and either
7742 terminating the HTTP transaction or bypassing the failure.
7744 The default for optional services is peer_connect_timeout.
7745 The default for essential services is connect_timeout.
7746 If this option is explicitly set, its value applies to all services.
7749 NAME: icap_io_timeout
7753 DEFAULT_DOC: Use read_timeout.
7754 LOC: Adaptation::Icap::TheConfig.io_timeout_raw
7757 This parameter specifies how long to wait for an I/O activity on
7758 an established, active ICAP connection before giving up and
7759 either terminating the HTTP transaction or bypassing the
7763 NAME: icap_service_failure_limit
7764 COMMENT: limit [in memory-depth time-units]
7765 TYPE: icap_service_failure_limit
7767 LOC: Adaptation::Icap::TheConfig
7770 The limit specifies the number of failures that Squid tolerates
7771 when establishing a new TCP connection with an ICAP service. If
7772 the number of failures exceeds the limit, the ICAP service is
7773 not used for new ICAP requests until it is time to refresh its
7776 A negative value disables the limit. Without the limit, an ICAP
7777 service will not be considered down due to connectivity failures
7778 between ICAP OPTIONS requests.
7780 Squid forgets ICAP service failures older than the specified
7781 value of memory-depth. The memory fading algorithm
7782 is approximate because Squid does not remember individual
7783 errors but groups them instead, splitting the option
7784 value into ten time slots of equal length.
7786 When memory-depth is 0 and by default this option has no
7787 effect on service failure expiration.
7789 Squid always forgets failures when updating service settings
7790 using an ICAP OPTIONS transaction, regardless of this option
7794 # suspend service usage after 10 failures in 5 seconds:
7795 icap_service_failure_limit 10 in 5 seconds
7798 NAME: icap_service_revival_delay
7801 LOC: Adaptation::Icap::TheConfig.service_revival_delay
7804 The delay specifies the number of seconds to wait after an ICAP
7805 OPTIONS request failure before requesting the options again. The
7806 failed ICAP service is considered "down" until fresh OPTIONS are
7809 The actual delay cannot be smaller than the hardcoded minimum
7810 delay of 30 seconds.
7813 NAME: icap_preview_enable
7817 LOC: Adaptation::Icap::TheConfig.preview_enable
7820 The ICAP Preview feature allows the ICAP server to handle the
7821 HTTP message by looking only at the beginning of the message body
7822 or even without receiving the body at all. In some environments,
7823 previews greatly speedup ICAP processing.
7825 During an ICAP OPTIONS transaction, the server may tell Squid what
7826 HTTP messages should be previewed and how big the preview should be.
7827 Squid will not use Preview if the server did not request one.
7829 To disable ICAP Preview for all ICAP services, regardless of
7830 individual ICAP server OPTIONS responses, set this option to "off".
7832 icap_preview_enable off
7835 NAME: icap_preview_size
7838 LOC: Adaptation::Icap::TheConfig.preview_size
7840 DEFAULT_DOC: No preview sent.
7842 The default size of preview data to be sent to the ICAP server.
7843 This value might be overwritten on a per server basis by OPTIONS requests.
7846 NAME: icap_206_enable
7850 LOC: Adaptation::Icap::TheConfig.allow206_enable
7853 206 (Partial Content) responses is an ICAP extension that allows the
7854 ICAP agents to optionally combine adapted and original HTTP message
7855 content. The decision to combine is postponed until the end of the
7856 ICAP response. Squid supports Partial Content extension by default.
7858 Activation of the Partial Content extension is negotiated with each
7859 ICAP service during OPTIONS exchange. Most ICAP servers should handle
7860 negotation correctly even if they do not support the extension, but
7861 some might fail. To disable Partial Content support for all ICAP
7862 services and to avoid any negotiation, set this option to "off".
7868 NAME: icap_default_options_ttl
7871 LOC: Adaptation::Icap::TheConfig.default_options_ttl
7874 The default TTL value for ICAP OPTIONS responses that don't have
7875 an Options-TTL header.
7878 NAME: icap_persistent_connections
7882 LOC: Adaptation::Icap::TheConfig.reuse_connections
7885 Whether or not Squid should use persistent connections to
7889 NAME: adaptation_send_client_ip icap_send_client_ip
7891 IFDEF: USE_ADAPTATION
7893 LOC: Adaptation::Config::send_client_ip
7896 If enabled, Squid shares HTTP client IP information with adaptation
7897 services. For ICAP, Squid adds the X-Client-IP header to ICAP requests.
7898 For eCAP, Squid sets the libecap::metaClientIp transaction option.
7900 See also: adaptation_uses_indirect_client
7903 NAME: adaptation_send_username icap_send_client_username
7905 IFDEF: USE_ADAPTATION
7907 LOC: Adaptation::Config::send_username
7910 This sends authenticated HTTP client username (if available) to
7911 the adaptation service.
7913 For ICAP, the username value is encoded based on the
7914 icap_client_username_encode option and is sent using the header
7915 specified by the icap_client_username_header option.
7918 NAME: icap_client_username_header
7921 LOC: Adaptation::Icap::TheConfig.client_username_header
7922 DEFAULT: X-Client-Username
7924 ICAP request header name to use for adaptation_send_username.
7927 NAME: icap_client_username_encode
7931 LOC: Adaptation::Icap::TheConfig.client_username_encode
7934 Whether to base64 encode the authenticated client username.
7938 TYPE: icap_service_type
7940 LOC: Adaptation::Icap::TheConfig
7943 Defines a single ICAP service using the following format:
7945 icap_service id vectoring_point uri [option ...]
7948 an opaque identifier or name which is used to direct traffic to
7949 this specific service. Must be unique among all adaptation
7950 services in squid.conf.
7952 vectoring_point: reqmod_precache|reqmod_postcache|respmod_precache|respmod_postcache
7953 This specifies at which point of transaction processing the
7954 ICAP service should be activated. *_postcache vectoring points
7955 are not yet supported.
7957 uri: icap://servername:port/servicepath
7958 ICAP server and service location.
7960 ICAP does not allow a single service to handle both REQMOD and RESPMOD
7961 transactions. Squid does not enforce that requirement. You can specify
7962 services with the same service_url and different vectoring_points. You
7963 can even specify multiple identical services as long as their
7964 service_names differ.
7966 To activate a service, use the adaptation_access directive. To group
7967 services, use adaptation_service_chain and adaptation_service_set.
7969 Service options are separated by white space. ICAP services support
7970 the following name=value options:
7973 If set to 'on' or '1', the ICAP service is treated as
7974 optional. If the service cannot be reached or malfunctions,
7975 Squid will try to ignore any errors and process the message as
7976 if the service was not enabled. No all ICAP errors can be
7977 bypassed. If set to 0, the ICAP service is treated as
7978 essential and all ICAP errors will result in an error page
7979 returned to the HTTP client.
7981 Bypass is off by default: services are treated as essential.
7984 If set to 'on' or '1', the ICAP service is allowed to
7985 dynamically change the current message adaptation plan by
7986 returning a chain of services to be used next. The services
7987 are specified using the X-Next-Services ICAP response header
7988 value, formatted as a comma-separated list of service names.
7989 Each named service should be configured in squid.conf. Other
7990 services are ignored. An empty X-Next-Services value results
7991 in an empty plan which ends the current adaptation.
7993 Dynamic adaptation plan may cross or cover multiple supported
7994 vectoring points in their natural processing order.
7996 Routing is not allowed by default: the ICAP X-Next-Services
7997 response header is ignored.
8000 Only has effect on split-stack systems. The default on those systems
8001 is to use IPv4-only connections. When set to 'on' this option will
8002 make Squid use IPv6-only connections to contact this ICAP service.
8004 on-overload=block|bypass|wait|force
8005 If the service Max-Connections limit has been reached, do
8006 one of the following for each new ICAP transaction:
8007 * block: send an HTTP error response to the client
8008 * bypass: ignore the "over-connected" ICAP service
8009 * wait: wait (in a FIFO queue) for an ICAP connection slot
8010 * force: proceed, ignoring the Max-Connections limit
8012 In SMP mode with N workers, each worker assumes the service
8013 connection limit is Max-Connections/N, even though not all
8014 workers may use a given service.
8016 The default value is "bypass" if service is bypassable,
8017 otherwise it is set to "wait".
8021 Use the given number as the Max-Connections limit, regardless
8022 of the Max-Connections value given by the service, if any.
8024 Older icap_service format without optional named parameters is
8025 deprecated but supported for backward compatibility.
8028 icap_service svcBlocker reqmod_precache icap://icap1.mydomain.net:1344/reqmod bypass=0
8029 icap_service svcLogger reqmod_precache icap://icap2.mydomain.net:1344/respmod routing=on
8033 TYPE: icap_class_type
8038 This deprecated option was documented to define an ICAP service
8039 chain, even though it actually defined a set of similar, redundant
8040 services, and the chains were not supported.
8042 To define a set of redundant services, please use the
8043 adaptation_service_set directive. For service chains, use
8044 adaptation_service_chain.
8048 TYPE: icap_access_type
8053 This option is deprecated. Please use adaptation_access, which
8054 has the same ICAP functionality, but comes with better
8055 documentation, and eCAP support.
8060 -----------------------------------------------------------------------------
8067 LOC: Adaptation::Ecap::TheConfig.onoff
8070 Controls whether eCAP support is enabled.
8074 TYPE: ecap_service_type
8076 LOC: Adaptation::Ecap::TheConfig
8079 Defines a single eCAP service
8081 ecap_service id vectoring_point uri [option ...]
8084 an opaque identifier or name which is used to direct traffic to
8085 this specific service. Must be unique among all adaptation
8086 services in squid.conf.
8088 vectoring_point: reqmod_precache|reqmod_postcache|respmod_precache|respmod_postcache
8089 This specifies at which point of transaction processing the
8090 eCAP service should be activated. *_postcache vectoring points
8091 are not yet supported.
8093 uri: ecap://vendor/service_name?custom&cgi=style¶meters=optional
8094 Squid uses the eCAP service URI to match this configuration
8095 line with one of the dynamically loaded services. Each loaded
8096 eCAP service must have a unique URI. Obtain the right URI from
8097 the service provider.
8099 To activate a service, use the adaptation_access directive. To group
8100 services, use adaptation_service_chain and adaptation_service_set.
8102 Service options are separated by white space. eCAP services support
8103 the following name=value options:
8106 If set to 'on' or '1', the eCAP service is treated as optional.
8107 If the service cannot be reached or malfunctions, Squid will try
8108 to ignore any errors and process the message as if the service
8109 was not enabled. No all eCAP errors can be bypassed.
8110 If set to 'off' or '0', the eCAP service is treated as essential
8111 and all eCAP errors will result in an error page returned to the
8114 Bypass is off by default: services are treated as essential.
8117 If set to 'on' or '1', the eCAP service is allowed to
8118 dynamically change the current message adaptation plan by
8119 returning a chain of services to be used next.
8121 Dynamic adaptation plan may cross or cover multiple supported
8122 vectoring points in their natural processing order.
8124 Routing is not allowed by default.
8126 Older ecap_service format without optional named parameters is
8127 deprecated but supported for backward compatibility.
8131 ecap_service s1 reqmod_precache ecap://filters.R.us/leakDetector?on_error=block bypass=off
8132 ecap_service s2 respmod_precache ecap://filters.R.us/virusFilter config=/etc/vf.cfg bypass=on
8135 NAME: loadable_modules
8137 IFDEF: USE_LOADABLE_MODULES
8138 LOC: Config.loadable_module_names
8141 Instructs Squid to load the specified dynamic module(s) or activate
8142 preloaded module(s).
8144 loadable_modules @DEFAULT_PREFIX@/lib/MinimalAdapter.so
8148 MESSAGE ADAPTATION OPTIONS
8149 -----------------------------------------------------------------------------
8152 NAME: adaptation_service_set
8153 TYPE: adaptation_service_set_type
8154 IFDEF: USE_ADAPTATION
8159 Configures an ordered set of similar, redundant services. This is
8160 useful when hot standby or backup adaptation servers are available.
8162 adaptation_service_set set_name service_name1 service_name2 ...
8164 The named services are used in the set declaration order. The first
8165 applicable adaptation service from the set is used first. The next
8166 applicable service is tried if and only if the transaction with the
8167 previous service fails and the message waiting to be adapted is still
8170 When adaptation starts, broken services are ignored as if they were
8171 not a part of the set. A broken service is a down optional service.
8173 The services in a set must be attached to the same vectoring point
8174 (e.g., pre-cache) and use the same adaptation method (e.g., REQMOD).
8176 If all services in a set are optional then adaptation failures are
8177 bypassable. If all services in the set are essential, then a
8178 transaction failure with one service may still be retried using
8179 another service from the set, but when all services fail, the master
8180 transaction fails as well.
8182 A set may contain a mix of optional and essential services, but that
8183 is likely to lead to surprising results because broken services become
8184 ignored (see above), making previously bypassable failures fatal.
8185 Technically, it is the bypassability of the last failed service that
8188 See also: adaptation_access adaptation_service_chain
8191 adaptation_service_set svcBlocker urlFilterPrimary urlFilterBackup
8192 adaptation service_set svcLogger loggerLocal loggerRemote
8195 NAME: adaptation_service_chain
8196 TYPE: adaptation_service_chain_type
8197 IFDEF: USE_ADAPTATION
8202 Configures a list of complementary services that will be applied
8203 one-by-one, forming an adaptation chain or pipeline. This is useful
8204 when Squid must perform different adaptations on the same message.
8206 adaptation_service_chain chain_name service_name1 svc_name2 ...
8208 The named services are used in the chain declaration order. The first
8209 applicable adaptation service from the chain is used first. The next
8210 applicable service is applied to the successful adaptation results of
8211 the previous service in the chain.
8213 When adaptation starts, broken services are ignored as if they were
8214 not a part of the chain. A broken service is a down optional service.
8216 Request satisfaction terminates the adaptation chain because Squid
8217 does not currently allow declaration of RESPMOD services at the
8218 "reqmod_precache" vectoring point (see icap_service or ecap_service).
8220 The services in a chain must be attached to the same vectoring point
8221 (e.g., pre-cache) and use the same adaptation method (e.g., REQMOD).
8223 A chain may contain a mix of optional and essential services. If an
8224 essential adaptation fails (or the failure cannot be bypassed for
8225 other reasons), the master transaction fails. Otherwise, the failure
8226 is bypassed as if the failed adaptation service was not in the chain.
8228 See also: adaptation_access adaptation_service_set
8231 adaptation_service_chain svcRequest requestLogger urlFilter leakDetector
8234 NAME: adaptation_access
8235 TYPE: adaptation_access_type
8236 IFDEF: USE_ADAPTATION
8239 DEFAULT_DOC: Allow, unless rules exist in squid.conf.
8241 Sends an HTTP transaction to an ICAP or eCAP adaptation service.
8243 adaptation_access service_name allow|deny [!]aclname...
8244 adaptation_access set_name allow|deny [!]aclname...
8246 At each supported vectoring point, the adaptation_access
8247 statements are processed in the order they appear in this
8248 configuration file. Statements pointing to the following services
8249 are ignored (i.e., skipped without checking their ACL):
8251 - services serving different vectoring points
8252 - "broken-but-bypassable" services
8253 - "up" services configured to ignore such transactions
8254 (e.g., based on the ICAP Transfer-Ignore header).
8256 When a set_name is used, all services in the set are checked
8257 using the same rules, to find the first applicable one. See
8258 adaptation_service_set for details.
8260 If an access list is checked and there is a match, the
8261 processing stops: For an "allow" rule, the corresponding
8262 adaptation service is used for the transaction. For a "deny"
8263 rule, no adaptation service is activated.
8265 It is currently not possible to apply more than one adaptation
8266 service at the same vectoring point to the same HTTP transaction.
8268 See also: icap_service and ecap_service
8271 adaptation_access service_1 allow all
8274 NAME: adaptation_service_iteration_limit
8276 IFDEF: USE_ADAPTATION
8277 LOC: Adaptation::Config::service_iteration_limit
8280 Limits the number of iterations allowed when applying adaptation
8281 services to a message. If your longest adaptation set or chain
8282 may have more than 16 services, increase the limit beyond its
8283 default value of 16. If detecting infinite iteration loops sooner
8284 is critical, make the iteration limit match the actual number
8285 of services in your longest adaptation set or chain.
8287 Infinite adaptation loops are most likely with routing services.
8289 See also: icap_service routing=1
8292 NAME: adaptation_masterx_shared_names
8294 IFDEF: USE_ADAPTATION
8295 LOC: Adaptation::Config::masterx_shared_name
8298 For each master transaction (i.e., the HTTP request and response
8299 sequence, including all related ICAP and eCAP exchanges), Squid
8300 maintains a table of metadata. The table entries are (name, value)
8301 pairs shared among eCAP and ICAP exchanges. The table is destroyed
8302 with the master transaction.
8304 This option specifies the table entry names that Squid must accept
8305 from and forward to the adaptation transactions.
8307 An ICAP REQMOD or RESPMOD transaction may set an entry in the
8308 shared table by returning an ICAP header field with a name
8309 specified in adaptation_masterx_shared_names.
8311 An eCAP REQMOD or RESPMOD transaction may set an entry in the
8312 shared table by implementing the libecap::visitEachOption() API
8313 to provide an option with a name specified in
8314 adaptation_masterx_shared_names.
8316 Squid will store and forward the set entry to subsequent adaptation
8317 transactions within the same master transaction scope.
8319 Only one shared entry name is supported at this time.
8322 # share authentication information among ICAP services
8323 adaptation_masterx_shared_names X-Subscriber-ID
8326 NAME: adaptation_meta
8328 IFDEF: USE_ADAPTATION
8329 LOC: Adaptation::Config::metaHeaders
8332 This option allows Squid administrator to add custom ICAP request
8333 headers or eCAP options to Squid ICAP requests or eCAP transactions.
8334 Use it to pass custom authentication tokens and other
8335 transaction-state related meta information to an ICAP/eCAP service.
8337 The addition of a meta header is ACL-driven:
8338 adaptation_meta name value [!]aclname ...
8340 Processing for a given header name stops after the first ACL list match.
8341 Thus, it is impossible to add two headers with the same name. If no ACL
8342 lists match for a given header name, no such header is added. For
8345 # do not debug transactions except for those that need debugging
8346 adaptation_meta X-Debug 1 needs_debugging
8348 # log all transactions except for those that must remain secret
8349 adaptation_meta X-Log 1 !keep_secret
8351 # mark transactions from users in the "G 1" group
8352 adaptation_meta X-Authenticated-Groups "G 1" authed_as_G1
8354 The "value" parameter may be a regular squid.conf token or a "double
8355 quoted string". Within the quoted string, use backslash (\) to escape
8356 any character, which is currently only useful for escaping backslashes
8357 and double quotes. For example,
8358 "this string has one backslash (\\) and two \"quotes\""
8360 Used adaptation_meta header values may be logged via %note
8361 logformat code. If multiple adaptation_meta headers with the same name
8362 are used during master transaction lifetime, the header values are
8363 logged in the order they were used and duplicate values are ignored
8364 (only the first repeated value will be logged).
8370 LOC: Adaptation::Icap::TheConfig.repeat
8371 DEFAULT_IF_NONE: deny all
8373 This ACL determines which retriable ICAP transactions are
8374 retried. Transactions that received a complete ICAP response
8375 and did not have to consume or produce HTTP bodies to receive
8376 that response are usually retriable.
8378 icap_retry allow|deny [!]aclname ...
8380 Squid automatically retries some ICAP I/O timeouts and errors
8381 due to persistent connection race conditions.
8383 See also: icap_retry_limit
8386 NAME: icap_retry_limit
8389 LOC: Adaptation::Icap::TheConfig.repeat_limit
8391 DEFAULT_DOC: No retries are allowed.
8393 Limits the number of retries allowed.
8395 Communication errors due to persistent connection race
8396 conditions are unavoidable, automatically retried, and do not
8397 count against this limit.
8399 See also: icap_retry
8405 -----------------------------------------------------------------------------
8408 NAME: check_hostnames
8411 LOC: Config.onoff.check_hostnames
8413 For security and stability reasons Squid can check
8414 hostnames for Internet standard RFC compliance. If you want
8415 Squid to perform these checks turn this directive on.
8418 NAME: allow_underscore
8421 LOC: Config.onoff.allow_underscore
8423 Underscore characters is not strictly allowed in Internet hostnames
8424 but nevertheless used by many sites. Set this to off if you want
8425 Squid to be strict about the standard.
8426 This check is performed only when check_hostnames is set to on.
8429 NAME: dns_retransmit_interval
8432 LOC: Config.Timeout.idns_retransmit
8434 Initial retransmit interval for DNS queries. The interval is
8435 doubled each time all configured DNS servers have been tried.
8441 LOC: Config.Timeout.idns_query
8443 DNS Query timeout. If no response is received to a DNS query
8444 within this time all DNS servers for the queried domain
8445 are assumed to be unavailable.
8448 NAME: dns_packet_max
8450 DEFAULT_DOC: EDNS disabled
8452 LOC: Config.dns.packet_max
8454 Maximum number of bytes packet size to advertise via EDNS.
8455 Set to "none" to disable EDNS large packet support.
8457 For legacy reasons DNS UDP replies will default to 512 bytes which
8458 is too small for many responses. EDNS provides a means for Squid to
8459 negotiate receiving larger responses back immediately without having
8460 to failover with repeat requests. Responses larger than this limit
8461 will retain the old behaviour of failover to TCP DNS.
8463 Squid has no real fixed limit internally, but allowing packet sizes
8464 over 1500 bytes requires network jumbogram support and is usually not
8467 WARNING: The RFC also indicates that some older resolvers will reply
8468 with failure of the whole request if the extension is added. Some
8469 resolvers have already been identified which will reply with mangled
8470 EDNS response on occasion. Usually in response to many-KB jumbogram
8471 sizes being advertised by Squid.
8472 Squid will currently treat these both as an unable-to-resolve domain
8473 even if it would be resolvable without EDNS.
8480 DEFAULT_DOC: Search for single-label domain names is disabled.
8481 LOC: Config.onoff.res_defnames
8483 Normally the RES_DEFNAMES resolver option is disabled
8484 (see res_init(3)). This prevents caches in a hierarchy
8485 from interpreting single-component hostnames locally. To allow
8486 Squid to handle single-component names, enable this option.
8489 NAME: dns_multicast_local
8493 DEFAULT_DOC: Search for .local and .arpa names is disabled.
8494 LOC: Config.onoff.dns_mdns
8496 When set to on, Squid sends multicast DNS lookups on the local
8497 network for domains ending in .local and .arpa.
8498 This enables local servers and devices to be contacted in an
8499 ad-hoc or zero-configuration network environment.
8502 NAME: dns_nameservers
8505 DEFAULT_DOC: Use operating system definitions
8506 LOC: Config.dns_nameservers
8508 Use this if you want to specify a list of DNS name servers
8509 (IP addresses) to use instead of those given in your
8510 /etc/resolv.conf file.
8512 On Windows platforms, if no value is specified here or in
8513 the /etc/resolv.conf file, the list of DNS name servers are
8514 taken from the Windows registry, both static and dynamic DHCP
8515 configurations are supported.
8517 Example: dns_nameservers 10.0.0.1 192.172.0.4
8522 DEFAULT: @DEFAULT_HOSTS@
8523 LOC: Config.etcHostsPath
8525 Location of the host-local IP name-address associations
8526 database. Most Operating Systems have such a file on different
8528 - Un*X & Linux: /etc/hosts
8529 - Windows NT/2000: %SystemRoot%\system32\drivers\etc\hosts
8530 (%SystemRoot% value install default is c:\winnt)
8531 - Windows XP/2003: %SystemRoot%\system32\drivers\etc\hosts
8532 (%SystemRoot% value install default is c:\windows)
8533 - Windows 9x/Me: %windir%\hosts
8534 (%windir% value is usually c:\windows)
8535 - Cygwin: /etc/hosts
8537 The file contains newline-separated definitions, in the
8538 form ip_address_in_dotted_form name [name ...] names are
8539 whitespace-separated. Lines beginning with an hash (#)
8540 character are comments.
8542 The file is checked at startup and upon configuration.
8543 If set to 'none', it won't be checked.
8544 If append_domain is used, that domain will be added to
8545 domain-local (i.e. not containing any dot character) host
8551 LOC: Config.appendDomain
8553 DEFAULT_DOC: Use operating system definitions
8555 Appends local domain name to hostnames without any dots in
8556 them. append_domain must begin with a period.
8558 Be warned there are now Internet names with no dots in
8559 them using only top-domain names, so setting this may
8560 cause some Internet sites to become unavailable.
8563 append_domain .yourdomain.com
8566 NAME: ignore_unknown_nameservers
8568 LOC: Config.onoff.ignore_unknown_nameservers
8571 By default Squid checks that DNS responses are received
8572 from the same IP addresses they are sent to. If they
8573 don't match, Squid ignores the response and writes a warning
8574 message to cache.log. You can allow responses from unknown
8575 nameservers by setting this option to 'off'.
8581 LOC: Config.dns.v4_first
8583 With the IPv6 Internet being as fast or faster than IPv4 Internet
8584 for most networks Squid prefers to contact websites over IPv6.
8586 This option reverses the order of preference to make Squid contact
8587 dual-stack websites over IPv4 first. Squid will still perform both
8588 IPv6 and IPv4 DNS lookups before connecting.
8591 This option will restrict the situations under which IPv6
8592 connectivity is used (and tested). Hiding network problems
8593 which would otherwise be detected and warned about.
8597 COMMENT: (number of entries)
8600 LOC: Config.ipcache.size
8602 Maximum number of DNS IP cache entries.
8609 LOC: Config.ipcache.low
8616 LOC: Config.ipcache.high
8618 The size, low-, and high-water marks for the IP cache.
8621 NAME: fqdncache_size
8622 COMMENT: (number of entries)
8625 LOC: Config.fqdncache.size
8627 Maximum number of FQDN cache entries.
8632 -----------------------------------------------------------------------------
8635 NAME: configuration_includes_quoted_values
8637 TYPE: configuration_includes_quoted_values
8639 LOC: ConfigParser::RecognizeQuotedValues
8641 If set, Squid will recognize each "quoted string" after a configuration
8642 directive as a single parameter. The quotes are stripped before the
8643 parameter value is interpreted or used.
8644 See "Values with spaces, quotes, and other special characters"
8645 section for more details.
8652 LOC: Config.onoff.mem_pools
8654 If set, Squid will keep pools of allocated (but unused) memory
8655 available for future use. If memory is a premium on your
8656 system and you believe your malloc library outperforms Squid
8657 routines, disable this.
8660 NAME: memory_pools_limit
8664 LOC: Config.MemPools.limit
8666 Used only with memory_pools on:
8667 memory_pools_limit 50 MB
8669 If set to a non-zero value, Squid will keep at most the specified
8670 limit of allocated (but unused) memory in memory pools. All free()
8671 requests that exceed this limit will be handled by your malloc
8672 library. Squid does not pre-allocate any memory, just safe-keeps
8673 objects that otherwise would be free()d. Thus, it is safe to set
8674 memory_pools_limit to a reasonably high value even if your
8675 configuration will use less memory.
8677 If set to none, Squid will keep all memory it can. That is, there
8678 will be no limit on the total amount of memory used for safe-keeping.
8680 To disable memory allocation optimization, do not set
8681 memory_pools_limit to 0 or none. Set memory_pools to "off" instead.
8683 An overhead for maintaining memory pools is not taken into account
8684 when the limit is checked. This overhead is close to four bytes per
8685 object kept. However, pools may actually _save_ memory because of
8686 reduced memory thrashing in your malloc library.
8690 COMMENT: on|off|transparent|truncate|delete
8693 LOC: opt_forwarded_for
8695 If set to "on", Squid will append your client's IP address
8696 in the HTTP requests it forwards. By default it looks like:
8698 X-Forwarded-For: 192.1.2.3
8700 If set to "off", it will appear as
8702 X-Forwarded-For: unknown
8704 If set to "transparent", Squid will not alter the
8705 X-Forwarded-For header in any way.
8707 If set to "delete", Squid will delete the entire
8708 X-Forwarded-For header.
8710 If set to "truncate", Squid will remove all existing
8711 X-Forwarded-For entries, and place the client IP as the sole entry.
8714 NAME: cachemgr_passwd
8715 TYPE: cachemgrpasswd
8717 DEFAULT_DOC: No password. Actions which require password are denied.
8718 LOC: Config.passwd_list
8720 Specify passwords for cachemgr operations.
8722 Usage: cachemgr_passwd password action action ...
8724 Some valid actions are (see cache manager menu for a full list):
8764 * Indicates actions which will not be performed without a
8765 valid password, others can be performed if not listed here.
8767 To disable an action, set the password to "disable".
8768 To allow performing an action without a password, set the
8771 Use the keyword "all" to set the same password for all actions.
8774 cachemgr_passwd secret shutdown
8775 cachemgr_passwd lesssssssecret info stats/objects
8776 cachemgr_passwd disable all
8783 LOC: Config.onoff.client_db
8785 If you want to disable collecting per-client statistics,
8786 turn off client_db here.
8789 NAME: refresh_all_ims
8793 LOC: Config.onoff.refresh_all_ims
8795 When you enable this option, squid will always check
8796 the origin server for an update when a client sends an
8797 If-Modified-Since request. Many browsers use IMS
8798 requests when the user requests a reload, and this
8799 ensures those clients receive the latest version.
8801 By default (off), squid may return a Not Modified response
8802 based on the age of the cached version.
8805 NAME: reload_into_ims
8806 IFDEF: USE_HTTP_VIOLATIONS
8810 LOC: Config.onoff.reload_into_ims
8812 When you enable this option, client no-cache or ``reload''
8813 requests will be changed to If-Modified-Since requests.
8814 Doing this VIOLATES the HTTP standard. Enabling this
8815 feature could make you liable for problems which it
8818 see also refresh_pattern for a more selective approach.
8821 NAME: connect_retries
8823 LOC: Config.connect_retries
8825 DEFAULT_DOC: Do not retry failed connections.
8827 This sets the maximum number of connection attempts made for each
8828 TCP connection. The connect_retries attempts must all still
8829 complete within the connection timeout period.
8831 The default is not to re-try if the first connection attempt fails.
8832 The (not recommended) maximum is 10 tries.
8834 A warning message will be generated if it is set to a too-high
8835 value and the configured value will be over-ridden.
8837 Note: These re-tries are in addition to forward_max_tries
8838 which limit how many different addresses may be tried to find
8842 NAME: retry_on_error
8844 LOC: Config.retry.onerror
8847 If set to ON Squid will automatically retry requests when
8848 receiving an error response with status 403 (Forbidden),
8849 500 (Internal Error), 501 or 503 (Service not available).
8850 Status 502 and 504 (Gateway errors) are always retried.
8852 This is mainly useful if you are in a complex cache hierarchy to
8853 work around access control errors.
8855 NOTE: This retry will attempt to find another working destination.
8856 Which is different from the server which just failed.
8859 NAME: as_whois_server
8861 LOC: Config.as_whois_server
8862 DEFAULT: whois.ra.net
8864 WHOIS server to query for AS numbers. NOTE: AS numbers are
8865 queried only when Squid starts up, not for every request.
8870 LOC: Config.onoff.offline
8873 Enable this option and Squid will never try to validate cached
8877 NAME: uri_whitespace
8878 TYPE: uri_whitespace
8879 LOC: Config.uri_whitespace
8882 What to do with requests that have whitespace characters in the
8885 strip: The whitespace characters are stripped out of the URL.
8886 This is the behavior recommended by RFC2396 and RFC3986
8887 for tolerant handling of generic URI.
8888 NOTE: This is one difference between generic URI and HTTP URLs.
8890 deny: The request is denied. The user receives an "Invalid
8892 This is the behaviour recommended by RFC2616 for safe
8893 handling of HTTP request URL.
8895 allow: The request is allowed and the URI is not changed. The
8896 whitespace characters remain in the URI. Note the
8897 whitespace is passed to redirector processes if they
8899 Note this may be considered a violation of RFC2616
8900 request parsing where whitespace is prohibited in the
8903 encode: The request is allowed and the whitespace characters are
8904 encoded according to RFC1738.
8906 chop: The request is allowed and the URI is chopped at the
8910 NOTE the current Squid implementation of encode and chop violates
8911 RFC2616 by not using a 301 redirect after altering the URL.
8916 LOC: Config.chroot_dir
8919 Specifies a directory where Squid should do a chroot() while
8920 initializing. This also causes Squid to fully drop root
8921 privileges after initializing. This means, for example, if you
8922 use a HTTP port less than 1024 and try to reconfigure, you may
8923 get an error saying that Squid can not open the port.
8926 NAME: balance_on_multiple_ip
8928 LOC: Config.onoff.balance_on_multiple_ip
8931 Modern IP resolvers in squid sort lookup results by preferred access.
8932 By default squid will use these IP in order and only rotates to
8933 the next listed when the most preffered fails.
8935 Some load balancing servers based on round robin DNS have been
8936 found not to preserve user session state across requests
8937 to different IP addresses.
8939 Enabling this directive Squid rotates IP's per request.
8942 NAME: pipeline_prefetch
8943 TYPE: pipelinePrefetch
8944 LOC: Config.pipeline_max_prefetch
8946 DEFAULT_DOC: Do not pre-parse pipelined requests.
8948 HTTP clients may send a pipeline of 1+N requests to Squid using a
8949 single connection, without waiting for Squid to respond to the first
8950 of those requests. This option limits the number of concurrent
8951 requests Squid will try to handle in parallel. If set to N, Squid
8952 will try to receive and process up to 1+N requests on the same
8953 connection concurrently.
8955 Defaults to 0 (off) for bandwidth management and access logging
8958 NOTE: pipelining requires persistent connections to clients.
8960 WARNING: pipelining breaks NTLM and Negotiate/Kerberos authentication.
8963 NAME: high_response_time_warning
8966 LOC: Config.warnings.high_rptm
8968 DEFAULT_DOC: disabled.
8970 If the one-minute median response time exceeds this value,
8971 Squid prints a WARNING with debug level 0 to get the
8972 administrators attention. The value is in milliseconds.
8975 NAME: high_page_fault_warning
8977 LOC: Config.warnings.high_pf
8979 DEFAULT_DOC: disabled.
8981 If the one-minute average page fault rate exceeds this
8982 value, Squid prints a WARNING with debug level 0 to get
8983 the administrators attention. The value is in page faults
8987 NAME: high_memory_warning
8989 LOC: Config.warnings.high_memory
8990 IFDEF: HAVE_MSTATS&&HAVE_GNUMALLOC_H
8992 DEFAULT_DOC: disabled.
8994 If the memory usage (as determined by gnumalloc, if available and used)
8995 exceeds this amount, Squid prints a WARNING with debug level 0 to get
8996 the administrators attention.
8998 # TODO: link high_memory_warning to mempools?
9000 NAME: sleep_after_fork
9001 COMMENT: (microseconds)
9003 LOC: Config.sleep_after_fork
9006 When this is set to a non-zero value, the main Squid process
9007 sleeps the specified number of microseconds after a fork()
9008 system call. This sleep may help the situation where your
9009 system reports fork() failures due to lack of (virtual)
9010 memory. Note, however, if you have a lot of child
9011 processes, these sleep delays will add up and your
9012 Squid will not service requests for some amount of time
9013 until all the child processes have been started.
9014 On Windows value less then 1000 (1 milliseconds) are
9018 NAME: windows_ipaddrchangemonitor
9019 IFDEF: _SQUID_WINDOWS_
9023 LOC: Config.onoff.WIN32_IpAddrChangeMonitor
9025 On Windows Squid by default will monitor IP address changes and will
9026 reconfigure itself after any detected event. This is very useful for
9027 proxies connected to internet with dial-up interfaces.
9028 In some cases (a Proxy server acting as VPN gateway is one) it could be
9029 desiderable to disable this behaviour setting this to 'off'.
9030 Note: after changing this, Squid service must be restarted.
9035 IFDEF: USE_SQUID_EUI
9037 LOC: Eui::TheConfig.euiLookup
9039 Whether to lookup the EUI or MAC address of a connected client.
9042 NAME: max_filedescriptors max_filedesc
9045 DEFAULT_DOC: Use operating system limits set by ulimit.
9046 LOC: Config.max_filedescriptors
9048 Reduce the maximum number of filedescriptors supported below
9049 the usual operating system defaults.
9051 Remove from squid.conf to inherit the current ulimit setting.
9053 Note: Changing this requires a restart of Squid. Also
9054 not all I/O types supports large values (eg on Windows).
9061 DEFAULT_DOC: SMP support disabled.
9063 Number of main Squid processes or "workers" to fork and maintain.
9064 0: "no daemon" mode, like running "squid -N ..."
9065 1: "no SMP" mode, start one main Squid process daemon (default)
9066 N: start N main Squid process daemons (i.e., SMP mode)
9068 In SMP mode, each worker does nearly all what a single Squid daemon
9069 does (e.g., listen on http_port and forward HTTP requests).
9072 NAME: cpu_affinity_map
9073 TYPE: CpuAffinityMap
9074 LOC: Config.cpuAffinityMap
9076 DEFAULT_DOC: Let operating system decide.
9078 Usage: cpu_affinity_map process_numbers=P1,P2,... cores=C1,C2,...
9080 Sets 1:1 mapping between Squid processes and CPU cores. For example,
9082 cpu_affinity_map process_numbers=1,2,3,4 cores=1,3,5,7
9084 affects processes 1 through 4 only and places them on the first
9085 four even cores, starting with core #1.
9087 CPU cores are numbered starting from 1. Requires support for
9088 sched_getaffinity(2) and sched_setaffinity(2) system calls.
9090 Multiple cpu_affinity_map options are merged.
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