Squid configuration directive icap_service
- Changes to icap_service in Squid-4:
New scheme icaps:// to enable TLS/SSL connections to Secure ICAP servers on port 11344.
New tls-cert= option to set TLS client certificate to use.
New tls-key= option to set TLS private key matching the client certificate used.
New tls-min-version=1.N option to set minimum TLS version allowed on server connections.
New tls-options= option to set OpenSSL library parameters.
New tls-flags= option to set flags modifying Squid TLS operations.
New tls-cipher= option to set a list of ciphers permitted.
New tls-cafile= option to set a file with additional CA certificate(s) to verify the server certificate.
New tls-crlfile= option to set a file with a CRL to verify the server certificate.
New tls-default-ca option to use the system Trusted CAs to verify the server certificate.
New tls-domain= option to verify the server certificate domain.
For older versions than 3.3 see the linked pages above
Defines a single ICAP service using the following format: icap_service id vectoring_point uri [option ...] id: ID an opaque identifier or name which is used to direct traffic to this specific service. Must be unique among all adaptation services in squid.conf. vectoring_point: reqmod_precache|reqmod_postcache|respmod_precache|respmod_postcache This specifies at which point of transaction processing the ICAP service should be activated. *_postcache vectoring points are not yet supported. uri: icap://servername:port/servicepath ICAP server and service location. icaps://servername:port/servicepath The "icap:" URI scheme is used for traditional ICAP server and service location (default port is 1344, connections are not encrypted). The "icaps:" URI scheme is for Secure ICAP services that use SSL/TLS-encrypted ICAP connections (by default, on port 11344). ICAP does not allow a single service to handle both REQMOD and RESPMOD transactions. Squid does not enforce that requirement. You can specify services with the same service_url and different vectoring_points. You can even specify multiple identical services as long as their service_names differ. To activate a service, use the adaptation_access directive. To group services, use adaptation_service_chain and adaptation_service_set. Service options are separated by white space. ICAP services support the following name=value options: bypass=on|off|1|0 If set to 'on' or '1', the ICAP service is treated as optional. If the service cannot be reached or malfunctions, Squid will try to ignore any errors and process the message as if the service was not enabled. No all ICAP errors can be bypassed. If set to 0, the ICAP service is treated as essential and all ICAP errors will result in an error page returned to the HTTP client. Bypass is off by default: services are treated as essential. routing=on|off|1|0 If set to 'on' or '1', the ICAP service is allowed to dynamically change the current message adaptation plan by returning a chain of services to be used next. The services are specified using the X-Next-Services ICAP response header value, formatted as a comma-separated list of service names. Each named service should be configured in squid.conf. Other services are ignored. An empty X-Next-Services value results in an empty plan which ends the current adaptation. Dynamic adaptation plan may cross or cover multiple supported vectoring points in their natural processing order. Routing is not allowed by default: the ICAP X-Next-Services response header is ignored. ipv6=on|off Only has effect on split-stack systems. The default on those systems is to use IPv4-only connections. When set to 'on' this option will make Squid use IPv6-only connections to contact this ICAP service. on-overload=block|bypass|wait|force If the service Max-Connections limit has been reached, do one of the following for each new ICAP transaction: * block: send an HTTP error response to the client * bypass: ignore the "over-connected" ICAP service * wait: wait (in a FIFO queue) for an ICAP connection slot * force: proceed, ignoring the Max-Connections limit In SMP mode with N workers, each worker assumes the service connection limit is Max-Connections/N, even though not all workers may use a given service. The default value is "bypass" if service is bypassable, otherwise it is set to "wait". max-conn=number Use the given number as the Max-Connections limit, regardless of the Max-Connections value given by the service, if any. connection-encryption=on|off Determines the ICAP service effect on the connections_encrypted ACL. The default is "on" for Secure ICAP services (i.e., those with the icaps:// service URIs scheme) and "off" for plain ICAP services. Does not affect ICAP connections (e.g., does not turn Secure ICAP on or off). ==== ICAPS / TLS OPTIONS ==== These options are used for Secure ICAP (icaps://....) services only. tls-cert=/path/to/ssl/certificate A client SSL certificate to use when connecting to this icap server. tls-key=/path/to/ssl/key The private TLS/SSL key corresponding to sslcert above. If 'tls-key' is not specified 'tls-cert' is assumed to reference a combined PEM format file containing both the certificate and the key. tls-cipher=... The list of valid TLS/SSL ciphers to use when connecting to this icap server. tls-min-version=1.N The minimum TLS protocol version to permit. To control SSLv3 use the tls-options= parameter. Supported Values: 1.0 (default), 1.1, 1.2 tls-options=... Specify various OpenSSL library options: NO_SSLv3 Disallow the use of SSLv3 SINGLE_DH_USE Always create a new key when using temporary/ephemeral DH key exchanges ALL Enable various bug workarounds suggested as "harmless" by OpenSSL Be warned that this reduces SSL/TLS strength to some attacks. See the OpenSSL SSL_CTX_set_options documentation for a more complete list. Options relevant only to SSLv2 are not supported. tls-cafile= PEM file containing CA certificates to use when verifying the icap server certificate. Use to specify intermediate CA certificate(s) if not sent by the server. Or the full CA chain for the server when using the tls-default-ca=off flag. May be repeated to load multiple files. tls-capath=... A directory containing additional CA certificates to use when verifying the icap server certificate. Requires OpenSSL or LibreSSL. tls-crlfile=... A certificate revocation list file to use when verifying the icap server certificate. tls-flags=... Specify various flags modifying the Squid TLS implementation: DONT_VERIFY_PEER Accept certificates even if they fail to verify. DONT_VERIFY_DOMAIN Don't verify the icap server certificate matches the server name tls-default-ca[=off] Whether to use the system Trusted CAs. Default is ON. tls-domain= The icap server name as advertised in it's certificate. Used for verifying the correctness of the received icap server certificate. If not specified the icap server hostname extracted from ICAP URI will be used. Older icap_service format without optional named parameters is deprecated but supported for backward compatibility. Example: icap_service svcBlocker reqmod_precache icap://icap1.mydomain.net:1344/reqmod bypass=0 icap_service svcLogger reqmod_precache icaps://icap2.mydomain.net:11344/reqmod routing=on
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