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🔗 Standards Compliance in Squid


Squid behaviour is governed by a great many International standards and requirements. Below is a list of the standards to which Squid is expected to obey and an indication of whether we believe it does.

:inforrmation_source: This list was updated 2022-06-09. Details are believed to be accurate for the current release 5.6 or later.

:information_source: this list is known to be incomplete. If you are aware of anything important which has been omitted please report it as a website bug.

🔗 Formal Certifications

At this point there are none on record. We are looking for information and possibly sponsorship to obtain any certifications which are required for use in your network.

🔗 IEFT RFC standards

RFC Name Status  
rfc 959
(IEN 149)
FILE TRANSFER PROTOCOL (FTP) :heavy_check_mark:  
rfc 1035 DOMAIN NAMES - IMPLEMENTATION AND SPECIFICATION :heavy_check_mark: client only
rfc 1157 A Simple Network Management Protocol (SNMP)   :information_source: version 2c
rfc 1413 Identification Protocol (IDENT) :heavy_check_mark: note bug Bug:2853
rfc 1436 The Internet Gopher Protocol«BR»(a distributed document search and retrieval protocol) :heavy_check_mark: client and gateway to HTTP
rfc 1902 Structure of Management Information«BR»for Version 2 of the«BR»Simple Network Management Protocol (SNMPv2)    
rfc 1905 Protocol Operations«BR»for Version 2 of the«BR»Simple Network Management Protocol (SNMPv2)    
rfc 1945 Hypertext Transfer Protocol – HTTP/1.0 :heavy_check_mark:  
rfc 2169 A Trivial Convention for using HTTP in URN Resolution :heavy_check_mark:  
rfc 2181 Clarifications to the DNS Specification :heavy_check_mark:  
rfc 2186 Internet Cache Protocol (ICP), version 2 :heavy_check_mark:  
rfc 2187 Application of Internet Cache Protocol (ICP), version 2 :heavy_check_mark:  
rfc 2227 Simple Hit-Metering and Usage-Limiting for HTTP    
rfc 2295 Transparent Content Negotiation in HTTP    
rfc 2296 HTTP Remote Variant Selection Algorithm – RVSA/1.0 :x:  
rfc 2310 The Safe Response Header Field :x: Specifications for this feature are deprecated.
rfc 2428 FTP Extensions for IPv6 and NATs :heavy_check_mark: since Squid 3.1
rfc 2518 HTTP Extensions for Distributed Authoring – WEBDAV :heavy_check_mark: since Squid 3.1
rfc 2722 Traffic Flow Measurement: Architecture :x:  
rfc 2756 Hyper Text Caching Protocol (HTCP/0.0) :heavy_check_mark:  
rfc 2774 An HTTP Extension Framework :heavy_check_mark:  
rfc 2817 Upgrading to TLS Within HTTP/1.1 :x:  
rfc 2964 Use of HTTP State Management    
rfc 2965 HTTP State Management Mechanism    
rfc 3225 Indicating Resolver Support of DNSSEC :heavy_check_mark: :information_source: no-support conditional compliance.
rfc 3226 DNSSEC and IPv6 A6 aware server/resolver message size requirements    
rfc 3253 Versioning Extensions to WebDAV«BR»(Web Distributed Authoring and Versioning) :heavy_check_mark: since Squid 3.1
rfc 3310 Hypertext Transfer Protocol (HTTP) Digest Authentication«BR»Using Authentication and Key Agreement (AKA)    
rfc 3493 Basic Socket Interface Extensions for IPv6 :heavy_check_mark:  
rfc 3507 Internet Content Adaptation Protocol (ICAP)   client only, PRECACHE vectors only
rfc 3596 DNS Extensions to Support IP Version 6 :heavy_check_mark:  
rfc 3744 Web Distributed Authoring and Versioning (WebDAV)
>Access Control Protocol
:heavy_check_mark: since Squid 3.1
rfc 3875 The Common Gateway Interface (CGI) Version 1.1 :heavy_check_mark: cachemgr.cgi
rfc 3986 Uniform Resource Identifier (URI): Generic Syntax :warning: since Squid-4.12. still uses rc1738 encoder on some URI segments and helper protocol. Merge Request SquidPr:335
rfc 4001 Textual Conventions for Internet Network Addresses :heavy_check_mark:  
rfc 4266 The gopher URI Scheme :heavy_check_mark: Removed in Squid-6
rfc 4288 The telnet URI Scheme :x:  
rfc 4291 IP Version 6 Addressing Architecture :heavy_check_mark:  
rfc 4559 SPNEGO-based Kerberos and NTLM HTTP Authentication«BR»in Microsoft Windows    
rfc 4918 HTTP Extensions for Web Distributed Authoring and Versioning (WebDAV)    
rfc 6266 Use of the Content-Disposition Header Field in the«BR»Hypertext Transfer Protocol (HTTP) :x:  
rfc 6540 «BR»(BCP 177) IPv6 Support Required for All IP-Capable Nodes :heavy_check_mark:  
rfc 6570 URI Template :x:  
rfc 6585 Additional HTTP Status Codes :heavy_check_mark:  
rfc 6762 Multicast DNS :heavy_check_mark: client only
rfc 6750 The OAuth 2.0 Authorization Framework: Bearer Token Usage :x: Merge Request SquidPr:30
rfc 6874 Representing IPv6 Zone Identifiers in«BR»Address Literals and Uniform Resource Identifiers :x:  
rfc 7236 Initial Hypertext Transfer Protocol (HTTP)«BR»Authentication Scheme Registrations almost missing support for Bearer and OAuth schemes
rfc 7237 Initial Hypertext Transfer Protocol (HTTP) Method Registrations :x:  
rfc 7239 Forwarded HTTP Extension :x: Merges Request SquidPr:55
rfc 7240 Prefer HTTP Extension :heavy_check_mark: conditional; proxy MUST relay unless listed in Connection header.
rfc 7541 HPACK: Header Compression for HTTP/2 :x: see Features/HTTP2 and Merge Request SquidPr:893
rfc 7595 Guidelines and Registration Procedures for URI Schemes :x: Missing prohibition of example: URI scheme
rfc 7616 HTTP Digest Access Authentication :warning: Missing support for several Digest features
rfc 7617 The ‘Basic’ HTTP Authentication Scheme :warning: missing new charset support.
rfc 7639 The ALPN HTTP Header Field :x:  
rfc 7725 An HTTP Status Code to Report Legal Obstacles :x:  
rfc 7838 HTTP Alternative Services :x:  
rfc 7858 Specification for DNS over Transport Layer Security (TLS) :x:  
rfc 8164 Opportunistic Security for HTTP/2 :x:  
rfc 8187 Indicating Character Encoding and Language for HTTP Header Field Parameters :x:  
rfc 8188 Encrypted Content-Encoding for HTTP :x:  
rfc 8246 HTTP Immutable Responses :heavy_check_mark: partial. see bug Bug:4774
rfc 8297 An HTTP Status Code for Indicating Hints :heavy_check_mark:  
rfc 8336 The ORIGIN HTTP/2 Frame :x:  
rfc 8441 Bootstrapping !WebSockets with HTTP/2 :x:  
rfc 8470 Using Early Data in HTTP :x: Merge Request SquidPr:873
rfc 8586 Loop Detection in Content Delivery Networks (CDNs) :heavy_check_mark: from Squid-5.
rfc 8615 Well-Known Uniform Resource Identifiers (URIs) :x:  
rfc 8673 HTTP Random Access and Live Content :x:  
rfc 8941 Structured Field Values for HTTP :x:  
rfc 8942 HTTP Client Hints :x:  
rfc 8999 Version-Independent Properties of QUIC :x: Merge Request SquidPr:919
rfc 9000 QUIC: A UDP-Based Multiplexed and Secure Transport :x: Merge Request SquidPr:919
rfc 9001 Using TLS to Secure QUIC :x:  
rfc 9002 QUIC Loss Detection and Congestion Control :x:  
rfc 9110 «BR»(STD 97) HTTP Semantics :heavy_check_mark: some conditional features, see Features/HTTP11
rfc 9111 «BR»(STD 98) HTTP Caching :heavy_check_mark: conditional, see Features/HTTP11
rfc 9112 «BR»(STD 99) HTTP/1.1 almost see Features/HTTP11
rfc 9113 HTTP/2 :warning: :information_source: HTTP/1.x relay and no-support conditional compliance. see Features/HTTP2 and Merge Request SquidPr:893
rfc 9114 HTTP/3 :x:  
rfc 9163 Expect-CT Extension for HTTP :x:  
rfc 9205 «BR»(BCP 56) Building Protocols with HTTP    
rfc 9209 The Proxy-Status HTTP Response Header Field :heavy_check_mark: Squid-4
rfc 9211 The Cache-Status HTTP Response Header Field :warning: conditional
rfc 9213 Targeted HTTP Cache Control :x:  
rfc 9218 Extensible Prioritization Scheme for HTTP :x:  
rfc 9220 Bootstrapping !WebSockets with HTTP/3 :x:  
rfc 9230 Oblivious DNS over HTTPS :warning: HTTPS relay only
rfc 9292 Binary Representation of HTTP Messages :x:  
rfc 9421 HTTP Message Signatures :x:  
rfc 9530 Digest Fields :x:  
rfc 9532 HTTP Proxy-Status Parameter for Next-Hop Aliases :x:  

🔗 IETF Drafts

wccp v1 WCCP 1.0 :heavy_check_mark:
wccp v2 WCCP 2.0 almost
wccp v2 r1 WCCP 2.0 rev 1 partial
CARP Microsoft CARP peering algorithm  
draft-ietf-radext-digest-auth RADIUS Extension for Digest Authentication  

🔗 ISO standards

ISO-8859-1 Latin alphabet No. 1 :heavy_check_mark:

🔗 Non-standard Protocols

PROXY The PROXY protocol, Versions 1 & 2 :heavy_check_mark:
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