Squid is a fully-featured HTTP/1.0 proxy with partial HTTP/1.1 support
The 6 series brings many new features and upgrades to the basic
networking protocols. A short list of the major new features is:

Squid 6 represents a new feature release, the most important of these
new features are:

* TLS ServerHello
* Log TLS Communication Secrets
* Ban ACL key changes in ACLs
* Block to-local Traffic
* RFC 9211: HTTP Cache-Status support
* RFC 9111: Stop treating Warning specially
* ext_kerberos_ldap_group_acl: Support -b with -D
* Remove Gopher Protocol Support
* Removed Outdated Tools