This is the next-generation Squid. In version 3.x squid has been ported to
C++ for code manageability.

Squid supports IPv6, WCCPv2, ICAP, Edge Side Include, SSL offloading, etc.

Squid in Debian now comes in two flavours, the GnuTLS flavour, which is the
one that has been tratitionally supplied by Debian's squid package and a new
OpenSSL flavour which is provided by the squid-openssl package.

Each flavour has its features, that's why we provide the two. The
traditional one is better at handling multiple certificates, while the
openssl flavour comes with SSL-Bump which allows full proxy transparency.

Both flavours have their own specific options to be setup at config files,
but they share the same config files, both /etc/squid/squid.conf file, as
well as the new /etc/squid/conf.d/ directory. Syntax of those files is the
same of previous versions of squid and each directive is largely commented
there.  Configuration files from 2.x versions of squid will mostly work in
later versions of squid. Changes to the configuration files are reported in
/usr/share/doc/squid-common/RELEASENOTES.html

Both flavours of squid share not only the config files but also the log
files and the cache. When purging squid, the package didn't remove the
cache files, typically at /var/spool/squid, and now, since version 4.13-6,
it also doesn't remove the logs at /var/log/squid, this means that if you
want to migrate to squid-openssl and, afterwards, purge squid, you must make
sure you have at least version 4.13-6 of squid installed, this way you won't
loose the logs when you purge squid. So, if you have version 4.13-6 or
later of the squid packages, you can switch flavours and try each flavour's
own features without any problem, but first make sure you have at least
version 4.13-6 of the squid packages, otherwise you'll probably loose the
config file and the logs.

This also means that if you want to fully purge all squid stuff from your
system, you must remove by yourself /var/spool/squid (to save time you can
use mkfs if you have them on a separate filesystem) and /var/log/squid if
you are completely sure that you don't need those files anymore.

The squid homepage is at http://www.squid-cache.org/
Squid was downloaded from that site with HTTP.

 -- The Debian Squid Maintainers <squid@packages.debian.org>, Tue, 23 Mar 2021 11:28:15 +0100