Found the answer to my own question. Maybe others might be intersted.
Definition: squidguard: filter, redirector and access controller plug for Squid squidGuard is a free (GPL), flexible and ultra fast filter, redirector and access controller plugin for squid. It lets you define multiple access rules with different restrictions for different user groups on a squid cache. squidGuard uses squid's standard redirector interface.
Definition: squid: Internet Object Cache (WWW proxy cache) This is the Squid Internet Object Cache developed by the National Laboratory for Applied Networking Research (NLANR) and Internet volunteers. This software is freely available for anyone to use. The Squid home page is http://
www.squid-cache.org/