Installation#16. Can I prevent my users from skipping around DansGuardian/Squid (or DansGuardian alone)?
Yes, every configuration of DansGuardian/Squid (under an OS like Linux) can always be made impossible to skip around. Generally this is done via addition of two or three Shorewall/IPtables rules (and tweaks to configurations to use 127.0.0.1 for communication between DansGuardian and Squid). Note that although preventing of skipping around is always possible, it’s not automatic; an initial installation of DansGuardian/Squid almost never includes what’s needed to prevent skipping around.