ufdbGuard is a squid redirector that is based on squidGuard.
It is a free URL filter and 9 times faster than squidGuard.

version 1.10 has a new unique feature to dynamically detect proxy
tunnels.
Since proxy tunnels are a security threat for most organisations,
ufdbGuard helps to secure corporate networks.

ufdbGuard can be downloaded from sourceforge.net:
http://sourceforge.net/projects/ufdbguard