Do you use Squid as a proxy? If so /var/log/squid/access.log
If not...
Get Squid Proxy and Squid Guard.
http://www.squid-cache.org/ << The proxy server
http://www.squidguard.org/ << Website filtering
I've been told you can use webalizer to keep after your Squid access logs.
http://www.webalizer.
I am running a Linux internet gateway/server at a school. (Currently RH 7.3
running ipchains firewall, apache, & sendmail. May upgrade to 8.0 in the
future.) They have asked if I can set up some type logging that would
record the ip of a machine requesting a web site and the web site
requested.
