Linux content filter firewall

I would like to build a Linux dedicated firewall with content filtering capabilities. I'm not looking for anything extremely robust, but light, fast and with the ability to block specific domains.

It looks like a custom Debian FW may be the right way to go, but I hadn't found any good documentation about content filtering on it.

Also looked at Gibralter, but I need something permanent and not being booted from a CD rom.

Any suggestions?

 

Check this http://www.untangle.com/

 

That's way better than what I had in mind.

Thanks