list of linux firewall destros.

http://www.smoothwall.org/

http://sourceforge.net/apps/trac/ipcop/wiki

http://www.devil-linux.org

I never used any of these Firewalls before, but I read on a lot of forums and websites I found online which recommends these Firewall Linux distros. for securing your internet and network. 

I might make a tutorial on Smoothwall, IPcop, and Devil-Linux when I have the time.