"1. IPCop
At its very core, IPCop is in fact a firewall appliance before all
else. And as many of you might suspect, IPCop happens to be a Linux
distribution with the sole function of acting as a hardware
firewall, thus protecting your network from threats outside and
from within. IPCop can be installed via CD, Flash Drive, HTTP/FTP
network setups and is fairly straight forward to setup.
"Considering the offering of multiple language support and the
fact that this little Linux distribution will run on pretty much
anything, it is a proven homegrown firewall. Speaking of support, I
should also point out that IPCop has a number of very cool add-ons
as well. My two favorites are Banish and Copfilter, which is used
to filter out malware and viruses in real time.