Dedicated Linux Firewall
If you’re looking for a firewall solution that can protect a whole network then you’re looking for a hardware firewall - and if you’re looking for a hardware firewall then you need one made out of Linux.
SmoothWall is a distribution of Linux that’s so that you could download it a hundred times before any other Linux distro finished downloading. Coming it at a little under 46MB for the ‘enhanced’ version which includes all sorts of manuals, the iso image of SmoothWall is worth checking out.
It’s designed to run on some old box and be a dedicated hardware firewall for you - running Linux. Why spend good money on a commercial firewall system when you can use a super-secure hardware firewall that touts itself as “free as in beer”?