I build firewalls using OpenBSD, "the most secure operating system that money can't buy." You can't buy the system because it is free software - free to everyone, in source code, forever. This means also that nobody can buy this up and take it over, no matter how big they are. It's free, it's open, it's OpenBSD. And it's very good for building internet firewalls.
On the other hand, it also takes some experience and expertise to know how to set it up and configure it. This is where I come in. I have been setting up internet firewalls since the early 1990's. I also teach a half-day course that I wrote and have taught at the O'Reilly Open Source Conference, the EuroBSD Conference, and elsewhere, telling the basics of setting up OpenBSD firewalls. I can deliver this course, or set up your firewall for you. Rates are reasonable!
Why build a firewall from UNIX instead of buying one from (Big Company)? Well, when you build it yourself you know what it does and how it works. I give you plenty of documentation on how your firewall works and how to change it, if you'd rather do it yourself. Or, I can maintain it for a small monthly fee.
By the way: Sure, everybody's a network security expert these days. Just like everybody was a Novell or Microsoft Expert a while back. Well, what can I say? I've been there. I've been working with UNIX-based Internet Firewalls since about 1990 and with OpenBSD since about 1996. In addition to my own Web sites, I designed and implemented the first version of SoftQuad's Web Site back in 1993, and designed and built their security firewall. We watched in mild amusement as people in Moscow and California tried to NFS-mount our source code tree through the firewall. They all failed. So I can build good network firewalls.
If you're interested, please contact me directly.