Its a good distro for firewalling. But if you really want to stay EVEN more secure, use distros (this may get me in trouble for EVEN mentioning this
) such as backtrack linux and the hackthissite gentoo live cd <-- hard to find. I know that i will get some dirty looks by saying this, but i have used the HTS live cd to search for security vulnerabilities in the past. It has about 50 programs that promote port scanning and the such, and they are all in the popular network languadges. It also comes with 200+ tutorials, so that you will never be stuck. To you the programs properly, you must scan/search/look for, a certain hole or "glitch" or vulnerability. The best way to go are with scanners that pick up real time info on what data is being transferred via the servers. Me and my friends have realized that if you use this on you're own system, you can fix up alot of problems very quick. Oh and Hackthissite was hacked and all its users passwords were stolen, so it proves that you can never be too safe
. And the HTS live cd can be found on pirate bay.org.