Here is a list of great sites with many tools for your security needs.

Firewalls....
www.bindview.com
www.netwarefiles.com/utils/hobjloc.zip
www.enteract.com/~ispitz/intrusion.html
www.kyuzz.org/antirez/hping.html
www.packetfactory.net/projects/firewall

TOOLS

ipeye. http://ntsecurity.nu
siphon. www.gravitino.net/projects/siphon
Cheops. www.marko.net/cheops
Netbios auditing tool. www.hackingexposed.com
antivirus experts. www.centralcommand.com
Unhide. www.webdon.com
intruder alert. www.enterprisesecurity.symantec.com/products
Kane security monitor. www.securitydynamics.com
win nt/2000 rootkit. www.rootkit.com
tripwire. www.tripwire.com
Security toolbox. http://ntsecurity.nu/toolbox

I hope some of these links will be of some use to you all here at AO. If you dont see what you are looking for I have more links Just tell me what you are looking for and what OS your looking to use it with and Ill see what I can come up with. If you like these links ask JP if he will put them in his link page. Thanks and have fun.