Firewall Related Links
Have your firewall running but not sure it's working?  Try these Firewall Test Resources
If you are interested in Firewalls, you might also want to look into some great Internet Connection Sharing Info
Distributed Intrusion Detection System - Compiles firewall logs from people and compiles hacking attempt statistics.
Port assignments
Port Assignments for All Well-known and Registered Ports
Other Software
SNORT for Windows, Linux, OSX and more
Snort is a lightweight network intrusion detection system, capable of performing  real-time  traffic analysis and packet logging on IP networks. 
TUCOWS:  Don't forget to check TUCOWS list of software for firewall tools.  They have many!

Download free firewall software
4 Users On-Line
Thank You!