Security suite for Linux. Open-source - AppArmor is also very useful for preventing scripts and programs running on Webservers from being hacked and exploited.
Size: 1MB
Guarddog is a firewall configuration utility for Linux iptables. It also lets you maintain and modify the firewall in place. It uses a "what is not explicitly allowed, is denied" philosophy. The software is released under the GNU GPL.
FirePanel Vista uses Microsoft's own firewall stack to deliver you the safest, most stable internet filtering software for Vista, without worrying about any bluescreens.
