I'd love to see a thread for linux security programs. Right now I am using: 1.) iptables(duh) 2.) psad(detect portscan and block ip's) 3.) snort 4.) rkhunter(rootkit hunter) 5.) aide(tripwire like program) 6.) no sshd/telnetd will help alot I haven't found that many very useful open source linux firewalls. Everyone says firestarter and guarddog but they are to limited. Fwbuilder and kmyfirewall are very good but no application level. The only really good application level firewalls for linux come in distros like astaro security linux and others.