The OWASP ZAP core project
Full-featured enterprise network management tool
yubikey-agent is a seamless ssh-agent for YubiKeys
Open source platform for covert data exfiltration operations.
Easy to use GlobalPlatform tool (and a Java library)
Collect and display host IP traffic statistics
linux tool to improve server security
Web based management tool for unixes
A protocol agnostic application layer denial of service attack.
Easy to use firewall for linux beginners.
Passive Proxy Daemon sniffs packets and creates squid proxy logs