Systrace enforces system call policies for applications by interactively constraining the application's access to the system (*bsd and Linux). Systrace is able to monitor daemons on remote machines and generate warnings at a central location.
A configurable web-base administration console written in PHP which can remotely manage, control, and monitor multiple Snort based Intrusion Detection System sensors.
An intrusion protection system in the form of a bash shell script that is designed to make the installation of Snort in inline mode on Fedora or Debian as easy as possible.
Shadow is an intrusion-detection system from the Naval Surface Warfare Center, shows promise in detecting previously unknown attacks for which no known detection signatures exist.
Open-source GPL rootkit scanner for Unix-like systems. Scans for rootkits, trojans, backdoors and local exploits. Tests include scanning of plaintext and binary files for MD5 hash comparisons, default rootkit files, binary permissions, suspect LKM/KLD...
QuIDScor is an Open Source project demonstrating the value in correlating information between Intrusion Detection Systems (such as Snort) and vulnerability assessment and management platforms such as QualysGuard.