World's Most Widely Used Host Intrusion Detection System - HIDS. OSSEC offers comprehensive host-based intrusion detection across multiple platforms including Linux, Solaris, AIX, HP-UX, BSD, Windows, Mac and VMware ESX.

The Samhain host-based intrusion detection system (HIDS) provides file integrity checking and log file monitoring/analysis, as well as rootkit detection, port monitoring, detection of rogue SUID executables, and hidden processes.