Samhain is an open source host-based intrusion detection system (HIDS) It provides file integrity checking and logfile monitoring/analysis, as well as rootkit detection, port monitoring, detection of rogue SUID executables, and hidden processes. It has been designed to monitor multiple hosts with potentially different operating systems, providing centralized logging and maintenance, although it can also be used as standalone application on a single host. The official change log includes a list of changes to samhain v2.8.5.
Source: https://thehackernews.com/2011/06/samhain-v285-intrusion-detection-system.html