SID is a Shell Intrusion Detection system. The kernel part plugs into a terminal-processing subsystem and logs hashed terminal lines. The user part reads log entries (hashes), consults a list of allowed entries, and takes appropriate action upon unexpected log entries. Currently supported are Solaris and Linux.
You can download it from the following link: https://packetstormsecurity.com/files/download/36109/sid-0.4.1.tar.gz
Source: https://packetstormsecurity.com/files/36109/sid-0.4.1.tar.gz.html