Sagan is multi-threaded, real-time system- and event-log monitoring software, but with a twist. Sagan uses a “Snort” like rule set for detecting nefarious events happening on your network and/or computer systems. If Sagan detects a “bad thing” happening, it can do a number of things with that information. Sagan can also correlate the events with your Intrusion Detection/Intrusion Prevention (IDS/IPS) system and basically acts like an SIEM (Security Information and Log Management) system.
You can download it from the following link: https://packetstormsecurity.com/files/download/99419/sagan-0.1.8.tar.gz
Source: https://packetstormsecurity.com/files/99419/Sagan-Log-Monitor-0.1.8.html