toscin is a basic IDS system that uses packet filtering to warn against possible attacks against specified services. It basically watches the local network for SYN connections to certain services, and sends notification. Solaris 2.x possibly others.
You can download it from the following link: https://packetstormsecurity.com/files/download/10781/tocsin116.tar.gz
Source: https://packetstormsecurity.com/files/10781/tocsin116.tar.gz.html