scanlogd is a system daemon which attempts to log all portscans of a host to the syslog, in a secure fashion.
You can download it from the following link: https://packetstormsecurity.com/files/download/123728/scanlogd-2.2.7.tar.gz
Source: https://packetstormsecurity.com/files/123728/scanlogd-2.2.7.html