port scan detection and active defense
PortSentry is part of the Abacus Project suite of security tools. 
It is a program designed to detect and respond to port scans against 
a target host in real-time. There are other port scan detectors that 
perform similar detection of scans, but PortSentry has some unique 
features that may make it worth looking into  

Maintainer: Kevin Lo <kevlo@openbsd.org>
