PortDog is a network anomaly detector aimed at identifying portscanning attacks. It is entirely written in python and has an easy-to-use interface.
You can download it from the following link: https://packetstormsecurity.com/files/download/132971/PortDog-master.zip
Source: https://packetstormsecurity.com/files/132971/PortDog-Network-Anomaly-Detector.html