Features of Arpon:

It detects and blocks Man In The Middle through ARP Spoofing/Poisoning attacks in statically, dinamically (DHCP), hybrid configured networks
It detects and blocks derived attacks: DHCP Spoofing, DNS Spoofing WEB Spoofing, Session Hijacking, SSL/TLS Hijacking & co
It detects and blocks unidirectional, bidirectional and distributed attacks
Doesn’t affect the communication efficiency of ARP protocol
Doesn’t affect the race response time from attacks
Multithreading on all OS supported
It manages the network interface into unplug, boot, hibernation and suspension OS features
It works in userspace for OS portability reasons
Easily configurable via command line switches, provided that you have root permissions
Tested against Ettercap, Cain & Abel, dsniff and other tools

Download
http://sourceforge.net/projects/arpon/files/