May 26, 2018
Detects and remedies ARP attacks
arpCounterattack is a program for detecting and remedying “ARP attacks.” It monitors traffic on any number of Ethernet interfaces and examines ARP replies and gratuitous ARP requests. If it notices an ARP reply or gratuitous ARP request that is in conflict with its notion of “correct” Ethernet/IP address pairs, it logs the attack if logging is enabled, and, if the Ethernet interface that the attack was seen on is configured as being in aggressive mode, it sends out a gratuitous ARP request and a gratuitous ARP reply with the “correct” Ethernet/IP address pair in an attempt to reset the ARP tables of hosts on the local network segment. The corrective gratuitous ARP request and corrective gratuitous ARP reply can be sent from an Ethernet interface other than the one that the attack was seen on.