arpwatch

Intrusion Detection Network Utilities System Monitoring

arpwatch is an open-source software that monitors a computer network for ARP-activity. It generates a log of IP address-MAC address pairings along with a timestamp when the pairing appeared on the network. The first and foremost reason to monitor ARP activity is to detect ARP spoofing. It is developed by Lawrence Berkeley National Laboratory, Network Research Group, and released under the BSD license.

http://www-nrg.ee.lbl.gov/

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