arp-scan sends ARP (Address Resolution Protocol) queries to the specified targets, and displays any responses that are received. It allows any part of the outgoing ARP packets to be changed, allowing the behavior of targets to non-standard ARP packets to be examined. The IP address and hardware address of received packets are displayed, together with the vendor details. These details are obtained from the IEEE OUI and IAB listings, plus a few manual entries. It includes arp-fingerprint, which allows a system to be fingerprinted based on how it responds to non-standard ARP packets.
