Blog post ⋮ Sending and processing ARP requests/responses using BPF
Located between the network interface and the Internet layer (2 and 3), the Address Resolution Protocol (ARP) is handled by the operating system. But controlling it from userland can be useful, to check the validity of the ARP cache, or to find hosts that do not respond to a ping request. On BSD systems, the Berkeley Packet Filter can be used to write your own ARP scanner.
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