arpaname

Translate IP addresses (IPv4 and IPv6) to the corresponding ARPA name

$ arpaname [ip_address]

arpaname IP_address

IP_address
    The IP address to resolve to a hostname.

The `arpaname` command is a simple utility used to resolve IP addresses to their corresponding hostnames using ARP cache information. It extracts and displays hostnames associated with IP addresses from the ARP cache. It's often used for quick network troubleshooting or investigation on a local network. The command leverages the kernel's ARP table to perform these lookups. It is useful for identifying devices on a network given their IP addresses. Note that the command relies on the ARP cache being populated, so devices must have recently communicated on the network for entries to be present. It's a read-only operation and does not modify the ARP cache in any way.

The `arpaname` command will only find hostnames that are currently stored in the ARP cache. If the ARP cache entry has timed out or has not yet been created for a particular IP address, `arpaname` will not be able to resolve it. The resolved hostname is also dependent on reverse DNS lookups configured on the network.

The command's output is a simple hostname. If the IP address is not found in the ARP cache, the output will be empty. If the command outputs `(incomplete)` for the hostname, the ARP entry is present, but the hostname lookup failed. This could indicate that reverse DNS is not properly configured.

This command typically does not require any special permissions. Access to the ARP cache is generally granted to any user.

The origin and development history of the `arpaname` command are somewhat obscure, it is generally a command that appears on some older systems. The primary function is to provide a straightforward way to determine hostnames from IP addresses using the ARP cache, something often useful in basic network administration and diagnosis.

arp(8), ping(8), traceroute(8), host(1)