arp
TLDR
Display ARP table
$ arp -a
Display in numeric format$ arp -n
Add static ARP entry$ sudo arp -s [192.168.1.1] [00:11:22:33:44:55]
Delete ARP entry$ sudo arp -d [192.168.1.1]
Show entries for specific interface$ arp -i [eth0]
SYNOPSIS
arp [-a] [-d address] [-s address hwaddr] [-i interface] [options_]
DESCRIPTION
arp manipulates the system's ARP (Address Resolution Protocol) cache. ARP maps IP addresses to MAC (hardware) addresses on a local network segment.
The ARP table is built dynamically as the system communicates, but entries can be manually added, deleted, or viewed for network troubleshooting.
PARAMETERS
-a
Display all entries (BSD style)-n, --numeric
Show numeric addresses (no DNS lookup)-d address
Delete entry for address-s address hwaddr_
Add static entry-i interface
Limit to specific interface-D
Use device's hardware address-v, --verbose
Verbose output-H type, --hw-type type
Hardware type (ether, arcnet, etc.)
CAVEATS
The arp command is deprecated in favor of ip neigh on modern Linux. Static entries don't survive reboots by default. ARP is only used for IPv4; IPv6 uses Neighbor Discovery.
HISTORY
arp has been part of Unix networking since the early days of TCP/IP in the 1980s. On Linux, it's part of net-tools, which is being replaced by iproute2.
SEE ALSO
ip-neighbour(8), arping(8), arp-scan(1)
