arp

View and manipulate the ARP cache

TLDR

Display ARP table in BSD style

$ arp -a

Display ARP table in numeric format without DNS resolution

$ arp -an

Display ARP table in default Linux format

$ arp -e

Add a static ARP entry

$ sudo arp -s [192.168.1.1] [00:11:22:33:44:55]

Delete an ARP entry

$ sudo arp -d [192.168.1.1]

Show entries for a specific interface

$ arp -i [eth0] -a

Load entries from a file

$ sudo arp -f [/etc/ethers]

SYNOPSIS

arp [-a] [-d address] [-s address hwaddr] [**-i** interface] [options_]

arp manipulates the system's ARP (Address Resolution Protocol) cache. ARP maps IPv4 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 in BSD style output format.

-e

Display entries in default Linux style with fixed columns.

-n, --numeric

Show numerical addresses instead of resolving hostnames.

-d address

Delete an entry for the specified address. Requires root.

-s address hwaddr_

Add a static ARP entry. Add temp to make it non-permanent.

-i If, --device If

Limit display to a specific network interface.

-D, --use-device

Use the hardware address of the specified interface instead of a hw_addr.

-f filename, --file filename

Load address entries from a file (default: /etc/ethers).

-v, --verbose

Verbose output.

-H type, --hw-type type

Hardware type (ether, arcnet, pronet, ax25, netrom).

INSTALL

sudo apt install net-tools

sudo dnf install net-tools

sudo pacman -S net-tools

sudo apk add net-tools

sudo zypper install net-tools

brew install net-tools

nix profile install nixpkgs#net-tools

CAVEATS

The arp command is deprecated in favor of ip neigh on modern Linux. Static entries do not survive reboots by default. ARP is only used for IPv4; IPv6 uses Neighbor Discovery Protocol (NDP).

HISTORY

arp has been part of Unix networking since the early days of TCP/IP in the 1980s. On Linux, it is part of the net-tools package, which is being superseded by iproute2.

arp