ip-neighbour

manages the ARP and NDP neighbour tables

TLDR

Display the neighbour/ARP table

$ ip neighbour

Flush entries for a specific device

$ sudo ip neighbour flush dev [eth0]

Lookup a neighbour entry

$ ip neighbour get [192.168.1.1] dev [eth0]

Add a static ARP entry

$ sudo ip neighbour add [192.168.1.100] lladdr [00:11:22:33:44:55] dev [eth0] nud reachable

Delete an ARP entry

$ sudo ip neighbour delete [192.168.1.100] dev [eth0]

Replace an ARP entry

$ sudo ip neighbour replace [192.168.1.100] lladdr [00:11:22:33:44:55] dev [eth0]

SYNOPSIS

ip neighbour [command] [options]

ip neighbour manages the ARP (IPv4) and NDP (IPv6) neighbour tables. These tables map IP addresses to link-layer (MAC) addresses for hosts on directly connected networks.
The neighbour cache is normally populated automatically through ARP/NDP protocols, but static entries can be added for hosts that don't respond to ARP or for security purposes.

PARAMETERS

show [dev DEVICE]

Display neighbour table entries

add IP lladdr MAC dev DEVICE

Add a neighbour entry

delete IP dev DEVICE

Remove a neighbour entry

change IP lladdr MAC dev DEVICE

Modify existing entry

replace IP lladdr MAC dev DEVICE

Add or change entry

flush dev DEVICE

Clear entries for a device

get IP dev DEVICE

Lookup single entry

nud STATE

Neighbour state: permanent, noarp, reachable, stale, etc.

CAVEATS

Modifying entries requires root privileges. Static entries may become stale if the actual MAC changes. IPv6 uses NDP instead of ARP but is managed through the same interface.

HISTORY

ip neighbour is part of iproute2 and replaces the older arp command from net-tools. It provides unified IPv4 and IPv6 neighbour management.