IP-NEIGHBOUR(8) Linux IP-NEIGHBOUR(8)
NAME
ip-neighbour - neighbour/arp tables management.
SYNOPSIS
ip [ OPTIONS ] neigh { COMMAND | help }
ip neigh { add | del | change | replace } { ADDR [ lladdr LLADDR ] [ nud STATE ] | proxy ADDR } [ dev DEV ]
ip neigh { show | flush } [ proxy ] [ to PREFIX ] [ dev DEV ] [ nud STATE ]
STATE := { permanent | noarp | stale | reachable | none | incomplete | delay | probe | failed }
DESCRIPTION
The ip neigh command manipulates neighbour objects that establish bindings between protocol addresses and link
layer addresses for hosts sharing the same link. Neighbour entries are organized into tables. The IPv4 neigh‐
bour table is also known by another name - the ARP table.
The corresponding commands display neighbour bindings and their properties, add new neighbour entries and
delete old ones.
ip neighbour add
add a new neighbour entry
ip neighbour change
change an existing entry
ip neighbour replace
add a new entry or change an existing one
These commands create new neighbour records or update existing ones.
to ADDRESS (default)
the protocol address of the neighbour. It is either an IPv4 or IPv6 address.
dev NAME
the interface to which this neighbour is attached.
lladdr LLADDRESS
the link layer address of the neighbour. LLADDRESS can also be null.
nud STATE
the state of the neighbour entry. nud is an abbreviation for 'Neighbour Unreachability Detec‐
tion'. The state can take one of the following values:
permanent
the neighbour entry is valid forever and can be only be removed administratively.
incomplete
the neighbour entry has not (yet) been validated/resolved.
delay neighbor entry validation is currently delayed.
probe neighbor is being probed.
failed max number of probes exceeded without success, neighbor validation has ultimately failed.
ip neighbour delete
delete a neighbour entry
The arguments are the same as with ip neigh add, except that lladdr and nud are ignored.
Warning: Attempts to delete or manually change a noarp entry created by the kernel may result in unpre‐
dictable behaviour. Particularly, the kernel may try to resolve this address even on a NOARP interface
or if the address is multicast or broadcast.
ip neighbour show
list neighbour entries
to ADDRESS (default)
the prefix selecting the neighbours to list.
dev NAME
only list the neighbours attached to this device.
proxy list neighbour proxies.
unused only list neighbours which are not currently in use.
nud STATE
only list neighbour entries in this state. NUD_STATE takes values listed below or the special
value all which means all states. This option may occur more than once. If this option is
absent, ip lists all entries except for none and noarp.
ip neighbour flush
flush neighbour entries
This command has the same arguments as show. The differences are that it does not run when no argu‐
ments are given, and that the default neighbour states to be flushed do not include permanent and
noarp.
With the -statistics option, the command becomes verbose. It prints out the number of deleted neigh‐
bours and the number of rounds made to flush the neighbour table. If the option is given twice, ip
neigh flush also dumps all the deleted neighbours.
AUTHOR
Original Manpage by Michail Litvak <[email protected]>
iproute2 20 Dec 2011 IP-NEIGHBOUR(8)
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