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 ] [ router ] [ use ] [
managed ] [ extern_learn ]
ip neigh { show | flush } [ proxy ] [ to PREFIX ] [ dev DEV ] [ nud
STATE ] [ vrf NAME ] [ nomaster ]
ip neigh get ADDR dev DEV
STATE := { permanent | noarp | stale | reachable | none | incomplete |
delay | probe | failed }
DESCRIPTION
The ip neigh command manipulates neighbour objects that establish bind-
ings between protocol addresses and link layer addresses for hosts
sharing the same link. Neighbour entries are organized into tables.
The IPv4 neighbour table is also known by another name - the ARP table.
The corresponding commands display neighbour bindings and their proper-
ties, 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.
proxy indicates whether we are proxying for this neighbour en-
try
router indicates whether neighbour is a router
use this neigh entry is in "use". This option can be used to
indicate to the kernel that a controller is using this
dynamic entry. If the entry does not exist, the kernel
will resolve it. If it exists, an attempt to refresh the
neighbor entry will be triggered.
managed
this neigh entry is "managed". This option can be used to
indicate to the kernel that a controller is using this
dynamic entry. In contrast to "use", if the entry does
not exist, the kernel will resolve it and periodically
attempt to auto-refresh the neighbor entry such that it
remains in resolved state when possible.
extern_learn
this neigh entry was learned externally. This option can
be used to indicate to the kernel that this is a con-
troller learnt dynamic entry. Kernel will not gc such an
entry.
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 Detection'. The state can
take one of the following values:
permanent
the neighbour entry is valid forever and can be
only be removed administratively.
noarp the neighbour entry is valid. No attempts to vali-
date this entry will be made but it can be removed
when its lifetime expires.
reachable
the neighbour entry is valid until the reachabil-
ity timeout expires.
stale the neighbour entry is valid but suspicious. This
option to ip neigh does not change the neighbour
state if it was valid and the address is not
changed by this command.
none this is a pseudo state used when initially creat-
ing a neighbour entry or after trying to remove it
before it becomes free to do so.
incomplete
the neighbour entry has not (yet) been vali-
dated/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 unpredictable 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.
vrf NAME
only list the neighbours for given VRF.
nomaster
only list neighbours attached to an interface with no
master.
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 arguments are given, and that
the default neighbour states to be flushed do not include perma-
nent and noarp.
With the -statistics option, the command becomes verbose. It
prints out the number of deleted neighbours 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.
ip neigh get
lookup a neighbour entry to a destination given a device
proxy indicates whether we should lookup a proxy neighbour en-
try
to ADDRESS (default)
the prefix selecting the neighbour to query.
dev NAME
get neighbour entry attached to this device.
EXAMPLES
ip neighbour
Shows the current neighbour table in kernel.
ip neigh flush dev eth0
Removes entries in the neighbour table on device eth0.
ip neigh get 10.0.1.10 dev eth0
Performs a neighbour lookup in the kernel and returns a neigh-
bour entry.
SEE ALSO
ip(8)
AUTHOR
Original Manpage by Michail Litvak <mci@owl.openwall.com>
iproute2 20 Dec 2011 IP-NEIGHBOUR(8)
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