ip-neighbour - neighbour/arp tables management.
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 }
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 neighbour 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.
- proxy
- indicates whether we are proxying for this neighbour entry
- 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 controller 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 validate this entry will be
made but it can be removed when its lifetime expires.
- reachable
- the neighbour entry is valid until the reachability 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 creating a neighbour entry or
after trying to remove it before it becomes free to do so.
- 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 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
permanent 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 entry
- to ADDRESS
(default)
- the prefix selecting the neighbour to query.
- dev
NAME
- get neighbour entry attached to this device.
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
neighbour entry.
Original Manpage by Michail Litvak
<mci@owl.openwall.com>