ip-neighbour(8) — Linux manual page


IP-NEIGHBOUR(8)                     Linux                    IP-NEIGHBOUR(8)

NAME         top

       ip-neighbour - neighbour/arp tables management.

SYNOPSIS         top

       ip [ OPTIONS ] neigh  { COMMAND | help }

       ip neigh { add | del | change | replace } { ADDR [ lladdr LLADDR ] [
               nud STATE ] | proxy ADDR } [ dev DEV ] [ router ] [
               extern_learn ]

       ip neigh { show | flush } [ proxy ] [ to PREFIX ] [ dev DEV ] [ nud
               STATE ] [ vrf NAME ]

       ip neigh get ADDR dev DEV

       STATE := { permanent | noarp | stale | reachable | none | incomplete
               | delay | probe | failed }

DESCRIPTION         top

       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

              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 neigbour

              router indicates whether neigbour is a router

                     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:

                            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.

                            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.

                            the neighbour entry has not (yet) been

                     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

       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.

              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

       ip neigh get
              lookup a neighbour entry to a destination given a device

              proxy  indicates whether we should lookup a proxy neigbour

              to ADDRESS (default)
                     the prefix selecting the neighbour to query.

              dev NAME
                     get neighbour entry attached to this device.

EXAMPLES         top

       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 dev eth0
              Performs a neighbour lookup in the kernel and returns a
              neighbour entry.

SEE ALSO         top


AUTHOR         top

       Original Manpage by Michail Litvak <mci@owl.openwall.com>

COLOPHON         top

       This page is part of the iproute2 (utilities for controlling TCP/IP
       networking and traffic) project.  Information about the project can
       be found at 
       If you have a bug report for this manual page, send it to
       netdev@vger.kernel.org, shemminger@osdl.org.  This page was obtained
       from the project's upstream Git repository
       ⟨https://git.kernel.org/pub/scm/network/iproute2/iproute2.git⟩ on
       2020-09-18.  (At that time, the date of the most recent commit that
       was found in the repository was 2020-09-14.)  If you discover any
       rendering problems in this HTML version of the page, or you believe
       there is a better or more up-to-date source for the page, or you have
       corrections or improvements to the information in this COLOPHON
       (which is not part of the original manual page), send a mail to

iproute2                         20 Dec 2011                 IP-NEIGHBOUR(8)

Pages that refer to this page: ip(8)