ip-neighbour

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 ] [ ex-
               tern_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
       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 neigbour entry

              router indicates whether neigbour is a router

              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.

              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 neigbour entry

              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)