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 ] [ 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

       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

              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.

              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.

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 neighbour entry.

SEE ALSO

       ip(8)

AUTHOR

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