NDP(8)                  NetBSD System Manager's Manual                  NDP(8)

     ndp -- control/diagnose IPv6 neighbor discovery protocol

     ndp [-nt] hostname
     ndp [-nt] -a | -c | -p
     ndp [-nt] -r
     ndp [-nt] -H | -P | -R
     ndp [-nt] -A wait
     ndp [-nt] -d hostname
     ndp [-nt] -f filename
     ndp [-nt] -i interface [expressions ...]
     ndp [-nt] -I [interface | delete]
     ndp [-nt] -s nodename etheraddr [temp] [proxy]

     The ndp command manipulates the address mapping table used by the Neigh-
     bor Discovery Protocol (NDP).

     -A wait
             Repeat -a (dump NDP entries) every wait seconds.

     -a      Dump the currently existing NDP entries.  The following informa-
             tion will be printed:

             Neighbor    IPv6 address of the neighbor.

             Linklayer Address
                         Linklayer address of the neighbor.  It could be
                         ``(incomplete)'' when the address is not available.

             Netif       Network interface associated with the neighbor cache

             Expire      The time until expiry of the entry.  The entry could
                         become ``permanent'', in which case it will never

             S           State of the neighbor cache entry, as a single let-

                         D       Delay
                         I       Incomplete
                         N       Nostate
                         P       Probe
                         R       Reachable
                         S       Stale
                         W       Waitdelete
                         ?       Unknown state (should never happen).

             Flags       Flags on the neighbor cache entry, in a single let-
                         ter.  They are: Router, proxy neighbor advertisement
                         (``p'').  The field could be followed by a decimal
                         number, which means the number of NS probes the node
                         has sent during the current state.

     -c      Erase all the NDP entries.

     -d      Delete specified NDP entry.

     -f      Parse the file specified by filename.

     -H      Harmonize consistency between the routing table and the default
             router list; install the top entry of the list into the kernel
             routing table.

     -I      Shows the default interface used as the default route when there
             is no default router.

     -I interface
             Specifies the default interface to be used when there is no
             interface specified even though required.

     -I delete
             The current default interface will be deleted from the kernel.

     -i interface [expressions ...]
             View ND information for the specified interface.  If additional
             arguments expressions are given, ndp sets or clears the flags or
             variables for the interface as specified in the expression.  Each
             expression should be separated by white spaces or tab characters.
             Possible expressions are as follows.  Some of the expressions can
             begin with the special character `-', which means the flag speci-
             fied in the expression should be cleared.  Note that you need --
             before -foo in this case.

             nud     Turn on or off NUD (Neighbor Unreachability Detection) on
                     the interface.  NUD is usually turned on by default.
                     Specify whether or not to accept Router Advertisement
                     messages received on the interface.  Note that the kernel
                     does not accept Router Advertisement messages, even if
                     the flag accept_rtadv is on, unless either the
                     net.inet6.ip6.accept_rtadv variable is non-0, or the flag
                     override_rtadv is on.  This flag is set to 1 by default.
                     Specify whether or not to perform automatic link-local
                     address configuration on interface.  This flag is set by
                     net.inet6.ip6.auto_linklocal sysctl variable.
                     Specify whether or not to override the
                     net.inet6.ip6.accept_rtadv variable.  If the flag is on,
                     then it will suffice to set the flag accept_rtadv to make
                     the kernel accept Router Advertisement messages on the
                     interface.  This flag is set to 0 by default.
                     Prefer addresses on the interface as candidates of the
                     source address for outgoing packets.  The default value
                     of this flag is off.  For more details about the entire
                     algorithm of source address selection, see the
                     IMPLEMENTATION file supplied with the KAME kit.
                     Disable IPv6 operation on the interface.  When disabled,
                     the interface discards any IPv6 packets received on or
                     being sent to the interface and any IPv6 addresses on the
                     interface are marked as ``tentative''.  When the disabled
                     flag is cleared, DAD will be performed.  In the sending
                     case, an error of ENETDOWN will be returned to the appli-
                     cation.  This flag is typically set automatically in the
                     kernel as a result of a certain failure of Duplicate
                     Address Detection.  While the flag can be set or cleared
                     by hand with the ndp command, it is not generally advis-
                     able to modify this flag manually.
                     Specify the BaseReachbleTimer on the interface in mil-
                     Specify the RetransTimer on the interface in millisecond.
                     Specify the Cur Hop Limit on the interface.

     -n      Do not try to resolve numeric addresses to hostnames.

     -P      Flush all the entries in the prefix list.

     -p      Show prefix list.

     -R      Flush all the entries in the default router list.

     -r      Show default router list.

     -s      Register an NDP entry for a node.  The entry will be permanent
             unless the word temp is given in the command.  If the word proxy
             is given, this system will act as a proxy NDP server, responding
             to requests for hostname even though the host address is not its

     -t      Print timestamp on each entry, making it possible to merge output
             with tcpdump(8).  Most useful when used with -A.

     The ndp command will exit with 0 on success, and non-zero on errors.


     The ndp command first appeared in the WIDE Hydrangea IPv6 protocol stack

NetBSD 9.0                     February 14, 2018                    NetBSD 9.0

You can also request any man page by name and (optionally) by section:


Use the DEFAULT collection to view manual pages for third-party software.

©1994 Man-cgi 1.15, Panagiotis Christias
©1996-2019 Modified for NetBSD by Kimmo Suominen