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NDP(8)			FreeBSD	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 utility manipulates the address mapping table used	by the Neigh-
     bor Discovery Protocol (NDP).

     -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 expire.

	     S	       State of	the neighbor cache entry, as a single letter:

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

	     Flags     Flags on	the neighbor cache entry, in a single letter.
		       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.

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

     -c	     Erase all the NDP entries.

     -d	     Delete specified NDP entry.

     -f	filename
	     Cause the file filename to	be read	and multiple entries to	be set
	     in	the NDP	table.	Entries	in the file should be of the form

		   hostname ether_addr [temp] [proxy]

	     with argument meanings as given above.  Leading whitespace	and
	     empty lines are ignored.  A `#' character will mark the rest of
	     the line as a comment.

     -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 used as the default route when
	     there is no default router.  The interface	will be	used as	the

     -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.  This flag is set by
		     net.inet6.ip6.accept_rtadv	sysctl variable.

		     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.

		     The address on the	outgoing interface is preferred	by
		     source addess selection rule.  If this flag is set, stop
		     treating the address on the interface as special even
		     when the interface	is outgoing interface.	The default
		     value of this flag	is off.

		     Disable IPv6 operation on the interface.  When disabled,
		     the interface discards any	IPv6 packets received on or
		     being sent	to the interface.  In the sending case,	an er-
		     ror of ENETDOWN will be returned to the application.
		     This flag is typically set	automatically in the kernel as
		     a result of a certain failure of Duplicate	Address	Detec-
		     tion.  If the auto_linklocal per-interface	flag is	set,
		     automatic link-local address configuration	is performed
		     again when	this flag is cleared.

		     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	     Show prefix list.	The following information will be printed:

	     if	     The network interface associated with this	prefix.

	     flags   The status	of the prefix, expressed by a combination of
		     the following letters:

		     A	     This prefix can be	used for stateless address au-
		     L,	O    This prefix can be	used for on-link determina-
			     tion; that	is, it can be used to determine
			     whether a given destination address is on-link.
		     D	     There are no reachable routers advertising	this

	     vltime  Valid lifetime; the length	of time	for which the prefix
		     and a stateless autoconfigured address generated from
		     this prefix can be	used for the source or destination ad-
		     dress of a	packet.

	     pltime  Preferred lifetime; the length of time for	which the pre-
		     fix and a stateless autoconfigured	address	generated from
		     this prefix can be	used by	upper-layer protocols unre-

	     expire  This is the remaining time	that the prefix	is in the
		     valid state.

	     ref     The number	of kernel references held for this prefix.

     -P	     Flush all the entries in the prefix list.

     -r	     Show default router list.

     -R	     Flush all the entries in the 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 for each entry, to	make it	possible to merge the
	     output with tcpdump(1).  Most useful when used with -A.

     The ndp utility exits 0 on	success, and >0	if an error occurs.


     The ndp utility first appeared in the WIDE	Hydrangea IPv6 protocol	stack
     kit.  The -I auto_linklocal flag first appeared in	FreeBSD	8.0.

FreeBSD	13.0			  May 9, 2014			  FreeBSD 13.0


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