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

NAME

     ndp -- control/diagnose IPv6 neighbor discovery protocol

SYNOPSIS

     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]

DESCRIPTION

     The ndp utility manipulates the address mapping table used by the Neighbor Discovery Protocol (NDP).

     -a      Dump the currently existing NDP entries.  The following information 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 entry.

	     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 rout-
	     ing 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
	     default.

     -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.

	     accept_rtadv
		     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.

	     auto_linklocal
		     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.

	     no_prefer_iface
		     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.

	     disabled
		     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 error 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 Detection.  If the auto_linklocal per-
		     interface flag is set, automatic link-local address configuration is performed again when this flag is cleared.

	     basereachable=(number)
		     Specify the BaseReachbleTimer on the interface in millisecond.

	     retrans=(number)
		     Specify the RetransTimer on the interface in millisecond.

	     curhlim=(number)
		     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 autoconfiguration.
		     L, O    This prefix can be used for on-link determination; that is, it can be used to determine whether a given destination
			     address is on-link.
		     D	     There are no reachable routers advertising this prefix.

	     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 address of a packet.

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

	     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 own.

     -t      Print timestamp for each entry, to make it possible to merge the output with tcpdump(1).  Most useful when used with -A.

EXIT STATUS

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

SEE ALSO

     arp(8)

HISTORY

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

BSD
								    May 9, 2014 							       BSD