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 fol

lowing 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

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 let

ter:

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

pen).

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.

-A wait

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

-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 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 ex

pression. 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 specified 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 Ad

vertisement
messages received on the interface. Note

that the kernel
does not accept Router Advertisement mes

sages unless the
net.inet6.ip6.accept_rtadv variable is

non-0, even if the
flag is on. This flag is set to 1 by de

fault.

prefer_source

Prefer addresses on the interface as candi

dates 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.

disabled

Disable IPv6 operation on the interface.

When disabled,
the interface discards any IPv6 packets re

ceived 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. 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.

basereachable=(number)

Specify the BaseReachbleTimer on the inter

face 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 host

names.

-p Show prefix list.

-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 serv

er, responding
to requests for hostname even though the host ad

dress is not its
own.

-t Print timestamp on each entry, making it possible to

merge output

with tcpdump(1). Most useful when used with -A.