NAME
ndp —
control/diagnose IPv6 neighbor
discovery protocol
SYNOPSIS
ndp |
[-nt] -i
interface
[expressions ...] |
ndp |
[-nt] -I
[interface |
delete ] |
ndp |
[-nt] -s
nodename etheraddr
[temp ]
[proxy ] |
DESCRIPTION
The
ndp command manipulates the address mapping table used by
the Neighbor Discovery Protocol (NDP).
-
-
- -A
wait
- Repeat -a (dump NDP entries) every
wait seconds.
-
-
- -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:
- 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 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.
-
-
- -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 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 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.
- 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.
- override_rtadv
- 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_source
- 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.
- disabled
- 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 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 advisable to modify
this flag manually.
- 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
- 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
own.
-
-
- -t
- Print timestamp on each entry, making it possible to merge
output with tcpdump(8).
Most useful when used with -A.
EXIT STATUS
The
ndp command will exit with 0 on success, and non-zero on
errors.
SEE ALSO
arp(8)
HISTORY
The
ndp command first appeared in the WIDE Hydrangea IPv6
protocol stack kit.