ndp
—
control/diagnose IPv6 neighbor discovery protocol
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 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
.
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 kit.