ndp —
control/diagnose IPv6 neighbor discovery
protocol
ndp |
-I [delete |
interface] |
ndp |
-i interface
[flags...] |
ndp |
-s [-nt]
-s nodename etheraddr
[temp] [proxy] |
The ndp command 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
- 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
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 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.
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.
proxy_prefixes- the interface is enabled to proxy neighbor discovery for global scope
prefixes matching those on link at other interfaces.
insecure
do not use cryptographically generated addresses (CGA) on this
interface.-
replicated
Address autoconfiguration proceeds under the assumption that interface
configuration is replicated by a sleep proxy at another node on the
link. Disables optimistic DAD and sends unsolicited NA with O=1 when DAD
completes. Ignores DAD failures from other hardware addresses.-
-l- Show link-layer reachability information.
-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.
-x- Show extended link-layer reachability information in addition to that
shown by the
-l flag.
-w- Show the cryptographically generated address (CGA) parameters for the
node.
The ndp command will exit with 0 on
success, and non-zero on errors.
The ndp command first appeared in WIDE
Hydrangea IPv6 protocol stack kit.