control/diagnose IPv6 Neighbor Discovery Protocol
-I [interface |
-i interface [flag ...]]
-s nodename etheraddr [
ndp command manipulates the address
mapping table used by the Neighbor Discovery Protocol (NDP).
-a (dump NDP entries) every
- Dump the currently existing NDP entries. The following information will be
- The IPv6 address of the neighbor.
- Linklayer Address
- The linklayer address of the neighbor. If the address is not
available, it will be displayed as “(incomplete)”.
- The network interface associated with the neighbor cache entry.
- The time until expiry of the entry. If the entry is marked
“permanent”, it will never expire.
- The state of the neighbor cache entry, as a single letter:
- Unknown state (should never happen).
- Flags on the neighbor cache entry, in a single letter. They are:
Router (‘R’) and proxy neighbor advertisement
(‘p’). This field may be followed by a decimal number,
representing the number of NS probes the node has sent during the
- Erase all the NDP entries.
- Delete the specified NDP entry.
- Parse the file specified by filename.
- Harmonize consistency between the routing table and the default router
list; install the top entry of the list into the kernel routing
- Shows the default interface used as the default route when there is no
- Specifies the default interface to be used when
there is no interface specified even though required.
- The current default interface will be deleted from the kernel.
interface [flag ...]
- View ND information for the specified interface. If additional arguments
ndp sets or clears the specified flags
for the interface. Each flag should be separated by whitespace or tab
characters. Possible flags are as follows. All of the flags can begin with
the special character ‘
means the flag should be cleared. Note that
would be needed before
-foo in this case.
- Turn on or off NUD (Neighbor Unreachability Detection) on the
interface. NUD is usually turned on by default.
- Specify whether or not to accept Router Advertisement messages
received on the interface. Note that the kernel
does not accept Router Advertisement messages unless the
net.inet6.ip6.accept_rtadv variable is non-0,
even if the flag is on. This flag is set to 1 by default. See
further details on how to set the
- Do not try to resolve numeric addresses to hostnames.
- Flush all the entries in the prefix list.
- Show the prefix list.
- Flush all the entries in the default router list.
- Show the default router list.
nodename etheraddr [
- Register an NDP entry for a node. The entry will be permanent unless the
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.
- Print a timestamp on each entry, making it possible to merge output with
tcpdump(8). Most useful
when used with
ndp utility exits 0 on success,
and >0 if an error occurs.
ndp command first appeared in the WIDE
Hydrangea IPv6 protocol stack kit.