NDP(8) FreeBSD System Manager's Manual 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 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
? 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.
-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.
accept_rtadv
Specify whether or not to accept Router Advertisement
messages received on the interface. This flag is set by
net.inet6.ip6.accept_rtadv sysctl variable.
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.
no_prefer_iface
The address on the outgoing interface is preferred by
source addess selection rule. If this flag is set, stop
treating the address on the interface as special even
when the interface is outgoing interface. The default
value of this flag is off.
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.
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 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.
EXIT STATUS
The ndp utility exits 0 on success, and >0 if an error occurs.
SEE ALSO
arp(8)
HISTORY
The ndp utility first appeared in the WIDE Hydrangea IPv6 protocol stack
kit. The -I auto_linklocal flag first appeared in FreeBSD 8.0.
FreeBSD 13.1-RELEASE-p6 May 9, 2014 FreeBSD 13.1-RELEASE-p6
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