ndisc6 - ICMPv6 Neighbor Discovery tool
ndisc6 [-1mnqv] [-r attempts] [-w wait_ms] < IPv6 address> <iface>
NDisc6 is an Unix program which implements the ICMPv6 Neighbor
Discovery in userland (it is normally done by the kernel). It is used
to lookup the link-layer address (layer 2 address, MAC in the case of
Ethernet) of any on-link IPv6 node.
The IPv6 address of the node must be specified, as well as the
networking interface on which to perform the lookup.
-1 or --single
Exit as soon as the first advertisement is received (default).
-h or --help
Display some help and exit.
-m or --multiple
Wait for possible duplicate advertisements and print all of
-n or --numeric
If the first parameter is not a valid IPv6 address, do not try
to resolve it as a DNS hostname.
-q or --quiet
Only display link-layer address. Display nothing in case of
failure. That is mostly useful when calling the program from a
-r attempts or --retry attempts
Send ICMPv6 Neighbor Discovery that many times until a reply is
received, or abort. By default, ndisc6 will try 3 times before
aborting (MAX_MULTICAST_SOLICIT and MAX_UNICAST_SOLICIT from
-V or --version
Display program version and license and exit.
-v or --verbose
Display verbose information. That is the default.
-w wait_ms or --wait wait_ms
Wait wait_ms milliseconds for a response before retrying. By
default, ndisc6 waits 1 second between each attempts
(RETRANS_TIMER from RFC2461).
If you get no response while you know the remote host is up, it is most
likely that it is not on-link, that is to say, you must cross one or
more routers to reach it. By design, IPv6 nodes ignore ICMPv6 Neighbor
Discovery packets received from nodes not on the same link (i.e.
Ethernet segment), for the sake of security. Technically, that is done
by ensuring that the Hop limit (TTL) is 255.
Note that you cannot use ndisc6 to lookup the local host’s link-layer
ndisc6 should be setuid root to allow use by non privileged users. It
will drop its root privileges before any attempt is made to send or
receive data from the network to reduce the possible impact of a
ping6(8), rdisc6(8), ipv6(7)
Rémi Denis-Courmont <rdenis at simphalempin.com>
$Id: ndisc6.8 483 2007-08-08 15:09:36Z remi $