NAME

       ndisc6 - ICMPv6 Neighbor Discovery tool

SYNOPSIS

       ndisc6 [-1mnqv] [-r attempts] [-s source_ip] [-w wait_ms] <IPv6 address> <iface>

DESCRIPTON

       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.

OPTIONS

       -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 them.

       -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 shell script.

       -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 RFC2461).

       -s source_ip or --source source_ip
              Specify the IPv6 address to be used as the source  for  the  neighbor  solicitation
              packets.

       -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 ndisc6 does not receive any response after the specified number of attempts waiting for
       wait_ms  milliseconds each time, it will exit with code 2. On error, it exits with code 1.
       Otherwise it exits with code 0. This makes it possible to use the exit code to  see  if  a
       host is on-link or not.

DIAGNOSTICS

       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 address.

SECURITY

       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 security vulnerability.

SEE ALSO

       ping6(8), rdisc6(8), ipv6(7)

AUTHOR

       Rémi Denis-Courmont <remi at remlab dot net>

       http://www.remlab.net/ndisc6/