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NDISC6(8)		     System Manager's Manual		       NDISC6(8)

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  re-
	    ceived,  or abort. By default, ndisc6 will try 3 times before abort-
	    ing (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 de-
	    fault, ndisc6 waits 1 second between  each	attempts  (RETRANS_TIMER
	    from RFC2461).

     If  ndisc6  does not receive any response after the specified number of at-
     tempts 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  ad-
     dress.

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
     Remi Denis-Courmont <remi at remlab dot net>

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

ndisc6				     $Date$			       NDISC6(8)

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