ndisc6(8)

1NDISC6(8)                   System Manager's Manual                  NDISC6(8)
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NAME

6       ndisc6 - ICMPv6 Neighbor Discovery tool
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SYNOPSIS

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

14       NDisc6 is an Unix program which implements the ICMPv6 Neighbor  Discov‐
15       ery  in  userland  (it  is  normally done by the kernel). It is used to
16       lookup the link-layer address (layer 2 address, MAC in the case of Eth‐
17       ernet) of any on-link IPv6 node.
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19       The IPv6 address of the node must be specified, as well as the network‐
20       ing interface on which to perform the lookup.
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OPTIONS

24       -1 or --single
25              Exit as soon as the first advertisement is received (default).
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28       -h or --help
29              Display some help and exit.
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32       -m or --multiple
33              Wait for possible duplicate  advertisements  and  print  all  of
34              them.
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37       -n or --numeric
38              If  the  first parameter is not a valid IPv6 address, do not try
39              to resolve it as a DNS hostname.
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42       -q or --quiet
43              Only display link-layer address.  Display  nothing  in  case  of
44              failure.   That is mostly useful when calling the program from a
45              shell script.
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48       -r attempts or --retry attempts
49              Send ICMPv6 Neighbor Discovery that many times until a reply  is
50              received,  or  abort. By default, ndisc6 will try 3 times before
51              aborting  (MAX_MULTICAST_SOLICIT  and  MAX_UNICAST_SOLICIT  from
52              RFC2461).
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55       -s source_ip or --source source_ip
56              Specify the IPv6 address to be used as the source for the neigh‐
57              bor solicitation packets.
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60       -V or --version
61              Display program version and license and exit.
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64       -v or --verbose
65              Display verbose information. That is the default.
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68       -w wait_ms or --wait wait_ms
69              Wait wait_ms milliseconds for a response  before  retrying.   By
70              default,   ndisc6   waits   1   second   between  each  attempts
71              (RETRANS_TIMER from RFC2461).
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74       If ndisc6 does not receive any response after the specified  number  of
75       attempts  waiting for wait_ms milliseconds each time, it will exit with
76       code 2. On error, it exits with code 1.  Otherwise it exits  with  code
77       0.  This makes it possible to use the exit code to see if a host is on-
78       link or not.
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DIAGNOSTICS

82       If you get no response while you know the remote host is up, it is most
83       likely  that  it  is not on-link, that is to say, you must cross one or
84       more routers to reach it. By design, IPv6 nodes ignore ICMPv6  Neighbor
85       Discovery packets received from nodes not on the same link (i.e. Ether‐
86       net segment), for the sake of security. Technically, that  is  done  by
87       ensuring that the Hop limit (TTL) is 255.
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89       Note  that  you cannot use ndisc6 to lookup the local host's link-layer
90       address.
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SECURITY

94       ndisc6 should be setuid root to allow use by non-privileged  users.  It
95       will  drop  its  root  privileges before any attempt is made to send or
96       receive data from the network to reduce the possible impact of a  secu‐
97       rity vulnerability.
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AUTHOR

105       Rémi Denis-Courmont <remi at remlab dot net>
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107       http://www.remlab.net/ndisc6/
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111ndisc6                              $Date$                           NDISC6(8)