NDP(8) | System Manager's Manual | NDP(8)

# NAME

`ndp` — control/diagnose IPv6 Neighbor Discovery Protocol (NDP)

# SYNOPSIS

`ndp` | [`-acnt`] [`-A` wait] [`-d` hostname] [`-f` filename] [`-i` interface] [`-s` nodename ether_addr [`temp`] [`proxy`]] [`-V` rdomain] [hostname]

# DESCRIPTION

The `ndp` command manipulates the address mapping table used by the Neighbor Discovery Protocol (NDP).

`-A` wait
  Repeat `-a` (dump NDP entries) every wait seconds.
`-a`
  Dump the currently existing NDP entries. The following information will be printed:
  Neighbor
    The IPv6 address of the neighbor.
  Linklayer Address
    The linklayer address of the neighbor. If the address is not available, it will be displayed as “(incomplete)”.
  Netif
    The network interface associated with the neighbor cache entry.
  Expire
    The time until expiry of the entry. If the entry is marked “permanent”, it will never expire.
  S
    The state of the neighbor cache entry, as a single letter:

    D
      Delay
    I
      Incomplete
    N
      Nostate
    P
      Probe
    R
      Reachable
    S
      Stale
    W
      Waitdelete
    ?
      Unknown state (should never happen).
  Flags
    Flags on the neighbor cache entry, in a single letter. They are: local (‘l’), Router (‘R’) and proxy neighbor advertisement (‘p’). This field may be followed by a decimal number, representing the number of NS probes the node has sent during the current state.
`-c`
  Erase all the NDP entries.
`-d` hostname
  Delete the specified NDP entry.
`-f` filename
  Parse entries from file to be inserted in the neighbor cache. See the `-s` option for a description of the file format.
`-i` interface
  View ND information for the specified interface.
`-n`
  Do not perform domain name resolution. If a name cannot be resolved without DNS, an error will be reported.
`-s` nodename ether_addr [`temp`] [`proxy`]
  Register an NDP entry for the node called nodename with the Ether address ether_addr. The Ethernet address is given as six hexadecimal bytes separated by colons. 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 an ND Proxy server, responding to requests for nodename even though the node address is not its own.
`-t`
  Print a timestamp on each entry, making it possible to merge output with tcpdump(8). Most useful when used with `-A`.
`-V` rdomain
  Select the routing domain.

# EXIT STATUS

The `ndp` utility exits 0 on success, and >0 if an error occurs.

# SEE ALSO

ip6(4), sysctl.conf(5), arp(8), sysctl(8), tcpdump(8)

# HISTORY

The `ndp` command first appeared in the WIDE Hydrangea IPv6 protocol stack kit.

August 23, 2019 | Debian