1IP-NEIGHBOUR(8)                      Linux                     IP-NEIGHBOUR(8)
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NAME

6       ip-neighbour - neighbour/arp tables management.
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SYNOPSIS

9       ip [ OPTIONS ] neigh  { COMMAND | help }
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12       ip neigh { add | del | change | replace } { ADDR [ lladdr LLADDR ] [
13               nud STATE ] | proxy ADDR } [ dev DEV ] [ router ] [
14               extern_learn ]
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16       ip neigh { show | flush } [ proxy ] [ to PREFIX ] [ dev DEV ] [ nud
17               STATE ] [ vrf NAME ]
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19       STATE := { permanent | noarp | stale | reachable | none | incomplete |
20               delay | probe | failed }
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DESCRIPTION

24       The ip neigh command manipulates neighbour objects that establish bind‐
25       ings between protocol addresses and link layer addresses for hosts
26       sharing the same link.  Neighbour entries are organized into tables.
27       The IPv4 neighbour table is also known by another name - the ARP table.
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30       The corresponding commands display neighbour bindings and their proper‐
31       ties, add new neighbour entries and delete old ones.
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34       ip neighbour add
35              add a new neighbour entry
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37       ip neighbour change
38              change an existing entry
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40       ip neighbour replace
41              add a new entry or change an existing one
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43              These commands create new neighbour records or update existing
44              ones.
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47              to ADDRESS (default)
48                     the protocol address of the neighbour. It is either an
49                     IPv4 or IPv6 address.
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52              dev NAME
53                     the interface to which this neighbour is attached.
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56              proxy  indicates whether we are proxying for this neigbour entry
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59              router indicates whether neigbour is a router
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62              extern_learn
63                     this neigh entry was learned externally. This option can
64                     be used to indicate to the kernel that this is a con‐
65                     troller learnt dynamic entry.  Kernel will not gc such an
66                     entry.
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69              lladdr LLADDRESS
70                     the link layer address of the neighbour.  LLADDRESS can
71                     also be null.
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74              nud STATE
75                     the state of the neighbour entry.  nud is an abbreviation
76                     for 'Neighbour Unreachability Detection'.  The state can
77                     take one of the following values:
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80                     permanent
81                            the neighbour entry is valid forever and can be
82                            only be removed administratively.
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84                     noarp  the neighbour entry is valid. No attempts to vali‐
85                            date this entry will be made but it can be removed
86                            when its lifetime expires.
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88                     reachable
89                            the neighbour entry is valid until the reachabil‐
90                            ity timeout expires.
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92                     stale  the neighbour entry is valid but suspicious.  This
93                            option to ip neigh does not change the neighbour
94                            state if it was valid and the address is not
95                            changed by this command.
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97                     none   this is a pseudo state used when initially creat‐
98                            ing a neighbour entry or after trying to remove it
99                            before it becomes free to do so.
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101                     incomplete
102                            the neighbour entry has not (yet) been vali‐
103                            dated/resolved.
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105                     delay  neighbor entry validation is currently delayed.
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107                     probe  neighbor is being probed.
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109                     failed max number of probes exceeded without success,
110                            neighbor validation has ultimately failed.
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113       ip neighbour delete
114              delete a neighbour entry
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116              The arguments are the same as with ip neigh add, except that
117              lladdr and nud are ignored.
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120              Warning: Attempts to delete or manually change a noarp entry
121              created by the kernel may result in unpredictable behaviour.
122              Particularly, the kernel may try to resolve this address even on
123              a NOARP interface or if the address is multicast or broadcast.
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126       ip neighbour show
127              list neighbour entries
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129              to ADDRESS (default)
130                     the prefix selecting the neighbours to list.
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133              dev NAME
134                     only list the neighbours attached to this device.
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137              vrf NAME
138                     only list the neighbours for given VRF.
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141              proxy  list neighbour proxies.
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144              unused only list neighbours which are not currently in use.
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147              nud STATE
148                     only list neighbour entries in this state.  NUD_STATE
149                     takes values listed below or the special value all which
150                     means all states. This option may occur more than once.
151                     If this option is absent, ip lists all entries except for
152                     none and noarp.
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155       ip neighbour flush
156              flush neighbour entries
157              This command has the same arguments as show.  The differences
158              are that it does not run when no arguments are given, and that
159              the default neighbour states to be flushed do not include perma‐
160              nent and noarp.
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163              With the -statistics option, the command becomes verbose. It
164              prints out the number of deleted neighbours and the number of
165              rounds made to flush the neighbour table. If the option is given
166              twice, ip neigh flush also dumps all the deleted neighbours.
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EXAMPLES

170       ip neighbour
171              Shows the current neighbour table in kernel.
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173       ip neigh flush dev eth0
174              Removes entries in the neighbour table on device eth0.
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SEE ALSO

178       ip(8)
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AUTHOR

182       Original Manpage by Michail Litvak <mci@owl.openwall.com>
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186iproute2                          20 Dec 2011                  IP-NEIGHBOUR(8)
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