man/man8/ip-neighbour.8

   1 .TH IP\-NEIGHBOUR 8 "20 Dec 2011" "iproute2" "Linux"
   2 .SH "NAME"
   3 ip-neighbour \- neighbour/arp tables management.
   4 .SH "SYNOPSIS"
   5 .sp
   6 .ad l
   7 .in +8
   8 .ti -8
   9 .B ip
  10 .RI "[ " OPTIONS " ]"
  11 .B neigh
  12 .RI " { " COMMAND " | "
  13 .BR help " }"
  14 .sp
  15
  16 .ti -8
  17 .BR "ip neigh" " { " add " | " del " | " change " | " replace " } { "
  18 .IR ADDR " [ "
  19 .B  lladdr
  20 .IR LLADDR " ] [ "
  21 .BR nud " { " permanent " | " noarp " | " stale " | " reachable " } ] | " proxy
  22 .IR ADDR " } [ "
  23 .B  dev
  24 .IR DEV " ]"
  25
  26 .ti -8
  27 .BR "ip neigh" " { " show " | " flush " } [ " proxy " ] [ " to
  28 .IR PREFIX " ] [ "
  29 .B  dev
  30 .IR DEV " ] [ "
  31 .B  nud
  32 .IR STATE " ]"
  33
  34
  35 .SH DESCRIPTION
  36 The
  37 .B ip neigh
  38 command manipulates
  39 .I neighbour
  40 objects that establish bindings between protocol addresses and
  41 link layer addresses for hosts sharing the same link.
  42 Neighbour entries are organized into tables. The IPv4 neighbour table
  43 is also known by another name - the ARP table.
  44
  45 .P
  46 The corresponding commands display neighbour bindings
  47 and their properties, add new neighbour entries and delete old ones.
  48
  49 .TP
  50 ip neighbour add
  51 add a new neighbour entry
  52 .TP
  53 ip neighbour change
  54 change an existing entry
  55 .TP
  56 ip neighbour replace
  57 add a new entry or change an existing one
  58 .RS
  59 .PP
  60 These commands create new neighbour records or update existing ones.
  61
  62 .TP
  63 .BI to " ADDRESS " (default)
  64 the protocol address of the neighbour. It is either an IPv4 or IPv6 address.
  65
  66 .TP
  67 .BI dev " NAME"
  68 the interface to which this neighbour is attached.
  69
  70 .TP
  71 .BI lladdr " LLADDRESS"
  72 the link layer address of the neighbour.
  73 .I LLADDRESS
  74 can also be
  75 .BR "null" .
  76
  77 .TP
  78 .BI nud " NUD_STATE"
  79 the state of the neighbour entry.
  80 .B nud
  81 is an abbreviation for 'Neighbour Unreachability Detection'.
  82 The state can take one of the following values:
  83
  84 .TP
  85 .B permanent
  86 the neighbour entry is valid forever and can be only
  87 be removed administratively.
  88 .TP
  89 .B noarp
  90 the neighbour entry is valid. No attempts to validate
  91 this entry will be made but it can be removed when its lifetime expires.
  92 .TP
  93 .B reachable
  94 the neighbour entry is valid until the reachability
  95 timeout expires.
  96 .TP
  97 .B stale
  98 the neighbour entry is valid but suspicious.
  99 This option to
 100 .B ip neigh
 101 does not change the neighbour state if it was valid and the address
 102 is not changed by this command.
 103 .RE
 104
 105 .TP
 106 ip neighbour delete
 107 delete a neighbour entry
 108 .RS
 109 .PP
 110 The arguments are the same as with
 111 .BR "ip neigh add" ,
 112 except that
 113 .B lladdr
 114 and
 115 .B nud
 116 are ignored.
 117
 118 .PP
 119 .B Warning:
 120 Attempts to delete or manually change a
 121 .B noarp
 122 entry created by the kernel may result in unpredictable behaviour.
 123 Particularly, the kernel may try to resolve this address even
 124 on a
 125 .B NOARP
 126 interface or if the address is multicast or broadcast.
 127 .RE
 128
 129 .TP
 130 ip neighbour show
 131 list neighbour entries
 132 .RS
 133 .TP
 134 .BI to " ADDRESS " (default)
 135 the prefix selecting the neighbours to list.
 136
 137 .TP
 138 .BI dev " NAME"
 139 only list the neighbours attached to this device.
 140
 141 .TP
 142 .BI proxy
 143 list neighbour proxies.
 144
 145 .TP
 146 .B unused
 147 only list neighbours which are not currently in use.
 148
 149 .TP
 150 .BI nud " NUD_STATE"
 151 only list neighbour entries in this state.
 152 .I NUD_STATE
 153 takes values listed below or the special value
 154 .B all
 155 which means all states. This option may occur more than once.
 156 If this option is absent,
 157 .B ip
 158 lists all entries except for
 159 .B none
 160 and
 161 .BR "noarp" .
 162 .RE
 163
 164 .TP
 165 ip neighbour flush
 166 flush neighbour entries
 167 .RS
 168 This command has the same arguments as
 169 .B show.
 170 The differences are that it does not run when no arguments are given,
 171 and that the default neighbour states to be flushed do not include
 172 .B permanent
 173 and
 174 .BR "noarp" .
 175
 176 .PP
 177 With the
 178 .B -statistics
 179 option, the command becomes verbose. It prints out the number of
 180 deleted neighbours and the number of rounds made to flush the
 181 neighbour table. If the option is given
 182 twice,
 183 .B ip neigh flush
 184 also dumps all the deleted neighbours.
 185 .RE
 186
 187 .SH EXAMPLES
 188 .PP
 189 ip neighbour
 190 .RS
 191 Shows the current neighbour table in kernel.
 192 .RE
 193 .PP
 194 ip neigh flush dev eth0
 195 .RS
 196 Removes entries in the neighbour table on device eth0.
 197 .RE
 198
 199 .SH SEE ALSO
 200 .br
 201 .BR ip (8)
 202
 203 .SH AUTHOR
 204 Original Manpage by Michail Litvak <mci@owl.openwall.com>