arp.tproj/arp.8

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  54 .\"     @(#)arp.8       8.1 (Berkeley) 6/6/93
  55 .\" $FreeBSD: src/usr.sbin/arp/arp.8,v 1.25.2.1 2008/04/25 16:38:14 sam Exp $
  56 .\"
  57 .Dd March 18, 2008
  58 .Dt ARP 8
  59 .Os
  60 .Sh NAME
  61 .Nm arp
  62 .Nd address resolution display and control
  63 .Sh SYNOPSIS
  64 .Nm
  65 .Op Fl n
  66 .Op Fl i Ar interface
  67 .Ar hostname
  68 .Nm
  69 .Op Fl n
  70 .Op Fl i Ar interface
  71 .Op Fl l
  72 .Fl a
  73 .Nm
  74 .Fl d Ar hostname
  75 .Op Cm pub
  76 .Op Cm ifscope interface
  77 .Nm
  78 .Fl d
  79 .Op Fl i Ar interface
  80 .Fl a
  81 .Nm
  82 .Fl s Ar hostname ether_addr
  83 .Op Cm temp
  84 .Op Cm reject
  85 .Op Cm blackhole
  86 .Op Cm pub Op Cm only
  87 .Op Cm ifscope interface
  88 .Nm
  89 .Fl S Ar hostname ether_addr
  90 .Op Cm temp
  91 .Op Cm reject
  92 .Op Cm blackhole
  93 .Op Cm pub Op Cm only
  94 .Op Cm ifscope interface
  95 .Nm
  96 .Fl f Ar filename
  97 .Sh DESCRIPTION
  98 The
  99 .Nm
 100 utility displays and modifies the Internet-to-Ethernet address translation
 101 tables used by the address resolution protocol
 102 .Pq Xr arp 4 .
 103 With no flags, the program displays the current
 104 .Tn ARP
 105 entry for
 106 .Ar hostname .
 107 The host may be specified by name or by number,
 108 using Internet dot notation.
 109 .Pp
 110 Available options:
 111 .Bl -tag -width indent
 112 .It Fl a
 113 The program displays or deletes all of the current
 114 .Tn ARP
 115 entries.
 116 .It Fl d
 117 A super-user may delete an entry for the host called
 118 .Ar hostname
 119 with the
 120 .Fl d
 121 flag.
 122 If the
 123 .Cm pub
 124 keyword is specified, only the
 125 .Dq published
 126 .Tn ARP
 127 entry
 128 for this host will be deleted.
 129 If the
 130 .Cm ifscope
 131 keyword is specified, the entry specific to the interface will be deleted.
 132 .Pp
 133 Alternatively, the
 134 .Fl d
 135 flag may be combined with the
 136 .Fl a
 137 flag to delete all entries.
 138 .It Fl i Ar interface
 139 Limit the operation scope to the
 140 .Tn ARP
 141 entries on
 142 .Ar interface .
 143 Applicable only to the following operations:
 144 display one, display all, delete all.
 145 .It Fl l
 146 Show link-layer reachability information.
 147 .It Fl n
 148 Show network addresses as numbers (normally
 149 .Nm
 150 attempts to display addresses symbolically).
 151 .It Fl s Ar hostname ether_addr
 152 Create an
 153 .Tn ARP
 154 entry for the host called
 155 .Ar hostname
 156 with the Ethernet address
 157 .Ar ether_addr .
 158 The Ethernet address is given as six hex bytes separated by colons.
 159 The entry will be permanent unless the word
 160 .Cm temp
 161 is given in the command.
 162 If the word
 163 .Cm pub
 164 is given, the entry will be
 165 .Dq published ;
 166 i.e., this system will
 167 act as an
 168 .Tn ARP
 169 server,
 170 responding to requests for
 171 .Ar hostname
 172 even though the host address is not its own.
 173 In this case the
 174 .Ar ether_addr
 175 can be given as
 176 .Cm auto
 177 in which case the interfaces on this host will be examined,
 178 and if one of them is found to occupy the same subnet, its
 179 Ethernet address will be used.
 180 If the
 181 .Cm only
 182 keyword is also specified, this will create a
 183 .Dq "published (proxy only)"
 184 entry.
 185 This type of entry is created automatically if
 186 .Nm
 187 detects that a routing table entry for
 188 .Ar hostname
 189 already exists.
 190 .Pp
 191 If the
 192 .Cm reject
 193 keyword is specified the entry will be marked so that traffic to
 194 the host will be discarded and the sender will be notified the
 195 host is unreachable.
 196 The
 197 .Cm blackhole
 198 keyword is similar in that traffic is discarded but the sender is
 199 not notified.
 200 These can be used to block external traffic to a host without
 201 using a firewall.
 202 .Pp
 203 If the
 204 .Cm ifscope
 205 keyword is specified, the entry will set with an additional property that
 206 strictly associate the entry to the interface. This allows
 207 for the presence of mutiple entries with the same destination
 208 on different interfaces.
 209 .It Fl S Ar hostname ether_addr
 210 Is just like
 211 .Fl s
 212 except any existing
 213 .Tn ARP
 214 entry for this host will be deleted first.
 215 .It Fl f Ar filename
 216 Cause the file
 217 .Ar filename
 218 to be read and multiple entries to be set in the
 219 .Tn ARP
 220 tables.
 221 Entries
 222 in the file should be of the form
 223 .Pp
 224 .Bd -ragged -offset indent -compact
 225 .Ar hostname ether_addr
 226 .Op Cm temp
 227 .Op Cm pub Op Cm only
 228 .Op Cm ifscope interface
 229 .Ed
 230 .Pp
 231 with argument meanings as given above.
 232 Leading whitespace and empty lines are ignored.
 233 A
 234 .Ql #
 235 character will mark the rest of the line as a comment.
 236 .It Fl x
 237 Show extended link-layer reachability information in addition to that shown by
 238 the
 239 .Fl l
 240 flag.
 241 .El
 242 .Sh SEE ALSO
 243 .Xr inet 3 ,
 244 .Xr arp 4 ,
 245 .Xr ifconfig 8 ,
 246 .Xr ndp 8
 247 .Sh HISTORY
 248 The
 249 .Nm
 250 utility appeared in
 251 .Bx 4.3 .