arp.tproj/arp.8

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  28 .\"     @(#)arp.8       8.1 (Berkeley) 6/6/93
  29 .\" $FreeBSD: src/usr.sbin/arp/arp.8,v 1.25.2.1 2008/04/25 16:38:14 sam Exp $
  30 .\"
  31 .Dd March 18, 2008
  32 .Dt ARP 8
  33 .Os
  34 .Sh NAME
  35 .Nm arp
  36 .Nd address resolution display and control
  37 .Sh SYNOPSIS
  38 .Nm
  39 .Op Fl n
  40 .Op Fl i Ar interface
  41 .Ar hostname
  42 .Nm
  43 .Op Fl n
  44 .Op Fl i Ar interface
  45 .Fl a
  46 .Nm
  47 .Fl d Ar hostname
  48 .Op Cm pub
  49 .Op Cm ifscope interface
  50 .Nm
  51 .Fl d
  52 .Op Fl i Ar interface
  53 .Fl a
  54 .Nm
  55 .Fl s Ar hostname ether_addr
  56 .Op Cm temp
  57 .Op Cm reject
  58 .Op Cm blackhole
  59 .Op Cm pub Op Cm only
  60 .Op Cm ifscope interface
  61 .Nm
  62 .Fl S Ar hostname ether_addr
  63 .Op Cm temp
  64 .Op Cm reject
  65 .Op Cm blackhole
  66 .Op Cm pub Op Cm only
  67 .Op Cm ifscope interface
  68 .Nm
  69 .Fl f Ar filename
  70 .Sh DESCRIPTION
  71 The
  72 .Nm
  73 utility displays and modifies the Internet-to-Ethernet address translation
  74 tables used by the address resolution protocol
  75 .Pq Xr arp 4 .
  76 With no flags, the program displays the current
  77 .Tn ARP
  78 entry for
  79 .Ar hostname .
  80 The host may be specified by name or by number,
  81 using Internet dot notation.
  82 .Pp
  83 Available options:
  84 .Bl -tag -width indent
  85 .It Fl a
  86 The program displays or deletes all of the current
  87 .Tn ARP
  88 entries.
  89 .It Fl d
  90 A super-user may delete an entry for the host called
  91 .Ar hostname
  92 with the
  93 .Fl d
  94 flag.
  95 If the
  96 .Cm pub
  97 keyword is specified, only the
  98 .Dq published
  99 .Tn ARP
 100 entry
 101 for this host will be deleted.
 102 If the
 103 .Cm ifscope
 104 keyword is specified, the entry specific to the interface will be deleted.
 105 .Pp
 106 Alternatively, the
 107 .Fl d
 108 flag may be combined with the
 109 .Fl a
 110 flag to delete all entries.
 111 .It Fl i Ar interface
 112 Limit the operation scope to the
 113 .Tn ARP
 114 entries on
 115 .Ar interface .
 116 Applicable only to the following operations:
 117 display one, display all, delete all.
 118 .It Fl n
 119 Show network addresses as numbers (normally
 120 .Nm
 121 attempts to display addresses symbolically).
 122 .It Fl s Ar hostname ether_addr
 123 Create an
 124 .Tn ARP
 125 entry for the host called
 126 .Ar hostname
 127 with the Ethernet address
 128 .Ar ether_addr .
 129 The Ethernet address is given as six hex bytes separated by colons.
 130 The entry will be permanent unless the word
 131 .Cm temp
 132 is given in the command.
 133 If the word
 134 .Cm pub
 135 is given, the entry will be
 136 .Dq published ;
 137 i.e., this system will
 138 act as an
 139 .Tn ARP
 140 server,
 141 responding to requests for
 142 .Ar hostname
 143 even though the host address is not its own.
 144 In this case the
 145 .Ar ether_addr
 146 can be given as
 147 .Cm auto
 148 in which case the interfaces on this host will be examined,
 149 and if one of them is found to occupy the same subnet, its
 150 Ethernet address will be used.
 151 If the
 152 .Cm only
 153 keyword is also specified, this will create a
 154 .Dq "published (proxy only)"
 155 entry.
 156 This type of entry is created automatically if
 157 .Nm
 158 detects that a routing table entry for
 159 .Ar hostname
 160 already exists.
 161 .Pp
 162 If the
 163 .Cm reject
 164 keyword is specified the entry will be marked so that traffic to
 165 the host will be discarded and the sender will be notified the
 166 host is unreachable.
 167 The
 168 .Cm blackhole
 169 keyword is similar in that traffic is discarded but the sender is
 170 not notified.
 171 These can be used to block external traffic to a host without
 172 using a firewall.
 173 .Pp
 174 If the
 175 .Cm ifscope
 176 keyword is specified, the entry will set with an additional property that
 177 strictly associate the entry to the interface. This allows
 178 for the presence of mutiple entries with the same destination
 179 on different interfaces.
 180 .It Fl S Ar hostname ether_addr
 181 Is just like
 182 .Fl s
 183 except any existing
 184 .Tn ARP
 185 entry for this host will be deleted first.
 186 .It Fl f Ar filename
 187 Cause the file
 188 .Ar filename
 189 to be read and multiple entries to be set in the
 190 .Tn ARP
 191 tables.
 192 Entries
 193 in the file should be of the form
 194 .Pp
 195 .Bd -ragged -offset indent -compact
 196 .Ar hostname ether_addr
 197 .Op Cm temp
 198 .Op Cm pub Op Cm only
 199 .Op Cm ifscope interface
 200 .Ed
 201 .Pp
 202 with argument meanings as given above.
 203 Leading whitespace and empty lines are ignored.
 204 A
 205 .Ql #
 206 character will mark the rest of the line as a comment.
 207 .El
 208 .Sh SEE ALSO
 209 .Xr inet 3 ,
 210 .Xr arp 4 ,
 211 .Xr ifconfig 8
 212 .Sh HISTORY
 213 The
 214 .Nm
 215 utility appeared in
 216 .Bx 4.3 .