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