1.\" $OpenBSD: arp.8,v 1.30 2011/09/01 21:21:25 jmc Exp $ 2.\" $NetBSD: arp.8,v 1.7 1995/03/01 11:50:59 chopps Exp $ 3.\" 4.\" Copyright (c) 1985, 1991, 1993 5.\" The Regents of the University of California. All rights reserved. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice, this list of conditions and the following disclaimer in the 14.\" documentation and/or other materials provided with the distribution. 15.\" 3. Neither the name of the University nor the names of its contributors 16.\" may be used to endorse or promote products derived from this software 17.\" without specific prior written permission. 18.\" 19.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29.\" SUCH DAMAGE. 30.\" 31.\" from: @(#)arp.8 8.1 (Berkeley) 6/6/93 32.\" 33.Dd $Mdocdate: September 1 2011 $ 34.Dt ARP 8 35.Os 36.Sh NAME 37.Nm arp 38.Nd address resolution display and control 39.Sh SYNOPSIS 40.Nm arp 41.Op Fl adn 42.Op Fl V Ar rdomain 43.Ar hostname 44.Nm arp 45.Op Fl F 46.Op Fl f Ar file 47.Op Fl V Ar rdomain 48.Fl s Ar hostname ether_addr 49.Op Cm temp | permanent 50.Op Cm pub 51.Nm 52.Fl W Ar ether_addr Op Ar iface 53.Sh DESCRIPTION 54The 55.Nm 56program displays and modifies the Internet-to-Ethernet address translation 57tables used by the address resolution protocol (ARP). 58.Pp 59.Nm 60displays the current ARP entry for 61.Ar hostname 62when no optional parameters are supplied. 63.Ar hostname 64may be specified by name or by number, 65using Internet dot notation. 66.Pp 67.Nm 68can also be used to send Wake on LAN (WoL) frames over a local 69Ethernet network to one or more hosts using their link layer (hardware) 70addresses. 71WoL functionality is generally enabled in a machine's BIOS 72and can be used to power on machines from a remote system without 73having physical access to them. 74.Pp 75The options are as follows: 76.Bl -tag -width Ds 77.It Fl a 78Display all of the current ARP entries. 79See also the 80.Fl d 81option below. 82.It Fl d 83Delete an entry for the host called 84.Ar hostname . 85Alternatively, the 86.Fl d 87flag may be combined with the 88.Fl a 89flag to delete all entries, with hostname lookups automatically 90disabled. 91Only the superuser may delete entries. 92.It Fl F 93Force existing entries for the given host to be overwritten 94(only relevant to the 95.Fl f 96and 97.Fl s 98options). 99.It Fl f Ar file 100Process entries from 101.Ar file 102to be set in the ARP tables. 103Any entries in the file that already exist for a given host 104will not be overwritten unless 105.Fl F 106is given. 107Entries in the file should be of the form: 108.Bd -filled -offset indent 109.Ar hostname ether_addr 110.Op Cm temp | permanent 111.Op Cm pub 112.Ed 113.Pp 114The entry will be static (will not time out) unless the word 115.Cm temp 116is given in the command. 117A static ARP entry can be overwritten by network traffic, unless the word 118.Cm permanent 119is given. 120If the word 121.Cm pub 122is given, the entry will be 123.Dq published ; 124that is, this system will act as an ARP server, 125responding to requests for 126.Ar hostname 127even though the host address is not its own. 128This behavior has traditionally been called 129.Em proxy ARP . 130.It Fl n 131Show network addresses as numbers (normally 132.Nm 133attempts to display addresses symbolically). 134.It Xo 135.Fl s Ar hostname ether_addr 136.Op Cm temp | permanent 137.Op Cm pub 138.Xc 139Create an ARP entry for the host called 140.Ar hostname 141with the Ethernet address 142.Ar ether_addr . 143The Ethernet address is given as six hexadecimal bytes separated by 144colons. 145.Pp 146The 147.Cm permanent , pub , 148or 149.Cm temp 150modifiers may be specified with meanings as given above. 151.Pp 152If the entry already exists for the given host, it will not 153be replaced unless 154.Fl F 155is given. 156.It Fl V Ar rdomain 157Select the routing domain. 158The default is 0. 159.It Fl W Ar ether_addr Op Ar iface 160Send the Wake on LAN frame from all interfaces on the local machine 161that are up, if 162.Ar iface 163has not been specified. 164Otherwise the frame will be sent from 165.Ar iface . 166.Ar ether_addr 167is the Ethernet address of the remote machine or a hostname entry in 168.Pa /etc/ethers . 169This option cannot be used in combination with any other option. 170.El 171.Sh FILES 172.Bl -tag -width "/etc/ethers" -compact 173.It /etc/ethers 174Ethernet host name database. 175.El 176.Sh EXAMPLES 177View the current 178.Xr arp 4 179table, 180showing network addresses symbolically: 181.Pp 182.Dl $ arp -a 183.Pp 184Create a permanent 185entry (one that cannot be overwritten by other network traffic): 186.Pp 187.Dl # arp -s 10.0.0.2 00:90:27:bb:cc:dd permanent 188.Pp 189Create proxy ARP 190entries on interface fxp0 191(MAC address 00:90:27:bb:cc:dd), 192for IP addresses 204.1.2.3 and 204.1.2.4: 193.Bd -literal -offset indent 194# arp -s 204.1.2.3 00:90:27:bb:cc:dd pub 195# arp -s 204.1.2.4 00:90:27:bb:cc:dd pub 196.Ed 197.Sh SEE ALSO 198.Xr inet 3 , 199.Xr arp 4 , 200.Xr ethers 5 , 201.Xr ifconfig 8 , 202.Xr ndp 8 203.Sh HISTORY 204The 205.Nm 206command appeared in 207.Bx 4.3 . 208Wake on LAN functionality was added in 209.Ox 4.9 . 210