1.\" $OpenBSD: arp.8,v 1.26 2009/06/05 06:47:12 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: June 5 2009 $ 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.Sh DESCRIPTION 52The 53.Nm 54program displays and modifies the Internet-to-Ethernet address translation 55tables used by the address resolution protocol (ARP). 56.Pp 57.Nm 58displays the current ARP entry for 59.Ar hostname 60when no optional parameters are supplied. 61.Ar hostname 62may be specified by name or by number, 63using Internet dot notation. 64.Pp 65The options are as follows: 66.Bl -tag -width Ds 67.It Fl a 68Display all of the current ARP entries. 69See also the 70.Fl d 71option below. 72.It Fl d 73Delete an entry for the host called 74.Ar hostname . 75Alternatively, the 76.Fl d 77flag may be combined with the 78.Fl a 79flag to delete all entries, with hostname lookups automatically 80disabled. 81Only the superuser may delete entries. 82.It Fl F 83Force existing entries for the given host to be overwritten 84(only relevant to the 85.Fl f 86and 87.Fl s 88options). 89.It Fl f Ar file 90Process entries from 91.Ar file 92to be set in the ARP tables. 93Any entries in the file that already exist for a given host 94will not be overwritten unless 95.Fl F 96is given. 97Entries in the file should be of the form: 98.Bd -filled -offset indent 99.Ar hostname ether_addr 100.Op Cm temp | permanent 101.Op Cm pub 102.Ed 103.Pp 104The entry will be static (will not time out) unless the word 105.Cm temp 106is given in the command. 107A static ARP entry can be overwritten by network traffic, unless the word 108.Cm permanent 109is given. 110If the word 111.Cm pub 112is given, the entry will be 113.Dq published ; 114that is, this system will act as an ARP server, 115responding to requests for 116.Ar hostname 117even though the host address is not its own. 118This behavior has traditionally been called 119.Em proxy ARP . 120.It Fl n 121Show network addresses as numbers (normally 122.Nm 123attempts to display addresses symbolically). 124.It Xo 125.Fl s Ar hostname ether_addr 126.Op Cm temp | permanent 127.Op Cm pub 128.Xc 129Create an ARP entry for the host called 130.Ar hostname 131with the Ethernet address 132.Ar ether_addr . 133The Ethernet address is given as six hexadecimal bytes separated by 134colons. 135.Pp 136The 137.Cm permanent , pub , 138or 139.Cm temp 140modifiers may be specified with meanings as given above. 141.Pp 142If the entry already exists for the given host, it will not 143be replaced unless 144.Fl F 145is given. 146.It Fl V Ar rdomain 147Select the routing domain. 148The default is 0. 149.El 150.Sh EXAMPLES 151View the current 152.Xr arp 4 153table, 154showing network addresses symbolically: 155.Pp 156.Dl $ arp -a 157.Pp 158Create a permanent 159entry (one that cannot be overwritten by other network traffic): 160.Pp 161.Dl # arp -s 10.0.0.2 00:90:27:bb:cc:dd permanent 162.Pp 163Create proxy ARP 164entries on interface fxp0 165(MAC address 00:90:27:bb:cc:dd), 166for IP addresses 204.1.2.3 and 204.1.2.4: 167.Bd -literal -offset indent 168# arp -s 204.1.2.3 00:90:27:bb:cc:dd pub 169# arp -s 204.1.2.4 00:90:27:bb:cc:dd pub 170.Ed 171.Sh SEE ALSO 172.Xr inet 3 , 173.Xr arp 4 , 174.Xr ifconfig 8 , 175.Xr ndp 8 176.Sh HISTORY 177The 178.Nm 179command appeared in 180.Bx 4.3 . 181