.\" $OpenBSD: arp.8,v 1.18 2007/05/31 19:20:22 jmc Exp $ .\" $NetBSD: arp.8,v 1.7 1995/03/01 11:50:59 chopps Exp $ .\" .\" Copyright (c) 1985, 1991, 1993 .\" The Regents of the University of California. All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" 3. Neither the name of the University nor the names of its contributors .\" may be used to endorse or promote products derived from this software .\" without specific prior written permission. .\" .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" .\" from: @(#)arp.8 8.1 (Berkeley) 6/6/93 .\" .Dd $Mdocdate: May 31 2007 $ .Dt ARP 8 .Os .Sh NAME .Nm arp .Nd address resolution display and control .Sh SYNOPSIS .Nm arp .Op Fl adn .Ar hostname .Nm arp .Op Fl F .Op Fl f Ar file .Fl s Ar hostname ether_addr .Op Cm temp | permanent .Op Cm pub .Sh DESCRIPTION The .Nm program displays and modifies the Internet-to-Ethernet address translation tables used by the address resolution protocol .Pq Xr arp 4 . With no flags, the program displays the current .Tn ARP entry for .Ar hostname . The host may be specified by name or by number, using Internet dot notation. .Pp Available options: .Bl -tag -width Ds .It Fl a Display all of the current .Tn ARP entries. See also the .Fl d option below. .It Fl d Delete an entry for the host called .Ar hostname . Alternatively, the .Fl d flag may be combined with the .Fl a flag to delete all entries, with hostname lookups automatically disabled. Only the superuser may delete entries. .It Fl F Force existing entries for the given host to be overwritten (only relevant to the .Fl f and .Fl s options). .It Fl f Ar file Process entries from .Ar file to be set in the .Tn ARP tables. Any entries in the file that already exist for a given host will not be overwritten unless .Fl F is given. Entries in the file should be of the form: .Bd -filled -offset indent .Ar hostname ether_addr .Op Cm temp | permanent .Op Cm pub .Ed .Pp The entry will be static, i.e., will not time out, unless the word .Cm temp is given in the command. A static .Tn ARP entry can be overwritten by network traffic, unless the word .Cm permanent is given. If the word .Cm pub is given, the entry will be .Dq published ; i.e., this system will act as an .Tn ARP server, responding to requests for .Ar hostname even though the host address is not its own. This behavior has traditionally been called .Em proxy ARP . .It Fl n Show network addresses as numbers (normally .Nm attempts to display addresses symbolically). .It Xo .Fl s Ar hostname ether_addr .Op Cm temp | permanent .Op Cm pub .Xc Create an .Tn ARP entry for the host called .Ar hostname with the Ethernet address .Ar ether_addr . The Ethernet address is given as six hexadecimal bytes separated by colons. .Pp The .Cm permanent , pub , or .Cm temp modifiers may be specified with meanings as given above. .Pp If the entry already exists for the given host, it will not be replaced unless .Fl F is given. .El .Sh EXAMPLES View the current .Xr arp 4 table: .Pp .Dl $ arp -a .Pp Create a permanent entry (one that cannot be overwritten by other network traffic): .Pp .Dl # arp -s 10.0.0.2 00:90:27:bb:cc:dd permanent .Pp Create proxy ARP entries on interface fxp0 (MAC address 00:90:27:bb:cc:dd), for IP addresses 204.1.2.3 and 204.1.2.4: .Bd -literal -offset indent # arp -s 204.1.2.3 00:90:27:bb:cc:dd pub # arp -s 204.1.2.4 00:90:27:bb:cc:dd pub .Ed .Sh SEE ALSO .Xr inet 3 , .Xr arp 4 , .Xr ifconfig 8 .Sh HISTORY The .Nm command appeared in .Bx 4.3 .