1.\" $OpenBSD: arp.8,v 1.12 2002/02/13 08:33:47 mpech 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. All advertising materials mentioning features or use of this software 16.\" must display the following acknowledgement: 17.\" This product includes software developed by the University of 18.\" California, Berkeley and its contributors. 19.\" 4. Neither the name of the University nor the names of its contributors 20.\" may be used to endorse or promote products derived from this software 21.\" without specific prior written permission. 22.\" 23.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33.\" SUCH DAMAGE. 34.\" 35.\" from: @(#)arp.8 8.1 (Berkeley) 6/6/93 36.\" 37.Dd July 14, 1999 38.Dt ARP 8 39.Os 40.Sh NAME 41.Nm arp 42.Nd address resolution display and control 43.Sh SYNOPSIS 44.Nm arp 45.Op Fl n 46.Ar hostname 47.Nm arp 48.Op Fl n 49.Fl a 50.Nm arp 51.Fl d Ar hostname 52.Nm arp 53.Fl d a 54.Nm arp 55.Fl s Ar hostname ether_addr 56.Op Ar temp | permanent 57.Op Ar pub 58.Nm arp 59.Fl f Ar filename 60.Sh DESCRIPTION 61The 62.Nm 63program displays and modifies the Internet-to-Ethernet address translation 64tables used by the address resolution protocol 65.Pq Xr arp 4 . 66With no flags, the program displays the current 67.Tn ARP 68entry for 69.Ar hostname . 70The host may be specified by name or by number, 71using Internet dot notation. 72.Pp 73Available options: 74.Bl -tag -width Ds 75.It Fl a 76The program displays or deletes all of the current 77.Tn ARP 78entries. 79.It Fl d 80A superuser may delete an entry for the host called 81.Ar hostname 82with the 83.Fl d 84flag. 85.Pp 86Alternatively, the 87.Fl d 88flag may be combined with the 89.Fl a 90flag to delete all entries, with hostname lookups automatically 91disabled. 92.It Fl n 93Show network addresses as numbers (normally 94.Nm 95attempts to display addresses symbolically). 96.It Fl s Ar hostname ether_addr 97Create an 98.Tn ARP 99entry for the host called 100.Ar hostname 101with the Ethernet address 102.Ar ether_addr . 103The Ethernet address is given as six hex bytes separated by 104colons. 105The entry will be static, i.e., not time out, unless the word 106.Ar temp 107is given in the command. 108A static ARP entry can be overwritten by network traffic, unless the word 109.Ar permanent 110is given. 111If the word 112.Ar pub 113is given, the entry will be 114.Dq published ; 115i.e., this system will 116act as an 117.Tn ARP 118server, 119responding to requests for 120.Ar hostname 121even though the host address is not its own. 122This behavior has traditionally been called 123.Em "proxy arp" . 124.It Fl f 125Causes the file 126.Ar filename 127to be read and multiple entries to be set in the 128.Tn ARP 129tables. 130Entries in the file should be of the form 131.Pp 132.Bd -filled -offset indent -compact 133.Ar hostname ether_addr 134.Op Ar temp | permanent 135.Op Ar pub 136.Ed 137.Pp 138with argument meanings as given above. 139.El 140.Sh EXAMPLES 141To view the current 142.Nm 143table: 144.Pp 145.Dl $ arp -a 146.Pp 147To create a 148.Em permanent 149.Nm entry 150(One that cannot be overwritten by other network traffic): 151.Pp 152.Dl # arp -s 10.0.0.2 00:90:27:bb:cc:dd permanent 153.Pp 154To create 155.Em proxy arp 156entries on an interface, fxp0, 157for the IP Addresses 204.1.2.3 and 204.1.2.4, do a: 158.Pp 159.Bd -unfilled -offset indent -compact 160# arp -s 209.1.2.3 00:90:27:bb:cc:dd pub 161# arp -s 209.1.2.4 00:90:27:bb:cc:dd pub 162.Ed 163.Pp 164(where 00:90:27:bb:cc:dd is the MAC address of fxp0) 165.Sh SEE ALSO 166.Xr inet 3 , 167.Xr arp 4 , 168.Xr ifconfig 8 169.Sh HISTORY 170The 171.Nm 172command appeared in 173.Bx 4.3 . 174