1.\" $NetBSD: arp.8,v 1.27 2021/12/05 07:11:56 msaitoh Exp $ 2.\" 3.\" Copyright (c) 1985, 1991, 1993 4.\" The Regents of the University of California. All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 3. Neither the name of the University nor the names of its contributors 15.\" may be used to endorse or promote products derived from this software 16.\" without specific prior written permission. 17.\" 18.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 19.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 22.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28.\" SUCH DAMAGE. 29.\" 30.\" from: @(#)arp.8 8.2 (Berkeley) 4/27/95 31.\" 32.Dd December 5, 2021 33.Dt ARP 8 34.Os 35.Sh NAME 36.Nm arp 37.Nd address resolution display and control 38.Sh SYNOPSIS 39.Nm 40.Op Fl n 41.Ar hostname 42.Nm 43.Op Fl nv 44.Fl a 45.Nm 46.Op Fl v 47.Fl d 48.Fl a 49.Nm 50.Op Fl v 51.Fl d Ar hostname 52.Op Cm proxy 53.Nm 54.Fl s Ar hostname ether_addr 55.Op Cm temp 56.Op Cm pub Op Cm proxy 57.Nm 58.Fl f Ar filename 59.Sh DESCRIPTION 60The 61.Nm 62program displays and modifies the Internet-to-Ethernet address translation 63tables used by the address resolution protocol 64.Pq Xr arp 4 . 65With no flags, the program displays the current 66.Tn ARP 67entry for 68.Ar hostname . 69The host may be specified by name or by number, 70using Internet dot notation. 71.Pp 72The state of the arp entry is shown as a single letter preceded by the 73time the state is applicable for: 74.Bl -tag -width indent -compact 75.It D 76Delay 77.It I 78Incomplete 79.It N 80Nostate 81.It P 82Probe 83.It R 84Reachable 85.It S 86Stale 87.It U 88Unreachable 89.It W 90Waitdelete 91.It ? 92Unknown state (should never happen). 93.El 94.Pp 95Available options: 96.Bl -tag -width Ds 97.It Fl a 98The program displays all of the current 99.Tn ARP 100entries. 101.It Fl d 102A super-user may delete an entry for the host called 103.Ar hostname 104with the 105.Fl d 106flag. 107If the 108.Cm proxy 109keyword is specified, only the published 110.Dq proxy only 111.Tn ARP 112entry 113for this host will be deleted. 114If used with 115.Fl a 116instead of a 117.Ar hostname , 118it will delete all arp entries. 119.It Fl f 120Causes the file 121.Ar filename 122to be read and multiple entries to be set in the 123.Tn ARP 124tables. 125Entries in the file should be of the form 126.Pp 127.Bd -filled -offset indent -compact 128.Ar hostname ether_addr 129.Op Cm temp 130.Op Cm pub 131.Ed 132.Pp 133with argument meanings as described below. 134.It Fl n 135Show network addresses as numbers (normally 136.Nm 137attempts to display addresses symbolically). 138.It Fl s Ar hostname ether_addr 139Create an 140.Tn ARP 141entry for the host called 142.Ar hostname 143with the Ethernet address 144.Ar ether_addr . 145The Ethernet address is given as six hex bytes separated by colons. 146The entry will be permanent unless the word 147.Cm temp 148is given in the command. 149If the word 150.Cm pub 151is given, the entry will be "published"; i.e., this system will 152act as an 153.Tn ARP 154server, 155responding to requests for 156.Ar hostname 157even though the host address is not its own. 158.Pp 159If the word 160.Cm proxy 161is also given, the published entry will be a 162.Dq proxy only 163entry. 164In this case the 165.Ar ether_addr 166can be given as 167.Cm auto 168in which case the interfaces on this host will be examined, 169and if one of them is found to occupy the same subnet, its 170Ethernet address will be used. 171.It Fl v 172Display verbose information when adding or deleting 173.Tn ARP 174entries. 175.El 176.Sh SEE ALSO 177.Xr inet 3 , 178.Xr arp 4 , 179.Xr ifconfig 8 180.Sh HISTORY 181The 182.Nm 183command appeared in 184.Bx 4.3 . 185