1.\" $OpenBSD: dhcrelay.8,v 1.12 2013/07/16 11:13:33 schwarze Exp $ 2.\" 3.\" Copyright (c) 1997 The Internet Software Consortium. 4.\" 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.\" 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 Internet Software Consortium nor the names 16.\" of its contributors may be used to endorse or promote products derived 17.\" from this software without specific prior written permission. 18.\" 19.\" THIS SOFTWARE IS PROVIDED BY THE INTERNET SOFTWARE CONSORTIUM AND 20.\" CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, 21.\" INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF 22.\" MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 23.\" DISCLAIMED. IN NO EVENT SHALL THE INTERNET SOFTWARE CONSORTIUM OR 24.\" CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 25.\" SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 26.\" LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF 27.\" USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND 28.\" ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 29.\" OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 30.\" OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31.\" SUCH DAMAGE. 32.\" 33.\" This software has been written for the Internet Software Consortium 34.\" by Ted Lemon <mellon@fugue.com> in cooperation with Vixie 35.\" Enterprises. To learn more about the Internet Software Consortium, 36.\" see ``http://www.isc.org/isc''. To learn more about Vixie 37.\" Enterprises, see ``http://www.vix.com''. 38.\" 39.Dd $Mdocdate: July 16 2013 $ 40.Dt DHCRELAY 8 41.Os 42.Sh NAME 43.Nm dhcrelay 44.Nd Dynamic Host Configuration Protocol relay agent 45.Sh SYNOPSIS 46.Nm 47.Op Fl do 48.Fl i Ar interface 49.Ar server1 Op Ar ... serverN 50.Sh DESCRIPTION 51The 52.Nm 53utility provides a means for relaying DHCP and BOOTP requests from a subnet 54to which no DHCP server is directly connected to one or more DHCP servers on 55other subnets. 56.Pp 57.Nm 58listens for DHCP requests on a given interface. 59When a query is received, 60.Nm 61forwards it to the list of DHCP servers specified on the command line. 62When a reply is received, it is broadcast or unicast on the network from 63whence the original request came. 64.Pp 65The name of at least one DHCP server to which DHCP and BOOTP requests 66should be relayed, 67as well as the name of the network interface that 68.Nm 69should attempt to configure, 70must be specified on the command line. 71.Pp 72.Nm 73supports relaying of DHCP traffic to configure IPsec tunnel mode 74clients when listening on the 75.Xr enc 4 76interface. 77The DHCP server has to support RFC 3046 to echo back the relay agent 78information to allow stateless DHCP reply to IPsec tunnel mapping. 79.Pp 80The options are as follows: 81.Bl -tag -width Ds 82.It Fl d 83.Nm 84normally runs in the foreground until it has configured 85an interface, and then reverts to running in the background. 86This option forces 87.Nm 88to always run as a foreground process. 89.It Fl i Ar interface 90The name of the network interface that 91.Nm 92should attempt to configure. 93At least one IPv4 address has to be configured on this interface. 94.It Fl o 95Add the relay agent information option. 96By default, this is only enabled for the 97.Xr enc 4 98interface. 99.El 100.Sh SEE ALSO 101.Xr dhclient 8 , 102.Xr dhcpd 8 103.Sh STANDARDS 104.Rs 105.%A R. Droms 106.%D March 1997 107.%R RFC 2131 108.%T Dynamic Host Configuration Protocol 109.Re 110.Pp 111.Rs 112.%A S. Alexander 113.%A R. Droms 114.%D March 1997 115.%R RFC 2132 116.%T DHCP Options and BOOTP Vendor Extensions 117.Re 118.Pp 119.Rs 120.%A M. Patrick 121.%D January 2001 122.%R RFC 3046 123.%T DHCP Relay Agent Information Option 124.Re 125.Pp 126.Rs 127.%A B. Patel 128.%A B. Aboba 129.%A S. Kelly 130.%A V. Gupta 131.%D January 2003 132.%R RFC 3456 133.%T Dynamic Host Configuration Protocol (DHCPv4) Configuration of IPsec Tunnel Mode 134.Re 135.Sh AUTHORS 136.An -nosplit 137.Nm 138was written by 139.An Ted Lemon Aq Mt mellon@fugue.com . 140.Pp 141The current implementation was reworked by 142.An Henning Brauer Aq Mt henning@openbsd.org . 143.Sh BUGS 144Relayed DHCP traffic could actually safely be protected by IPsec but, 145like 146.Xr dhcpd 8 147and 148.Xr dhclient 8 , 149.Nm 150will bypass IPsec for all its traffic. 151