.\"	$OpenBSD: dhcrelay.8,v 1.4 2004/04/13 17:27:48 jmc Exp $
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.\" This software has been written for the Internet Software Consortium
.\" by Ted Lemon <mellon@fugue.com> in cooperation with Vixie
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.Dd April 12, 2004
.Dt DHCRELAY 8
.Os
.Sh NAME
.Nm dhcrelay
.Nd Dynamic Host Configuration Protocol Relay Agent
.Sh SYNOPSIS
.Nm
.Op Fl d
.Op Fl p Ar port
.Fl i Ar interface
.Ar server0 Op Ar ... serverN
.Sh DESCRIPTION
The
.Nm
utility provides a means for relaying DHCP and BOOTP requests from a subnet
to which no DHCP server is directly connected to one or more DHCP servers on
other subnets.
.Pp
.Nm
listens for DHCP requests on a given interface.
When a query is received,
.Nm
forwards it to the list of DHCP servers specified on the command line.
When a reply is received, it is broadcast or unicast on the network from
whence the original request came.
.Pp
The name of at least one DHCP server to which DHCP and BOOTP requests
should be relayed,
as well as the name of the network interface that
.Nm
should attempt to configure,
must be specified on the command line.
.Pp
The options are as follows:
.Bl -tag -width Ds
.It Fl d
.Nm
normally runs in the foreground until it has configured
an interface, and then reverts to running in the background.
This option forces
.Nm
to always run as a foreground process.
.It Fl i Ar interface
The name of the network interface that
.Nm
should attempt to configure.
.It Fl p Ar port
Tells
.Nm
to listen and transmit on a port other than the standard
.Pq port 67 .
It should be followed by the UDP port number that
.Nm
should use.
This is mostly useful for debugging purposes.
The relay agent will transmit responses to clients
at a port number that is one greater than the one specified \- i.e., if
you specify
.Fl p
67, then the relay agent will listen on port 67 and transmit to port 68.
Transmissions to servers will be sent to the same port number
that is specified with the
.Fl p
flag.
.El
.Sh SEE ALSO
.Xr dhclient 8 ,
.Xr dhcpd 8
.Pp
RFC 2132, RFC 2131.
.Sh AUTHORS
.Nm
was written by
.An Ted Lemon Aq mellon@fugue.com .
.Pp
The current implementation was reworked by
.An Henning Brauer Aq henning@openbsd.org .
.Sh BUGS
Relayed DHCP traffic could actually safely be protected by IPsec but,
like
.Xr dhcpd 8
and
.Xr dhclient 8 ,
.Nm
will bypass IPsec for all its traffic.