DHCRELAY(8)             OpenBSD System Manager's Manual            DHCRELAY(8)

NAME
     dhcrelay - Dynamic Host Configuration Protocol Relay Agent

SYNOPSIS
     dhcrelay [-do] -i interface server1 [... serverN]

DESCRIPTION
     The dhcrelay utility provides a means for relaying DHCP and BOOTP re-
     quests from a subnet to which no DHCP server is directly connected to one
     or more DHCP servers on other subnets.

     dhcrelay listens for DHCP requests on a given interface.  When a query is
     received, dhcrelay 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.

     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
     dhcrelay should attempt to configure, must be specified on the command
     line.

     dhcrelay supports relaying of DHCP traffic to configure IPsec tunnel mode
     clients when listening on the enc(4) interface.  The DHCP server has to
     support RFC 3046 to echo back the relay agent information to allow state-
     less DHCP reply to IPsec tunnel mapping.

     The options are as follows:

     -d      dhcrelay normally runs in the foreground until it has configured
             an interface, and then reverts to running in the background.
             This option forces dhcrelay to always run as a foreground pro-
             cess.

     -i interface
             The name of the network interface that dhcrelay should attempt to
             configure.  At least one IPv4 address has to be configured on
             this interface.

     -o      Add the relay agent information option.  By default, this is only
             enabled for the enc(4) interface.

SEE ALSO
     dhclient(8), dhcpd(8)

     RFC 2132, RFC 2131, RFC 3046, RFC 3456

AUTHORS
     dhcrelay was written by Ted Lemon <mellon@fugue.com>.

     The current implementation was reworked by Henning Brauer
     <henning@openbsd.org>.

BUGS
     Relayed DHCP traffic could actually safely be protected by IPsec but,
     like dhcpd(8) and dhclient(8), dhcrelay will bypass IPsec for all its
     traffic.

OpenBSD 4.7                    September 3, 2009                             1
