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

NAME
     dhcrelay - Dynamic Host Configuration Protocol Relay Agent

SYNOPSIS
     dhcrelay [-p port] [-d] [-q] [-i if0 [... -i ifN]] server0 [... serverN]

DESCRIPTION
     The Internet Software Consortium DHCP Relay Agent, dhcrelay, 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 sub-
     nets.

OPERATION
     The DHCP Relay Agent listens for DHCP requests on all interfaces attached
     to a host, unless one or more interfaces are specified on the command
     line with the -i flag.

     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.

     It is possible to specify a set of interfaces on which dhcrelay will lis-
     ten, so that if dhcrelay is connected through one interface to a network
     on which there is no DHCP server, but is connected on another interface
     to a network on which there is a DHCP server, it will not relay DHCP and
     BOOTP requests from the network on which the server exists to that serv-
     er.  This is an imperfect solution.

COMMAND LINE
     The names of the network interfaces that dhcrelay should attempt to con-
     figure may be specified on the command line using the -i option.  If no
     interface names are specified on the command line, dhcrelay will identify
     all network interfaces, eliminating non-broadcast interfaces if possible,
     and attempt to configure each interface.

     If dhcrelay should listen and transmit on a port other than the standard
     (port 67), the -p flag may used.  It should be followed by the UDP port
     number that dhcrelay should use.  This is mostly useful for debugging
     purposes.  If the -p flag is specified, the relay agent will transmit re-
     sponses to clients at a port number that is one greater than the one
     specified - i.e., if you specify -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 -p flag.

     dhcrelay will normally run in the foreground until it has configured an
     interface, and then will revert to running in the background.  To force
     dhcrelay to always run as a foreground process, the -d flag should be
     specified.  This is useful when running dhcrelay under a debugger, or
     when running it out of inittab on System V systems.

     dhcrelay will normally print its network configuration on startup.  This
     can be annoying in a system startup script - to disable this behaviour,
     specify the -q flag.

     The name of at least one DHCP server to which DHCP and BOOTP requests
     should be relayed must be specified on the command line.

SEE ALSO
     dhclient(8), dhcpd(8)

     RFC 2132, RFC 2131.

AUTHORS
     dhcrelay has been written for the Internet Software Consortium by Ted
     Lemon <mellon@fugue.com> in cooperation with Vixie Enterprises.  To learn
     more about the Internet Software Consortium, see http://www.vix.com/isc.
     To learn more about Vixie Enterprises, see http://www.vix.com.

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 3.5                     January 1, 1997                              2
