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

NAME
     dhcrelay -- Dynamic Host Configuration Protocol relay agent

SYNOPSIS
     dhcrelay [-dor] [-C circuit-id] [-R remote-id] -i interface destination
	      ...

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	destinations specified
     on	the command line.  When	a reply	is received, it	is broadcast or	uni-
     cast on the network from whence the original request came.

     The server	might be a name, address or interface.	dhcrelay will operate
     in	layer 2	mode when the specified	servers	are interfaces,	otherwise it
     will operate in layer 3 mode.

     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 using layer	3 mode only.
     The DHCP server has to support RFC	3046 to	echo back the relay agent in-
     formation to allow	stateless DHCP reply to	IPsec tunnel mapping.

     The options are as	follows:

     -C	circuit-id
	     The circuit-id relay agent	information sub-option value that
	     dhcrelay should append on relayed packets.	 If this option	is not
	     specified it will use the interface number	by default.

     -d	     Do	not daemonize.	If this	option is specified, dhcrelay will run
	     in	the foreground and log to stderr.

     -i	interface
	     The name of the network interface that dhcrelay should attempt to
	     configure.	 For layer 3 mode 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.

     -R	remote-id
	     The remote-id relay agent information sub-option value that
	     dhcrelay should append on relayed packets.	 If this option	is not
	     specified it will use the destination address by default.

     -r	     Replace incoming Relay Agent Information with the one configured.

SEE ALSO
     dhclient(8), dhcpd(8)

STANDARDS
     R.	Droms, Dynamic Host Configuration Protocol, RFC	2131, March 1997.

     S.	Alexander and R. Droms,	DHCP Options and BOOTP Vendor Extensions, RFC
     2132, March 1997.

     M.	Patrick, DHCP Relay Agent Information Option, RFC 3046,	January	2001.

     B.	Patel, B. Aboba, S. Kelly, and V. Gupta, Dynamic Host Configuration
     Protocol (DHCPv4) Configuration of	IPsec Tunnel Mode, RFC 3456, January
     2003.

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.

BSD			       February	15, 2017			   BSD

NAME | SYNOPSIS | DESCRIPTION | SEE ALSO | STANDARDS | AUTHORS | BUGS

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