DHCRELAY(8) | System Manager's Manual | DHCRELAY(8) |
dhcrelay
— Dynamic
Host Configuration Protocol relay agent
dhcrelay |
[-dor ] [-C
circuit-id] [-R
remote-id] -i
interface destination ... |
The dhcrelay
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.
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 unicast 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
information to allow stateless DHCP reply to IPsec tunnel mapping.
The options are as follows:
-C
circuit-iddhcrelay
should append on relayed
packets. If this option is not specified it will use the interface number
by default.-d
dhcrelay
will run in the foreground and log to
stderr.-i
interfacedhcrelay
should attempt to configure. For layer 3 mode at least one IPv4 address
has to be configured on this interface.-o
-R
remote-iddhcrelay
should append on relayed
packets. If this option is not specified it will use the destination
address by default.-r
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.
dhcrelay
was written by
Ted Lemon
<mellon@fugue.com>.
The current implementation was reworked by Henning Brauer <henning@openbsd.org>.
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.
February 15, 2017 | OpenBSD-current |