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DHCP-HELPER(8) System Manager's Manual DHCP-HELPER(8)


dhcp-helper - A DHCP/BOOTP relay agent.


dhcp-helper [OPTION]...


dhcp-helper is a DHCP and BOOTP relay agent. It listens for DHCP and BOOTP broadcasts on directly connected subnets and relays them to DHCP or BOOTP servers elsewhere. It also relays replies from the remote servers back to partially configured hosts. Once hosts are fully configured they can communicate directly with their servers and no longer need the services of a relay.


The only required option is at least one DHCP server to relay to. The simplest way to configure dhcp-helper on a router is just to give the interface to the network containing the DHCP server with a -b option. All the other interfaces present on the machine will then accept DHCP requests. On a machine which does not have an interface on the network containing the DHCP server, use a -s option instead.

Specify a DHCP or BOOTP server to relay to. The server may be given as a machine name or dotted-quad IP address. More than one server may be specified.
Relay to a DHCP or BOOTP server using broadcast via <interface>. This eliminates the need to give a server address. <interface> is automatically added to the list of interfaces which will not receive DHCP requests.
Specify which local interfaces to listen on for DHCP/BOOTP broadcasts. If no -i flags are given all interfaces are used except those specified by -e flags and those specified by -b flags.
Specify which local interfaces to exclude.
Use alternative ports (1067/1068) for the DHCP client and server.
Report the software release version and copyright information.
Debug mode, do not change UID, write a pid-file or go into the background.
Specify an alternate path for dhcp-helper to record its process-id in. Normally /var/run/
Specify the userid to which dhcp-helper will change after startup. The daemon must normally be started as root, but it will drop root priviledges after startup by changing id to another user. Normally this user is "nobody" but that can be over-ridden with this switch.


Dhcp-helper requires a 2.2 or later Linux kernel. The "Linux packet filter" and "packet socket" facilities are not required, which is the chief advantage of this software over the ISC DHCP relay daemon.


This manual page was written by Simon Kelley <>.