I am trying to configure dhcrelay on OpenBSD. The man page is very brief and does not mention how to use rcctl. I can get rcctl to enable dhcrelay, but where to I place the interface(s) and dhcp server ip address. Some distributions have mentioned a config file and others just use command line switches.

Not sure about OpenBSD, but in FreeBSD you could create a sh script and drop it in /usr/local/etc/rc.d. Everything that has executable bit set and has sh extension will be executed in this directory at startup.

You might try:See the rcctl(8) man page for examples of setting flags.

You may also manually edit your rc.conf.local(5) file, if you prefer.

That looks like what I am after. Do I need to use a -i before each interface that dhcrelay listens on?

When I use the above command and then try and start the service, it fails. Log says that it cannot find the address I enter after -i.

192.168.2.10 is my wifi interface and 192.168.1.21 is the dhcp server.

I'm not a dhcrelay user. But according to the dhcrelay(8) man page, -i requires an interface, not an address. This is the interface that listens for DHCP/BOOTP requests. Server1 through ServerN are the addresses of the DHCP servers where dhcrelay forwards those requests for processing, on other networks. Each instance of dhcrelay can only listen to a single interface.

If you require forwarding of DHCP requests from more than one network, you will need multiple instances of dhcrelay. The rc.subr(8) system configured with rcctl(8) and rc.conf.local(5) cannot be used for more than a single instance of the same service. You may start as many instances as you need via rc.local(8), which is a user-defined shell script called at the end of the rc(8) bootup sequence.

Another alternative might be to run a DHCP server on the OpenBSD system, rather than relaying to external servers. A single server can be configured to support many interfaces.

Thank you for your responses. I changed the interface to athn0 and it seems to be working. I will test more tomorrow.