bridged with dhcpd on one interface only, how?

Hello,

I have an embedded device with 2 interfaces, eth0 and usb0. I need to provide a DHCP server on usb0 but not eth0. Also, I need to bridge eth0 and usb0, so the entire device has only one IP address that can be accessed by either (or both) interfaces.

Do I need to use ebtables, or can I use iptables with the -i option?

Thanks!

Aras Vaichas