OpenWrt & "Advanced DMZ"

I honestly think @fantom-x is asking about just simple DMZ in OpenWrt..

If your ISP/Edge router is "Advanced DMZ'ing" (meaning, it's just forwarding anything inbound to the OpenWrt device), and you want to pass that through to a device behind the OpenWrt router, you'd just (again) DMZ the OpenWrt device to pass through to whatever device you assign.