I'm trying to configure an openwrt router so that I get two wan IP addresses by dhcp - one for the router itself and one for a DMZ host. I followed the DMZ howto. It appears that the host on the DMZ interface sends a request for a IP but does not receive one. Config files are here.
WANs are usually point-to-point connections. In this way, they are not going to assign two IP addresses to a router. Instead, a local LAN is configured for DMZ and externally connections are masked as if they were coming from/to the router IP.
This forwarding is what is achieved for port 80 with the following lines of howto:
# Make 192.168.2.2:80 publicly accessible config 'redirect' option '_name' 'http' option 'src' 'wan' option 'proto' 'tcp' option 'src_dport' '80' option 'dest_ip' '192.168.2.2'
I think you can get a fully transparent DMZ if you remove lines with
src_dport, then your DMZ server would look to the external networks as having the IP of the router.