Here's a description of what I'd like to do with my router.  I'm pretty sure it should be possible, but have no idea how.

* On the single WAN port get 2 IP addresses. (I'm allowed 5 by my connection.)
* Configure the DHCP server as follows:
   * Assign LAN computers on 172.18.0.0/255.255.255.0 (1 week lease).
   * Assign wireless computers on 172.18.1.0/255.255.255.0 (6 hr lease).
   * Allow communication by all computers throughout the 172.18.0.0/255.255.254.0 subnet.
   * Always give certain clients specific IP addresses (I know the stock firmware could do this.  I do have reasons for not statically setting them on the clients.)
* Forward all requests on the second WAN address to 172.18.0.2.  (Yes, it has its own firewall.)
* Use updatedd to assign a separate DynDNS address to each external IP.

I'd recommend using ddns-scripts package.

OK, that seems simple enough that way.  Plus, I figured out how to do the iptables to do the forwarding.  After further research, my DHCP question is down to what goes where "red" is in "dhcp-range=red,192.168.0.50,192.168.0.150"?  Is it just the interface name, or do I need something else?  I still have no clue on how to get multiple IP addresses from a single WAN port.