ip range

i set up a firewall with iptables
the firewall has three interface :
eth0 (192.168.1.1) connecting the lan with a server and three workstations (192.168.1.xxx)
eth1 (192.168.2.1) connecting the dmz with a webserver (192.168.2.xxx) eth2 (192.168.4.1) connected to the internet via a cable router

the webserver (apache 2.0) on the dmz has three interface : eth0 (192.168.2.2), eth1 (192.168.2.3) and eth2 (192.168.2.4) for SSL purpose that not support virtualhost directive
I use dyndns service with three dynamic hosts, one for each interface My problem is that I don't know how to foward port 80 requests to all ip addresses. I just succeeded to foward one by one but apache serves the same site for each dynamic host

I had read the DNAT howto but I not sure it's what I need to do ? any idea please ?

Laurent