Enable DMZ on Speedtouch 780WL

I was struggling for hours to set up a DMZ on my Speedtouch 780WL. It's wasn't easy to figure out what to do, but i finally made it. Here is how I did it.

In this example is my external IP (the one I got from my ISP) AA.BB.CC.DD. My internal IP to the computer I want to have in a DMZ is 192.168.1.70. The Speedtouch modem is on 192.168.1.254. I'm using firmware 5.4.0.14 which you install with this wizard.

Open a terminal to telnet to your modem.

telnet 192.168.1.254

The login information is by default:
Username: Administrator (note the capital A)
Password:

When you are logged in run

{Administrator}=>nat maplist
Idx Type Interface       Outside Address                Inside Address                 Use
  1 NAT  Internet          AA.BB.CC.DD                  127.0.0.1                      0
  1 NAPT Internet          AA.BB.CC.DD                  unmapped                       97

{Administrator}=>nat mapdelete intf=Internet index=1
{Administrator}=>nat mapdelete intf=Internet index=1
{Administrator}=>:nat maplist                            
Idx Type Interface       Outside Address                Inside Address                 Use

{Administrator}=>nat mapadd intf=Internet type=nat outside_addr=AA.BB.CC.DD inside_addr=192.168.1.70
{Administrator}=>nat mapadd intf=LocalNetwork type=nat outside_addr=AA.BB.CC.DD inside_addr=192.168.1.70

That will do the trick. If you want to have some explanations (or if, of course, this doesn't work for you) you can read further. The "1 NAPT Internet AA.BB.CC.DD unmapped 97" says "if a package from Internet comes down to this rule, throw it away". Thats is something you don't want to do. You want every package to go to the computer in the DMZ. Therefore remove that rule and add a new one. "nat mapadd intf=Internet type=nat outside_addr=AA.BB.CC.DD inside_addr=192.168.1.70".

If you want do connect to you DMZ-computer with the external IP from an other computer within the network, you have to add the second rule as well. "nat mapadd intf=LocalNetwork type=nat outside_addr=AA.BB.CC.DD inside_addr=192.168.1.70"

If it still doesn't work for you, you may want to try Henrik Nordström's solution. You may also want to read the CLI manual.