To setup your ADSL modem so that all the ports are stealthed:
- Enable the DMZ and add 10.0.0.252 in the IP field
- Save changes
Running a port scan test will now indicate that all ports are shown as stealthed.
If you want specific ports open (80-HTTP, 3389-Remote Desktop, etc) then you must add those ports to the Virtual Server ( see FAQ 848 for instructions ). After adding your ports and directing them to your local computer hosting the service, save the changes and reboot. Trying to access any port that you have added to the Virtual Server will respond on the WAN side appropriately.
Please note: The only significance to adding (10.0.0.252) in the DMZ is knowing that unwanted traffic will NOT be sent to a non-existent IP address. You can add any IP address in the DMZ that is not being used in your LAN and it will also accomplish the same thing.