How to configure your Alcatel SpeedTouch 510 ADSL modem not to use NAT?

Posted on January 7, 2009 by Daniel Petri in Alcatel with 0 Comments

This document describes how you can configure an Alcatel SpeedTouch 510 ADSL modem not to use NAT anymore. This process is often called DHCP SPOOFING. The public IP will be sent to your machine by DHCP therefore eliminating NAT. It is also for setups where combination of an Ethernet gateway routers which do not have PPTP dialer support are in placed. Doing so will enable you to configure an internal router or a server that has routing software installed and have it receive an IP address from your ISP – instead of having the dialer obtain the address for you.

The difference between DHCP SPOOFING and BRIDGING (described here Configure Alcatel SpeedTouch Pro to Act as a Transparent Bridge) is that with bridging the end-machine/router does the dialing, and so it gets the real IP address from the ISP. With spoofing the modem dials for you, receives the IP address from the ISP, and then gives it to the end-machine/router.

This method will work if one of the following assumptions is true:

  • Your modem is connected to the Internet and another computer is connected to your modem.
  • Your modem is connected to the Internet and you have a router that is connected to the modem. This router must have NAT capabilities. The router will then be connected to a hub/switch, and to it other computers will connect.
  • Your modem is connected to the Internet and you have a server computer that is connected to the modem. This server must have Routing and NAT capabilities. The server will then be configured with another NIC, and to it you connect another computer.
  • Your modem is connected to the Internet and you have a server computer that is connected to the modem. This server must have Routing and NAT capabilities. The server will then be configured with another NIC, to which you will then connect a hub/switch, and to it other computers will connect.

Make a note of the fact that the modem will stop acting as a router with NAT/PAT which means that you’ll have to connect it to a router or server that has NAT capabilities. Without such configuration you won’t be able to connect to the Internet.

Note: This configuration tip will only work in the 510 modem or on a HOME modem that was upgraded to PRO and then upgraded to 510: Upgrade from Alcatel SpeedTouch Home to Pro and Upgrade from Alcatel SpeedTouch Pro to 510.

Proposed layout:

configure-alcatel-speedtouch-510-for-dhcp-spoofing_1234556284900

  1. The ADSL cable goes to the splitter.
  2. The ADSL modem is connected to the splitter.
  3. The ADSL modem is configured as 510.
  4. NAT is disabled on the modem.
  5. The Ethernet cable from the modem is connected to the router (or server with RRAS and NAT
  6. The router / server is connected to the switching hub.
  7. All PC’s are connected to the switching hub.

Disclaimer & Warning

Messing with the software settings of your modem and/or messing with the registry or internal settings of your operating system can render your modem or operating system useless. Read the whole article and manual before you do any changes. Following these steps might work for you. It did for me and for many others, but that does not necessarily mean they will! I take no responsibility for anything bad that might happen to your OS or modem, and since you’re on your own – Do not ask me for help! It’s your modem!

Applying this hack will definitely VOID WARRANTY! If you are not experienced with tricks like these STOP NOW! Besides, some ISPs might stop supporting you if they find out that you messed up with your modem.

Configure your modem as Pro

You’ll have to configure the modem as Pro. If you have an Alcatel SpeedTouch Home please follow this guide: Upgrade from Alcatel SpeedTouch Home to Pro.

Upgrade your modem to 510

You’ll have to upgrade the modem to 510. Please follow this guide: Upgrade from Alcatel SpeedTouch Home to Pro.

Step One – Configure your modem

You’ll have to disconnect from the ADSL service to configure the following settings, so maybe now’s a good time to print this screen.

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Open the web browser and again go to http://10.0.0.138.

You must now download the definitions file for your ISP or country.

Israeli users: Use THIS file.

Netherlands users: Use THIS file – courtesy of Martijn.

Save the file in a folder on your computer.

Note: I’m looking for other definition files made for European ISPs. If any of you have links to such files please let me know (I cannot verify these files but I can post the info here) .

On the left toolbar press the Upgrade link.

On the right pane scroll down to the Configuration section and press the Browse button. In the open dialog box browse to the definition file, select it and press Open.

Now press Upload and let the modem upload the file.

A Red warning will appear, saying you must restart the modem for the configuration changes to take place.

Press the Restart link.

Step Two – Configuring the workstation / router / server

If it’s a workstation that’s connected directly to the modem you should configure it’s NIC to obtain it’s IP address automatically (each OS has it’s own phrasing of this feature).

I think you know how to do that by now. If you’ve got amnesia here are a few screenshots of a Windows XP workstation. Figure it out on your own.

(don’t mind the rest of the icons…)

You configure the DNS server to be the same as the IP address of your ISP’s DNS server, or if you want – to be the same as the inner IP address of the modem itself.

If that computer also acts as a DC then it must already have an installed DNS service. With that said all you have to do is to configure forwarding between the DNS and the DNS server of your ISP. See the Active Directory pages on my site for more info on AD requirements – Active Directory Installation Requirements, How to Install Active Directory on Windows 2000 and How to Install Active Directory on Windows 2003, and the DNS pages for info on DNS Forwarding – Configure DNS Forwarding on Windows 2000 and No Forwarding or Root Hints on Windows 2000 DNS server?.

If it’s a server then you have to configure it as a router (which is beyond the scope of this lesson)  with NAT capabilities. You configure the NIC that is connected to the modem to obtain an IP address automatically, and you assign a private IP address to the LAN interface, such as 192.168.0.1 and a default Subnet Mask of 255.255.255.0.

If it’s a router – you configure the WAN interface to obtain and IP address automatically. On the LAN interface you either manually configure the IP network ID etc, or you deploy a configured DHCP with all their needs.

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