How to Set up an ISA Server with a Cable Modem Connection.

In this tutorial we will look at how to setup and configure ISA Server to work with a Cable Modem connection that uses dynamic IP address allocation.

Perform the following steps to setup your ISA Server to work with a Cable Modem:

1. First, install the cable modem. After the cable modem is installed, open a command prompt and type the ipconfig /all command. You should see what appears in the figure below. Make a note of the physical address of the cable modem.

Click on Image for larger version

2. From the Run Command, open Regedt32. When a new Network Card is installed and your IP address isn't specified, Windows 2000 will automatically assign it an address using Automatic Private IP Addressing (APIPA). To disable APIPA, you need to create a key in the Windows registry at HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\Interfaces\[your_adapter's_MAC_address]. Create the Value IPAutoconfigurationEnabled and set it to 0x0.

Click on Image for larger version

3. Restart the server for the changes to take effect. Now, open a command prompt and type ipconfig /all. Note that the IP address of the adapter Cable Modem is now configured to 0.0.0.0 and that the parameter Autoconfiguration Enabled is now set to No.

Click on Image for larger version

4. Open the ISA Management console, expand your server or array, and then expand the Access Policy node in the left pane. Click on the IP Packet Filters node, and then double click on the DHCP Client packet filter.

Click on Image for larger version

5. On the General tab, enable the DCHP Client packet filter by putting a checkmark in the checkbox for Enable this filter.

6. On the Filter Type tab, leave the default settings and do not change them.

7. On the Local Computer tab, choose the option This ISA Server's external IP address and type 0.0.0.0.

8. On the Remote Computer tab, you need to specify the IP address of the remote DHCP Server. If you don't know the address of the remote DHCP server, type the ipconfig /all command after restarting the computer. You DHCP server's address should be listed there. After you obtain the DHCP server's IP address, select the This remote computer option and type in the IP address of the DHCP server. Click Apply and then click OK.
   
9. Restart the ISA Server. Your Cable Modem should work fine! Open a command prompt and type ipconfig /all. You should see the IP addressing information assigned to your Cable adapter.
   Note: if the cable connection still does not work, you need to stop the Microsoft ISA Server Control (isactrl) and type ipconfig /renew at the command prompt. Then restart the ISA Server Control service.
   
10. To stop the ISA Server Control Service, open the Services applet from the Adminstrative Tools menu. Right click on the Microsoft ISA Server Control and stop it. Then issue the ipconfig /all command. After issuing the renew command, restart the ISA Server Control service by right clicking on it and clicking Start in the Services applet.

Click on Image for larger version

11. Run ipconfig /all again and you should find joy!

Edited by Thomas W Shinder MD MCSE

Author: Alexandre Cavalcante Alencar
Technical Support / Director
Aspec - Assessoria, Processamento e Contabilidade S/C Ltda
Microsoft Certified Partner
www.aspec.com.br
Phone: +55 (85) 254-3223
Fax: +55 (85) 254-4779
Cell: +55 (85) 9995-3649 / 9995-3302

Alexandre Cavalcante Alencar is a technical support / director of Aspec,
develop, support, consulting, account firm located in Fortaleza, CE Brazil
specializing in account software. Current project is to develop a practical
how to manual for the ISA Server and Windows 2000 OS Server/Professional.