• Microsoft Proxy Server versions 1.0, 2.0
• Microsoft Windows NT Server version 4.0

SUMMARY

This article discusses how to set up the simultaneous configuration of DHCP client and DHCP server on a multi-homed computer.

The following instructions allow the use of a DHCP server and DHCP client on the same computer. This is useful in a single-server environment where a cable modem or digital subscriber line (DSL) modem receives an IP address from the Internet service provider using DHCP, and the server also acts as a DHCP server for the local network.

NOTE: This capability has not been regression-tested by Microsoft. Any of these modifications may be destabilizing in a production environment.

MORE INFORMATION

This configuration has been tested on a multi-homed server (2 NICs). This document assumes that the external NIC is connected to the Internet.

1. Configure the server normally as a DHCP server by assigning static IP addresses to both NICs.
   
   NOTE: The "external" NIC static IP address should be an address that is not used on your internal network. It should also be on a different logical segment. Preferably, you should use an address from one of the reserved ranges of IP addresses. These addresses are intended for private networks and are not routable on the Internet. This IP address is only intended as a placeholder, it serves no other purpose.



2. When the DHCP server is configured and running, you must make a registry modification to enable the DHCP client on the Internet NIC.
   
   WARNING: Using Registry Editor incorrectly can cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that problems resulting from the incorrect use of Registry Editor can be solved. Use Registry Editor at your own risk.
   
   For information about how to edit the registry, view the "Changing Keys and Values" Help topic in Registry Editor (Regedit.exe) or the "Add and Delete Information in the Registry" and "Edit Registry Data" Help topics in Regedt32.exe. Note that you should back up the registry before you edit it. If you are running Windows NT or Windows 2000, you should also update your Emergency Repair Disk (ERD).
   
   
   To enable DHCP on the Internet NIC, perform the following steps:
   
   NOTE: The DHCP server may need to be set to Manual Startup in order to successfully configure the NIC.
   
   
   1. Run the Registry Editor (Regedt32.exe).
   
   
   
   2. Go to the following key in the registry:

      HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\NETCARD1\Parameters\TcpIp

      NOTE: NETCARD1 is the manufacturers driver name for the NIC.
   
   
   
   3. Find the entry called "EnableDHCP."
   
   
   
   4. Edit this entry and change the value from 0 to 1.
   
   
   
   5. Check for the existence of the "DhcpIPAddress" "DhcpSubnetMask" values. If present, set them to 0.0.0.0. If these values are not present, they may need to be manually created. To add these manually, choose Add Value from the edit drop-down menu. Add the following values:

      DhcpIPAddress:REG_SZ:0.0.0.0
      DhcpSubnetMask:REG_SZ:0.0.0.0

      Double-click the IPAddress value and make sure that it is set to 0.0.0.0.
      
      Double-click the SubnetMask value and make sure that it is set to 0.0.0.0.
   
   
   
   6. Exit the Registry Editor. In Control Panel Services, select the DHCP Client. Click Startup, and then select the radio button for Automatic, Click OK, and then click Close.
   
   
   
   7. When the computer has been restarted, the external NIC will have an IP address assigned dynamically by DHCP and the static placeholder IP address that was manually configured. The internal NIC will have the static IP address.
   
   
   

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