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The server PC must have two TCP stacks bound to the single card.
  technofile
Al Fasoldt's reviews and commentaries, continuously available online since 1983

How a PC with a only one network card can provide access to the Internet to multiple PCs


By Al Fasoldt
Copyright © 1998, Al Fasoldt

   Normally, WinGate (and similar proxy services) require two network interface cards (NICs) in the PC that is used as the server on a small network, along with a hub. The Ethernet cables from each PC go into the hub, and the cable modem connects to the uplink port of the hub. One network card communicates between the cable modem and the server PC, and the other card communicates between the server PC and the rest of the network. The other PCs on the network require only one card in each one. This is the best way of hooking up your network to a cable modem, but it is not the only way.
   WinGate can be configured so that the server PC does not need a second network card. In this setup, the NIC in the server does double duty. The server PC must have two TCP stacks bound to the single card. In other words, you must install the TCP protocol and bind it to the card twice, then set up each of the TCP stacks with different parameters.
   Because of a quirk in Windows 95 and Windows 98 (and possibly in Windows NT), you cannot bind (attach by installing) more than one TCP stack to a single card if the dialup networking adaptor is installed in the Networking applet of the Control Panel. This simply means that you must remove the dialup adaptor first, then do whatever is needed to install the second TCP stack, then put the dialup adaptor back in. (The problem is that Windows binds all extra TCP stacks to the dialup adaptor if it is present.)
   Here are the step-by-step instructions, assuming that you already have the single network card in the server PC working properly and set up properly for your network.
   On the server PC:
   1. Right click on the Network Neighborhood icon and choose Properties.
   2. Click on the dialup adaptor and choose Remove.
   3. Click Add. Choose Protocol, click Add, click Microsoft, click TCP. You will now have two TCP stacks. They are both bound to the network card.
   4. Choose the first TCP stack and click Properties. Click IP Address, and set it up to obtain an IP address automatically. Click DNS Configuration and choose Disable DNS. Click Gateway and leave it blank. Click WINS Configuration and choose Disable WINS Resolution. Leave Bindings, Advanced and NetBIOS alone. This stack communicates with the cable modem.
   5. Choose the second TCP stack and set it up the same way EXCEPT for the IP address. Specify 192.168.0.1 as the IP address. Specify 255.255.255.0 as the subnet address. This stack communicates with the other PCs on the network.
   6. Close the Network applet and reboot the server. Make sure WinGate is properly installed. (WinGate runs only on the server PC, so do not install it on the other PCs.)
    
   On the other PCs:
   1. Run the WG2UTIL program on each client PC. It will create the proper HOSTS file. (It may also change your browser settings to what it needed. I'll explain them later in case it doesn't.)
   2. Open the Network applet on each client machine. Click IP Address and choose Specify an IP address. Type the address THAT PC SHOULD HAVE on the network. The first client should have an IP address of 192.168.0.2, with a subnet mask of 255.255.255.0. The second client PC should have an IP address of 192.168.0.3, with the same subnet mask, and so on.
   3. Click DNS Configuration. Choose Enable DNS. Type the name of your computer (the network name) in the Host field. (This name can be anything. "Foo" works, for example. The name is not used for anything, but you can't leave it blank.) In the DNS Server Search Order field, type 192.168.0.1 and click Add. In the Domain Suffix Search Order field, type 255.255.255.0.
   4. Close the Network applet and reboot each client.
    
   Setting up Gatekeeper on the server PC:
   1. Open the DNS server configuration applet under Services.
   2. Click Bindings. Choose "Connections will be accepted on the following interface only." Make sure 192.168.0.1 is showing in the little window. That allows your client PCs to get DNS information through the server's network card.
   3. Configure any of the other services according to the descriptions in the WinGate Help file and in the FAQ available from WinGate's Web site. (These work the same basic way whether you have two cards or one in the server.)
    
   Setting up proxies:
   There is no change from the way this is done. The WinGate Help file explains this very well. WinGate does not operate any differently when only one NIC card is used, although the card itself is doing twice the work. (This should not be a problem, but if it seems to slow things down, add another card and use the two-card setup.)