Setting Up Internet Connection (using NAT) and Routing in Windows 2000 Server

by

Chris Perkins

Background: What is NAT (Network Address Translation)?

The Internet and number of computers using it have grown at an alarming rate. As a result the number of available IP address is dropping. This is where NAT comes into play. Network Address Translation allows a single device, such as a router, to act as an agent between the Internet (or "public network") and a local (or "private") network. This means that only a single, unique IP address is required to represent an entire group of computers.

How NAT works:

Basically the client will send a packet to the router. The router running NAT changes the packet header and sends the packet over the internet to the web server. The web server sends a reply to the router running NAT. The router determines the destination, changes the packet header and sends the packet to the client that requested it.

What this manual will cover:

This manual will cover setting up your computer as an Internet Connection Server (using NAT) AND setting up your computer as a Router in Windows 2000 Server

Requirements:

A PC running Windows 2000 Server and 2 network cards (NIC).

And of course make sure both your networks are hooked up to these cards. :)

Setting Your Computer Up As a Internet Connection Server And NAT

1. Click Start and go to Settings/Control Panel

2. Double Click on Administrative Tools

3. Double Click on Routing and Remote Access

4. The Routing and Remote Access Server Setup Wizard should pop up (NOTE: if these services were running before, you will need to be able to disable them first. Once disabled, re-enable them and the wizard will appear). Disabling and Enabling is done by right clicking on your server name in the left window.

5. Click Next.

6. Select the type of connectivity server you plan on using it for. For our example we will choose Internet connection server.Click Next.

7. Select the Set Up a Router with the Network Address Translation routing protocol and click Next.

8. Next select which NIC/network card will be used as the default gateway.

9. You will now see the existing configuration.

10. Expand the IP Routing Tree in the left window. Here you should a list. At the bottom of the list is NAT. Right click on Network Address Translation (NAT) and hit Properties.

11. Click on the Translation tab: Don't make any additional changes here. Leave it the way it is for now.

12. Now click on the Address Assignment tab: Again don't check anything here for our purposes. But these can be adjusted later for future use.

13. Now click on the Name Resolution tab and check the Clients using Domain Name System check box. Then click Apply and OK.

14. Going back to the Routing and Remote Access window single click on NAT (in the left window). A list of your network interfaces will show in the right window. Right click on the interface that will serve as your router and click Properties.

15. Next click on the Special Ports tab and from there add any special ports that you feel are necassary.

Setting Your Computer Up As A Network Router

1. Click Start and go to Settings/Control Panel

2. Double Click on Administrative Tools

3. Double Click on Routing and Remote Access

4. The Routing and Remote Access Server Setup Wizard should pop up (NOTE: if these services were running before, you will need to be able to disable them first. Once disabled, re-enable them and the wizard will appear). Disabling and Enabling is done by right clicking on your server name in the left window.

5. Click Next.

6. Select the Network Router option and click Next.

7. In the following box you should see a listing of the routed protocols. Make sure TCP/IP is listed. If it is, make sure the radio button selection is on "Yes, all of my available protocols are listed." Then click Next.

8. On the next screen should ask about Demand Dial Connections. For our purposes we won't worry about this, so make sure the radio button selection is on "No" and then Click Next.

9. Click Finish as you are done with the wizard.

10. From here you will need to make sure the IP addresses of both network cards are different (This can be set from My Network Places->Properties->"Your Local Area Connection"->TCP/IP->Properties). These settings can also set under the following in Routing and Remote Access: IP Routing->General->Right Click "Local Area Connection ??"->Properties->Configuration tab. Make sure you know which connection serves as your local network connection AND the one which will be used as your router.

Some Common Problems We Encountered:

One of our biggest problems was just the overall configuration with running it as a router. For example: we could ping each other in our group but couldn't ping to those outside our group. This was eventually resolved by some IP address settings/issues. With this in mind, pay attention to IP addresses within your network as well as the other networks.