Configure Internet Connection Sharing (ICS) in Windows Vista

Before you start

Objectives: Learn how to configure ICS in Windows Vista, and when should we use this feature.

Prerequisites: you should understand what is ICS in general.

Key terms: ics, network, connection, internet, private, address, configure, enable, ip, nat, select

How to Enable ICS

When we enable ICS in Windows, we actually configure our machine as a simple NAT router. To configure ICS in Vista, let’s go to the Control Panel > Network Connections. Notice that we have two connections in our case. One connection is connected to the Internet, and the other is connected to our private network.


Network Connections

Remember that we have to enable ICS on the connection which is connected to the Internet. That’s because we want to share that Internet connection with other computers on the network. In our case we will right-click the “Internet Connection”, select Properties, and then open the Sharing tab. Here we have to select the “Allow other network users to connect trough this computer’s Internet connection” option.

ICS Checked

ICS Checked

To configure NAT features we can click on the Settings button here. In this window we can select the services which will be available to Internet users. We will not enable any services now.

Advanced Settings

Advanced Settings

When we click on the OK button, several things will happen. First, our LAN (private) network adapter will be configured to use IP address We can check this on our private connection. Let’s open the properties of our Local Area Connection, select “Internet Protocol Version 4 (TCP/IPv4)”, and click the Properties button.

IPv4 Properties

IPv4 Selected

Notice that our adapter is configured to use the IP address and the subnet mask This happened when we enabled ICS on our Internet connection.

Private Adapter Settings

Private Adapter Settings

Our ICS computer is now configured as a limited NAT router. It uses NAT on the Internet connection to translate addresses from the private network to the public address. Our ICS server is also configured as a limited DHCP server which provides IP address information for hosts on the private network. ICS computer is also configured as a DNS proxy. Note that other computers on the private network must be DHCP enabled. This way they will get proper IP address information from our ICS server.