Using ICS (Internet Connection Sharing)

If you want to share one Internet connection among several computers, you have two options:

Use Internet Connection Sharing (ICS).
Use a router.

For information about using a router, see Setting up a home network.

How does ICS work?

First, you need one computer, called the host computer, that is connected to the Internet and that has a separate connection to the other computers on your network. You enable ICS on the Internet connection. The other computers on your network then connect to the host computer, and from there to the Internet through the host computer's shared Internet connection.

A network using Internet Connection Sharing (ICS)

Enabling ICS

To enable ICS, on your host computer:

Open Network Connections by clicking the Start button , clicking Control Panel, clicking Network and Internet, clicking Network and Sharing Center, and then clicking Manage network connections.
Right-click the connection that you want to share, and then click Properties. If you are prompted for an administrator password or confirmation, type the password or provide confirmation.
Click the Sharing tab, and then select the Allow other network users to connect through this computer’s Internet connection check box.

Note

The Sharing tab will not be available if you have only one network connection.
If desired, you can also select the Allow other network users to control or disable the shared Internet connection check box.
Optionally, to allow other network users to use services running on your network, click Settings and select the services you want to allow.

When you enable ICS, your local area network (LAN) connection gets a new static IP address and configuration, so you'll need to reestablish any TCP/IP connections between your host computer and the other network computers.

To test your network and Internet connection, see if you can share files between computers and make sure each computer can reach a website.

Configure TCP/IP

To use ICS, make sure the local area network (LAN) connection on each network computer is configured to get an IP address automatically. To do this:

Open Network Connections by clicking the Start button , clicking Control Panel, clicking Network and Internet, clicking Network and Sharing Center, and then clicking Manage network connections.
Right-click the LAN connection, and then click Properties. If you are prompted for an administrator password or confirmation, type the password or provide confirmation.
Click Internet Protocol Version 4 (TCP/IPv4) or Internet Protocol Version 6 (TCP/IPv6), and then click Properties.
Click Obtain an IP address automatically or Obtain an IPv6 address automatically.

The Internet options on your network computers should also be configured for ICS. For more information, see Change Internet settings for ICS (Internet Connection Sharing).

Do not use ICS on a network with domain controllers, DNS servers, gateways, or DHCP servers. And don't use ICS on systems configured for static IP addresses.

ICS and VPN connections

If you create a virtual private network (VPN) connection on your host computer to a corporate network and then enable ICS on that connection, all Internet traffic is routed to the corporate network and all of the computers on your home network can access the corporate network. If you don't enable ICS on the VPN connection, other computers will not have access to the Internet or corporate network while the VPN connection is active on the host computer.

ICS and ad hoc networks

If you share your Internet connection on an ad hoc network, ICS will be disabled if:

You disconnect from the ad hoc network.
You create a new ad hoc network without disconnecting from the ad hoc network for which you enabled ICS.
You log off and then log back on (without disconnecting from the ad hoc network).