What Is Internet Connection Sharing (ICS)?

A quick guide for Windows devices

Internet Connection Sharing, or ICS, is a built-in feature of Windows computers that allows multiple devices to connect to the internet using one internet connection on one computer. ICS is a type of local area network (LAN).

ICS Features

ICS uses a single computer as the gateway (or host) through which other devices connect to the internet. Computers wired to the gateway computer or connecting to it wirelessly via an ad-hoc wireless network can use ICS.

There are several reasons why you might want to set up this type of network:

  • Allows most devices (including non-Windows and older Windows systems) to connect without installing additional client software.
  • Support for all connected clients to use many different protocols, including VPN and internet gaming.
  • Clients are automatically given an IP address and configured for DNS through the ICS computer.

In Windows 98 or Windows Me, ICS needed to be enabled or installed on the host computer from the Control Panel Add/Remove Programs setting. (To access this setting, go to the Windows Setup tab, and select Internet Tools > Internet Connection Sharing.)

Windows XP, Vista, and Windows 7 have this setting built-in. (Look in the Local Area Connection properties for a setting under the Sharing tab to "Allow other network users to connect through this computer's internet connection.")

ICS requires the host computer to have a wired connection to a modem, such as a DSL or cable modem, or an AirCard or other mobile data modem. The client computers must also be either wired to the host computer or connected via a wireless adapter.

ICS for Different Versions of Windows and Mac

For more information, learn how to share internet access on Windows XP, Vista, and Windows 7. You can also share your Mac's wired internet connection via Wi-Fi; this process does not use ICS, but it is similar.

To share one internet connection among several computers, either use a router or, on Windows, enable Internet Connection Sharing so that other computers connect to one computer that has an internet connection.

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