Share an Internet Connection on Windows Vista

Many hotels, virtual offices, and other locations only provide a single wired Ethernet connection. If you need to share that one Internet connection with multiple devices, you can use the built-in Internet Connection Sharing feature in Windows Vista to allow other computers or mobile devices to go online as well. In essence, you can turn your computer into a wireless hotspot (or wired router) for other devices nearby.

Windows XP and Windows 7 instructions for using ICS are similar, detailed under How to Share Internet Access (XP) or Share an Internet Connection on Windows 7. If you have a Mac, you can also Share Your Mac's Internet Connection via Wi-Fi. The instructions here share a wired Internet connection (your computer is directly connected to a cable or DSL modem, for example) or a separate 3G cellular data modem installed on your computer. If you have a wireless Internet connection that you want to share with other devices, you can Turn Your Windows 7 Laptop into a Wi-Fi Hotspot using Connectify.

Difficulty: Average

Time Required: 20 minutes

Here's How

Log on to the Windows host computer (the one connected to the Internet) as an Administrator
Go to Network Connections in your Control Panel by going to Start > Control Panel > Network and Internet > Network and Sharing Center and then click "Manage network connections".
Right-click your Internet connection that you want to share (e.g., Local Area Connection) and click Properties.
Click the Sharing tab.
Check the "Allow other network users to connect through this computer's Internet connection" option. (Note: for the sharing tab to show up, you will need to have two types of network connections: one for your Internet connection and another that the client computers can connect to, such as a wireless adapter).
Optional: If you want other network users to be able to control or disable the Internet connection, select that option. This is useful for dial-up network connections; otherwise, it's probably best left disabled.
You can also optionally allow other network users to use services running on your network, such as a mail or web server, under the Settings option.

Once ICS is enabled, you can Set Up an Ad Hoc Wireless Network or use newer Wi-Fi Direct technology so the other devices can connect directly to your host computer for Internet access.

Tips

Clients that connect to the host computer should have their network adapters set to get their IP address automatically (look in the network adapter properties, under TCP/IPv4 or TCP/IPv6 and click "Obtain an IP address automatically")
If you create a VPN connection from your host computer to a corporate network, all of the computers on your local network would be able to access the corporate network if you use ICS.
If you share your Internet connection over an ad-hoc network, ICS will be disabled if you disconnect from the ad hoc network, create a new ad hoc network, or log off from the host computer.