How to Use a Laptop as a Wireless Router

If you've ever stepped into a room full of colleagues and noticed in frustration that there was only one Ethernet jack in the wall for the seventeen people at the table, you will appreciate this information. It is possible to turn modern computers into wireless routers so a single Internet connection may be shared among several computer users.

Things You'll Need

• Computer with both wired and wireless Ethernet Apple Macintosh OS X or Microsoft Windows XP or Vista 1 Ethernet cable Internet connection

Instructions

1. Disable the wireless Ethernet. This is a temporary measure, but a useful one in order to ensure the wired Ethernet is working cleanly before adding back in the wireless as a service. On most Microsoft Windows systems, there will be a toolbar icon for your wireless Ethernet device. Though the menu is device-dependent, a right-click on the icon will typically show a menu item similar to "disconnect."

2. Connect to the wired network. Using an Ethernet cable, connect your computer to the wall jack, a hub, switch, Internet modem, or whatever device you intend to share with your wireless colleagues. Most computers will have at least one small light near the Ethernet cable which will glow green when the physical connection is established.

3. Test the wired connection. Simply starting a web browser and trying to access a common site is an easy way to test the Ethernet connection. If this does not work, you will need to troubleshoot this wired connection first. The rest of the steps will be meaningless if the wired connection does not already work without the wireless connection being active.

4. Enable "Internet Connection Sharing" on a Windows XP system. Assuming your system is running Microsoft XP, you would open the Control Panel, then Network and Internet Connections, and then click Network Connections. By right-clicking on the icon for the wired Network Interface Card (NIC) you can select "Configure." The Advanced tab of this menu has a check-box labeled "Internet Connection Sharing." Check this box to allow network packets to flow between this NIC and the wireless NIC on your system. Save these settings.

5. 

   Enable "Internet Sharing" on your Macintosh. If your system is running Mac OS X, simply open up System Preferences and click on the "Sharing" folder in the Internet and Network section. There will be a list of services running down the left-hand side of the screen. Check Internet Sharing and set your preferences to the right. In our example, you would share your connection from Ethernet to computers using Airport.

6. Check your protocols and firewall settings. In general, it is a poor idea to share files with the Internet. Hackers have exploited such situations many times. If you are going to use your system as an Internet router, turn off file sharing. If you cannot turn off file sharing, be sure your firewall settings for the Ethernet side block access to files on your hard drive. Turn off your firewall settings, however, on the wireless NIC. If you leave the firewall protections up on the wireless NIC your colleagues may be unable to share your Internet connection.

7. Re-activate your wireless NIC. On Windows XP, if you have not already done so, right-click on your wireless NIC icon in the toolbar and select "Connect" or a similar menu item from the context-menu.

Tips & Warnings

• Shut down your wireless connection before testing the wired Ethernet connection.

• Be sure to check your firewall settings. They should be aggressive on the wired Ethernet and largely open on the wireless Ethernet side. Do not allow file sharing across the wired Internet connection.

Resources

• Microsoft XP Technet Article