Using Internet Connection Sharing

Internet Connection Sharing, or ICS, first introduced with Windows 98, enables you to connect one computer to the Internet and set up all other computers on the network to share the Internet connection. This feature is specifically designed for home networks or small office networks that do not have a centralized server.

Note 

With ICS, you need only one Internet connection and one piece of hardware; each computer does not need a modem or broadband hardware, such as a cable modem or DSL modem. Through sharing, you save money and aggravation because you don’t have to configure each computer to use the Internet.

If you decide that ICS is right for your networking environment, you must first ensure that your network is up and running. ICS will work with any kind of networking hardware, such as Ethernet, HomePNA, or even wireless networks. HomePNA is a networking technology that uses a home or office’s existing phone lines as the network cabling, without interfering with voice conversations. This technology makes home and small office networking a real snap, and HomePNA kits are available at most computer stores, often for under $70.

Next, you determine which Windows XP computer will function as the host computer. This computer is the only computer connected to the Internet; all other computers, called the client computers, will access the Internet through the host computer. ICS is supported on Windows 98, Windows Me, Windows NT 4.0, Windows 2000, and Windows XP computers. You cannot use ICS with Windows 95 or earlier versions or other operating systems, such as Macintosh.

Note 

ICS is designed for use with broadband Internet access (ISDN, DSL, cable, satellite, and so on). Although you can use ICS with a 56KB modem, your modem will operate very slowly if several people are trying to use the Internet connection at the same time. This is due to the fact that a 56KB modem does not have enough bandwidth to perform at a desirable speed. However, if users on your network do not access the Internet at the same time, the 56KB modem shared connection will be fine.

How ICS Works

When you use ICS, your Windows XP computer should be the ICS host. All other computers on your network, called ICS clients, access the host to get information from the Internet. Using this setup, your host computer has a connection to the Internet and a connection to your home network. All of the client computers only need a network adapter so they can connect to the host. (Again, Windows 95 clients are not compatible.) Under this setup, it appears as though only one computer is accessing the Internet. You don’t have to use the Windows XP computer as the host; you can use a different computer, such as Windows Me. However, you will have fewer operational problems if the Windows XP computer is the ICS host.

Secret 

ICS does not work with some versions of AOL. Check with AOL to see whether ICS supports your version of AOL. It is also possible, although unlikely, that your ISP will charge you for multiple computer connections to the Internet. Check with your ISP to make certain that you will not incur additional charges.

When you set up the ICS host, the local area connection for your internal NIC is configured as 192.168.0.1 with a subnet mask of 255.255.255.0. If the ICS host has more than one NIC for your workgroup, such as in the case of a multisegment network, you need to bridge those connections so that both network segments can use ICS. The DHCP Allocator service is configured on the ICS host. When additional network clients are added to the network, the DHCP Allocator assigns those clients IP addresses, ranging from 192.168.0.2 through 192.168.0.254, with a subnet mask of 255.255.255.0. A DNS proxy is also used so that no additional DNS servers are required on your network. These services run automatically and in the background and require no additional configuration from you. If a modem connection is used on the ICS host, autodial is turned on by default so that the connection is automatically dialed when an ICS client makes a request to the Internet. Also, ICF is automatically used on the shared connection, which you can learn more about later in this chapter.