Use the Internet Connection Firewall to Secure Your Small Network

A firewall is a security system that acts as a protective boundary between a network and the outside world. Windows XP includes Internet Connection Firewall (ICF) software you can use to restrict what information is communicated between the Internet and your home or small office network. ICF also protects a single computer connected to the Internet with a cable modem, a DSL modem, or a dial–up modem.

If your network uses Internet Connection Sharing (ICS) to provide Internet access to multiple computers, you should use ICF on the shared Internet connection. However, ICS and ICF can be enabled separately. You should not enable the firewall on any connection that does not directly connect to the Internet, and ICF is not needed if your network already has a firewall or proxy server.

You must be logged on to your computer with an owner account in order to complete this procedure. You should not enable Internet Connection Firewall on virtual private networking (VPN) connections or on client computers because ICF will interfere with file and printer sharing. ICF cannot be enabled on the private connections of the Internet Connection Sharing host computer.

To enable or disable Internet Connection Firewall

Click the Dial–up, LAN or High–Speed Internet connection that you want to protect, and then, under Network Tasks, click Change settings of this connection.

On the Advanced tab, under Internet Connection Firewall, select one of the following:

To enable Internet Connection Firewall (ICF), select the Protect my computer and network by limiting or preventing access to this computer from the Internet check box.

To disable Internet Connection Firewall, clear the Protect my computer and network by limiting or preventing access to this computer from the Internet check box. This disables the firewall, your computer and network are then vulnerable to intrusions