Windows XP includes ICF, which allows you to protect a single computer, or the shared Internet connection (ICS) computer, if you are not already protected via a proxy or firewall.

To enable / disable ICF:

  1. Control Panel / Network Connections.

  3. Press the Dial-up, LAN or High-Speed Internet connection that you want to protect press Change settings of this connection (under Network Tasks).
  4. Select the Advanced tab. Check or clear: