A firewall is software or hardware that creates a protective barrier between your computer and potentially damaging content on the Internet or network.
To enable the Windows Firewall in XP:
- Open the Start Menu and click Run
- When the gray box opens, type Firewall.cpl and click OK
- Under the General tab, click On (recommended) and then OK
To enable the Windows Firewall in Vista:
- Open the Start Menu and click on Control Panel
- Click Security and then Windows Firewall
- Click Turn Windows Firewall on or off
- Click On (recommended) and then OK