If you’re running Windows XP Service Pack 2 (SP2) the new Windows Firewall is turned on by default.
Because a firewall restricts communication between your computer and the Internet, you might need to adjust settings for some programs that prefer an open connection. These adjustments are called “exceptions.”
Windows Firewall now has three settings: On, On with no exceptions, and Off.
Windows Firewall was first introduced as part of Windows XP Service Pack 2. Every type of network connection, whether it is wired, wireless, VPN, or even FireWire, has the firewall enabled by default, with some built-in exceptions to allow connections from machines on the local network. It also fixed a problem whereby the firewall policies would not be enabled on a network connection until several seconds after the connection itself was created, thereby creating a window of vulnerability. A number of additions were made to Group Policy, so that Windows system administrators could configure the Windows Firewall product on a company-wide level. XP’s Windows Firewall cannot block outbound connections; it is only capable of blocking inbound ones.
To enable Windows Firewall in Windows XP, follow these steps:
1. Click Start, click Run, type Firewall.cpl, and then click OK.
2. On the General tab, click On (recommended).
3. Click OK.
If the General tab or the On (recommended) option is unavailable, the system may have a policy against running the firewall. Contact the system administrator for more information about how to enable the firewall. In addition, the system may already be running a third-party firewall (Zone Alarm or Norton Internet Security, for example). Contact the system administrator for help in determining whether a firewall is already running on the system.