A firewall is hardware or software and attempts to prevent the intrusion of the attackers from the Internet or other network of some kind, such as a LAN. With the introduction of Windows XP, Microsoft has included a software firewall as part of the operating system to help protect the integrity of the system from malicious attacks. Often, you can not turn firewall or a program can change the settings without your knowledge, so it is advisable to check the firewall status from time to time to ensure that it is on.

Instructions
Click on “Start” in the lower left-hand portion of your desktop screen.

Select Control Panel and then Security Center to open the Windows Security Center.

Navigate to the bottom of the form and click the “Windows Firewall” link.

Select one of the two radio buttons as desired on the Windows Firewall form that opens. The “On” radio button is the recommended choice.

Click the “OK” button at the bottom of form.

Close the Windows Security Center window and close the Control Panel window.