A firewall is a piece of software or hardware that helps keep out hackers, viruses, and worms that try to reach your computer over the Internet. If you are a home user or small-business user, using a firewall is the most effective and important first step you can take to help protect your computer. It is important to turn on your firewall and antivirus software on all devices that are connecting to your internet.

If you have Windows Vista or Windows XP Service Pack 2 (SP2) running on your computer, you can check to see if your firewall is turned on through the Windows Security Center:

Step 1: Click Start, and then click Control Panel.

Step 2: Click Security Center, and then click Windows Firewall.

If you have a different version of Windows, such as Windows 2000, Windows Millennium Edition, or Windows 98, you should obtain a hardware or software firewall from another company and install it. You can check the manuals of your home networking devices, such as wireless access points or broadband routers, to determine if they include built-in hardware firewalls. If you don't know if a software firewall is on your computer, you can check in the All Programs folder.

Step 1: Click Start.

Step 2: Click All Programs.

Step 3: Look for a firewall program. Some common brand names for software firewalls for home users include McAfee, Symantec, and Tiny Personal Firewall.

You may run into an issue where other programs seem to have stopped working after turning on Windows Firewall. The reason for this is because in order to work correctly, some programs need to have specific ports open so that traffic can pass through the Firewall. Consult your firewall documentation to learn how to enable ports.