A. If you have Microsoft 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:

1) Click Start, and then click Control Panel.
2) Click Security Center, and then click Windows Firewall.

If you have Windows XP, but you don't have Service Pack 2 running on your computer, you can download it by visiting the Microsoft Update Web site. You can also check to make sure the firewall is enabled with the following steps:

1) Click Start, and then click Control Panel.
2) Click Network and Internet Connections, and then click Network Connections.

Tip If the Network and Internet Connections category is not visible, click Switch to Category View on the upper left of the window.
3) Under the Dial-Up or LAN or High Speed Internet category, click the icon to select the connection that you want to help protect.
4) In the task pane on the left, under Network Tasks, click Change settings of this connection (or right-click the connection you want to help protect, and then click Properties).
5) On the Advanced tab, under Internet Connection Firewall, make sure the box is checked next to Protect my computer and network by limiting or preventing access to this computer from the Internet. If a check mark is in the box, the firewall is on. If the box is clear, the firewall is off and your computer is potentially vulnerable on the Internet.

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 are uncertain whether a software firewall has been installed on your computer, you can check in the All Programs folder. Click Start, and then click All Programs. Look for a firewall program that is installed. Some common brand names for software firewalls for home users include McAfee, Symantec, Tiny Personal Firewall, and ZoneAlarm.