The Built-In Firewall in Windows XP and Windows Vista

Both Windows XP and Windows Vista come with a built-in packet-filtering firewall. If you don't have a separate firewall router, you can use this built-in firewall to provide a basic level of protection. Here are the steps to activate this feature in Windows XP or Vista:

1. Choose Start Control Panel.

   The Control Panel appears.

2. Click the Windows Firewall link.

   This brings up the dialog box, as shown in Figure 23-2.

   
   Figure 23-2: The Windows Firewall dialog box.

3. Select the On (Recommended) option.

   This option enables the firewall.

4. Click OK.

   That's all there is to it.

Warning 

Do not enable the Windows Firewall if you're using a separate firewall router to protect your network. Because the other computers on the network are connected directly to the router and not to your computer, the firewall won't protect the rest of the network. Additionally, as an unwanted side effect, the rest of the network will lose the ability to access your computer.

Tip 

With Windows XP Service Pack 2, the firewall is turned on by default. If your computer is already behind a firewall, disable the Windows Firewall that's enabled by Service Pack 2.

Tip 

Windows Vista includes an advanced version of the Windows Firewall that has additional configuration options. Unless you're well versed in security techniques, you'll want to leave these advanced options configured with their default settings.