Windows 8.1: The Missing Manual

Windows Firewall

If you have a broadband, always-on connection, you’re connected to the Internet 24 hours a day. It’s theoretically possible for some cretin to use automated hacking software to flood you with files or to take control of your machine. Fortunately, the Windows Firewall feature puts up a barrier to such mischief.

The firewall acts as a gatekeeper between you and the Internet. It examines all Internet traffic and lets through only communications that it knows are safe; all other traffic is turned away at the door.

How It Works

Every kind of electronic message sent to or from your PC—instant messaging, music sharing, file sharing, and so on—conducts its business on a specific communications channel, or port. Ports are numbered tunnels for certain kinds of Internet traffic.

The problem with Windows before Vista came along was that Microsoft left all your ports open for your convenience—and, as it turns out, for the bad guys’. Starting with Vista, all the ports arrive on your PC closed.

The firewall blocks or permits signals based on a predefined set of rules. They dictate, for example, which programs are permitted to use your network connection, or which ports can be used for communications.

You don’t need to do anything to turn on the Windows Firewall. When you turn on Windows, it’s already at work. But the Windows Firewall can be turned off.

To do that, or to fiddle with any of its settings, there are plenty of ways to find it. It’s an icon in the Control Panel, for example. ...