Sometimes the biggest threat doesn't come from an unknown stranger but from someone you already know, whether it's a coworker, a relative, or even your own spouse. When you're away from your computer, how can you be sure that nobody is using it in your absence? If you know that someone is using your computer, maybe you're suspicious of what they're really doing with your computer.

In cases like these, you may want to spy on your own computer. That way you can see who is using your computer, what programs they are running, and even what they are typing at any given time. Perhaps your employees are giving trade secrets away, your children are looking at pornography, and your spouse is setting up extra-marital liaisons with people through chat rooms.

Spying with a webcam

With the right software, you can turn any webcam into a surveillance camera. The moment someone steps within view of the webcam, the webcam software detects the motion and starts recording video or still images so you can see exactly who used your computer at a specific time and date. For greater security, the webcam program can even email the images to you or post them on a website. That way, if the intruder erases your hard disk, you'll still have copies of the images that can identify who the perpetrator may be.

Sometimes you may want to monitor an area where people come and go all the time, such as inside a store. Just tell your webcam program what time to start and stop capturing images, and how long you want your computer to store those images before deleting them (see Figure 15-2). Now if something unusual happens, such as someone robbing the cashier, your webcam will capture it all on your computer.

Click To expand Figure 15-2: You can program your webcam to capture images in secret and email them to you.

To turn your webcam into a surveillance camera, download Microsoft's free Webcam Timershot (http://www.microsoft.com) or try these programs:



Video Security




Spying with software

A webcam may show you who used your computer, but it won't necessarily show you what they did while they were using your computer. To find out this type of information, you need to use a desktop-monitoring program that can show you which programs someone used, what they typed to someone else in a chat room or instant messenger program, and even what images they saw on the screen (see Figure 15-3).

Click To expand
Figure 15-3: A desktop-monitoring program can capture screen images so you can see exactly what the other person did on your computer.

By using a desktop-monitoring program, you can capture proof of someone's illegal activities that you can use to confront them with later, or just keep it a secret so you can gather even more incriminating evidence later. (See Chapter 12 for more information about desktop-monitoring programs.)