Batten Down Those Ports

Don't let malicious intruders find a way into your system. We tell you how they try to sneak in-and how to keep them out.

With worms such as Blaster prowling the Net, every user ought to know the ways a computer may be exposing itself to attacks. One of the simplest but most vital tests you can do to determine potential vulnerabilities is to find out which ports your PC has open to the outside world.