Network security is a critical issue for businesses because of the potential for data theft, denial-of-service (DoS) attacks, and other threats. Knowing the exposure level for a given computer will help you better protect your machines.

The fewer ports open and listening on a computer, the less exposure there is to attack and potential compromise of the system. You can use the netstat program that comes with Windows to identify which ports are open on a system and identify current connections.

To identify ports, open a command console and type the following command:

netstat -a

To view an IP address for local and remote addresses rather than host names, add the -n switch:

nestat -an

If you only want to view active connections and not listening ports, use the netstat command without any switches.