Take Control of Running Windows on a Mac, 3rd Edition

Use a Firewall

In computing terms, a firewall is a program that monitors all the network traffic to and from your computer and filters or blocks communication based on a set of rules. For example, a firewall may let you view Web pages and send email but prevent other computers from accessing your files, installing new software, or hijacking your computer to act as a spam-sending robot. A great deal of malware gets onto Windows computers because a potentially harmful avenue of network access was left open, so a firewall is an important first line of defense.

Kaspersky Internet Security (included with Parallels) and McAfee VirusScan Plus (included with Fusion) include firewalls, so if you installed either product with its default settings, you're ...