Worms and Prevention
Since worms spread by taking advantage of vulnerabilities in operating systems or application programs (remember from earlier discussion, vulnerabilities are software errors that allow some kind of unauthorized access when they are used or exploited). You do not need to do anthing special to get a worm except to connect to the internet or an infected network with a system that has vulnerabilities. There are several good defenses against worms.
What is a Firewall?
A firewall is a device that limits access to your system from the outside. A firewall may be a software program running on your computer or it may be a piece of hardware outside your computer. The firewall screens any attempts to access your system and only allows access that you decide to allow. In this way many vulnerabilities that could be used to gain unauthorized access to your system are eliminated.
There are three defenses against worms. They are as follows:
Of the above measures the first two are the most effective against worms. For more information about personal firewalls, why you should use them, and how you can update your system, see the Home Computer Security article on this site.