They can even gain control of your machine. You should be. The term firewall loosely describes hardware or software that prevents unauthorized access to or from a private network. On a company network, all data entering or leaving via their internal network or Intranet must first pass through the firewall and meet specified security criteria. It's relatively easy to find a firewall for a company system, but there are far fewer personal firewalls.
Protection is at hand, however.
To safeguard your computer, you can download one of several personal firewall applications that are available through the Internet. ZoneAlarm is easy to use, even for those who are not particularly computer literate, and its Web site is informative and not too technical. On the job ZoneAlarm works by screening all Internet traffic, both to and from your machine. Only the Internet applications approved by you are allowed through ZoneAlarm's firewall. You would most likely set ZoneAlarm to allow browsers such as Netscape Communicator or Internet Explorer to access the Internet, as well as e-mail programs such as Eudora and Outlook.