Fortunately, many firewall programs provide such services. The trick is implementing and configuring the services correctly. Of course, firewalls represent only one part of a complete computer security system. Any cracker worth his or her salt knows that the easiest way into a network isn't through your Internet gateway-it's through your employees. That slip of paper in someone's desk containing a list of passwords is your most threatening network security hole.
Firewalls are helpless against a host of additional security problems.
For example, if someone downloads a virus-infected file using an approved Web site, your firewall won't do you any good. Besides, security experts say most computer crimes are committed by disgruntled employees snug inside the firewall. Talk about a sad state of affairs. Customers want to believe that a firewall is a static Maginot Line that can repel any attacker. The Germans proved France wrong in 1940, and any competent cracker will prove the same in 1998 against a firewall that is installed and forgotten.