Introduction

Early in human history, people recognized fire as both a tool and a danger. We could easily say the same thing about information the right information in the wrong hands has probably destroyed almost as many companies as fires have. Therefore, borrowing an architectural term used to denote a structure for containing a potential disaster seems apropos. A firewall, when discussed in the realm of computers, prevents unauthorized access to protected networks from users outside the protected network.

Firewalls likely serve as the most important component to network security, second only to the physical security of the network. Prior to the Internet, most firewalls were used in networks that protected high-security installations where employees had distinct security ratings, such as defense contractors. Firewalls were originally employed for the purpose of allowing certain employees to connect to the inner sanctum of the company s data as a form of access control.

The Internet has changed the purpose and function of the firewall. By plugging in a single cable, a network administrator has the potential to make a company s data as accessible to the CEO as it is to the other six billion people on the planet. The new breed of firewall needs to allow a small population of that six billion to have expanded access, and the rest must be stopped at the door. All this must be accomplished with the flexibility to protect against attacks that hackers haven t even invented yet. Of course, a piece of hardware cannot take the...