Chapter List

1.1 Chapter Objectives

• Showing the components of a firewall

• Showing what firewalls can and cannot do

• Comparing firewall types

• Using application proxies

• Showing the four-way security model

Today, when an organization connects its private network to the Internet, security has to be a primary concern. In the past, before the widespread interest in the Internet, most network administrators were concerned about attacks on their networks from within, perhaps from disgruntled workers. But for most organizations now connecting to the Internet and big business and big money moving toward electronic commerce at warp speed, the motive for mischief from outside is growing rapidly and creating a major security risk to enterprise networks.

Reacting to this threat, an increasing number of network administrators are installing the latest firewall technology as a first line of defense in the form of a barrier against outside attacks. These firewall gateways provide a choke point at which security and auditing can be imposed. They allow access to resources on the Internet from within the organization while providing controlled access from the Internet to hosts inside the virtual private network (VPN).