Firewall Fundamentals

Modern firewalls provide a wide variety of significant services to the end user, whether it is a personal firewall or a network firewall used to protect an enterprise network. Firewall capabilities have increased dramatically over the past few years, and they have quickly become a nexus of security services to a network (or an individual machine). This increase of capabilities has caused firewall administrators to reevaluate and in some cases redefine the expectations of what a firewall can do. At the same time, however, firewalls are not complete solution, and there are limits to how effectively a firewall can provide many advanced features. This chapter explores many of the advanced features that firewalls can provide, while at the same time illustrating the limitations of firewalls in providing these advanced features.