Hack I.T.: Security Through Penetration Testing

Chapter 20. Firewalls

Many people have asked why we included a chapter on firewalls in a book about penetration testing. Due to the importance of firewalls in protecting networks and the large role they play in penetration testing, we feel it is important to cover the relevant aspects of firewalls. This chapter is not meant to be a comprehensive description of or guide to firewalls. It is intended to provide an overview to help readers understand what a firewall is and its role in penetration testing.

Definition

A firewall is a device that screens incoming network traffic and allows or disallows the traffic based on a set of rules. Firewalls normally sit at the perimeter of an organization's network, protecting it from the Internet, business partners, ...