It ain't enough to get the breaks. You gotta know how to use 'em. - AnonymousThis chapter illustrates some of the concepts introduced in the previous chapters. The purpose of the chapter is both to show how intrusion attempts are attempted and to try to get across the philosophy or mindset of such intrusions. Seeing examples of actual break-ins and understanding the steps and thought processes involved may give us some insight when trying to protect against such attempts.
This chapter is divided into three section, a host security, network security and a combined security case study. The case studies are of intrusions, using one or more of the methods introduced in the last two chapters. In the network security section, we reintroduce the distinction between internal and external security. This distinction is made apparent by two subsections, showing how we would go about attempting to get into hosts from inside the network and from outside. A convention used throughout the chapter is that lines beginning with a percent (%) sign are the author's comments. When these appear before a command, they describe what is about to be attempted. When appearing after a command, they are either be introductory of the next command or explanatory of the results of the previous one.