Counter Hack aims to provide the reader with enough knowledge to strengthen their Unix and Microsoft Windows systems against attacks in general, and with specific knowledge of the more common types of attacks that can be done by relatively unskilled "script kiddies." The author Ed Skoudis has chosen approach is effective, in the sense that his readers accumulate the knowledge they need and generally enjoy the process. The best part of this book may be two chapters, one each for Windows and Unix, which explains the essential security terms, conventions, procedures, and behavior of each operating system. This is the kind of information that readers need - a Unix person go to the administration of Windows for the first time to the introduction of Microsoft's security scheme, and vice versa. With the foundation in place, Skoudis explains how (with emphasis on tools) attackers look for vulnerabilities in systems, gain access, and maintain their access for periods of time without being discovered.