I am a senior engineer for network security operations. I read "Maximum Linux Security" (MLS) to learn more about defending Linux hosts in hostile environments (i.e., the Internet). Compared to recent editions of "Maximum Security," MLS is more useful and accessible. I recommend this book as a supplement to "Hacking Linux Exposed" and "Real World Linux Security."
MLS is less list-oriented than the typical "Maximum Security" book. Useful advice on practical security measures takes the place of exploit listings. While you'll find discussions of older vulnerabilities, the most ancient are isolated in appendix B. The appendix also offers lengthy, detailed command listings and glossaries, unlike any I've recently seen.
The friendly tone of the book reminded me of a mentor speaking to a novice. Furthermore, the authors clearly know their material. For example, Linux frequently demands compiling tools from source code. Sometimes this process requires tweaking the code before running 'make'. The authors regularly give specific advice on the changes needed to get the code working properly. This attention to detail impressed me, and helped me run some of the example applications as I read the text. The authors also gave great clues on applying patches, a task required of every system administrator.
Beyond its specific use as a Linux security text, MLS also lets readers learn of other resources useful to security practioners. I was pleased to check out the Linux Cross Reference project, where I can browse and link to several incarnations of the Linux kernel.
On the negative side, the back cover advertises MLS as an "intermediate-advanced" text. While I thought the diagrams and explanations of the introductory chapters were well-done, they clearly depicted basic material. I also felt the discussion of intrusion detection failed to reflect front line experience with that technology and process.
If you're looking for a more defensive-minded Linux security book, give MLS a try. Those with an offensive mindset (like penetration testers) should stick with the Hacking Exposed series. Readers looking for the high end of Linux security theory will like Bob Toxen's "Real World Linux Security."
(Disclaimer: I received a free review copy from the publisher.)