linux

I wasn't a fan of Hacking Exposed, largely because its Unix section was a mere 50 pages of superficial, outdated, and obvious fluff. Hacking Linux Exposed makes up for that lack by digging into Unix in much more depth.Though it is modeled after the attack/countermeasure style of the original HE, this book includes a whole chapter of security measures at the beginning that you can implement instantly to get your machine locked down before getting into the nitty-gritty detail about other things in the hacker's arsenal.I was particularly enthralled with chapter 10, which talks about what the hacker will do after they have gained root access, from simple things like adding accounts to complicated issues like kernel modules, complete with source code. Chapter 7 includes some really wonderful examples of how the hacker can abuse networking protocols themselves, something I haven't seen covered in such depth before.The book is logically organized. The first part covers the way the hackers find and probe your machine. The second talks about getting in from the outside, be it network or physical. The third part talks about gaining additional priveleges, and the last part of the book is dedicated to mail, ftp, web, and firewalls. The appendicies are actually useful. They seem to have dropped the small 1-page case studies from the original book and replaced them with longer hacker-eye-views of real attacks which are an interesting read, and really tie the book together.This book is Linux specific in it's countermeasures, but I'd recommend this to any unix user. They do a good job of discussing differences between Linux variants as well, they don't just assume everyone has a RedHat box on their desk. Very refreshing.This book is great for both the theory and practical uses. I could spend weeks implementing all the suggestions they have, but they seem to have thought of this because their risk ratings let you know where you should concentrate as you secure your systems.Like Hacking Exposed, this book also has a website, (...) but it seems more up-to-date -- for example when the ptrace bug in older kernels came out, they posted a kernel module you could compile to protect your system until you could upgrade -- and includes all the source code contained in the book.I bought two of these, one for home and one for the office, and I suggest you do the same.

I am a senior engineer for network security operations. I read "Hacking Linux Exposed" (HLE) to learn how adversaries compromise Linux hosts. HLE impressed me at every level. I highly recommend system administrators and security personnel read and heed this book's recommendations.

The "Hacking Exposed" series is known for its unique example-driven style. Rather than telling the reader about a technique or problem, the authors demonstrate the issue using command-line examples. I find myself reading with book and laptop at hand, ready to duplicate the authors' sample commands. This process reinforces the authors' message, while the reader learns if a specific problem applies to his situation. Furthermore, by showing exactly how to execute certain commands, the authors impart bits of wisdom and trickery not found elsewhere.

For example, chapter 11 describes attacks and defenses for FTP servers. To explain active and passive FTP sessions, the authors demonstrate running an FTP client with the -d switch to illustrate raw instructions sent by the client over the FTP command channel. I had never seen this switch in use, but as an intrusion detector I constantly see raw FTP instructions like those revealed by the -d switch. These and other tidbits, like using the chattr -i command or setting the "sticky bit", make HLE exceptional.

Beyond these benefits, readers will enjoy clear, thorough explanations of Linux security issues. HLE gives first-rate descriptions of ssh and web man-in-the-middle attacks, race conditions, and FTP data hijacking. HLE also provides great illustrated examples of FTP bounce attacks, giving intrusion detectors the minutiae we need to recognize these techniques. I had heard of most of the compromise methods offered by HLE, but never seen them discussed in such practical detail.

If the material in chapters 1-13 of HLE don't prompt you to verify your Linux host's integrity, then the case studies in appendix D will. The security community needs more of these narratives. These stories, based on true events, show the lengths to which some attacks will go to penetrate target machines.

"Hacking Linux Exposed" is another strong addition to the "Hacking Exposed" series, and the security community will benefit as a result.

(Disclaimer: I received a free review copy from the publisher.)

When I first starting using Linux systems and putting them online I had NO idea what sort of grief I was in for. The reason for that grief: I had NO clue how to 'harden' a system or what that term even meant. By not knowing that I put up systems that were quickly exploited by script kiddies and SPAM houses looking for open relays to use for SPAM and for 'zombies' to use in Distributed Denial of Service (DDoS) attacks. I bought this book, read it, and haven't had those problems since. If you are going to do *anything* with Linux on the internet then GET THIS BOOK NOW. Unless, of course, you *want* to have your computers destroyed on a weekly basis...