Real World Linux Security

A poll taken in July 2001 for Network World asked 100 network executives what their biggest technology concerns were in 2001. It turns out that their biggest concern was "making sure the network is hackerproof." I?ll ignore for now the fact that there is no such word as hackerproof; I?ll take license and substitute the term bulletproof, which dictionary.com informally defines as impervious to assault, damage, or failure; guaranteed. With that, can network security and commercial off-the-shelf operating systems ever be impervious to assault, damage, or failure? Not even the largest seller of security snake oil would say yes to such a statement. Information security adversaries are already at the gate, posing legitimate threats; it is not a question of if networks will be attacked, but when. It is within this framework that Bob Toxen presents Real World Linux Security, a superb overview of how to comprehensively secure a Linux system. Toxen is one of the original developers of Berkeley Unix, and his book is full of interesting historical tidbits from the computer science halls of UC Berkeley in the early 1970s. When it comes to Unix security, Toxen?s mantra is certainly "been there, done that." Toxen is one of a very few writers who can write in the first person about developing operating systems while dropping names such as Bill Joy and Ken Thompson. Although it comprises nearly 700 pages, Real World Linux Security is light on filler and bursting with important information on how to secure a Linux host. In reference to space filler, other books often have about a third of their content made up of screen prints and source code listing. Toxen's book fortunately does not use that route and instead directs readers to either a Web site or the companion CD-ROM for source code. The book is useful for all flavors of Linux, yet nearly all of the topics can be applied to other operating systems as well, because the threats are basically the same -- only the common line usage changes. At page 25 -- where many other security books would still be addressing abstract ideas about computer security -- Real World Linux Security deals with Linux?s "Seven Most Deadly Sins." Some of them are: weak passwords, old software versions, open network ports, and poor physical security. Just a few of the other critical security topics covered in the book are: common break-ins by subsystem, establishing security policies, hardening your system, and scanning your system for anomalies. While much of the book is akin to "Linux Security 101," advanced topics and defenses are also covered. The wide-ranging topics of the book include not only Linux host security, but also what to do when an intrusion has occurred. Part 4 of the book is "Recovering From an Intrusion." The knee-jerk response of many systems administrators is to power down a system in the event of an intrusion. However, in reality, that is often the worst thing to do. Powering-down a system makes digital forensics muc

With shelves of GNU Linux and Unix security books out there, choosing which ones to grace your bookshelf with can be difficult. Real World Linux Security is a hands down winner, covering every aspect of Linux system security. With many books being a tired rehash of the same tips designed to harden your system against script-kiddies, this book goes many steps further into protecting your systems against skilled crackers, and exploring advanced cracking techniques, and defenses against them. Something missing from most other books, this book has extensive coverage on preparing for an attack, how to tell if your system has been cracked, and what to do afterwards (contrary to what your instincts may tell you, don't just pull the plug!) If you have only one Linux security book, this is definitely the one. As a bonus, the book is excellently indexed, and has frequent references to other parts of the book where appropriate, making it easy to navigate.

Out of all the books on various Linux topics that I own, and I own several, this one is the best. It covers security issues very well, it's full of real-world examples and it's fun to read. I would reccommend this book to anyone who is interested in securing their Linux box. And to those who aren't concerned about security, I would HIGHLY reccommend this book.

Having read alot of books on computer security in 7 years in the unix profession. I have seen some really bad books. Some books had good chapters. Some totally forgot a whole compnent of security. Bob has covered it all. He covers the whole nine yards and then some. This book is up their with hacking exposed as a must in every administrators library.PS. One gripe. Has the Kerberos logo variation on the cover. But no talk of kerberos.

After being cracked two weeks ago, we hired Bob Toxen to come in and evaluate our SGI systems. Many thanks to Bob Toxen for his help at reasonable rates. One reason we hired Bob was that he was involved in porting Unix to the SGIs many years ago. At our first meeting, he gave me a copy of the book. (Thanks Bob!) After reading the first two chapters, I immediately realized that our break in was due to procrastination. A topic not usually addressed but of prime importance in keeping security tight. His book identified several other holes that weren't apparent to me as well. We are, thanks to Bob, plugging the holes and restoring the systems. You should definitely buy this book. I am buying a friend a copy since I was given one. Give a copy to your boss or management as well as to yourself. Maybe you'll get the understanding you need from up the chain of command! This particular crack was the Telnetd vulnerability exposed last August. I had asked for time to fix it and was asked to keep doing research rather than sysadmin. We were under pressure to keep papers coming in our project, so I kept researching! Around Nov. 16-28, possibly more than one cracker easily broke in. Some systems showed activity from another university, while one was obviously in the midst of a DoS attack on someone. We shut everything down, but have spent at least $10K on lost time, extra labor, and consulting. Our university security person spent many days investigating and coordinating everyone's efforts. The origination of the attack has not been determined but the other university, with 60K machines on campus, did not have even one security person we could contact for help. Our efforts are to only restore and prevent attacks since we are unable to pursue the crackers any further without more help or leads. We've lost weeks and money. I highly recommend that you take Bob's book seriously so that you will not be in this situation as we are. Our projects, online classes, and reputation have been put at risk and that is unacceptable as you might agree. Thanks for your time! I hope I've made my point! By the way, everything I have said here is my opinion and not to be construed as that of my employer. However, I am sure they are as happy Bob is helping as I am!!