I decided to purchase this book based in large part on the fact that all the reviews at the time I was shopping gave it 5 stars. I was also looking for something that seemed a good introduction without being either totally non-technical or overwhelming technical.

I'm well into the book now and can tell you that it definitely lives up to all those 5 star ratings. As others have said, it is an easy, enjoyable, and very informative read. Depending on your ultimate objectives you may eventually want to get even deeper into the technical aspects of security but for starters and for a good long term reference this book is excellent.

Buy it. You won't be disappointed.

The fundamental ideas of how to stave off hacks likely won't change for years to come (though some individual methods or protocols do), so this book is a decent guide to help start out anyone interested in network security.

Good book dinamic and simple. it does not use complicated words and easy to fallow.

After reading the introduction chapter, you get excited and think that this book might actually be some what different than any other hacking book on the market. It really isn't.

If you have experience, the first 144 pages are a complete waste.

The author provides a review of TCP/IP, Unix and NT in 144 pages.

I have no doubt that the author is a seasoned professional. He even makes mention of the fact that he provides advice to the groups of authors who make the SANS security publications. Maybe he does, but this book is not written very well.

If you actually read this entire book, you'll find yourself

saying "I've read this somewhere else". Don't get me wrong, buy the book only if you have not read other security books. There are others that you should get before you read this one.

For those of you out there who are new to computer security, or who understand theory and concepts and want some practical explanations about what's out there, this is a book you cannot do without. If you are really serious about wanting to know details about what you are up against when protecting your organization, or your PC from attacks you will not just want to glance through the book but read it from cover to cover. The is not a book that will teach you theory about encryption, PKI and all the mathamatical and computer science concepts that Computer Science or Computer Engineering majors usually learn. There are plenty of good books out there for that. This book is more of a practical hands-on approach to how attacks are executed and how to stop and defend against them.

Ed Skoudis has really done a phenomenal job presenting the material in an organized, easy-to-follow format without making it like a 'security for dummies' type of book. He gives you knowledge and techniques you can apply. Ed begins with 3 chapters on the basics of TCP/IP, UNIX and Windows NT/2000. I found these three chapter very helpful in preparing for the rest of the book even though I have read books on and worked with all three before. Ed presents a few ideas about the vulnerabilities of these systems without going into detail. That comes later. Then he serves up the main course. The 5 phases of an attack are outlined and the following is a brief description:

Phase 1: How do attackers do research on their targets ? This includes web sites where they look up their info, social engineering techniques, etc.

Phase 2: How do they find vulnerable systems ? This includes war dialers, port scanners, network mappers etc. He also gives you detailed information about where you can find these tools how to use the most popular ones and how they actually work internally.

Phase 3: What can an attacker actually do once he has found the vulnerabilities in your system and breached security ? This tells you about cracking passwords in UNIX and NT, how to attack web apps by finding bad cgi scripts, stack buffer overflows, packet sniffing, IP spoofing, etc. This once again has detailed explanations on where to get the tools and how they are used.

Phase 4: How does the attacker maintain access to the system ? This tells you about trojan horses, back doors, Rootkits, etc

Phase 5: How does the attacker cover his tracks ?

Ed finally ties it all together by describing attacks using the phases and tools he talks about above with examples along with a discussion of mistakes made by system admins. I should also mention that for all the attacks mentioned in the book, Ed always fills you in on how to defend against them so you don't feel like you are fighting a losing battle as a system admin. The book is written in a way that is very easy to follow. It is almost like someone standing in front of you in a classroom and explaining things to you. Ed uses personal experiences along with light-hearted comments about system administrators and hackers that will make you smile so that the reading doesn't stay too serious.

This book is worth reading and keeping as a reference. I gave it 5 stars because it is the best book I have seen on practical computer security.

Let me start with a disclaimer. I find network and computer security very interesting, but have never looked into it in-depth before (other than a paper I once wrote on worms and viruses). I have a strong programming background (The usual suspects - C/C++, Perl, Fortran, Pascal, Assembly), but I'd never even HEARD of netcat before, and sure as heck didn't know what a rootkit did. Sure, knowing Assembly I understand how a stack functions, so buffer overflows made sense before Ed's explanation. But the rest of the book was all foreign to me, so keep in mind this a review from a security newbie.

This book was excellent for me. I read it cover to cover, and it was almost like reading a spy and/or detective novel, with details of what the spies and detectives do. The plot was the phases of a network attack, and I could almost hear the Mission Impossible theme in the background at times when I was looking at the output from some of the applications. I don't know if this is normal for a security book (like I said, I'm a newb), but Counter Hack was great to read straight-through, and I have no doubt I'll frequently refer to portions in the future.

I found Ed's overviews of topics that would be used in the rest of the book exceptional - they really were exactly what you needed to know, with no extra fluff. Concisely written and well-explained, but I didn't feel like I was being treated as a three-year-old. I had previous knowledge of OS's and networking, but Counter Hack's first few chapters were excellent refreshers, and in some cases spectacular insight into how things work together (I constantly referred back to OSI's 7-layer model for TCP/IP).

To be honest, I did find some typos and things that were odd (though perhaps I just thought them odd due to lack of knowledge). For example, Ed says a subnet mask is XOR'd with an IP address to determine the network address versus the host address. XOR? If I XOR my address... let's see:

11000000 10101000 00000001 00000001 (192.168.1.1)

11111111 11111111 11111111 00000000 (255.255.255.0)

00111111 01010111 11111110 00000001 (127.87.254.1?!)

This is an obvious typo for someone who has background knowledge of networking... but isn't that my point? Should have been caught before going to press. Still, when I have to pick out a single WORD of an entire book to have something bad to say, you know the book is a great one.

I highly recommend this book, definitely to people new to the field (like me!), but perhaps those of you who have in-depth knowledge will learn some things you didn't know (or fully understand) before. And now, onto Malware!

Recent security books have dealt exclusively with point security issues such as Windows NT security, Cisco router security, and TCP/IP security. Although point security is necessary, it does not provide the necessary level of security unless the varied points are integrated. This year, a number of security books have bucked the point-security-only trend and have concentrated on security from an integrated architecture perspective. The most noteworthy of these titles has been Ross Anderson's Security Engineering.

Another worthy title is Counter Hack: A Step-by-Step Guide to Computer Attacks and Effective Defenses. The self-described Next Generation Hacker Book promises to be "a step-by-step guide to defending against hacker intrusions." Rather than focusing on a single technology to secure, Skoudis shows readers how to design and defend their networks against myriad threats. His step-by-step approach is to partition the hacking process into five phases (Reconnaissance, Scanning, Gaining Access, Maintaining Access, Covering Tracks, and Hiding) and to detail the steps within each phase.

As noted by Anderson in Security Engineering, most systems are designed to keep out the "good guys" --those who follow the rules but may occasionally bypass them. Hackers and other adversaries -- who do not follow the rules -- require a unique set of constraints to keep them out of corporate networks.

The book opens with a crucial topic: knowing your threats and not underestimating your adversary. Although most people may put all adversaries under the blanket class of "hackers," there are a number of antagonistic groups, each of which possesses a unique set of threats. Unless an organization knows who its adversaries are -- whether internal employees (the true cause of most security incidents), organized crime, disgruntled consultants, remote hackers, customers, suppliers, or hactivists -- there is no way its network can be appropriately secured. Counter Hack details what course of action to take in order to protect against attacks, whether they originate from a low-level script kiddy or a world-class hacker.

Skoudis' step-by-step approach to effectively securing a network begins with an introduction to the operations of TCP/IP. Most experienced readers can bypass this section. The next two chapters provide an overview of Unix and Windows NT/2000, which are the most commonly installed operating systems in corporate America. Although most security books address Windows NT/2000 and Windows PPTP (Point-to-Point Tunneling Protocol), Skoudis astutely notes the huge security ramifications of running them.

The following sections detail how hackers perform reconnaissance and scanning attacks against networks in order to penetrate them. Skoudis details the fundamentals of port scanning and the use of scanning tools such as nmap.

Chapter 7 covers applications and operating-system-level attacks. It includes an excellent overview of buffer-overflow attacks and how to obviate them. This is a crucial point for programmers who are often unaware of the specific dangers of buffer overflows.

The book details the dangers of Trojan horses, backdoors, and root kits, which are often difficult to detect once they are installed. Skoudis covers the nastiest backdoor, kernel-level root kits, and execution redirection in particular. The danger of execution redirection is that the hacker can intercept a call to run a certain application and map that call to another application . It is basically a bait-and-switch attack, except that the victims do not know that they are being attacked.

Skoudis has an easy-to-read style. When he mentions a hacking tool, he effectively describes how the tool works and how it can be employed to secure a system. Skoudis also includes a number of stories written in the first-person. It is a pleasure to read a security book written by a professional who has in-the-trenches experience, as opposed to someone who thinks copying RFC's makes for an original book.

If you have a network connected to the Internet, you will inevitably be hacked. This book shows how to avert such attacks with a counter hack. For a wide-ranging overview of how to secure a system against myriad adversaries, do yourself, your employer, and your networks a favor and read Counter Hack.

Enter: The Hacker. Throughout the years, there have been many articles, papers, and books that attempt to describe what a hacker does and how one thinks. Typically, these have focused upon either one specific detail or incident publicized in the media, or one specific incident or experience in the life of the author, and as such, they have not had a great appeal to the majority of the intended audiences. Any book focusing on information security will have two major types of readers; Information security or IT specialists with a few years of experience in the industry, and people who are looking for introductory knowledge and who are beginning to learn about information security.

Counter Hack offers introductory knowledge in information security to anyone interested in the filed. Ed's methods of explaining advanced concepts compares to the methods of some of the finest university professors that I have had the pleasure of learning from. He often begins on a personal note, explaining in lay man's terms the details of what would normally be considered a difficult or abstract concept. He then follows with technical details, and provide examples that drive home the points he was trying to make.

For the seasoned professional, there is still quite a bit of information that would be beneficial - no matter the area of IT or information security. Ed puts an interesting - and often funny - twist on the angles he uses to describe hacker styles. No one person will remember every tool, method, or example that comprises the sum of his/her experiences. In this case, Counter Hack serves the requirement for a reference book on Hacker tools and methods. If you're looking for a way to explain to management how a particular vulnerability was exploited on your network, find the appropriate chapter, and look at how Ed did it.

Ed Skoudis has taken the sum of his experience in working with, dealing with, and responding to hacker and cracker incidents, and formulated his thoughts into a methodical approach to explaining the tools, practices, and methods surrounding this environment. Counter Hack is one of, if not the, finest book to date that I have had the pleasure of reading on this topic.

Jeffrey Posluns, CISA, CISSP, SSCP, CCNP

Chief Technology Officer

SecureOps, Inc.

Windows と Unix の基本構造から始まり、

IDS や sniffer の基本的な仕組みを経て、

バックドアを仕掛けたあとの攻撃者の行動パターンまで考慮する本。

攻撃者の心理、利点、弱点を考えてから対処策を解説する形式。

攻撃者が IDS を避けるためのフラグメンテーションなどの仕組みを、

TCP/IP の細かい規定などには触れずに、

豊富な図とともに簡明に解説していたのが印象に残っている。

全体的に図や例が多くて具体的であるが、将来の脅威にも

対応できるように、一般性を失うことなく書かれている。

私は自分のコンピュータに侵入された経験がないので、

読む前は「どんな攻撃があるのか」「攻略されたあとにどうなるか」

「侵入されたことに気付いたあとはどうすれば良いか」

いずれもわからないで漠然とした不安だけがあったのだが、

著者の見てきた実際の被害やアングラ情報に基づく解説によって、

脅威と対策を実際的に考慮することができるようになった。

私が「暗号の秘密とウソ」のような一般論を読んだあとで

この本を読んだのは、偶然であるが最適な順序だったと考えている。

セキュリティの考え方と、正確かつ最新の知識、いずれも

重要である。ある程度セキュリティの概要をつかんだあとは、

本書でひととおり攻撃と防御の手段を学ぶようお勧めする。

厚い本だが、類書をいくつも読むより時間の節約になると思う。