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Hacking Linux Exposed

Hacking Linux Exposed

4.7 6
by Brian Hatch, James Lee, George Kurtz, Saumil Shah

Tighten holes and maintain security on your Linux system! From the publisher of the international best-seller, Hacking Exposed: Network Security Secrets & Solutions, comes this must-have security handbook for anyone running Linux. This up-to-date edition shows you how to think like a Linux hacker in order to beat the Linux hacker. You'll get detailed


Tighten holes and maintain security on your Linux system! From the publisher of the international best-seller, Hacking Exposed: Network Security Secrets & Solutions, comes this must-have security handbook for anyone running Linux. This up-to-date edition shows you how to think like a Linux hacker in order to beat the Linux hacker. You'll get detailed information on Linux-specific hacks, both internal and external, and how to stop them.

Editorial Reviews

The Barnes & Noble Review
Remember when people used to say Linux was inherently secure because all bugs are shallow, including security bugs -- and, anyhow, the “black hats” only hate Microsoft? Yeah, right! Unfortunately, you do need Hacking Linux Exposed, Second Edition.

Authors Brian Hatch and James Lee have added 200 pages of new content to this edition -- and they’ve overhauled everything else to reflect the latest Linux exploits, cracking tools, and countermeasures. To help you set priorities on defense, every exploit is rated from 0 to 10 on popularity, simplicity, impact, and overall risk.

We found the sections on break-ins particularly useful. You’ll find everything here from “Mitnick-ian” social engineering to physical and network attacks. For example, you probably know that systems running LILO are susceptible to being booted to single-user mode without passwords; you may not realize that newer systems using GRUB have their own vulnerabilities. Hatch and Lee offer countermeasures for both.

You’ll learn how to prevent insecure program execution, buffer overflows, race conditions, and symlink attacks; how to validate user input; and how to create temporary files securely. There are updated chapters on email and FTP security; web servers and dynamic content; and denial-of-service attacks.

There’s also an entirely new three-chapter section on what crackers do after they’ve broken in. You’ll learn how they cover their tracks -- from removing log entries through replacing your binaries with versions that don’t betray their presence. There’s a detailed chapter on backdoors, and another on kernel changes and other advanced methods for hiding one’s activities. If you’re running Linux for anything that matters, this book’s a must. Bill Camarda

Bill Camarda is a consultant, writer, and web/multimedia content developer. His 15 books include Special Edition Using Word 2000 and Upgrading & Fixing Networks for Dummies, Second Edition.

Product Details

McGraw-Hill Companies, The
Publication date:
McGraw-Hill Computer Security Series
Edition description:
Older Edition
Product dimensions:
7.42(w) x 9.08(h) x 1.36(d)

Related Subjects

Read an Excerpt

Chapter 1: Linux Security Overview

This chapter introduces you to some of the security features of the Linux operating system. We will also cover aspects of Linux that differ from other UNIX-like operating systems. This chapter covers the basics of Linux security; if you are a seasoned Linux administrator, you will more than likely find much of this chapter familiar territory.

The highest-level user on a Linux machine is named root (you'll learn more about users later). The root user has complete and total control over all aspects of the machine-you can't hide anything from root, and root can do whatever root wants to do. Therefore, for a hacker to "root your box" means the hacker becomes the root user, thereby gaining complete control over your machine.

There are kernel patches such as LIDS (discussed in Chapter 2) that can contain the all-powerful nature of root and make your machine more secure, even in the event of a root compromise.

A common misconception of many Linux users is that their Linux machine is not important enough to be hacked. They think, "But I don't have anything important on my machine; who would want to hack me?"

This type of user is exactly who hackers want to hack. Why? Because hacking is easy. And usually, the hacker's ultimate goal is not the machine he or she has hacked, but other, more important machines.

They Want Your Bandwidth Hackers may want to hack your machine to use it as a stepping stone. In other words, they will hack your machine and do evil deeds from your machine so it appears as though you are doing it, thereby hiding their trail.

Or they may want to use your machine as a stepping stone to another machine, and from that machine move to another machine, and from that machine move to another machine, and so on, on their way to obtaining root on a . gov machine. Or they may want to use your machine as part of a group of computers they have compromised with the purpose of using them together to perform distributed denial-of-service (DDoS) attacks, such as those that took down eBay at the beginning of 2000.

Or they may want access to your machine so that they can then have access to your employer's machine. Or your friend's machine. Or your kid's machine, especially if your child has a more sophisticated computer than you do.

They Want Your CPU Hackers may want to hack your machine to use your CPU to execute their programs. Why waste their own resources cracking the numerous password files they procure when they can have your machine do it for them?

They Want Your Disk Hackers may want to store data on your machine so they don't use up their own disk space. Perhaps they have pirated software (warez) they'd like to make available, or maybe they just want to store MPEGs of questionable moral content.

They Want Your Data Hackers may want your business' trade secrets for personal use or to sell. Or they may want your bank records. Or they may want your credit card numbers. Or they may want to make you look like a hacker when they launch from your machine.

Or they may just want to wreak havoc on you. The sad fact is that there are people in the world who like to sabotage other people's computer systems for no other reason than that they can. And maybe they think it is cool. And maybe they have destructive personalities. And maybe it brings them some sort of bizarre pleasure. And maybe they want to impress their hacker friends. And maybe they are bored and have nothing better to do with their lives. Who knows why they want to hack your machine? But the fact is: they do want to hack your machine. My machine. Our machines.

Therefore, it is up to us to educate ourselves on their tactics, strategies, and methods and protect ourselves from them.

Linux is part of what is now known as the open source movement. The Linux operating system is free, but more important, Linux is open. That means that the source code for the operating system is available-anyone can view the source code and examine it, modify it, and suggest and make changes to it. There are many programs that are part of the open source movement, and some of the programs are the most popular programs used around the world:

Apache A web server that is used on approximately two-thirds of all web sites on the Internet.

  • Perl A popular programming language used to solve all sorts of problems.
  • Sendmail The most popular mail transfer program used to route 80 percent of the email on the Internet.
  • Netscape A previously closed source program that became open source; a popular web browser.
Each of these programs are available on almost all distributions of Linux.

Open Source and Security

Proponents of open source claim that the nature of open source software makes it more secure. Critics of open source claim that open software is less secure.

Plusses of the Open Source Model

Open source is more secure because anyone can view it. And anyone can improve it. And in the case of the Linux kernel and applications, thousands of people do just that. In 1997, Eric Raymond wrote a watershed paper titled "The Cathedral and the Bazaar" (ht tp : //www. tuxedo. org/-esr/writ ings/cathedral-bazaar/)...

Meet the Author

Brian Hatch is a UNIX/Linux security consultant, administrator, and expert hacker with Onsight, Inc. He has taught various courses at Northwestern University and is the co-maintainer of Stunnel, a widely used secure SSL wrapper.

James Lee is a Perl hacker, Linux administrator, security consultant, and open-source advocate. James is the founder and CEO of Onsight Inc., a consulting firm specializing in Perl training and web development.

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Hacking Linux Exposed 4.7 out of 5 based on 0 ratings. 6 reviews.
Guest More than 1 year ago
This book really gives you tons of very valuble information. Most of witch you do not need to be a super advanced computer wizard to comprehend. I have learned a lot and my knowledge of the subjects covered has been exponentialy expanded. I highly recommend this book for anyone who is looking for computer safty from hackers and/or computer knowledge of highly used systems.
Guest More than 1 year ago
I used to put 'Hacking Exposed' at the top of my security/hacking list, but it has finally been defeated. Not suprising it was by another in the same line. Hacking Linux Exposed delves much more than HE was able to (given that it covered so much). Want to learn how to secure your Linux machine by seeing into the hacker's eyes? Hacking Linux Exposed is for you.
Guest More than 1 year ago
just got my copy in the mail and can't put it down. this book rocks. easy to read, well organized, and very detailed. it really shows you what hacks look like, and gives you the solution that'll keep you safe now and in the future.
Guest More than 1 year ago
I flipped through this book at a friends house, and was shocked to see how much networking info was here. In spite of the fact that we don't have too many Linux machines at my office, I bought this book. The covered a ton of things that helped get our network into shape. We now have a dedicated Linux machine as a firewall and mail gateway protecting our other machines, and are logging (and denying) all the attacks we didn't know about before. We had no idea how vulnerable we were.
Guest More than 1 year ago
I've bought most of the linux books that have been written, and this is the only one I haven't given away after reading it. I find this to be an excellent resource, unlike most of the books low on content and high in scare tactics and pretty pictures. This book gives you the nitty gritty -- real code, real problems, and real answers. You want to keep the bad guys off your machine, this is the book you need. Forget the rest.
Guest More than 1 year ago
This book has many hacking exposures, and utils. If your an above average security keeper, then theres no REAL need for this book. It does provide with great points and ways to keep hackers out, but not leet hackers ;)~~~ Every hacker needs to know anything there is and will be in computer security or exposures, so buy the book! not with a credit card though, go to the book store and buy with IN CASH! (keep the FBI off of you)