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[Review] Real World Linux Security: Intrusion Prevention, Detection, and Recovery
From: InfoSec News <isn () c4i org>
Date: Tue, 4 Sep 2001 04:15:53 -0500 (CDT)

http://unixreview.com/articles/2001/0108/0108l/0108l.htm

Real World Linux Security: Intrusion Prevention, Detection, and
Recovery 
by Bob Toxen 
Prentice Hall, 2001 
ISBN: 0130281875 
$44.99 

Review by Ben Rothke 

[Read an exceprt from this book. 
http://unixreview.com/articles/books/book25/rwls_ch10.pdf ]

A poll taken in July 2001 for Network World 
( www.nwfusion.com/you2001/concerns/concerns.html ) 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."  Ill ignore for now the fact that there is no such word
as hackerproof; Ill 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, Toxens 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 Linuxs "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 much more difficult.  A methodical and planned
approach to intrusions is required, and the book details the
appropriate steps to use.

The book comes with a CD that has a lot of useful programs and
custom-written scripts.  The CD-ROM includes most of the popular
security tools including, nmap, crack, tcpdump, snort, and more.  
Although most of the software is freeware and available on the
Internet, having all of the tools on a single CD-ROM is a timesaver.

The only complaint I have about the book is the use of skulls for the
danger level.  One skull indicates a minor effect or risk, while five
skulls means the risk is too dangerous.  It is often hard to discern
whether the skulls refer to the topic just mentioned, or the
subsequent one.

While many of the threats and vulnerabilities in the book indeed have
five skulls, Real World Linux Security deserves five stars.  It is an
excellent reference about Linux security -- a topic that, while
timely, does not always get the respect it deserves.


Ben Rothke is a New York-city based Senior Security Analyst with
Camelot Information Technologies.  He can be reached at:
brothke () camelot com 



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