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802.11 Networks, The Definitive Guide 92

Posted by timothy from the little-signals dept.
cpfeifer writes with the review below of O'Reilly's 802.11 Wireless Networks: The Definitive Guide; he warns that this is not a book for everyone setting up a casual home wireless network, but says it's excellent for its intended audience. Read on for his complete review.
802.11 Wireless Networks : The Definitive Guide
author Matthew S. Gast
pages 443
publisher O’Reilly & Associates
rating 9/10
reviewer cpfeifer
ISBN 0-596-00183-5
summary A thorough survey of the features, issues and potential solutions of deploying 802.11 based wireless networks.

The Scenario

For a lot of folks, implementing an 802.11 network involves selecting and purchasing an access point and adapter cards, and installing or compiling the proper drivers. From there, we are off and running, usually in under an hour. However for the few, the proud, the sysadmins of the world it's a whole different ballgame. Sysadmins need a deeper understanding of network technologies to be able effectively design, deploy and debug them.

What's Bad?

Most of the book is right on the mark when it comes to the sysadmin audience, however chapters 8 (the PCF, for contention free service), 10 (the ISM PHYs) and 11 (802.11a overview) are only of interest to folks who are implementing 802.11 hardware, IMHO. These chapters contain very low-level material about the 802.11 transmission protocol, and will not be generally useful since equipment manufacturers do not provide access to this layer. A dead giveaway that you can skip over chapter 8 is the phrase "The PCF has not been widely implemented." If it's not widely implemented, chances are you won't have the option of using it in a deployment.

After this bellycrawl through the weeds, chapters 12 and 14 give click-by-click instructions for installing two commercially available 802.11 access point/client adapter pairs on your Windows box. The selected products are Nokia's A032 Access Point along with their C110/C111 and Lucent's Orinoco (formerly WaveLan) Access Point and client adapter. It's worth noting that these are two of the most expensive 802.11 solutions available on the market and have enhanced features that are not present in other models. These chapters are simply rehashed vendor installation documentation for these products and provide very little added value. There's nothing that I hate more than paying $30-$50 for a book which repackages documentation that is freely available on the web. Skip these chapters; the rest of the book is excellent.

What's Good?

This book starts off with six strong chapters that cover the 802.11 protocol specification, why WEP is vulnerable, and some upcoming security specifications. The first six chapters are invaluable reading for any sysadmin that is planning (or already responsible) for an 802.11 deployment. This is your ammunition when users come and ask why the wireless network is slower than the wired network with fewer users (preventing contention adds more overhead in wireless) or why they really really should tunnel every wireless connection over SSH (because WEP is fundamentally flawed). The chapter that covers the current WEP implementation demystifies the "40 bit" vs. "64 bit" key-length sleight of hand that some vendors play. The standard WEP key length is 64 bits. However, 24 of those bits are used as WEP's initialization vector for the RC4 cipher. These bits aren't encrypted in an 802.11 packet, so by sniffing 802.11 traffic you can examine the IVs of the packets and see how many distinct keys are in use, and even retrieve the actual key once you have captured enough packets. AirSnort retrieves WEP keys by implementing the Fluhrer/Martin/Shamir attack (orig paper, Stubblefield paper). Chapter 16 covers using tools such as Airsnort and Ethereal to analyze the 802.11 traffic on your network. Remember to use your powers for good and not evil.

The final 3 chapters address deployment, analysis and tuning of 802.11 networks. These chapters, combined with the first six are the heart of this book and the whole motivation for buying the book. The analysis chapter has a particularly wonderful section about gathering user requirements with respect to 802.11 specific issues (security requirements, roaming ...) and a very practical section about physical installation that clearly illustrates the author's mastery of integrating 802.11 technologies into an existing infrastructure.

So What's In It For Me?

If you're an sysadmin and implementing 802.11 technologies is on the horizon, this book is a solid reference of the current state of 802.11 solutions, both good and bad. It pulls no punches in presenting issues and weaknesses with the current solutions and documents forthcoming standards that are being proposed or developed to address them. If you're considering a smaller deployment at home, the security aspects of the text are still applicable, but the design/deployment sections are more rigorous than you will need. There is a bit of starch (repackaged vendor installation documentation) and unnecessary details (knowing that 802.11 frequency hopping uses Gaussian frequency shift keying is good for impressing women at parties, but doesn't really impact the design/deployment of an 802.11 network) but the other chapters redeem themselves and make this a very valuable text.

Table of Contents
  1. Preface
  2. Introduction to Wireless Networks
  3. Overview of 802.11 Networks
  4. The 802.11 MAC
  5. 802.11 Framing in Detail
  6. Wired Equivalent Privacy (WEP)
  7. Security, Take 2: 802.1x
  8. Management Operations
  9. Contention-Free Service with the PCF
  10. Physical Layer Overview
  11. The ISM PHYs: FH, DS, and HR/DS
  12. 802.11a: 5-GHz OFDM PHY
  13. Using 802.11 on Windows
  14. Using 802.11 on Linux
  15. Using 802.11 Access Points
  16. 802.11 Network Deployment
  17. 802.11 Network Analysis
  18. 802.11 Performance Tuning
  19. The Future, at Least for 802.11
  20. 802.11 MIB
  21. 802.11 on the Macintosh
  22. Glossary
  23. Index

You can purchase 802.11 Wireless Networks : The Definitive Guide from bn.com. Slashdot welcomes readers' book reviews -- to submit yours, read the book review guidelines, then visit the submission page.
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802.11 Networks, The Definitive Guide More

802.11 Networks, The Definitive Guide

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  • Length... (Score:3, Funny)

    by Smelly Jeffrey ( 583520 ) on Monday July 01, 2002 @11:02AM (#3800928) Homepage
    This book damn well better be 802.11 pages in length. Else, it couldn't possibly be called definitive.

  • Not a party piece (Score:5, Funny)

    by mccalli ( 323026 ) on Monday July 01, 2002 @11:13AM (#3801009) Homepage
    knowing that 802.11 frequency hopping uses Gaussian frequency shift keying is good for impressing women at parties

    I can guarantee you that it isn't...

    Cheers,
    Ian

  • Really, they were one of the first vendors to offer 802.11 networking with the airport. Why are they relegated to the last chapter before the glossary?

    • Re:why is the Mac 802.11 chapter so far down? (Score:1, Insightful)

      by Anonymous Coward
      cause this is ment to discuss the standard. So McQuirks (or <insertAnyVendor>Quirks) only rate a small mention when they are different.
    • There are VERY FEW McQuirks to speak of when discussing AirPort technologies. AirPort is straight 802.11b protocol stuff, and you can connect easily to Access Points from Ornico, Nokia, Intel, D-Link, LinkSys, etc - all while using WEP. You should really know about Macintosh before you trash-talk them.
    • The chapter is on the setup of your Airport Network. Have you ever set up an Airport network? Did you need a manual? The chapter goes over the settings and such of the different settings of the computer and setup of the basestation, but nothing that's not in the online help really, and it's even missing info (Like how to type in a HEX password that's used on non-apple AP's. But again, that info is in the help on the Mac anyway.) The chapter is only 14 pages long, with lots of pictures. I'm glad they threw it in there, but if you own a Mac and an Airport card, you probably know everything that's in the chapter already. Trust me, if you need to know the info that's in that chapter, the rest of the book will fry your brain :)
    • If my memory serves, from my quick read of the book a week or two ago, there is a simple reason for it...All of the info on 802.11 on the Mac OS / Hardware got stuck in an appendix (and is also short and incomplete) because Apple was very slow in providing the promised loaner hardware to the book's author so that it could be included in the book. The author mentions that fact and does actually give Apple's hardware and software glowing reviews but he admits that the coverage is not as complete as he would like because of the printing deadlines combined with Apple's foot-dragging.

      -tcp

  • I just order a PhatStackO'Books and this was one of them, haven't had a chance to read it through yet.

    But flipping through, I was surprised how thorough it is. This isn't a book on how to set up your Apple AirPort or something (for some reason that's what I thought it was), it's hardcore on all the details including the radio and communications theory necessary to understand how the 802.11 physical layer works. Looks like the title is absolutely true, this is a definitive guide.

    • it's hardcore on all the details including the radio and communications theory necessary to understand how the 802.11 physical layer works

      last time i checked, wireless or radio does not "really" have any physcal properties they are just vibrations of molcules screwing with our hearing......

  • Quite a Good Book (Score:4, Interesting)

    by peatbakke ( 52079 ) <[gro.taep] [ta] [taep]> on Monday July 01, 2002 @11:25AM (#3801076) Homepage

    I would actually recommend this book to anyone who has more than a passing interest in wireless networks -- sure, there's a lot of nitty gritty details, but that's better than being short on information, right?

    Anyhow, for those of you who are interested in setting up a public node, I definitely recommend you check out the NoCat [nocat.net] project. It's an authentication/monitoring system for admins interested in having a little control over who accesses their wireless networks.

    Another fun resource is the Personal Telco Project [personaltelco.net]. There's lots of smart folks involved who can tell you everything you need to know about setting up wireless nodes with old abandoned computers and home built antennas. Yes. Wireless can be done cheaply.

    Enjoy!

  • I am faced with deploying a wireless environment that requires such security.

    Does the book discuss the security aspect of these new standards?
    • It does cover 802.11g and the 802.* stack (but not 801), but only very briefly and from a high level.
    • There is not a lot of info out there for 802.1x yet. Some pointers for you if you already didn't know about them.

      Microsoft has a howto for EAP-TLS W/ IAS server and AD, which is what I use at home w/ a Orinoco AP-500 and it works very well. http://www.microsoft.com/windowsxp/pro/techinfo/de ployment/wireless/default.asp

      Funk software offers a EAP-TTLS solution as well here is their press release.
      http://www.funk.com/News&Events/8021x_pa rtner.asp

      Finally in the free software world, freeradius offers experimental EAP-TLS as well.

      BTW if you google there are a few articles out there that say 802.1x is insecure. These are outdated and WRONG. Current 8021.x solutions use Mutual authentication NOT one-way as alluded to in previous articles. I even emailed one of the authors of one of those articles and they agreed that the current solutions solve the problem.
  • My application is outside line-of-sight to avoid having to trench communication cables. Does this book cover this (anybody read it yet?), or is it a strictly indoor only reference?

    Thx
  • On a related matter, how are people covering 9 to 25 stores buildings?
    I thought that an Yagi antenna at the roof, aiming down, could do the job, but I'm not quite sure.
    How do you solve this? Several antennas, several AP's?

    Comments and suggestions would be greatly appreciated.

    Best regards...
    • Put an access point in the elevator shaft Since the elevator shaft would open to just about every floor, you'd get the most bang for your buck there. Of course, a lot depends upon the wall material and layout of your building.
    • It would depend heavily on the building, particulary the wall's and floors, as 2.4ghz will be completly blocked by metal and significantly degraded by multiple levels of different objects / materials..

      Also remember that most AP's claim a usable maximum of 64 users, for any real use (fast use) less than 30. Best bet of course would be an AP + omni on each level (or maybe every second), but some buildings you *may* be able to get away with a few AP's spread around the building..

      This isnt a science, a site survey is _required_ in any potential building, there is no 'standard'. :(

  • 802.11 Throughput (Score:5, Informative)

    by RiBread ( 181983 ) on Monday July 01, 2002 @11:49AM (#3801225)

    This is your ammunition when users come and ask
    why the wireless network is slower than the wired network with fewer users (preventing contention adds more overhead in wireless)

    The right answer is: wireless networks are just plain slower than wired ones. Wired networks claim 100Mb/s access and wireless ones claim ~1/10 of that at 11Mb/s.

    Actually CSMACA [ucsd.edu] (as opposed to CSMACD [ucsd.edu] the medium contention handling mechanism wired 802.3 networks use) really plays only a small part in the speed of .11 networks. It's the format of .11 physical layer packets and quality of current PHY layer chips which limits the throughput of most solutions to around 4 Mb/s.

    New cards coming out from US Robitics [80211-planet.com] using TI 802.11 silicon get consistent throughput close to 7Mb/s. Linksys also uses the TI ACX100 chipset, but doesn't have quite the marketing machine USR does.

    If you need more speed you ought to check them out. Still not like a wired network but a hell of a lot better than 4 Mb/s.

  • The author Matthew Gast... (Score:4, Informative)

    by mattyohe ( 517995 ) <matt.yoheNO@SPAMgmail.com> on Monday July 01, 2002 @11:52AM (#3801239)
    also published two articles on wireless security...

    Seven Security Problems of 802.11 Wireless
    http://www.oreillynet.com/pub/a/wireless/2002/05/2 4/wlan.html [oreillynet.com]
    May 2002

    Wireless LAN Security: A Short History
    http://www.oreillynet.com/pub/a/wireless/2002/04/1 9/security.html [oreillynet.com]
    April 2002

  • The REAL definitive guide - free! (Score:5, Informative)

    by morcheeba ( 260908 ) on Monday July 01, 2002 @11:52AM (#3801243) Journal
    And all this time I thought that this was the definitive guide [ieee.org]. Silly me. It's cool that 802 standards (which usually cost big bucks) are now available for a free download once they've been in print for 6 months. Way to go, IEEE! Now, if we can just convince ANSI to do the same... See also the main 802.11 homepage [ieee.org]

  • Not really a con. (Score:4, Insightful)

    by sinserve ( 455889 ) on Monday July 01, 2002 @12:06PM (#3801306)
    Most of the book is right on the mark when it comes to the sysadmin audience, however chapters 8 (the PCF, for contention free service), 10 (the ISM PHYs) and 11 (802.11a overview) are only of interest to folks who are implementing 802.11 hardware, IMHO. These chapters contain very low-level material about the 802.11 transmission protocol, and will not be generally useful since equipment manufacturers do not provide access to this layer.

    These are strong points dummy. One can always learn the surface material and interface rather quickly, a book the provides strong "internals" information about a given piece of computer system almost always beats the shallow publications. It is good to abstract yourself from the details of a given technology is you are just a casual user, but if you are the administrator, you are expect to know your protocol specs and header formats.

  • Book WWW (Score:2, Interesting)

    by G0SP0DAR ( 552303 )
    Not to digress or anything, but I just saw this book at a local bookstore last week, and couldn't help but notice how expensive books are these days. When it comes to technical matters, especially with wireless networking, what can be found in a book that can not be found on the Internet? I don't doubt that the book may be good, but I just suppose that I'm a jaded outcast of the paper world and do not see the need to spend money on a book when I could get that info for free on the web, and then save the cash for other network hardware, since that isn't cheap either!
    • i wish i could get weaned off books and only use the Internet for research but i still like having a couple of good books in front of me while i work. My armadillo and crab books are always within easy reach.

      your right about book prices, some are just insane. If you're in college then you know exactly what i mean, if not, take a stroll through a college bookstore and check out the price on technical books. Most of my textbooks are between $75 and $120 bucks a pop.

      Overall I think you can save about $5 or $10 dollers with Oreilly over other publishers and the material is usually better too.
    • Books tend to have more credibility and research behind them than web sites (not always of course). Plus you might have to search quite a while to find all the info in a book as on the web.
  • Anyone out there deployed a wireless network over a LANE backbone. Roaming doesn't work, but I'm wondering if I can reduce the timers suffiently that it will nearly work ?

    Any ideas ?
  • Here [oreillynet.com] is a link for an O'Reilly article on setting up a home 802.11b network using Linux and a 802.11b network card.

    I'm sure it isn't as thorough as the book, but its here fast and free.

    Jeremy

  • PCF -- Cisco supports it (Score:3, Informative)

    by JoshuaDFranklin ( 147726 ) <joshuadfranklin@NOSPAM.yahoo@com> on Monday July 01, 2002 @02:37PM (#3802504) Homepage
    A word of warning about that easy-to-skip chapter: Cisco's Aironet series supports the PCF. So if you really want to understand what's going on, read that chapter too. So just because it's not "widely implemented" doesn't mean it doesn't exist.

    I've also been very impressed with the Aironet gear. Reliable, lots of options, good interface. If you've just got a few nodes it probably isn't worth the cost, but if you're serious get Cisco (or Lucent).

    • FWIW, the Lucent, Cisco, and Buffalo 802.11 gear is excellent, and all are built by the same Japanese company. Here in the US, they use the Buffalo brand - take them apart, and you'll see that Buffalo, Cisco, and Lucent 802.11 gear is indeed all identical, except for a few questionable "value-added" features (which are pretty much non-standard, by definition) and, of course, the price. (I think they may not build the high-end Cisco units, but they're priced out of reason, anyhow.)

      Buffalo has also been known to offer good group discounts to "wireless clubs" like the one here in Austin. BTW, Buffalo also has a wide range of antennas and antenna adapters/cables.


  • I've been sitting here for a couple of hours dinking around with snmpwalk and MRTG trying to track down a problem in one of our cells (Wireless ISP) that is in a really ugly area in terms of interference.

    A book that explains the underlying operations in excrutiating detail would be most welcome ... I am going to pick it up tonight.

  • Amazon has 802.11 Wireless Networks: The Definitive Guide [amazon.com] (affilate link, just so ya know) for a little over $30. Currently has a 4.5 out of 5 star rating, although not very many reviews. It is the top book which returns for 802.11, which means it is probably the most popular for that keyword...usually a good sign.

    They have free shipping over $49 if anyone is looking for a cheap place to pick it up. 30% off, with 0 shipping cost if you get something else too (to hit the $49 threshold) is a good deal for a brand new tech book.

    -Pete

  • Once again, bookpool has the cheapest price in town. [bookpool.com] $27.50
  • Come on Mr. Pfeifer, everyone knows that Cisco has some of the most expensive networking hardware... Lucent is just almost as expensive. Remember, if you're going to pay a lot for hardware, make sure its big, blue, and says "Cisco" all over!

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