Linux Unwired

Alex Moskalyuk writes "Remember the Best Buy commercial where a puppet asks a woman for a laptop computer, and upon hearing that it's a 'wireless' laptop, starts imagining his life free of strings and limitations? That guy doesn't know it yet, but soon the harsh reality will kick in, ironically kicking him off the wireless network periodically if he uses Microsoft Windows Wireless Zero Configuration or if he wants to run Linux on a laptop with WiFi card that doesn't support Linux. This book, however, is not just about getting your Linux laptop onto the wireless network. Granted, WiFi plays a big role in today's business and personal networks, and three chapters are dedicated to exactly that purpose, but behind that wireless adjective we have a variety of technologies." Read on for the rest of Alex's review of Linux Unwired, from O'Reilly. Linux Unwired: A Complete Guide to Wireless Configuration author Roger Weeks, Edd Dumbill, Brian Jepson pages 300 publisher OReilly rating 8 reviewer Alex Moskalyuk ISBN 0596005830 summary Complete guide to wireless configuration on Linux

Infrared, Bluetooth, 802.11 (in current a, b and g offerings, 802.11i is also being discussed), wireless access points friendly to Linux, United States commercial cellular networks and GPS systems are all covered in a single title that surprisingly fits all of this information into 284 pages. All the chapters can be subdivided into two large parts - familiarizing yourself with the technology (the primer on GPS is pretty good) and running Linux on it (with code and shell command samples and lots of URLs).

Introduction

The authors start up with introduction to wireless, intended for Linux geeks who are not quite up to speed on radio technologies. The concepts of waves, spectrum and radio wave behavior are explained, so later the reader can explain what a retracted radio wave is. Then the first chapter moves on to explain antenna behavior, wireless infrastructure modes and some common problem, like a hidden node in ad-hoc infrastructure. The chapter is well-written, and you're not expected to have an advanced radio degree or ARRL membership to understand the terms.

WiFi cards

Chapters 2, 3 and 4 deal with connecting a Linux desktop or notebook to a wireless 802.11 network. The first issue is that of chipsets used in the wireless card, and even though enough research has been done already, authors discuss different quirks relevant to Intersil Prism, Lucent WavelLan/Orinoco, Aironet/Cisco, Symbol, Atmel, Atheros and Broadcom chipsets. We need to discuss chipsets instead of discussing the actual wireless cards, since some hardware may be shipped under the same brand name with different internals. "A good case in point: the D-Link DWL-650. This radio card initially shipped with a Prism II chipset and was very popular, because it worked on a Linux box. However, D-Link changed chipsets when it released the DWL-650 Version 2, choosing the ADMtek chipset. It is very difficult to tell from the packaging which version of the DWL-650 you are purchasing".

The chapters are done in traditional walk-through mode. They are not HOWTOs or compendia of reference information, available from the manufacturer's Web sites. The authors made an effort to ensure the reader is capable of starting up a wireless connection on Linux box, knowing nothing about it while learning important technology in the process. Certain wireless drivers need to be compiled into Linux kernel, so the task is not for the meek, but with detailed explanation, plenty of URLs and nice fonts and paragraph formatting O'Reilly Publishing uses to differentiate between the text, commands entered at the shell, and URLs, the book is easy to read.

Chapter 3 (available in PDF) teaches the reader how to connect to existing wireless network once the wireless card has been recognized by the system and proven functional. By the time the book hit the stores it was already a bit out of date, since the very first hotspot operator, Cometa Networks, shut down in May 2004. Chapter 4 discusses wireless security, touching WEP settings, a $20 Linuxant utility allowing the user to implement WiFi Protected Access, as well as authentication utilities wpa_supplicant and XSupplicant.

WiFi access points

The issue of WiFi access points is not trivial either, as many vendors out there will ship the product with a Windows app being the only way to set it up. However, for the access point setups that are Web-based, a browser in Linux will do the job. The most Linux-friendly access point include Linksys, Netgear, D-Link, Cisco, SMC, EnGenius, Belkin, US Robotics, Microsoft and ActionTec. Again, harsh reality kicked in between the time the book was written and went to press, and it's sad to see yet another Linux-friendly access point vendor quitting the market.

Not satisfied with commercial offerings out there? Chapter 6 takes the reader into the task of building your own access point. Don't forget that an access point doesn't need to be a compact portable - your old 486 with Linux on it and a wireless card connected to it might serve the purpose. Unfortunately, after all the hardware is bought and assembled, the final product might still cost you the quadruple (in case you go with smaller form-factor motherboards and CompactFlash cards for software storage), so consider this more as a geek project, not a viable solution. The authors use LinuxAP distribution for this task.

16 pages are dedicated to hacking Linksys WRT54G access point with Sveasoft, described as disruptive technology by Robert X. Cringely. The authors also take a brief look at Wifi-box and OpenWRT.

Other wireless technologies

Bluetooth, Infrared, cellular and GPS chapters follow the same chapter plan - first the basics of the technology and simple use case scenarios of what you might use it for, then the hardware needed to implement the wireless technology, available Linux software to do the jobs, accompanied with the list of shell commands to successfully talk to a wireless product, and after that typical applications of the working link.

The authors tested various wireless data plans in the United States, although this data, once again, is constantly changing as the operators buy one another and introduce new data plans. The winner of the quality and the fastest download tests, by the way, was a Motorola v120e phone on Verizon Wireless network. In upload speed tests a Merlin C201 PCMCIA card on Sprint PCS network won. T-Mobile also offers a PCMCIA card for its GPRS network, so the authors install and run it under Linux in Chapter 9.

The last chapter discusses using Linux computers with GPS devices and open-source GPSdrive project for reading GPS data.

The book

For those just venturing into the wireless world, the book would be useful. All the information provided on WiFi connectivity can perhaps be googled and found in various HOWTOs. With wireless operators, GPS systems and Infrared connection one would have to rely on enthusiast sites and newsgroups. Having such informative title that covers all of the technologies would be very useful to a Linux enthusiast.

With that, the book can be quite overwhelming, although it's probably not intended to be read from page 1 to the end. There's usually more than one correct way to do things in Linux, and for each successful project another competitor appears on SourceForge the next day. I like the authors' approach of dedicating most of the chapter space to one, leading, Linux package that seems to be dominant in the field, and then briefly mentioning the others. A notable omission is Intel's Centrino drivers for Linux, as the company is bound to become a leader in the chipset marketplace with 42% of notebooks shipped in 2003 running Centrino chipsets.

But overall the book proved to have a high informational and educational value, not only you follow the steps on setting up wireless technologies on Linux, but you also learn the internals of the technology and why certain things are done that way, but not another.

You can purchase Linux Unwired from bn.com. Slashdot welcomes readers' book reviews -- to see your own review here, carefully read the book review guidelines, then visit the submission page.

Comments

That's a genuine problem

[metlin]

From the article --

Microsoft disputes the notion that there's a problem with the way Windows XP works with Wi-Fi.

That's a blatant lie, typical Microsoft attitude.

For the longest time, the wi-fi connection of my notebook would keep dropping and I thought it was because of a bad wireless card.

I changed my wireless card, I tried everything possible.

What I had not noticed was everything I was in Linux, this never happened - no matter what! There are areas in my school where the wi-fi signal strength is particularly weak, and even in those areas I never lost connection from Linux.

Somehow, when I would boot into Windows, my wi-fi link would keep dropping. I still haven't figured the problem yet, I just use Linux instead everytime.

And so contrary to what Microsoft may say, there is a problem with Windows XP (I have the problem whether am on XP Home or XP Pro). I wonder whether they EVER admit their mistakes.

Re:That's a genuine problem

[__Maad__]

I have the same problem mentioned in the Wired article, have seen it in numerous places and know of others who have the same problem.

At the very end of the article they state that you can bring the connection back to life by stopping and starting XP's Wireless Zero Configuration service -- I wish I had known that during some very ill-timed outages! This suggests that XP has everything to do with the problem but I'd still be careful in blaming Microsoft outright. Still, what a disaster.

I wonder now if on my centrino-based Dell laptop it is possible to simply turn off XP's zero config option if Intel's PROSet tools are running. Anybody know?

Re:That's a genuine problem

[networkBoy]

Yes you can. The Intel PROSet driver works far better when compared to the zero config. Set up a list of preferred APs and the PROSet tools will connect in order of preference and NOT continue to bump you around to other APs when they show up as long as any on your preferences are available. If you wan't I beleive you can even turn that off and go for a fully static config.

HTH,
-nB

Re:That's a genuine problem

[jfmiller]

I would like to point all of you to this article at Ars Technica. It explains the problem and how to fix it.

Good Luck

JFMILLER

Re:That's a genuine problem

[swv3752]

The problem with the Zero Config service is a known issue. If your card has its own config util and you disable the zero config util, there is no problem. If you connect with the zero config and then disable zero config, there will be no problem. The zero config has a bug that will drop connections.

Re:That's a genuine problem

[ElForesto]

I could have told you that! *grins* WinXP's utility is useless. On a lot of systems, I couldn't get it to hook up to a router of the same brand 2 feet away with the default settings. I tell Microsoft what it can do with it's utility, install the one from the manufacturer, and BAM, it works.

I should have known better than to trust software from Microsoft over the software from the manufacturer.

Windows Wireless Zero Configuration Problem

[MBCook]

I (and probably everyone else with XP) have expirianced that problem of getting your connection dropped. I learned how to fix it a while ago (and then Ars Technica wrote on it).

The problem is if Windows can find a network that broadcasts it's SSID when yours doesn't, it will try to switch. There are three (or four) soltuions.

1. Find the other network and get the owner to turn off broadcasting
2. Turn broadcasting on for your network
3. Once you are connected to your network, disable the WZC service (set it to manual and disable it). Windows will KEEP the current settings (the ones that work) and won't change them every, so you'll stay on your network. You will have to re-enable WZC if you want to switch networks though
4. The fourth option is to use a 3rd party application to manage your wireless configuration (your WiFi vendor probably gave you one). But if your vendor doesn't have one for XP, this isn't an option.

I REALLY hope that they fix this in SP2, because it's my number one complaint.

Re:Windows Wireless Zero Configuration Problem

[crimbil]

Or #5. Open the properties for your wireless connection. Click the tab for wireless networks. Click the Advanced button. Remove the check from the box titled "Automatically connect to non-preferred networks."

DWL-650

[Nemi]

I just got this card working on an IBM thinkpad 240. I spent a good week or more trying to get the prism2 drivers to work because all documentation I found said that that is the chipset it had.

After going through many different drivers and kernel compiles, I Later found that some 650's not only have an ADMTek chipset but some also have be a Realtek chipset. After trying the ADMTek drivers I found my particular card had a Realtek chipset and it came right up using the ndiswrapper driver using the windows Realtek driver (the driver supplied by d-link on the cd would not work. I had to get the windows driver from Realteks site). The thing works like a champ now with Fedora core 1.

Mapping Wi-Fi under Linux

[drewzhrodague]

There are quite an assortment of GIS tools available for Linux, too, for those of us mapping wi-fi. Check out Mapserver, GRASS, and PostGIS.

Re:Easy solution

[NewNole2001]

If you are using Windows, then look at the link at the beginning of the article to see what might be causing your problems.

WPA was the source of my woes

[EkiM in De]

I discovered that both of my Windows Laptops were dropping the connection approximately every hour and it was driving me nuts. (They are a Dell with a Broadcom 4306 (802.11g) and a Centrino Toshiba.) Even with a Linksys 802.11g WAP and an SMC 802.11b WAP I was still getting the disconnections.

Eventually after one night's worth of Windows's Eventlog data, when I forgot to switch my laptop off, I realised that there was almost precisely an hour between disconnections. An alarm bell rang in my head because on the Linksys there was an option for altering the "Group Key Renewal" for WPA. This was by default set to 3600 seconds.

One quick switch back to 128bit WEP and my connection is rock solid on both laptops.

P.S.

[kfg]

Thanks for the link. It's a good one. I've bookmarked it.

The page also notes another reason for not attributing it to Churchill, no one is even sure he is the original source. Common sayings, or saying of little know men, often get attributed to great men post priori in this manner.

Take "Lafayette, we are here", for instance.

A lot a Mark Twain "quotes" fall into this catagory. There's no denying he said them, but when he said them he was using what he understood his audience understood to be a common witticism from another source. When the audience, for one reason or another, perhaps just the passage of time, fail to understand that they attribute it to Twain himself.

Many of the witticisms of such great men are thus "stolen" themselves.

KFG