Product Description

The popularity of wireless networking has grown exponentially over the past few years, despite a general downward trend in the telecommunications industry. More and more computers and users worldwide communicate via radio waves every day, cutting the tethers of the cabled network both at home and at work. Wireless technology changes not only the way we talk to our devices, but also what we ask them to do. With greater flexibility, broader range, and increased mobility, wireless networks let us live, work, and think differently. Wireless networks also open up a vast range of tasty new hack possibilities, from fine-tuning network frequencies to hot-rodding handhelds. The second edition of "Wireless Hacks", co-authored by Rob Flickenger and Roger Weeks, brings readers more of the practical tips and tricks that made the first edition a runaway hit, selling nearly 30,000 copies. Completely revised and updated, this version includes over thirty brand-new hacks, major overhauls of over thirty more, and timely adjustments and touch-ups to dozens of other hacks introduced in the first edition. From passive network scanning to aligning long-distance antennas, beefing up wireless network security, and beyond, "Wireless Hacks" answers real-life networking needs with direct solutions. Flickenger and Weeks both have extensive experience in systems and network administration, and share a passion for making wireless more broadly available. The authors include detailed coverage in "Wireless Hacks" for important new changes in specifications, hardware and software, and delve deep into cellular and Bluetooth technologies. Whether you need your wireless network to extend to the edge of your desk, fit into your backpack, or cross county lines, the proven techniques in "Wireless Hacks" will show you how to get the coverage and functionality you're looking for.

Product Details

• Amazon Sales Rank: #269438 in Books
• Published on: 2005-11-22
• Original language: English
• Number of items: 1
• Binding: Paperback
• 440 pages

From the Publisher
Wireless technology gives us the flexibility, range and mobility to live, work and think differently. It also opens up a vast range of tasty new hack possibilities, 100 of which are explored in the second edition of Wireless Hacks, by Rob Flickenger and Roger Weeks. Completely revised and updated, Wireless Hacks includes over thirty brand-new hacks, major overhauls of over thirty more, and timely adjustments and touch-ups to dozens of others introduced in the first edition. Wireless Hacks answers real-life networking needs with direct solutions.

About the Author
Rob Flickenger has been a professional systems administrator for more than 10 years, and all around hacker for as long as he can remember. Rob enjoys spreading the good word of open networks, open standards, and ubiquitous wireless networking. His current professional project is Metrix Communication LLC, which provides wireless hardware and software that embodies the same open source principles he rants about in his books. Rob also works with the U.N. and various international organizations to bring these ideas to places where communications infrastructure is badly needed. He hopes that all of this effort is contributing toward the ultimate goal of infinite bandwidth everywhere for free. He is the author of two other O'Reilly books: Linux Server Hacks and Building Wireless Community Networks (which is in its second edition).

Roger Weeks is a coauthor of Linux Unwired. He has nearly a decade of experience in systems and network administration and has been building Linux systems at home and in the enterprise since 1998. His first computer was an Atari 800, which was promptly taken apart so he could add more memory before he attached the 300bps modem. He is currently the senior network administrator for Mendocino Community Network, a small ISP in coastal northern California. MCN is owned by the local school district, and puts their profits back into the local schools. Prior to that position, he was involved with community wireless (http://www.nocat.net) and an Internet co-op (http://www.wscicc.org) in Sonoma County, CA.

Excerpted from Wireless Hacks by Rob Flickenger, Roger Weeks. Copyright © 2005. Reprinted by permission. All rights reserved.
#20
Hack #20 Share Your GPS
Caravanning with friends,but only one person has a GPS? Play nice and share.

Road trip caravans are more fun when the people in the two cars can communicate with each other.People have used CBs and Family Band Radio Service (FRS)radios for years just for this purpose.If you want to exchange data instead of voice over radio, you can set up a roving Wi-Fi network and then share a GPS between vehicles.

Connect a GPS to one computer and then set up a wireless network.Clients in other vehicles can connect to the GPS on the host machine.Normally,only one program at a time can access a serial port –connected GPS.This can quickly become a problem.You probably want to run gpsmap [Hack #22 ]to get maps,and then a program to log your position, and perhaps another program to let you create spatial annotations of your travels.

That is way too many connections for a single-user serial port! Fortunately, GPSd is available as a daemon that connects directly to the GPS and then acts as a server for position information. Once you have GPSd installed, all of your GPS aware applications can share a single GPS.

$tar xvfz gpsd-x.xx .tar.gz
$cd gpsd-x.xx
$./configure
$make
$make install

Connecting the GPS

Most GPS units have a serial port and can be configured to output the current position using a standard protocol called NMEA.GPSD expects your GPS to send NMEA formatted data,but can also accept data in different formats. Check the GPSd site for how to enable other formats if you have a GPS that does not output standard NMEA sentences.

Once it is installed you can run it with this command:

$gpsd -p /dev/ttyS0 -s 4800

If you have problems getting GPSd to start,consult the documentation. Once you ’ve got it running you can connect to it with telnet to see what it is reporting:

$telnet localhost 2947
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.

Now you are connected to GPSD.The commands are single characters, and you can chain them together.So if you want your Position,Altitude,and GPS Status,issue this command:

PADS

You will get the full GPS position,with your latitude and longitude,altitude, current date and time,and GPS status.The status is the last section: S=0 or S=1 ,where 1 means the GPS is connected and sending data and 0 means there is no data coming from the GPS.

You can now run Kismet, GPSDrive, and any other GPS-aware applications at the same time, and your friends in the other car can connect to your GPS over the Wi-Fi network. The Perl code in Example 1-1 will connect to GPSd and print the current position and time.

Example 1-1.Connecting to GPSd with dump_gps.pl

#!/usr/bin/perl

#/usr/local/sbin/gpsd -p /dev/ttyS0
use 5.6.1;
use IO::Socket;
use Term::ReadKey;
use strict;

BEGIN {$|++};#autoflush STDOUT.

#Set parameters based on command line options,with defaults.
my $GPSD =shift(@ARGV )||"localhost:2947";

#Connect to gpsd.
warn "connecting to gpsd \n";
my $gps =IO::Socket::INET->new($GPSD)
or die "Can't connect to gpsd at $GPSD:$!\n";

while (1){
#Tell gpsd we want position,altitude,date,and status.
$gps->print("pads \n");

#Parse out the response.If the date is blank,gpsd needs
#a second to catch up.
my $location =;

my ($lat,$long,$alt,$date,$status)=
($location =~/P=(.+?)(.+?),A=(.+?),D=(.+?),S=(.+?)/gos);

next unless $status;

#Print a line of data to both STDOUT and STDERR,and wait.
print $_join("|",$lat,$long,$alt,$date ||""),"\n"
for (\*STDOUT,\*STDERR );

sleep(1 );
}

Save this into a file called dump_gps.pl and run it with this command:

$./dump_gps.pl

You will get coordinates,the altitude,and current date at one-second intervals. We use this trick further in "Broadcast Your GPS Position "[Hack #21 ].

See Also
•Casey West ’s O ’Reilly Network article on his cross-car road trip network:
oreillynet.com/pub/a/wireless/2002/08/01/highway_lan.html

—Rich Gibson

Customer Reviews

Top banana
If you have a wi-fi enabled PDA or laptop buy this book. I found it well written and full of usefull tips for both bright eyed begineers, and the more savvy. Clear technical explanations for each 'hack' and most importantly how to adapt the 'hack' for the OS you have, whether it is OSX, Linux, XP, or Pocket PC. I particularly liked the sections on 'how to build your own wave guide' and 'How to test your home wireless network'. In short this book is a real gem and one I think I will keep on going back to. If you want to 'get your toes wet' with wifi or do something a bit different with your current setup, you could do far worse than by this book.

Into wireless.....get this!
If like me you have a wirelss lan (or are thinking of setting one up), you will want to learn all the little tricks to make it just that more great.

The book introduces you to some of the coolest bits of software on the free market as well as some of the more less known ones.

It also shows you how to secure your wireless network, cool bluetooth tricks, monitor what your LAN users are viewing in real time!

AND LOTS MORE!

Outstanding
This book is an absolutely fantastic recipe book for those wanting to play with wireless comms (in particular, wireless computer networking). We have a remote farmhouse in Spain and the projects relating to stretching the coverage over greater distance are just what the doctor ordered.