No Starch The Book Of Wireless A Painless Guide To WiFi And Broadband Wireless 2nd Edition Jan 2008 ISBN 1593271697 pdf

B O B B E C K

G E T C O N N E C T E D . W I R E L E S S L Y. G E T C O N N E C T E D . W I R E L E S S L Y

• Use VoIP over a wireless connection to talk on the
• Evaluate wireless data services based on cost, speed,
• Extend your network to give your neighbors free

IT

  IT

  2 N D E D I T I O N THE BOOK OF WIRELESS

  2 N D E D I T I O N

  2 N D E D

  2 N D E D

  ION

J O H N R O S S A P A I N L E S S G U I D E T O W I - F I A N D B R O A D B A N D W I R E L E S S THE BOOK OF WIRELESS

ION TH E B O O K O F W

• Select and configure hardware and software for
• Secure your network using WPA encryption or a
• Discover open networks and maintain your privacy

  (No Starch Press).

  A B O U T T H E A U T H O R Motorola and AT&T. He is the author of more than two House), (Sybex), and

C O V E R S W I N D O W S, M A C, L I N U X , U N I X , A N D S M A R T P H O N E S C O V E R S W I N D O W S, M A C, L I N U X , U N I X , A N D S M A R T P H O N E S

RO S S TH E B O O K O F W

PRAISE FOR THE FIRST EDITION, THE BOOK OF WI-FI

  “A plain-English guide for consumers, a bridge over troubled waters for those who want to go wireless but don’t know where to start, what to buy or how to make it all work.” — SACRAMENTO BEE “Although there are many good Wi-Fi tutorials available in the market these days . . . The Book of Wi-Fi definitely belongs to the top notch. The author’s practical and fluff-free style liberates this book from the hype and dogmatic tone that prevail in other books.” —

  “Highly readable.” — LINUX USER AND DEVELOPER “An outstanding book which gives you a good working knowledge of every aspect of wireless networking and how to set up a small home network or a larger corporate Wi-Fi network with a firewall and VPN.” — FLASHMX . COM “Covers the issues without belaboring the details.” — DESKTOPENGINEER . COM “The author has done an absolutely fabulous job of taking complex information and explaining it in laymen’s terms.” — BITYARD . COM “Shines a big bright spotlight on the murky world of Wi-Fi.” — DINGBAT MAGAZINE “Provides a useful foundation for anyone wishing to set up, use, and secure an 802.11b network.”

  —

T H E B O O K o f

  

W I R E L E S S

  

A P A I N L E S S G U I D E T O W I - F I A N D

B R O A D B A N D W I R E L E S S

by John Ross

  

San Francisco

^®

  THE BOOK OF WIRELESS, 2ND EDITION. Copyright © 2008 by John Ross.

  

All rights reserved. No part of this work may be reproduced or transmitted in any form or by any means, electronic or

mechanical, including photocopying, recording, or by any information storage or retrieval system, without the prior

written permission of the copyright owner and the publisher.

  Printed on recycled paper in the United States of America 12 11 10 09 08 1 2 3 4 5 6 7 8 9

  ISBN-13: 978-1-59327-169-5 Publisher: William Pollock Production Editor: Megan Dunchak Cover and Interior Design: Octopod Studios Developmental Editor: Tyler Ortman Technical Reviewer: Mike Kershaw Copyeditor: Jeanne Hansen Compositor: Riley Hoffman Proofreader: Michael Shorb Indexer: Nancy Guenther For information on book distributors or translations, please contact No Starch Press, Inc. directly: No Starch Press, Inc. 555 De Haro Street, Suite 250, San Francisco, CA 94107 phone: 415.863.9900; fax: 415.863.9950; info@nostarch.com; www.nostarch.com Librar y of Congress Cataloging-in-Publication Data Ross, John, 1947- The book of wireless : a painless guide to Wi-Fi and broadband wireless / John Ross. -- 2nd ed. p. cm. Rev. ed. of: Book of Wi-Fi. c2003. Includes index.

  TK5105.78.R67 2008 004.6'8--dc22 2007048461

No Starch Press and the No Starch Press logo are registered trademarks of No Starch Press, Inc. Other product and

company names mentioned herein may be the trademarks of their respective owners. Rather than use a trademark

symbol with every occurrence of a trademarked name, we are using the names only in an editorial fashion and to the

benefit of the trademark owner, with no intention of infringement of the trademark.

  

The information in this book is distributed on an “As Is” basis, without warranty. While every precaution has been

taken in the preparation of this work, neither the author nor No Starch Press, Inc. shall have any liability to any person or entity with respect to any loss or damage caused or alleged to be caused directly or indirectly by the information contained in it.

  You see, wire telegraph is a kind of a very, very long cat. You pull his tail in New York and his head is meowing in Los Angeles. Do you understand this? And radio operates exactly the same way: you send signals here, they receive them there. The only difference is there is no cat.

  —Albert Einstein

B R I E F C O N T E N T S

  

Acknowledgments ....................................................................................................... xvii

Introduction .................................................................................................................xix

  

Chapter 1: Introduction to Networking ..............................................................................1

Chapter 2: Introduction to Wireless Networks ..................................................................11 Chapter 3: How Wi-Fi Works ........................................................................................29 Chapter 4: The Hardware You Need for Wi-Fi ................................................................43 Chapter 5: Managing Your Wi-Fi Connections ................................................................73 Chapter 6: Wi-Fi for Windows ......................................................................................97 Chapter 7: Wi-Fi for Linux and Unix .............................................................................115 Chapter 8: Wi-Fi for Mac ............................................................................................133 Chapter 9: Installing and Configuring Wi-Fi Access Points ...............................................143 Chapter 10: Long Range Point-to-Point Links ...................................................................181 Chapter 11: Connecting to an Existing Wi-Fi Network ....................................................195 Chapter 12: Wireless Network Security ........................................................................211 Chapter 13: Alternatives to Wi-Fi: Wireless Broadband Data ..........................................239 Chapter 14: Smartphones and PDAs ............................................................................255

  

Chapter 15: Virtual Private Networks ...........................................................................265

Chapter 16: Using Broadband for Telephone Calls ........................................................285 Chapter 17: Tips and Troubleshooting ..........................................................................293 Index .........................................................................................................................307

C O N T E N T S I N D E T A I L

  

A CK N O W LED GM EN T S xvii

  

I NT RO D UC TI O N xix

  1 I NT RO D UC TI O N T O N ET WO R K IN G

  1 Moving Data Around ................................................................................................. 2 Bits and Bytes .............................................................................................. 2 Error Checking............................................................................................. 3 Handshaking ............................................................................................... 3 Finding the Destination ................................................................................. 4

  

The ISO OSI Model ................................................................................................... 7

The Physical Layer ........................................................................................ 7 The Data Link Layer ...................................................................................... 8 The Network Layer ....................................................................................... 8 The Transport Layer ...................................................................................... 8 The Session Layer......................................................................................... 9 The Presentation Layer .................................................................................. 9 The Application Layer ................................................................................... 9

  

Summary.................................................................................................................. 9

  2 I NT RO D UC TI O N T O W I REL ES S N ET WO R K S

  11 How Wireless Networks Work ................................................................................. 12 Radio ....................................................................................................... 13 Wireless Data Networks ............................................................................. 15

  

Benefits of Wireless ................................................................................................. 19

Wireless Data Services ............................................................................................ 20

Wi-Fi ........................................................................................................ 20 Cellular Mobile Wireless Services ................................................................ 23 WiMAX .................................................................................................... 25 What About Bluetooth? ............................................................................... 26 Frequency Allocations................................................................................. 26

Choosing a Service ................................................................................................. 27

  3 HO W WI - FI W O R KS

  29 Wi-Fi Network Controls ........................................................................................... 29 The Physical Layer ...................................................................................... 30 The MAC Layer.......................................................................................... 31 Other Control Layers .................................................................................. 32

  

Wi-Fi Network Protocols........................................................................................... 32

Wi-Fi Radio Frequencies .......................................................................................... 33

Wireless Channels ..................................................................................... 33 Reducing Interference ................................................................................. 34

  

Wireless Network Devices........................................................................................ 36

Network Adapters...................................................................................... 36 Access Points ............................................................................................. 38 Building a Network .................................................................................... 39 Public and Private Networks ........................................................................ 40

Putting It All Together ............................................................................................... 41

  4 TH E H A RD WA RE Y O U N EED F O R WI - FI

  43 Everybody Speaks the Same Language (More or Less) ................................................. 44

Network Adapters................................................................................................... 45

Form Factor ............................................................................................... 46

  Internal vs. External Antennas ...................................................................... 50 Interoperability........................................................................................... 51 Finding Drivers for Your Adapter.................................................................. 52 Ease of Use ............................................................................................... 54 Securing Your Network............................................................................... 56 Documentation and Technical Support .......................................................... 56 Reputation ................................................................................................. 57

Adapters for Ad Hoc Networks ................................................................................. 58

  

Dual-Purpose Adapters............................................................................................. 58

Access Points .......................................................................................................... 59

Operating Standards .................................................................................. 60 Pure Wireless LANs .................................................................................... 60 Wireless Access to a Wired LAN ................................................................. 61 Combining the Access Point with a Wired Hub ............................................. 62 Broadband Gateways................................................................................. 63 Multiple Access Points................................................................................. 63 Enhanced-Performance Access Points ............................................................ 65

External Antennas ................................................................................................... 65

Antenna Characteristics .............................................................................. 67 How to Choose an Antenna ........................................................................ 68 Rolling Your Own....................................................................................... 69 Where to Use a Directional Antenna ............................................................ 69 Antennas Are a Whole Other World ............................................................ 71

It’s Time to Buy........................................................................................................ 71

  5 M A N AGI N G Y O UR W I- F I CO NN EC TI O N S

  73 Installing PC Card Adapters ..................................................................................... 74

Installing USB Adapters............................................................................................ 74

Installing an Internal Adapter in a Laptop Computer .................................................... 75

Installing an Internal Adapter in a Desktop System....................................................... 76

  Loading the Driver Software ..................................................................................... 76 Choosing a Control Program .................................................................................... 77

The Microsoft Wireless Network Connection Utility......................................... 78

The Intel PROSet/Wireless Program.............................................................. 86

Other Wi-Fi Adapters and Control Programs ................................................. 88

Status Information.................................................................................................... 90

  Changing Your Adapter’s Configuration Settings ........................................................ 91 Configuring a Network Connection ........................................................................... 92

The Mobile Life: Moving from One Network to Another .................................. 92

Beyond Windows.................................................................................................... 93

  Signal Strength vs. Signal Quality ............................................................................. 94

  6 W I- FI FO R W I N DO W S

  97 Windows Network Configuration in General.............................................................. 99

  

IP Addresses .............................................................................................. 99

The Subnet Mask...................................................................................... 101

Gateways ............................................................................................... 101

Domain Name Servers.............................................................................. 101

File and Printer Sharing............................................................................. 102

Network Interface Adapter Options ............................................................ 102

Naming Your Computer ............................................................................ 102

Configuring Windows ........................................................................................... 104

Do You Have the Latest Firmware? ............................................................. 104

Using the Windows Wireless Tools............................................................. 105

Network Interface Adapter Options ............................................................ 110

Naming Your Computer ............................................................................ 111

  Troubleshooting the Connection .............................................................................. 113

  7 W I- FI FO R L I N UX AN D U N IX 115 Drivers, Back Seat and Otherwise ........................................................................... 116

Where to Find Drivers............................................................................... 118

  

Linux Drivers ............................................................................................ 118

Unix Drivers............................................................................................. 120

Wi-Fi Control Programs.......................................................................................... 121

Using Built-in Software .............................................................................. 121

  

Add-on Wi-Fi Programs............................................................................. 123

Looking Under the Hood ........................................................................... 125

Wireless Tools ......................................................................................... 126

Programs Based on the Wireless Tools........................................................ 127

Status Display Programs ............................................................................ 127

Configuring an Access Point ................................................................................... 128

  Wi-Fi for Unix ....................................................................................................... 129

Configuration Tools .................................................................................. 129

wiconfig and wicontrol ............................................................................. 129

  8 W I- FI FO R M A C 133

  

AirPort Components............................................................................................... 134

Setting Up an AirPort Network ................................................................................ 135

Installing the Hardware............................................................................. 135 Running the AirPort Setup Assistant............................................................. 136 The AirPort Utility ..................................................................................... 137 The AirPort Status Icon .............................................................................. 137 Using an AirPort Network ......................................................................... 137

Connecting Macintosh Clients to Other Networks...................................................... 138

  

Using Non-Apple Adapters with a Mac.................................................................... 138

Connecting an AirPort Card to a Non-AirPort Access Point ......................................... 139

Connecting Other Wi-Fi Clients to an AirPort Network ............................................... 140

Network Properties................................................................................... 140

Configuring an AirPort Extreme from Windows ......................................................... 141

Is AirPort the Answer?............................................................................................ 141

  9 I NS T AL L IN G A N D C O N F I GUR IN G W I- FI AC C ESS PO IN TS 143

  

Installing Access Points........................................................................................... 144

Configuring the Access Point Through a Browser.......................................... 146 DHCP and Other Distractions..................................................................... 148 DNS Addresses........................................................................................ 148 Configuration Commands and Settings ....................................................... 149

How Many Access Points?...................................................................................... 152

Using Multiple Access Points...................................................................... 154

Performing a Site Survey ........................................................................................ 156

Make a Site Plan . . ................................................................................. 156 Testing, Testing . . . ................................................................................. 160

  

Interference Problems............................................................................................. 163

Advantages of Mixed Networks .............................................................................. 165

Access Points Combined with Hubs and Gateway Routers ............................. 166

Extending the Network........................................................................................... 167

Legal Issues ............................................................................................. 167 Outdoor Antennas and Access Points.......................................................... 170 Campus Networks.................................................................................... 175

Connecting the Access Points to a LAN and the Internet ............................................. 176

  

Networking Your Neighborhood............................................................................. 177

Keeping Your ISP Happy........................................................................... 178 Network Security: Everybody Is Your Neighbor ........................................... 179

  1 0

L O N G R AN G E P O I NT -T O -P O I N T L I N KS 181

  

Extending the LAN ................................................................................................ 182

Bridge Routers ...................................................................................................... 184

Point-to-Point and Point-to-Multipoint ......................................................................... 185

  Installing a Point-to-Point Link................................................................................... 185

Choose a Signal Path ............................................................................... 186

Reaching the Boondocks: Long-Range Links ................................................. 186

Aligning the Antennas .............................................................................. 187

Obstructions and Relays............................................................................ 189

Alternatives to Wi-Fi for Point-to-Point ....................................................................... 190

  Antennas for Network Adapters .............................................................................. 191

Build Your Own Antenna?......................................................................... 191

1 1 C O NN EC TI N G TO AN EX IS TI N G WI - FI N ET WO R K 195 Public Wi-Fi Is Not Secure ...................................................................................... 196 Finding a Wi-Fi Hot Spot........................................................................................ 197 Keeping Your Data Secure ..................................................................................... 199 NetStumbler and Other Sniffer Tools........................................................................ 200

  

Public Hot Spots ....................................................................................... 202

Municipal Wi-Fi Networks ..................................................................................... 204 “Free Public WiFi”................................................................................................. 205 Unprotected Private Access Points ........................................................................... 208 1 2 W IR EL ESS N ETW O RK S EC U RI TY 211 Protecting Your Network and Your Data................................................................... 214

Protecting Your Computer.......................................................................... 216

Wi-Fi Security Tools ............................................................................................... 217

Network Name (SSID) .............................................................................. 217

  

WEP Encryption ....................................................................................... 219

WPA Encryption ...................................................................................... 222

Access Control (MAC Authentication) ......................................................... 224

Virtual Private Networks ............................................................................ 225

Authentication: The 802.1x Standard ......................................................... 225

Firewalls .............................................................................................................. 226

Keep Wireless Intruders at Bay .................................................................. 227

Isolate Your Network from the Internet ........................................................ 228

Access Points with Firewalls....................................................................... 229

Firewall Software ..................................................................................... 231

  Turn Off DHCP...................................................................................................... 232 Turn Off the Power ................................................................................................ 233 Physical Security ................................................................................................... 233 Sharing Your Network with the World ..................................................................... 235 Some Final Thoughts About Wi-Fi Security................................................................ 237 1 3 A LT ERN A TI V ES TO W I- F I: W IR EL ESS BR O AD BA N D DA TA 239 What’s Wrong with Wi-Fi?..................................................................................... 240 Broadband Data Services....................................................................................... 240

  

Comparing Technologies ....................................................................................... 242

Choosing a Service Provider................................................................................... 244

Coverage................................................................................................ 245 Data Speed ............................................................................................. 246 Cost ....................................................................................................... 246 Choosing a Network Adapter.................................................................... 247 Service and Support ................................................................................. 247 Broadband Wireless Services Around the World ......................................... 248

  

Connecting to a Wireless Broadband Network ......................................................... 248

Using More Than One Computer ............................................................................ 249

Broadband Security............................................................................................... 250

Clearwire, Sprint, and Other Pre-WiMAX Services .................................................... 250

Broadband Wireless in Automobiles and Other Vehicles............................................ 251

TracNet ................................................................................................. 253

  External Antennas .................................................................................... 254 Safety Issues ........................................................................................... 254 1 4

S M AR TP H O N ES A ND P D A S 255

Connecting to the Internet Through PDAs and Other Handheld Devices........................ 256

Choosing a Smartphone ........................................................................................ 257

  Smartphone Operating Systems ................................................................ 258

Which Is Best? ...................................................................................................... 263

1 5

V IR TU AL PR I VA TE N ETW O R KS 265

  

VPN Methods ....................................................................................................... 268

  

VPN Servers ......................................................................................................... 268

Configuring a Windows Server for a Wireless VPN ..................................... 269

  VPN Servers for Unix ................................................................................ 270 Network Hardware with Built-in VPN Support .............................................. 271

  

VPN Client Software.............................................................................................. 272

Configuring Windows for VPN .................................................................. 272 The Microsoft L2TP/IPsec VPN Client .......................................................... 276 Making the Connection in Windows........................................................... 276 Windows XP Options ............................................................................... 277

  VPN Clients for Unix................................................................................. 279

Using a Wireless VPN ........................................................................................... 280

Making the Connection............................................................................. 282 Bypassing the VPN ................................................................................... 283 Using a VPN Through a Public Network...................................................... 283

  1 6 US I N G B RO A D BA ND F O R T ELEP H O N E C A LL S 285 VoIP over Broadband Wireless and WiMAX ............................................................ 287 Voice over Wi-Fi ................................................................................................... 289 1 7 TI P S A ND T RO U BL E S HO O TI N G 293 My computer doesn’t detect my network adapter. ..................................................... 293 The wireless control program tries to run, even if I’m not using my adapter. ................. 295 My computer won’t associate with the local network. ................................................ 296 My computer connects to the wrong network. .......................................................... 296 I can see the local network, but I can’t connect to the Internet. ................................... 297 I can see the Internet, but I can’t see other computers on my LAN. ............................... 297 The signal strength is weak or signal quality is low. .................................................. 297 I can’t find a public network. ................................................................................. 298 I don’t know if I’m within range of a network. .......................................................... 298 The network is slow. ............................................................................................. 298 My computer drops its connection. ......................................................................... 299 My Wi-Fi network has crashed. .............................................................................. 299 Can I improve performance with an external antenna? .............................................. 300 What else can I do to improve performance? ........................................................... 300 When I move to a different access point, the adapter loses the connection. ................. 301 Where can I find a copy of the Wi-Fi standards? ...................................................... 301 How can I find out who made my network adapter?.................................................. 301 Is the software that came with my network adapter or access point up to date? .................................................................................. 302 I’m having trouble connecting to a broadband network. ............................................ 303

  I’m having trouble connecting to my VPN. ............................................................... 303 How can I extend the life of my computer’s battery? .................................................. 304 Can I use my access point as a network bridge? ....................................................... 304 I’ve heard that radio signals from cellular phones might be dangerous.

  What about Wi-Fi? ......................................................................................... 305

  I ND EX 307

A C K N O W L E D G M E N T S

  I’m grateful to everybody at No Starch Press for their help and advice as this book moved from idea to print. In particular, Tyler Ortman, Megan Dunchak, Michael Kershaw, and Riley Hoffman have made this a much better book than it would have been without their attention. Any remaining faults in the book are, of course, my responsibility.

  Thanks also to Georgia Taylor at Verizon Wireless and Helen Chung at Clearwire, who allowed me to borrow equipment and use their networks, and to all the manufacturers and software developers who allowed us to use photographs of their hardware and software.

  

I N T R O D U C T I O N

This is a book for people who want to use the Internet everywhere—not just in the office or in the room at home where there’s a telephone or cable connection, but in the backyard,

at the public library, at a highway rest area, or in a hotel

lobby. In this book you will learn how to choose the

  best wireless data service for your particular needs, how to set up your com- puter for wireless, and how to design and install your own wireless network. We’ll also describe some wireless products and services that you might not have known about, such as the ability to make low-cost, worldwide Voice over Internet (VoIP) telephone calls from your laptop computer.

  The combination of wireless Internet services and portable computers can make a huge difference in the way we use the Internet. By eliminating the tether to a wired network, we can gather information, watch and listen to streaming video or audio, and exchange messages wherever we might be, rather than only at specific locations. It’s no longer necessary to return home or to the office or search for an Internet café or a public library. Like mobile telephones (which use related technology), go-anywhere, always-accessible Internet services can change the way we live, work, and entertain ourselves. When wireless broadband Internet services work properly, they’re practically invisible; just turn on the computer or a smaller portable device such as a smartphone, and a universe of information is immediately at your fingertips. But we’re talking about computers, so complications are always possible. In order to help you identify the causes and solutions for wireless connection problems, the first few chapters of this book offer details about how wireless data communication systems work, including the surprising tale of the avant- garde composer and the glamorous actress whose wartime invention provided the foundation of modern spread-spectrum technology.

  As you read this book, I hope you will remember that a wireless network, and for that matter, any kind of communications technology, is a means to an end that you use to achieve some other objective. Remember that your original goal was to find out if your favorite team won, invite your friends to a dinner party, read your class notes, or watch the latest YouTube videos. If you have to concentrate on making your wireless connection, you’re doing some- thing wrong.

  You’re in control. The computer and the network should do things the way you want to do them, rather than forcing you to adjust your life or work to meet the machine’s requirements. If you have trouble making your wire- less connection (or any other computer activity) work “properly,” it’s almost always the computer’s fault, or the fault of the people who designed the hardware and software. The computer and the network are your servants, and not the other way around.

  New wireless network products and services are appearing all the time, so the information in this book represents a snapshot of a moving target. Within another year or two, manufacturers will have replaced some of the products described here with new and better models, and the wireless service providers will offer faster connections over wider areas. The specific makes and models will change, but the general principles ought to remain.

  The first edition of this book, The Book of Wi-Fi, was limited to 802.11b Wi-Fi networks, which were the only practical choice when that book was published in 2003. When I wrote that book, I expected Wi-Fi networks to replace or supplement wired home and office networks, but I did not anti- cipate that a huge number of additional Wi-Fi hot spots would also cover public locations. In my Seattle neighborhood, I can connect my laptop com- puter to the Internet at a branch library, half a dozen coffee shops, three taverns, four pizza joints, and a supermarket. Today, Wi-Fi signals are every- where, and other broadband services offer wireless signals that cover much wider areas than any Wi-Fi network. A few years from now, more and better wireless services will offer even faster connections. The dream of a high- speed wireless service that works almost everywhere is rapidly coming true.

  The first three chapters of this book explain how data networks operate, how wireless technology can extend data networks beyond the reach of wired connections, and how Wi-Fi networks work. Next, Chapter 4 describes the hardware needed for Wi-Fi and how to design and install your own Wi-Fi network. Chapters 5 and 6 provide the information you need to use a Wi-Fi network to connect to the Internet from a computer running Microsoft Windows. Chapter 7 covers Wi-Fi clients for the Linux and Unix operating systems, and Chapter 8 provides similar information for Macintosh OS X. Chapter 9 explains how to install and configure Wi-Fi access points, and Chapter 10 covers long-range, point-to-point Wi-Fi links. Chapters 11 and 12 cover connecting to existing Wi-Fi networks and Wi-Fi security.

  In Chapter 13, we’ll move away from Wi-Fi and describe some alter- native broadband wireless services, including EV-DO, EDGE, and WiMAX.

  Chapter 14 explains how to use Wi-Fi and broadband services with smart- phones and other pocket-size computers, Chapter 15 describes virtual private networks (VPNs), and Chapter 16 explains how to use wireless links to place telephone calls through the Internet. Finally, Chapter 17 offers trouble- shooting tips and general advice.

  Most readers won’t read this book from cover to cover, but you’ll probably find something you can use in every chapter. In particular, please don’t ignore the chapters on security and VPNs—they contain essential information that can keep your network and your data safe. If all your computers use Windows, you can skip the Linux/Unix and Macintosh chapters.

  If I have done my job as author, this book will improve your experience with Wi-Fi and other wireless data services. I hope it will help you understand how data moves through the air between your computer and the Internet and how to set up and use your own system for best performance. After your wireless connection is ready to use, you shouldn’t have to think about the network at all. Along the way, I hope you enjoy both the book and your time online.

  

1

I N T R O D U C T I O N T O

N E T W O R K I N G

Broadband wireless networks are one more step toward the Internet’s ultimate destiny of interconnecting everything in the known universe.

  A wireless network combines two kinds of communication technology: data networks that make it possible to share information among two or more computers, and radio (or wireless) communication that uses electromagnetic radiation to move information from one place to another.

  The earliest Wi-Fi systems provided a convenient way to connect a laptop computer to an office network and to connect computers to a home network without stringing cables between rooms. Today, Wi-Fi and other broadband services allow millions of users to connect to the Internet when they’re away from their homes or offices, as wireless signals cover entire metropolitan areas.