802.11 wireless networks: the definitive guide. - Previous ed.: 2002. - ''Creating et administering wireless networks''--Cover. - ''Covers 802.11a, g, n, et i''--Cover. - Includes index

Table of Contents 5 Foreword 11 Preface 13 Prometheus Untethered: The Possibilities of Wireless LANs 13 Audience 14 Overture for Book in Black and White, Opus 2 15 Major Changes from the First Edition 19 Conventions Used in This Book 19 Using Code Examples 20 Safari® Books Online 21 How to Contact Us 21 Acknowledgments 22 Chapter 1. Introduction to Wireless Networking 25 Why Wireless? 25 Radio Spectrum: The Key Resource 27 The ISM bands 29 What Makes Wireless Networks Different 30 Lack of Physical Boundary 30 Dynamic Physical Medium 30 Security 32 A Network by Any Other Name... 32 The Wonderful Thing About Standards... 33 Chapter 2. Overview of 802.11 Networks 37 IEEE 802 Network Technology Family Tree 38 802.11 Nomenclature and Design 39 Types of Networks 41 Independent networks 41 Infrastructure networks 42 Extended service areas 43 Multi-BSS environments: “virtual APs” 44 Robust security networks (RSNs) 45 The Distribution System, Revisited 45 Interaccess point communication as part of the distribution system 46 Wireless bridges and the distribution system 47 Network Boundaries 47 802.11 Network Operations 48 Network Services 49 Station services 52 Distribution system services 52 Confidentiality and access control 52 Spectrum management services 53 Mobility Support 54 Designing Networks for Mobility 55 Proprietary mobility systems 56 Chapter 3. 802.11 MAC Fundamentals 57 Challenges for the MAC 59 RF Link Quality 59 The Hidden Node Problem 60 MAC Access Modes and Timing 62 Carrier-Sensing Functions and the Network Allocation Vector 62 Interframe Spacing 64 Interframe spacing and priority 65 Contention-Based Access Using the DCF 66 Error Recovery with the DCF 67 Using the retry counters 68 Backoff with the DCF 68 Fragmentation and Reassembly 69 Frame Format 71 Frame Control 72 Duration/ID Field 75 Duration: setting the NAV 75 Frames transmitted during contention-free periods 76 PS-Poll frames 76 Address Fields 76 Sequence Control Field 77 Frame Body 78 Frame Check Sequence 78 Encapsulation of Higher-Layer Protocols Within 802.11 79 Contention-Based Data Service 80 Broadcast and Multicast Data or Management Frames 81 Unicast Frames 82 Basic positive acknowledgment (final fragment) 82 Fragmentation 82 RTS/CTS 83 RTS/CTS with fragmentation 84 Powersaving Sequences 85 Immediate response 85 Deferred response 86 Multirate Support 87 Rate selection and fallback 88 Frame Processing and Bridging 89 Wireless Medium to Wired Medium (802.11 to Ethernet) 89 Wired Medium to Wireless Medium (Ethernet to 802.11) 91 Quality of Service Extensions 92 Chapter 4. 802.11 Framing in Detail 93 Data Frames 93 Frame Control 94 Duration 94 Addressing and DS Bits 95 Variations on the Data Frame Theme 99 Applied Data Framing 100 IBSS frames 100 Frames from the AP 100 Frames to the AP 101 Frames in a WDS 101 Encrypted frames 102 Control Frames 102 Common Frame Control Field 103 Request to Send (RTS) 104 Clear to Send (CTS) 105 Acknowledgment (ACK) 106 Power-Save Poll (PS-Poll) 107 Management Frames 108 The Structure of Management Frames 109 Address fields 109 Duration calculations 110 Frame body 110 Fixed-Length Management Frame Components 110 Authentication Algorithm Number 111 Authentication Transaction Sequence Number 111 Beacon interval 112 Capability Information 112 Current AP Address 114 Listen interval 114 Association ID 115 Timestamp 115 Reason Code 115 Status Code 117 Management Frame Information Elements 118 Service Set Identity (SSID) 119 Supported Rates 120 FH Parameter Set 121 DS Parameter Set 122 Traffic Indication Map (TIM) 122 CF Parameter Set 123 IBSS Parameter Set 123 Country 123 Hopping Pattern Parameters and Hopping Pattern Table 124 Request 125 Challenge Text 125 Power Constraint 125 Power Capability 126 TPC Request 126 TPC Report 126 Supported Channels 127 Channel Switch Announcement 127 Measurement Request and Measurement Report 128 Quiet 128 IBSS DFS 128 ERP Information 129 Robust Security Network 130 Extended Supported Rates 132 Wi-Fi Protected Access (WPA) 132 Types of Management Frames 133 Beacon 133 Probe Request 134 Probe Response 134 IBSS announcement traffic indication map (ATIM) 134 Disassociation and Deauthentication 135 Association Request 135 Reassociation Request 136 Association Response and Reassociation Response 137 Authentication 137 Action frame 137 Frame Transmission and Association and Authentication States 138 Frame Classes 138 Class 1 frames 138 Class 2 frames 139 Class 3 frames 139 Chapter 5. Wired Equivalent Privacy (WEP) 141 Cryptographic Background to WEP 142 Stream Cipher Security 143 Cryptographic Politics 144 WEP Cryptographic Operations 144 WEP Data Processing 145 WEP data transmission 146 WEP key length 147 Types of WEP keys 147 Manual (static) versus automatic (dynamic) WEP 148 WEP key numbering and storage 149 WEP Encapsulation 150 Problems with WEP 150 Cryptographic Properties of RC4 150 Design Flaws of the WEP System 151 Key Recovery Attacks Against WEP 152 Key recovery defenses 154 Dynamic WEP 154 Chapter 6. User Authentication with 802.1X 157 The Extensible Authentication Protocol 158 EAP Packet Format 158 EAP Requests and Responses 160 Type code 1: Identity 160 Type code 2: Notification 161 Type code 3: NAK 161 EAP Authentication Methods 161 EAP Success and Failure 162 A Sample EAP Exchange 162 EAP Methods 164 Cryptographic Methods 164 LEAP 165 Code 13: EAP-TLS 165 Code 21: EAP-TTLS and Code 25: EAP-PEAP 166 Noncryptographic EAP Methods 166 Code 4: MD-5 Challenge 167 Code 6: Generic Token Card 167 Code 29: EAP-MSCHAP-V2 167 Code 18: EAP-SIM and Code 23: EAP-AKA 167 Other Inner Authentication Methods 168 Password Authentication Protocol (PAP) 168 Challenge Handshake Authentication Protocol (CHAP) 168 MS-CHAP, version 1 168 802.1X: Network Port Authentication 169 802.1X Architecture and Nomenclature 170 802.1X frame filtering 171 EAPOL Encapsulation 172 Addressing 173 802.1X on Wireless LANs 173 Sample 802.1X Exchange on 802.11 173 Dynamic keying 175 Chapter 7. 802.11i: Robust Security Networks, TKIP, and CCMP 177 The Temporal Key Integrity Protocol (TKIP) 177 TKIP Differences from WEP 178 TKIP initialization vector use and key mixing 178 TKIP sequence counter and replay protection 179 The Michael integrity check and countermeasures 180 TKIP Data Processing and Operation 180 TKIP key mixing and key construction 181 TKI P data transmission 182 TKIP reception 183 The Michael Integrity Check 184 Michael data processing 186 Michael countermeasures 187 Counter Mode with CBC-MAC (CCMP) 188 CCMP Data Processing 189 CCMP data transmission 190 CCMP reception 191 Robust Security Network (RSN) Operations 192 802.11i Key Hierarchy 192 Pairwise key hierarchy 192 Group key hierarchy 193 802.11i Key Derivation and Distribution 193 Updating pairwise keys: the four-way handshake 194 Updating group keys: the group key handshake 195 Mixing Encryption Types 196 Key Caching 196 Chapter 8. Management Operations 199 Management Architecture 199 Scanning 200 Passive Scanning 201 Active Scanning 202 Scan Report 203 Joining 205 Authentication 205 802.11 “Authentication” 206 Open-system authentication 206 The legacy of shared-key authentication 207 Defeating shared-key authentication 209 Preauthentication 209 802.11 Preauthentication 210 802.11i Preauthentication and Key Caching 211 Association 213 Association Procedure 213 Reassociation Procedure 214 Power Conservation 217 Power Management in Infrastructure Networks 217 Unicast frame buffering and delivery using the Traffic Indication Map (TIM) 218 Delivering multicast and broadcast frames: the Delivery TIM (DTIM) 221 IBSS Power Management 222 Timer Synchronization 226 Infrastructure Timing Synchronization 226 IBSS Timing Synchronization 227 Spectrum Management 228 Transmit Power Control (TPC) 228 Basic operation of transmit power control 230 Changes to the association process 230 Changing the transmission power 230 Dynamic Frequency Selection (DFS) 231 Basic operation of DFS 231 Quieting the channel 232 Measuring 232 Radar scan 233 IBSS operation 234 Action Frames 235 Measurement Request frame 236 Measurement Report 238 TPC Request and Report 241 Channel Switch Announcement 241 Chapter 9. Contention-Free Service with the PCF 243 Contention-Free Access Using the PCF 243 PCF Operation 244 Reserving the medium during the contention-free period 244 The polling list 245 Transmissions from the Access Point 245 Contention-Free Period Duration 247 Detailed PCF Framing 247 Contention-Free End (CF-End) 250 CF-End+CF-Ack 251 CF Parameter Set 251 Power Management and the PCF 252 Chapter 10. Physical Layer Overview 255 Physical-Layer Architecture 255 The Radio Link 255 Licensing and Regulation 257 Frequency allocation and unlicensed frequency bands 257 Other unlicensed bands 259 Spread Spectrum 260 Types of spread spectrum 261 RF Propagation with 802.11 262 Signal Reception and Performance 262 The Shannon limit 263 Path Loss, Range, and Throughput 264 Multipath Interference 266 Inter-Symbol Interference (ISI) 267 RF Engineering for 802.11 268 RF Components 268 Antennas 268 Amplifiers 270 Chapter 11. The Frequency-Hopping (FH) PHY 271 Frequency-Hopping Transmission 271 802.11 FH Details 272 802.11 Hop Sequences 274 Joining an 802.11 Frequency-Hopping Network 274 ISM Emission Rules and Maximum Throughput 275 Effect of Interference 275 Gaussian Frequency Shift Keying (GFSK) 276 2-Level GFSK 276 4-Level GFSK 277 FH PHY Convergence Procedure (PLCP) 278 Framing and Whitening 279 Frequency-Hopping PMD Sublayer 281 PMD for 1.0-Mbps FH PHY 281 PMD for 2.0-Mbps FH PHY 281 Carrier sense/clear channel assessment (CS/CCA) 282 Characteristics of the FH PHY 282 Chapter 12. The Direct Sequence PHYs: DSSS and HR/DSSS (802.11b) 283 Direct Sequence Transmission 283 Encoding in 802.11 Direct Sequence Networks 285 Radio Spectrum Usage in 802.11 Direct Sequence Networks 286 Channel energy spread 287 Adjacent channel rejection and channel separation 288 Maximum theoretical throughput 289 Interference response 290 Differential Phase Shift Keying (DPSK) 290 Differential Binary Phase Shift Keying (DBPSK) 290 Differential Quadrature Phase Shift Keying (DQPSK) 292 The “Original” Direct Sequence PHY 293 PLCP Framing and Processing 294 DS Physical Medium Dependent Sublayer 295 Transmission at 1.0 Mbps 295 Transmission at 2.0 Mbps 295 CS/CCA for the DS PHY 296 Characteristics of the DS PHY 296 Complementary Code Keying 297 High Rate Direct Sequence PHY 298 PLCP Framing and Scrambling 298 HR/DSSS PMD 301 Transmission at 1.0 Mbps or 2.0 Mbps 301 Transmission at 5.5 Mbps with CCK 302 Transmission at 11 Mbps with CCK 303 Clear channel assessment 304 Optional Features of the 802.11b PHY 304 Characteristics of the HR/DSSS PHY 305 Chapter 13. 802.11a and 802.11j: 5-GHz OFDM PHY 307 Orthogonal Frequency Division Multiplexing (OFDM) 308 Carrier Multiplexing 308 Orthogonality Explained (Without Calculus) 309 Guard Time 309 Cyclic Extensions (Cyclic Prefixes) 311 Windowing 313 OFDM as Applied by 802.11a 313 OFDM Parameter Choice for 802.11a 314 Structure of an Operating Channel 314 Subchannel modulation techniques 314 Forward error correction with convolutional coding 316 Subchannel interleaving 318 Operating Channels 319 OFDM PLCP 322 Framing 322 Preamble 322 Header 323 Data 324 Trailer 324 OFDM PMD 324 Encoding and Modulation 325 Radio Performance: Sensitivity and Channel Rejection 325 Clear Channel Assessment 326 Transmission and Reception 327 Acknowledgment 327 An example of OFDM encoding 328 Characteristics of the OFDM PHY 328 Chapter 14. 802.11g: The Extended-Rate PHY (ERP) 331 802.11g Components 331 Compatibility Changes 332 Protection 333 ERP Physical Layer Convergence (PLCP) 336 ERP-OFDM Framing 337 Single-Carrier Framing with 802.11g 337 PBCC coding 339 DSSS-OFDM framing 340 ERP Physical Medium Dependent (PMD) Layer 340 Clear Channel Assessment (CCA) 341 Reception Procedure 342 Characteristics of the ERP PHY 343 Chapter 15. A Peek Ahead at 802.11n: MIMO-OFDM 345 Common Features 346 Multiple-Input/Multiple-Output (MIMO) 346 Channel Width 347 MAC Efficiency Enhancements 347 WWiSE 348 MAC Enhancements 348 Channels and radio modes 349 Protection 349 Aggregation, bursting, and acknowledgment 350 The WWiSE MIMO PHY 351 Structure of an operating channel 351 Modulation and encoding 352 Interleaver 352 Space-time block coding 352 Modulation rates 353 MIMO and transmission modes 354 WWiSE PLCP 355 The SIGNAL-N field 356 WWiSE PMD 357 Characteristics of the WWiSE PHY 358 TGnSync 359 TGnSync MAC Enhancements 360 Channels, radio modes, and coexistence 360 Aggregation and bursting 361 Protection 363 Powersaving 366 TGnSync PHY Enhancements 367 Structure of a channel 367 Basic MIMO rates 367 Transmit modes 368 Optional coding 369 Optional short guard interval 370 TGnSync Physical Transmission (PLCP and PMD) 370 Legacy header 370 High Throughput header 371 High-Throughput training fields 373 Data, tail, and padding 373 TGnSync PMD 374 Comparison and Conclusions 374 Chapter 16. 802.11 Hardware 377 General Structure of an 802.11 Interface 377 Software-Defined Radios: A Digression 379 A Few Words on 802.11 Hardware Implementations 381 Learning more about cards: FCC filings 381 Implementation-Specific Behavior 382 Rebooting Interface Cards 382 Scanning and Roaming 383 Rate Selection 384 Reading the Specification Sheet 384 Sensitivity Comparison 385 Delay Spread 385 Chapter 17. Using 802.11 on Windows 387 Windows XP 387 Card Installation 388 Third-party 802.1X stacks and the driver update process 388 Cisco client software 389 Choosing a Network 390 Configuring Security Parameters and 802.1X 391 Configuring EAP Methods 395 EAP-TLS 395 PEAP version 0 396 Clearing credentials from the registry 397 SecureW2: TTLS with ZeroConfig 399 WPA Configuration and Installation 400 Windows 2000 401 Dynamic WEP Configuration 403 Windows Computer Authentication 403 How It Works 404 Chapter 18. 802.11 on the Macintosh 407 The AirPort Extreme Card 407 Software Installation 408 Configuring and Monitoring an AirPort Interface 409 Basic configuration with the AirPort status icon 410 Configuration with the System Preferences application 411 Monitoring the wireless interface 412 802.1X on the AirPort 412 Configuring EAP Methods 413 TTLS configuration 413 PEAP configuration 414 The Keychain 415 Adding to the keychain 416 Troubleshooting 417 Chapter 19. Using 802.11 on Linux 421 PCMCIA Support on Linux 421 PCMCIA Card Services Overview 422 Interface names in Linux 424 Hotplug system for automatic configuration 424 PCMCIA Card Services Installation 425 Monitoring the Cards 425 The lights are not useful 427 Troubleshooting Resource Conflicts 427 IRQs 427 I/O ports 428 Linux Wireless Extensions and Tools 430 Compiling and Installing 430 Interface Configuration with Wireless Tools and iwconfig 430 Finding networks 431 Setting the network name 432 Setting the network channel 433 Setting the network mode and associating with an access point 434 Setting the data rate 434 Configuring static WEP keys 434 Tuning 802.11 parameters 435 Agere (Lucent) Orinoco 436 Compiling and Installing 437 PCMCIA configuration 437 Doing it yourself 437 Configuring the orinoco_cs Interface 438 Atheros-Based cards and MADwifi 439 Driver Architecture and the Hardware Access Layer (HAL) 439 Requirements 440 Building the Driver 440 Using the Driver 441 802.1X on Linux with xsupplicant 442 Requirements 442 Compiling and Installing xsupplicant 443 Configuring xsupplicant 443 Pseudorandom number generation 445 Connecting and Authenticating to a Network 445 WPA on Linux 448 Chapter 20. Using 802.11 Access Points 449 General Functions of an Access Point 450 Types of Access Points 452 For the home: residential gateways 452 For the office: enterprise access points 454 For the large office: wireless switches 456 Power over Ethernet (PoE) 456 Types of PoE 457 Selecting Access Points 458 Are Access Points Really Necessary? 461 Cisco 1200 Access Point 462 Setting Up the 1200 462 Configuring Radio Interfaces 463 Internetworking 464 Configuring Security 465 Configuring WPA-PSK 466 Monitoring 466 Troubleshooting 467 Apple AirPort 467 First-Time Setup 468 The Management Interface 468 Configuring the wireless interface 469 Configuration of the LAN interface 469 Access control 471 Chapter 21. Logical Wireless Network Architecture 473 Evaluating a Logical Architecture 473 Mobility 473 Defining “mobility” 474 Security 478 Performance 479 Backbone Engineering 484 Beacons, BSSIDs, and VLAN integration 484 IP addressing 485 Network Services 485 DHCP 485 Operating system login 486 Client Integration 486 Topology Examples 487 Topology 1: The Monolithic Single-Subnet Network 487 Mobility 488 Address assignment through DHCP 491 Security 492 Backbone engineering 492 Performance 492 Client integration 493 Topology 2: “E.T. Phone Home” or “Island Paradise” 494 Mobility 495 Security 496 Performance 497 Backbone 498 Client 498 Topology 3: Dynamic VLAN Assignment 499 Mobility 499 Security 500 Performance 502 Backbone 502 Client 504 Topology 4: Virtual Access Points 504 Mobility 506 Security 507 Performance 508 Backbone 508 Client 508 Choosing Your Logical Architecture 509 Chapter 22. Security Architecture 513 Security Definition and Analysis 514 Wireless LAN Security Problems 515 Your credentials, please: authentication 515 Secrecy over the air: encryption 515 Secrecy and integrity of the whole network: rogue access points 516 Network integrity: traffic injection 517 Network availability: denial of service 517 Network integrity and availability: rogue clients 517 Network integrity: traffic separation 518 Authentication and Access Control 519 Station Authentication and Association 520 Link-Layer Authentication 521 WPA Personal (preshared key) 522 802.1X-based EAP authentication 523 Network Layer Authentication 525 Integrating User Authentication Through RADIUS 526 RADIUS authentication and Microsoft Windows databases 527 Ensuring Secrecy Through Encryption 528 Static WEP 529 Dynamic WEP Keying with 802.1X 530 Improved RC4-Based Encryption: TKIP 532 CCMP: Encryption with AES 532 Higher Layer Security Protocols (IPsec, SSL, and SSH) 533 Selecting Security Protocols 536 Applying Security in the Protocol Stack 536 Compound binding vulnerabilities 537 Encryption 538 Security certifications 538 Network support 539 Choose Authentication 540 Choosing an EAP method 540 Authentication architecture 543 Choose Encryption 545 Multiple SSID support 546 Rogue Access Points 547 Detection 547 Physical Location 548 Disabling Rogue APs 550 And now, a word from your lawyers 552 Chapter 23. Site Planning and Project Management 555 Project Planning and Requirements 556 Network Requirements 558 Coverage Requirements 559 Coverage and physical installation restrictions 561 Performance Requirements 562 Exploring the coverage/quality trade-off and total area throughput 563 Client limitations 565 Realistic throughput expectations 566 Number of users per access point 567 Mobility Requirements 568 Network Integration Requirements 568 Physical integration 568 Logical integration 569 Physical Layer Selection and Design 569 2.4 GHz (802.11b/g) Channel Layout 570 Limitations of the 2.4 GHz channel layout 572 5 GHz (802.11a) Channel Layout 573 Mixed Channel Layouts (802.11a+b/g Networks) 573 Planning Access-Point Placement 574 The Building 574 Constraints on AP placement 575 Buildings in progress 577 The Preliminary Plan 577 The preliminary report 579 Radio Resource Management and Channel Layout 579 Refining and Testing the Plan 580 Validation and test tools 581 RF fingerprint collection 582 Preparing the Final Report 582 Using Antennas to Tailor Coverage 582 Antenna Types 583 Antenna cabling 586 Antenna diversity 587 Amplifiers: bring on the heat 588 Chapter 24. 802.11 Network Analysis 591 Network Analyzers 591 802.11 Network Analyzers 593 Ethereal 594 Compilation and Installation 594 Setting the Wireless Interface for Monitor Mode 595 Cisco Aironet cards 595 Prism cards 595 Orinoco cards 596 Atheros-based cards 596 Running Ethereal 597 Capturing data 598 Data Reduction 599 Capture filters 599 Display filters 599 Using Ethereal for 802.11 Analysis 600 Display filters 600 Understanding the LLC header to isolate a protocol 602 802.11 Network Analysis Checklist 603 Display Filter Primitives 603 Excluding Beacon frames 604 Isolating traffic from one station 604 Isolating a protocol 605 Common Troubleshooting Tasks 605 Authentication troubleshooting 605 Key distribution troubleshooting 606 Performance troubleshooting 606 Decrypting WEP traffic 608 RADIUS analysis 608 Other Tools 608 Finding, Measuring, and Mapping Networks 609 WEP Key Recovery 610 Key recovery time estimates 610 Authentication 610 Chapter 25. 802.11 Performance Tuning 611 802.11 Performance Calculations 611 Example Calculation 613 Other components to a performance model 614 Block acknowledgments 614 Improving Performance 614 Tunable 802.11 Parameters 616 Radio Management 616 Beacon interval 616 RTS threshold 617 Fragmentation threshold 618 Retry limits 618 Tuning Power Management 618 Listen interval 619 DTIM Period 619 ATIM window 620 Timing Operations 620 Scan timing 620 Timers related to joining the network 620 Dwell time (frequency-hopping networks only) 621 Summary of Tunable Parameters 621 Chapter 26. Conclusions and Predictions 623 Standards Work 623 New Standards 624 Task group E: quality of service extensions 624 Task group K: radio resources 624 Task group N: high-throughput (100+ Mbps) MIMO PHY 624 More distant standards 625 Related standards 625 Current Trends in Wireless Networking 625 Security 626 Authentication protocols 626 Admission control 627 Rogue device control 627 Deployment and Management 628 Planning a network 628 Backhaul 629 Mini-"regulators” and arbitrators 629 Guest access 630 Applications 631 Location 631 Voice 632 Datacasting 632 Protocol Architecture 633 Federations and mobility 633 Future protocols 634 The End 635 Glossary 637 Index 647 As we all know by now, wireless networks offer many advantages over fixed (or wired) networks. Foremost on that list is mobility, since going wireless frees you from the tether of an Ethernet cable at a desk. But that's just the tip of the cable-free iceberg. Wireless networks are also more flexible, faster and easier for you to use, and more affordable to deploy and maintain.The de facto standard for wireless networking is the 802.11 protocol, which includes Wi-Fi (the wireless standard known as 802.11b) and its faster cousin, 802.11g. With easy-to-install 802.11 network hardware available everywhere you turn, the choice seems simple, and many people dive into wireless computing with less thought and planning than they'd give to a wired network. But it's wise to be familiar with both the capabilities and risks associated with the 802.11 protocols. And 802.11 Wireless Networks: The Definitive Guide, 2nd Edition is the perfect place to start.This updated edition covers everything you'll ever need to know about wireless technology. Designed with the system administrator or serious home user in mind, it's a no-nonsense guide for setting up 802.11 on Windows and Linux. Among the wide range of topics covered are discussions on:deployment considerationsnetwork monitoring and performance tuningwireless security issueshow to use and select access pointsnetwork monitoring essentialswireless card configurationsecurity issues unique to wireless networksWith wireless technology, the advantages to its users are indeed plentiful. Companies no longer have to deal with the hassle and expense of wiring buildings, and households with several computers can avoid fights over who's online. And now, with 802.11 Wireless Networks: The Definitive Guide, 2nd Edition, you can integrate wireless technology into your current infrastructure with the utmost confidence. As we all know by now, wireless networks offer many advantages over fixed (or wired) networks. Foremost on that list is mobility, since going wireless frees you from the tether of an Ethernet cable at a desk. But that's just the tip of the cable-free iceberg. Wireless networks are also more flexible, faster and easier for you to use, and more affordable to deploy and maintain. The de facto standard for wireless networking is the 802.11 protocol, which includes Wi-Fi (the wireless standard known as 802.11b) and its faster cousin, 802.11g. With easy-to-install 802.11 network hardware available everywhere you turn, the choice seems simple, and many people dive into wireless computing with less thought and planning than they'd give to a wired network. But it's wise to be familiar with both the capabilities and risks associated with the 802.11 protocols. And 802.11 Wireless The Definitive Guide , 2nd Edition is the perfect place to start. This updated edition covers everything you'll ever need to know about wireless technology. Designed with the system administrator or serious home user in mind, it's a no-nonsense guide for setting up 802.11 on Windows and Linux. Among the wide range of topics covered are discussions With wireless technology, the advantages to its users are indeed plentiful. Companies no longer have to deal with the hassle and expense of wiring buildings, and households with several computers can avoid fights over who's online. And now, with 802.11 Wireless The Definitive Guide , 2nd Edition, you can integrate wireless technology into your current infrastructure with the utmost confidence.