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• Familiarity with computer basics

• Basic knowledge of computer operating systems

A quick, easy introduction

to Windows

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Sams Teach YourselfShell Programming in

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A beginner’s guide to finding and fixing networkproblems

What this book will help you learn…

• How to set up and administer a TCP/IP network

• How to troubleshoot network problems

Sams Teach Yourself

24 in

Hours

Sams Teach Yourself TCP/IP in 24 Hours

Copyright © 2009 by Pearson Education, Inc

All rights reserved No part of this book shall be reproduced, stored in a retrieval system, or

transmitted by any means, electronic, mechanical, photocopying, recording, or otherwise, without

written permission from the publisher No patent liability is assumed with respect to the use of

the information contained herein Although every precaution has been taken in the preparation of

this book, the publisher and author assume no responsibility for errors or omissions Nor is any

liability assumed for damages resulting from the use of the information contained herein

1 TCP/IP (Computer network protocol) I Title II Title: Teach yourself TCP/IP in 24 hours

III Title: TCP/IP in 24 hours

TK5105.585.C37 2009

005.7’1376—dc22

2008031826Printed in the United States of America

First Printing September 2008

Trademarks

All terms mentioned in this book that are known to be trademarks or service marks have been

appropriately capitalized Sams Publishing cannot attest to the accuracy of this information Use

of a term in this book should not be regarded as affecting the validity of any trademark or service

mark

Warning and Disclaimer

Every effort has been made to make this book as complete and as accurate as possible, but no

warranty or fitness is implied The information provided is on an “as is” basis The author and the

publisher shall have neither liability nor responsibility to any person or entity with respect to any

loss or damages arising from the information contained in this book

Bulk Sales

Sams Publishing offers excellent discounts on this book when ordered in quantity for bulk

pur-chases or special sales For more information, please contact

U.S Corporate and Government Sales

Contents at a Glance

Part I: TCP/IP Basics

HOUR 1 What Is TCP/IP? . 7

2 How TCP/IP Works . 21

Part II: The TCP/IP Protocol System HOUR 3 The Network Access Layer . 35

4 The Internet Layer . 47

5 Subnetting and CIDR . 69

6 The Transport Layer . 83

7 The Application Layer . 107

Part III: Networking with TCP/IP HOUR 8 Routing . 121

9 Getting Connected . 143

10 Firewalls . 175

11 Name Resolution . 185

12 Automatic Configuration . 215

13 IPv6—The Next Generation . 229

Part IV: TCP/IP Utilities HOUR 14 TCP/IP Utilities . 243

15 Monitoring and Remote Access . 275

Part V: TCP/IP and the Internet HOUR 16 The Internet: A Closer Look . 297

17 HTTP, HTML, and the World Wide Web . 305

18 Email . 321

19 Streaming and Casting . 339

Part VI: Advanced Topics

HOUR 20 Web Services . 353

21 The New Web . 363

22 Network Intrusion . 375

23 TCP/IP Security . 391

24 Implementing a TCP/IP Network—Seven Days in the Life of a Sys Admin . 413

Index . 425

iv

Sams Teach Yourself TPC/IP in 24 Hours

Table of Contents

Part I: TCP/IP Basics

Networks and Protocols . 8

The Development of TCP/IP . 10

TCP/IP Features . 12

Standards Organizations and RFCs . 17

Summary . 18

Q&A . 19

Key Terms . 19

HOUR 2: How TCP/IP Works 21 The TCP/IP Protocol System . 22

TCP/IP and the OSI Model . 24

Data Packages . 26

A Quick Look at TCP/IP Networking . 28

Summary . 30

Q&A . 30

Key Terms . 31

Part II: The TCP/IP Protocol System HOUR 3: The Network Access Layer 35 Protocols and Hardware . 35

The Network Access Layer and the OSI Model . 37

Network Architecture . 38

Physical Addressing . 40

Ethernet . 41

Anatomy of an Ethernet Frame . 43

Summary . 44

Q&A . 44

Key Terms . 45

HOUR 4: The Internet Layer 47 Addressing and Delivering . 48

Internet Protocol (IP) . 50

Address Resolution Protocol (ARP) . 62

Reverse ARP (RARP) . 63

Internet Control Message Protocol (ICMP) . 63

Other Internet Layer Protocols . 64

Summary . 65

Q&A . 65

Workshop . 66

Key Terms . 66

HOUR 5: Subnetting and CIDR 69 Subnets . 69

Dividing the Network . 70

Converting a Subnet Mask to Dotted Decimal Notation . 73

Working with Subnets . 75

Classless Internet Domain Routing (CIDR) . 80

Summary . 81

Q&A . 81

Key Terms . 82

HOUR 6: The Transport Layer 83 Introducing the Transport Layer . 84

Transport Layer Concepts . 85

Understanding TCP and UDP . 91

Firewalls and Ports . 101

vi

Sams Teach Yourself TPC/IP in 24 Hours

Summary . 102

Q&A . 103

Key Terms . 104

HOUR 7: The Application Layer 107 What Is the Application Layer? . 107

The TCP/IP Application Layer and OSI . 108

Network Services . 109

APIs and the Application Layer . 114

TCP/IP Utilities . 115

Summary . 116

Q&A . 116

Key Terms . 117

Part III: Networking with TCP/IP HOUR 8: Routing 121 Routing in TCP/IP . 121

Routing on Complex Networks . 134

Examining Interior Routers . 136

Classless Routing . 138

Higher in the Stack . 139

Summary . 140

Q&A . 140

Key Terms . 141

HOUR 9: Getting Connected 143 Dial-Up Networking . 144

Cable Broadband . 151

Digital Subscriber Line (DSL) . 153

Wide Area Networks (WANs) . 154

Wireless Networking . 155

Connectivity Devices . 167

Contents vii

Summary . 171

Q&A . 171

Key Terms . 172

HOUR 10: Firewalls 175 What Is a Firewall? . 175

Firewall Options . 177

The DMZ . 178

Firewall Rules . 180

Proxy Service . 181

Reverse Proxy . 182

Summary . 183

Q&A . 183

Key Terms . 184

HOUR 11: Name Resolution 185 What Is Name Resolution? . 185

Name Resolution Using Hosts Files . 187

DNS Name Resolution . 189

Registering a Domain . 195

Managing DNS . 196

Dynamic DNS . 203

NetBIOS Name Resolution . 204

Summary . 211

Q&A . 211

Workshop . 212

Key Terms . 212

HOUR 12: Automatic Configuration 215 The Case for Server-Supplied IP Addresses . 215

What Is DHCP? . 216

How DHCP Works . 217

Configuring DHCP . 220

DHCP Server Configuration . 221

viii

Sams Teach Yourself TPC/IP in 24 Hours

Network Address Translation (NAT) . 223

Zero Configuration . 224

Summary . 227

Q&A . 227

Key Terms . 228

HOUR 13: IPv6—The Next Generation 229 Why a New IP? . 229

IPv6 Header Format . 232

IPv6 Addressing . 236

IPv6 with IPv4 . 237

IPv6 and Quality of Service (QoS) . 238

Summary . 239

Q&A . 239

Key Terms . 240

Part IV: TCP/IP Utilities HOUR 14: TCP/IP Utilities 243 Connectivity Problems . 244

Protocol Dysfunction and Misconfiguration . 245

Line Problems . 252

Name Resolution Problems . 253

Network Performance Problems . 254

Using Connectivity Utilities to Troubleshoot Problems . 261

File Transfer Protocol (FTP) . 262

Trivial File Transfer Protocol (TFTP) . 267

Remote Copy . 267

Integrating Network File Access . 268

Summary . 270

Q&A . 270

Workshop . 271

Key Terms . 272

Contents ix

Telnet . 275

Berkeley Remote Utilities . 278

Secure Shell (SSH) . 282

Screen Sharing . 283

Simple Network Management Protocol . 284

Remote Monitoring . 289

Summary . 291

Q&A . 291

Key Terms . 292

Part V: TCP/IP and the Internet HOUR 16: The Internet: A Closer Look 297 How the Internet Looks . 297

What Happens on the Internet . 299

URIs and URLs . 301

Summary . 304

Q&A . 304

Key Terms . 304

HOUR 17: HTTP, HTML, and the World Wide Web 305 What Is the World Wide Web? . 305

Understanding HTML . 308

Understanding HTTP . 313

Dynamic HTML . 316

Summary . 318

Q&A . 318

Key Terms . 319

HOUR 18: Email 321 What Is Email? . 321

Email Format . 322

How Email Works . 324

x

Sams Teach Yourself TPC/IP in 24 Hours

Simple Mail Transfer Protocol (SMTP) . 326

Retrieving the Mail . 328

Email Readers . 331

Webmail . 333

Spam . 334

Summary . 336

Q&A . 337

Workshop . 337

Key Terms . 338

HOUR 19: Streaming and Casting 339 The Streaming Problem . 339

Realtime Transport Protocol (RTP) . 341

Transport Options . 343

Multimedia Links . 344

Podcasting . 346

Voice Over IP (VoIP) . 347

Summary . 348

Q&A . 349

Key Terms . 349

Part VI: Advanced Topics HOUR 20: Web Services 353 Understanding Web Services . 353

XML . 355

SOAP . 357

WSDL . 358

Web Service Stacks . 358

E-Commerce . 359

Summary . 361

Q&A . 362

Key Terms . 362

Contents xi

Web 2.0 . 363

XHTML . 367

Peer-to-Peer . 368

IRC and Instant Messaging . 369

The Semantic Web . 371

Summary . 372

Q&A . 373

Key Terms . 373

HOUR 22: Network Intrusion 375 Vandals and Cyber-Crooks . 375

What Do Intruders Want? . 376

Root Access . 385

Going Phishing . 386

Denial-of-Service Attacks . 387

Summary . 389

Key Terms . 389

HOUR 23: TCP/IP Security 391 Encryption . 391

Securing TCP/IP . 402

Virtual Private Networks (VPNs) . 404

Kerberos . 406

Summary . 409

Q&A . 409

Key Terms . 410

HOUR 24: Implementing a TCP/IP Network—Seven Days in the Life of a Sys Admin 413 A Brief History of Hypothetical, Inc . 413

Seven Days in the Life of Maurice . 414

Summary . 422

Q&A . 423

xii

Sams Teach Yourself TPC/IP in 24 Hours

About the Author

Joe Casad is an engineer, author, and editor who has written widely on computer

network-ing and system administration He has written or co-written 12 books on computers and

networking In a past life, he was the editor of C/C++ Users Journal and senior editor of

UnixReview.com

Thanks to Trina MacDonald, Michael Thurston, Betsy Harris, and Ravi Prakash for their

patience and good advice I would also like to acknowledge the following individuals for

their contributions to previous editions of Sams Teach Yourself TCP/IP in 24 Hours: Bob

Willsey, Sudha Putnam, Walter Glenn, Art Hammond, Jane Brownlow, Jeff Koch, Mark

Renfrow, Vicki Harding, Mark Cierzniak, Marc Charney, and Jenny Watson

We Want to Hear from You!

As the reader of this book, you are our most important critic and commentator We value

your opinion and want to know what we’re doing right, what we could do better, what

areas you’d like to see us publish in, and any other words of wisdom you’re willing to pass

our way

You can email or write me directly to let me know what you did or didn’t like about this

book—as well as what we can do to make our books stronger

Please note that I cannot help you with technical problems related to the topic of this book, and

that due to the high volume of mail I receive, I might not be able to reply to every message.

When you write, please be sure to include this book’s title and author as well as your name

and phone or email address I will carefully review your comments and share them with the

author and editors who worked on the book

E-mail: networking@samspublishing.com

Editor-in-ChiefSams Publishing

1330 Avenue of the AmericasNew York, NY 10019 USA

Reader Services

Visit our website and register this book at informit.com/register for convenient access to any

updates, downloads, or errata that might be available for this book

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Introduction

Welcome to Sams Teach Yourself TCP/IP in 24 Hours, Fourth Edition This book provides a clear

and concise introduction to TCP/IP for newcomers, and also for users who have worked with

TCP/IP but would like a little more of the inside story The fourth edition includes new

material on recent developments in TCP/IP and offers a closer look at topics such as

. Firewalls

. Streaming

. Web services

You’ll find new chapters on casting and streaming, web services, and the new Web, as well

as several new sections throughout the book on recent developments in TCP/IP

Does Each Chapter Take an Hour?

Each chapter is organized so that you can learn the concepts within one hour The chapters

are designed to be short enough to read all at once In fact, you should be able to read a

chapter in less than one hour and still have time to take notes and reread more complex

sections in your one-hour study session

How to Use This Book

The books in the Sams Teach Yourself series are designed to help you learn a topic in a few

easy and accessible sessions Sams Teach Yourself TCP/IP in 24 Hours, Fourth Edition, is divided

into six parts Each part brings you a step closer to mastering the goal of proficiency in

TCP/IP

. Part I, “TCP/IP Basics,” introduces you to TCP/IP and the TCP/IP protocol stack

. Part II, “The TCP/IP Protocol System,” takes a close look at each of TCP/IP’s protocol

layers: the Network Access, Internet, Transport, and Application layers You learn

about IP addressing and subnetting, as well as physical networks and application

services You’ll also learn about the protocols that operate at each of TCP/IP’s layers

. Part III, “Networking with TCP/IP,” describes some of the devices, services, and utilities

necessary for supporting TCP/IP networks You learn about routing and network

hard-ware, DHCP, DNS, and IPv6

. Part IV, “TCP/IP Utilities,” introduces some of the common utilities used to configure,

manage, and troubleshoot TCP/IP networks You learn about Ping, Netstat, FTP,

Telnet, and other network utilities

. Part V, “TCP/IP and the Internet,” describes the world’s largest TCP/IP network: the

Internet You learn about the structure of the Internet You also learn about HTTP,

HTML, XML, email, and Internet streaming

. Part VI, “Advanced Topics,” describes topics such as web services, messaging, the

semantic web, and TCP/IP security Part VI ends with a case study showing how the

components of TCP/IP interact in a real working environment

The concepts in this book, like TCP/IP itself, are independent of a system and descend from

the standards defined in Internet Requests for Comment (RFCs)

How This Book Is Organized

Each hour in Sams Teach Yourself TCP/IP in 24 Hours, Fourth Edition, begins with a quick

intro-duction and a list of goals for the hour You can also find the following elements

Main Section

Each hour contains a main section that provides a clear and accessible discussion of the

hour’s topic You’ll find figures and tables helping to explain the concepts described in the

text Interspersed with the text are special notes labeled By The Way? These notes come

with definitions, descriptions, or warnings that help you build a better understanding of the

material

These boxes clarify a concept that is discussed in the text A By The Way mightadd some additional information or provide an example, but they typically aren’tessential for a basic understanding of the subject If you’re in a hurry, or if youwant to know only the bare essentials, you can bypass these sidebars

2

Sams Teach Yourself TCP/IP in 24 Hours

By the

Way

Q&A

Each hour ends with some questions designed to help you explore and test your

under-standing of the concepts described in the hour Complete answers to the questions are also

provided

Additionally, some hours include Workshops—exercises designed to help you

through the details or give you practice with a particular task You’ll find them only

in hours where a little real-world exploration will help build a better understanding

of the material Even if you don’t have the necessary software and hardware to

undertake some of the exercises in the Workshop, you might benefit from reading

through the exercises to see how the tools work in a real network implementation

Key Terms

Each hour includes a summary of important key terms that are introduced in the hour The

key terms are compiled into an alphabetized list at the end of each hour

Introduction

3

By the

Way

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PART I

TCP/IP Basics