Internet技术基础 英文版PDF电子书下载

Preface 1

Chapter 1 The Internet Has Arrived 1

The World Is Changing 1

Numbers Do Not Tell The Story 2

Learning About The Internet 3

Understanding The Big Picture 3

Terininology And Technology 4

Growth And Adaptability 4

The Impact Of The Internet 4

Organization Of The Book 4

A Personal Note 5

Chapter 2 Getting Started: Hands-On Experience 7

Introduction 7

Using A Browser 8

Web Browsers and Browsing 8

The Web: Sites And Pages 8

Examples Of Wed Sites And Services 9

Summary 11

PART I Introduction To Networking 15

Chapter 3 Telephones Everywhere 15

Introduction 15

A Communication Service 15

Selling Communication 15

Limited Access 16

High Cost 17

The Difficult Transition 17

Ubiquitous Access 18

Relevance To The Internet 19

Sound, Vibrations, And Analog Recording 21

Chapter 4 The World Was Once Analog 21

Introduction 21

Analog Electronic Devices 22

Many Electronic Devices Are Analog 23

The First Analog Communication 23

Analog Is Simple But Inaccurate 23

Sending An Analog Signal Across A Wire 24

Digital Music 25

The Digital Revolution 25

Computers Are Digital 26

Digital Recording 26

Using Digital To Recreate Analog 26

Why Digital Music? 28

Summary 28

The World Was Once Digital 31

Chapter 5 The Once And Future Digital Network 31

Introduction 31

A Telegraph Is Digital 32

Morse Code 32

Letters And Digits In Morse Code 33

Users Did Not Encounter Morse Code 34

Virtually Instant Communication 34

Speed Is Relative 34

The Telephone Became Digital 35

Televance To The Internet 35

Binary Encoding Of Data On The Internet 36

Why Use Two Symbols? 36

Summary 36

Introduction 37

Communication Using Electricity 37

Chapter 6 Basic Communication 37

Signals On Wires 38

Information Coding 38

Modems Allow Two-Way Traffic 39

A Character Code For Digital Information 40

Detecting Errors 41

Summary 43

Chapter 7 The Local Area Network Arrives 45

Introduction 45

Motivation 45

Interchangeable Media 46

A Computer Consists Of Circuit Boards 46

Circuit Boards Plug Into A Computer 46

Connecting One Computer To Another 47

LAN Technologies 48

Connecting A Computer To A LAN 49

The Importance Of LAN Technology 50

Relationship To The Internet 51

PARR II A Brief History Of The Internet 55

Chapter 8 Internet: The Early Years 55

Many Independent Networks 55

The Proliferation Of LANs 55

Facts About LANs 56

LANs Are Incompatible 57

Wide Area Technologies Exist 57

Few WANs, Many LANs 58

WANs and LANs Are Incompatible 58

The Desirability Of A Single Network 59

The Department Of Defense Had Multiple Networks 59

The ARPANET Backbone 60

Connecting Disconnected Machines 60

The Internet Emerges 60

Internet Software 61

The Name Is TCP/IP 61

The Shock Of An Open System 61

Open Systems Are Necessary 62

TCP/IP Documentation Is Online 63

The Military Adopts TCP/IP 64

Summary 64

A Personal Note 64

Chapter 9 Two Decades Of Incredible Growth 67

Introduction 67

Disseminating The Software 67

Meanwhile, Back In Computer Science 68

The Internet Meets UNIX 68

The Internet Doubles In Size In One Year 69

The U.S. Military Makes A Commitment 69

Every Computer Science Department 70

Graduate Students Volunteer Their Time 70

The IAB evolves 71

The IETF 72

Doubling Again In A Year 72

The Internet Improves Science 72

NSF Takes A Leadership Role 73

Target: All Of Science And Engineering 73

NSF s Approach 73

The NSFNET Backbone 74

The ANS Backbone 74

Exponential Growth 75

The End Of Growth 77

A Commercial Assessment 77

Introduction 79

Early ARPA Networks 79

Electronic Mail Among Computers 79

Chapter 10 The Global Internet 79

BITNET And FIDONET 80

Networks In Europe 80

EBONE: The Internet In Europe 82

Backbones And Internet Hierarchy 82

Internet On All Continents 83

The World Of Internet after 1998 84

A Personal Note 85

Introduction 87

Existing Infrastructure 87

Chapter 11 A Global Information Infrastructure 87

Communication Infrastructure 88

The Internet Infrastructure 90

The Internet Offers Diverse Information Services 90

TCP/IP Provides Communication Facilities 90

A Personal Note 91

PART III How The Internet Works 95

Chapter 12 Packet Switching 95

Introduction 95

Sharing Saves Money 95

Sharing Introduces Delays 95

Sharing Wires 96

Selectable Channels 96

Sharing By Taking Turns 97

Computers Have Addresses 98

Each Packet Must Be Labeled 98

Packet Switching Avoids Delays 98

Packets Are Not All The Same Size 99

Packet Transmission Seems Instantaneous 99

Sharing Is Automatic 99

Network Hardware Handles Sharing 100

Many Devices Can Use Packet Switching 100

Relevance To The Internet 100

Summary 101

Chapter 13 Internet: A Network Of Networks 103

Introduction 103

Network Technologies Are Incompatible 103

Coping With Incompatibility 104

Two Fundamental Concepts 104

Using A Computer To Interconnect Networks 106

Interconnecting Computers Are Called Routers 107

Interconnecting Computers Pass Packets 107

Routers Are The Building Blocks Of The Internet 108

Routers Accommodate Multiple Types Of Networks 108

Routers Can Interconnect WANs And LANs 109

Interconnecting Networks Was Revolutionary 110

Summary 110

Chapter 14 ISPs And Network Connections 111

Introduction 111

Internet Service Providers And Fees 111

Customer Connections Form The Last Mile 112

Leased Circuits Are Expensive 112

Most Individuals Choose Dial-up Access 113

The Important Concept Of Continuous Connectivity 113

Instantaneous Access Changes Use 114

Newer Technologies Offer Inexpensive Dedicated Access 115

A Personal Note 117

Wireless Can Reach Everyone 117

Chapter 15 IP: Software To Create A Virtual Network 119

Introduction 119

Protocol: An Agreement For Communication 119

Basic Functionality: The Internet Protocol 120

IP Software On Every Machine 120

Internet Packets Are Called Datagrams 120

The Illusion Of A Giant Network 121

The Reality Of Internal Structure 122

Datagrams Travel In Packets 123

Every Computer Is Assigned A Unique Address 123

An Odd IP Address Syntax 124

IP Addresses Are Not Random 124

Internet Addresses 124

An Example Trip Through The Internet 125

Summary 126

Chapter 16 TCP: Software For Rellable Communication 127

Introduction 127

A Packet Switching System Can Be Overrun 127

TCP Helps IP Guarantee Delivery 129

TCP Provides A Connection Between Computer Programs 130

The Magic Of Recovering Lost Datagrams 130

TCP Retransmission Is Automatic 131

TCP And IP Work Together 131

Summary 132

Chapter 17 Clients+Servers=Distributed Computing 133

Introduction 133

Large Computers Use Networks For Input And Output 133

Distributed Computing On The Internet 134

Small Computers Use Networks To Interact 134

A Single Paradigm Explains All Distributed Computing 135

Programs Are Clients Or Servers 136

A Server Must Always Run 137

Summary 137

Chapter 18 Names For Computers 139

Introduction 139

People Prefer Names To Numbers 139

Naming A Computer Can Be Difficult Or Fun 140

Computer Names Must Be Unique 141

Suffixes On Computer Names 141

Names With Many Parts 142

Domain Names Outside The US 143

Translating A Name To An Equivalent IP Address 143

Computer Name Lookup Is Automatic 144

Domain Name System Works Like Directory Assistance 144

IP Addresses And Domain Names Are Unrelated 146

Summary 147

Chapter 19 Why The Internet Works Well 149

Introduction 149

The Internet Works Well 149

IP Provides Flexibility 150

TCP Provides Reliability 151

TCP/IP Software Was Engineered For Efficiency 151

TCP/IP Research Emphasized Practical Results 152

The Formula For Success 152

Summary 153

Description Of Functionality 157

Introduction 157

Chapter 20 Electronic Mail 157

PART IV Services Available On The Internet 157

The Best Of All Worlds 158

Each User Has A Mailbox For E-mail 158

Sending An E-mail Message 158

Notification That E-mail has Arrived 158

Reading An E-mail Message 159

E-mail Messages Look Like Interoffice Memos 159

E-mail Software Fills In Header Information 160

How E-mail Works 161

Using E-mail From A Personal Computer 162

Mailbox Address Format 162

Abbreviations Make E-mail Friendly 163

Aliases Permit Arbitrary Abbreviations 163

Sending To Multiple Recipients 164

Aliases Shared By All Users Of A Computer System 164

Mailing List: An Alias for Multiple Recipients 165

Public Mailing Lists And Mail Exploders 165

E-mail To And From Non-Internet Sites 166

Access To Services Via E-mail 167

Speed, Reliability, And Expectations 167

Impact And Significance Of Electronic Mail 168

Joining A Mailing List 169

Chapter 21 Bulletin Board Service (Network News) 171

Introduction 171

Description Of Functionality 171

Many Bulletin Boards With Diverse Topics 172

Network News 173

Newsgroup Names 173

Obtaining Network News And The Software To Read Articles 174

How Network News Appears To A User 175

Checking For News Articles 175

Article Expiration 175

Reading Network News 176

Selecting Articles 176

Subscribing And Unsubscribing To Newsgroups 178

Submitting An Article 178

Moderated Newsgroups 178

Size Of Network News 179

How Network News Works 179

Redundant Newsfeeds And Duplcate Elimination 180

Relationship Between Netnews And Electronic Mail 181

Impact And Significance Of Network News And Mailing Lists 181

Hints And Conventions For Participating In Discussions 182

Summary 183

Chapter 22 Browsing The World Wide Web 185

Introduction 185

Description Of Functionality 185

Browsing Vs. Information Retrieval 186

Early Browsing Services Used Menus 186

A Menu Item Can Point To Another Computer 187

How A Browser Works 187

An Example Point-And-Click Interface 188

Combining Menu Items With Text 189

The Importance Of Integrated Menus 191

Menus Embedded In Text Are Called Hypertext 191

Multimedia 193

Video And Audio References Can Be Embedded In Text 194

Browser Software Used To Access The Web 195

The World Wide Web 195

An Example Hypermedia Display 196

Control Of The Browser 198

External References 199

Recording The Location Of Information 199

Bookmarks 201

How The World Wide Web Works 202

A URL Tells A Browser Which Computer To Contact 202

A URL Tells A Browser Which Server To Contact 202

Use Of The Name WWW In URLs 203

A Browser Provides Access To Multiple Services 204

Inside A Browser Program 204

Summary 205

An Observation About Hypermedia Browsing 206

Display Hardware Varies 207

Chapter 23 World Wide Web Documents (HTML) 207

Introduction 207

A Browser Translates And Display A Web Document 208

A Consequence Of The Web Approach 208

HTML, The Language Used For Web Documents 209

Instructions In A Web Page Control The Output 210

A Web Page Is Divided Into Two Main Sections 210

Indentation Can Make HTML Readable 211

The Body Of A Web Page Can Contain Text 212

Indentation Can Make Paragraphs Easier To Find 213

A Web Page Can Link To Another Page 214

HTML Allows Numbered And Unnumbered Lists 215

Images On A Web Page Are Digital 216

HTML Allows A Web Page To Include An Image 217

Text Can Appear Adjacent To An Image 218

Images Can Link To Another Web Page 219

Some Browsers Can Stretch Or Shrink Images 220

The Background Can Be Controlled 220

Other Features Of HTML 220

Importance Of HTML 221

GUI Tools Help With Web Page Creation 221

Summary 222

Chapter 24 Advanced Web Technologies (Forms, Frames, Plugins, CGI, Java, JavaScript) 223

Introduction 223

Conventional Web Pages Are Static 223

How A Server Stores Static Web Pages 224

Fetching Items One At A Time 226

Conventional Web Pages Use The Entire Screen 226

A Web Page Can Change Part Of the Screen 227

The Web, Advertising, And Frames 229

Static Document Have Disadvantages 230

Controlling How A Browser Processes Data 230

Plugins Allow Variety 232

A Server Can Compute A Web Page On Demand 232

How CGL Works 233

Professional Programmers Build CGI Programs 235

Personalized Web Pages 235

Personalized Advertisements 236

Web Pages Can Interact 236

Shopping Carts 237

Cookies 237

Should You Accept Cookies? 238

A Web Page Can Display Simple Animations 238

Active Documents Are More Powerful 239

JavaScript Is An Active Document Technology 241

Java Is An Active Document Technology 241

The Importance Of Advanced Web Technologies 242

Chapter 25 Automated Web Search (Search Engines) 243

Introduction 243

Description Of Functionality 243

Browsing Vs. Automated Searching 244

A Search Engine Helps Users Get Started 244

A Search Tool Can Help Recover From Loss 245

Automated Searching By Name 245

How An Automated Search Service Operates 246

Modern Systems Search Web Page Contents 248

How A Web Search Appears To A User 248

How A Search Engine Returns Results 249

Automated Search Services Use String Matching 250

The Advantages And Disadvantages Of String Matching 251

Advanced Search Programs That Use Multiple Keys 252

Aevanced Services Offer More Sophisticated Matching 252

Personalized Search Results 253

How An Automated Content Search Works 254

Searches Are Restricted 255

Advertising Pays For Searching 255

Examples Of Automated Search Services 256

Significance Of Automated Web Search 256

Chapter 26 Audlo And Video Communication 257

Introduction 257

Description Of Functionality 257

Audio And Video Require Special Hardware 258

Real-Time Means No Delay 259

Internet Audio In Real-Time 259

An Audio Clip Resembles An Audio CD 259

Radio Programs On The Internet 260

Real-Time Transmission Is Called Webcasting 261

Internet Telephone Service Is Possible 261

Audio Teleconferencing 262

A Cooperative Document Markup Service 262

Marking A Document 264

The Participants Discuss And Mark A Document 265

Video Teleconferencing 266

Video Teleconference Among Groups Of People 267

A Combined Audio, Video, And Whiteboard Service 267

Summary 267

A Personal Note 268

Sending A Fax 269

Introduction 269

Chapter 27 Faxes And Files (FTP) 269

The Internet Can Be Used To Copy Files 270

Data Stored In Files 270

Copying A File 271

FTP IS Interactive 271

Example FTP Commands 271

A User Can Store Or Retrieve A File 272

Commands For Binary And Text File Format 272

Choosing ASCII or Binary Transfer 273

Commands For Authorization And Anonymous FTP 273

A Browser Can Use FTP 274

How FTP Works 274

Impact And Significance Of FTP 275

Summary 275

Early Computers Used Textual Interfaces 277

Introduction 277

Chapter 28 Remote Login And Remote Desktops (TELNET) 277

A Timesharing System Requires User Identification 278

Remote Login Resembles Conventional Login 278

How Remote Login Works 279

Escaping From Remote Login 280

Displays And Windows 280

The Internet Remote Login Standard Is TELNET 280

Remote Access Can Display A Desktop 281

How Remote Desktops Operate 282

Assessment Of Remote Login And Desktops 282

Remote Access Is General 283

Generality Makes Remote Login And Desktops Powerful 283

Remots Access Accommodates Multiple Types Of Computers 283

Summary 284

Unexpected Results From Remote Access 284

Chapter 29 Facilities For Secure Communication 287

Introduction 287

The Internet Is Unsecure 287

Lack Of Security Can Be Important 288

Authentication And Privacy Are Primary Problems 288

Data May Be Changed 289

Encoding Keeps Messages Private 289

Computer Encryption Uses Mathematics 289

No Network Is Absolutely Secure 290

Encryption Makes E-mail Private 290

Encryption Software Needs A Key 291

Two Keys Means Never Having To Trust Anyone 291

Secure E-Mail In Practice 293

Summary 293

E-Commerce Is Big Business 295

Chapter 30 Electronic Commerce And Business 295

Introduction 295

Security Made E-Commerce Possible 296

Secure Sockets 296

Public Key Encryption Provides Authenticity 297

Digital Signatures 298

Certificates Contain Public Keys 298

What Is Digital Money? 299

Digital Cash Is Not Widely Available 299

Business And E-Commerce 300

A Business Must Protect Its Networks 300

Firewalls Protect Networks 300

A Firewall Filters Packets 301

Firewalls Guard Against Trojan Horses 301

A Cornucopia Of Services 303

Chapter 31 The Global Digital Library 303

Introduction 303

New Services Appear Regularly 304

Flexibility Permits Change 304

A Digital Library 305

Card Catalogs And Search Tools 305

Internet Services Can Be Integrated 305

Mr. Dewey, Where Are You? 306

Information In The Digital Library 307

What Is The Internet? 307

A Personal Note 307

Appendix 1 Example Netnews Newsgroups 309

Appendix 2 Glossary Of Internet Terms 319

Index 345