The Internet book: everything you need to know about computer networking and how the Internet works/ Douglas E. Comer

Includes index.

Chapter 1 The Internet Has Arrived
The World Is Changing 1
Numbers Do Not Tell The Story 2
Learning About The Internet 3
Understanding The Big Picture 3
Terminology 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
Introduction 7
The Web: Sites And Pages 8
Web Browsers and Browsing 8
Using A Browser 8
Examples Of Web Sites And Services 9
Summary 11
PART I Introduction To Networking
Chapter 3 Telephones Everywhere
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
Chapter 4 The World Was Once Analog
Introduction 21
Sound, Vibrations, And Analog Recording 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
Chapter 5 The Once And Future Digital Network
Introduction 31
The World Was Once Digital 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 Commumcation 34
Speed Is Relative 34
The Telephone Became Digital 35
Relevance To The Internet 35
Binary Encoding Of Data On The Internet 36
Why Use Two Symbols? 36
Summary 36
Chapter 6 Basic Communication
Introduction 37
Communication Using Electricity 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 Locai Area Network Arrives
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
PART II A Brief History Of The Internet
Chapter 8 Internet: The Early Years
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
Connecting Disconnected Machines 60
The Internet Emerges 60
The ARPANET Backbone 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
Chapters Two Decades Of Incredible Growth
Introduction 67
Disseminating The Software 67
Meanwhile, Back In Computer Science 68
The Internet Meets UNIX 68
The U.S. Military Makes A Commitmmt 69
The Internet Doubles In Size In One Year 69
Every Computer Science Department 70
Graduate Students Volunteer Their Time 70
The lAB evolves 71
The IETF 12
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
A Commercial Assessment 77
The End Of Growth 77
Chapter 10 The Global Internet
Introduction 79
Early ARPA Networks 79
Electronic Mail Among Computers 79
BFTNET 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
Chapter 11 A Global Information Infrastructure
Introduction 87
Existing Infrastructure 87
Communication Infrastructure 88
The Internet Infrastructure 90
The Internet C^ers Diverse Information Services 90
TCP/IP Provides Communication Facilities 90
A Personal Note 91
PART III How The Internet Works
Chapter 12 Packet Switching
Introduction 95
Sharing Saves Money 95
Sharing Introduces Delays 95
Sharing Wires 96
Selectable Channels 96
Sharing By Taking Turns 97
Packet Switching Avoids Delays 98
Each Packet Must Be Labeled 98
Computers Have Addresses 98
Packets Are Not All The Same Size 99
Packet Transmission Seems Instantaneous 99
Sharing Is Automatic 99
Network Hardware. Handles Sharing 1(K)
Many Devices Can Use Packet Switching 100
Relevance To The Internet 100
Summary 101
Chapter 13 internet: A Network Of Networks
Introduction 103
Network Technologies Are Incompatible 103
Coping With Incompatibility 104
Two Fundamental Concepts 104
Using A Computer To Interconnect Networks 106
Interconnecting Computers Pass Packets 107
Interconnecting Computers Are Called Routers 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
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
Wireless Can Reach Everyone 117
A Personal Note 117
Chapter 15 IP: Software To Create A Virtual Network
•
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
Internet Addresses 124
An Odd IP Address Syntax 124
IP Addresses Are Not Random 124
An Example Trip Through The Internet 125
Summary 126
Chapter 16 TCP: Software For Reliable Communication
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 s Distributed Computing
Introduction 133
Large Computers Use Networks For Input And Output 133
Small Computers Use Networks To Interact 134
Distributed Computing On The Internet 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
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
Domain Name System Works Like Directory Assistance 144
Computer Name Lookup Is Automatic 144
IP Addresses And Domain Names Are Unrelated 146
Summary 147
Chapter 19 Why The internet Works Weil
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
PART IV Services Available On The Internet
Chapter 20 Electronic Mall
Introduction 157
Description Of Functionality 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
Aliases Shared By All Users Of A Computer System 164
Sending To Multiple Recipients 164
Mailing List: An Alias for Multiple Recipients 165
Public Mailing Lists And Mail Exploders 165
E-mail To And From Non-Intemet 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)
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 s ,,
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 Duplicate 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
Introduction 185
Description Of Functionality 185
Browsing Vs. Information Retrieval 186
Early Browsing Services Used Menus 186
A Mqnu 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
The World Wide Web 195
Browser Software Used To Access The 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
Chapter 23 World Wide Web Documents (HTML)
Introduction 207
Display Hardware Varies 207
A Browser Translates And Displays 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)
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 Til
The Web, Advertising, And Frames 229
Static Documents Have Disadvantages 230
XX O
Controlling How A Browser Processes Data 230
Plugins Allow Variety 232
A Server Can Compute A Web Page On Demand 232
How CGI 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 Single Animations 238
Active Documents Are More Powerful 239
Java Is An Active Document Technology 241
JavaScript Is An Active Document Technology 241
The Importance Of Advanced Web Technologies 242
Chapter 25 Automated Web Search (Search Engines)
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
Modem 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
Advanced 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 OfAutomated Search Services 256
Significance Of Automated Web Search 256
Chapter 26 Audio And Video Communication
Introduction 257
Description Of Functionality 257
Audio And Video Require Special Hardware 258
An Audio Clip Resembles An Audio CD 259
Real-Time Means No Delay 259
Internet Audio In Real-Time 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
Chapter 27 Faxes And Fiies (FTP)
Introduction 269
Sending A Fax 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 21A ^
How FTP Works 21A
Impact And Significance Of FTP 275
Summary 275
Chapter 28 Remote Login And Remote Desktops (TELNET)
Introduction 277
Early Computers Used Textual Interfaces 211
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
Remote Access Accommodates Multiple Types Of Computers 283
Unexpected Results From Remote Access 284
Summary 284
Chapter 29 Facilities For Secure Communication
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
Chapter 30 Electronic Commerce And Business
Introduction 295
E-Commerce Is Big Business 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
Chapter 31 The Global Digital Library
Introduction 303
A Cornucopia Of Services 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 301