“在可读性和清晰度方面，Douglas的表达力无出其右。本书的写作风格直接而且重点突出。……本书是适合网络初学者的一本优秀教材。”
——Raymond Hsieh，纽约州立大学布法罗分校
“本书以一种简洁的语言向学生介绍了因特网，指出了关键所在及未来发展方向。”
——RobinPeek，西蒙斯学院
Douglas Comer是著名的网络技术作家、教师和顾问，他对因特网的概念和工作原理有其独到的见解和清晰的认识。在本书的第4版中，Comer教授从一种非技术化的角度来解释因特网后台的工作机制、计算机的通信方式、服务器以及因特网技术的原理。作者借助实用的方法，以清晰易懂且科学准确的语言介绍了因特网的各种技术及其不同的应用，向读者展示出网络互连和因特网的全景图。
本书主要特色
● 三大新增章节：
NAT：介绍因特网的连接。
远程安全接入 (VPN)。
公司和个人网页 (Wiki及Blog)。
● 关键网络概念，如分组交换、局域网、协议软件和域名。
● 全新的内容，包括Wi-Fi的无线联网技术、Web制作工具，以及关于网络安全性的讨论。
● 包括电子商务的概述以及如何利用网络进行业务和商业交易。
● 采用更多易于理解的定义扩展了术语表的内容。
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Douglas E. Comer：Douglas E. Comer: 美国普度大学教授，著名的网络技术专家。他每年都要向学生、专业人士等讲授计算机网络和Internet课程。他编写的《TCP/IP网际互联》（3卷本）、《计算机网络和因特网》等都是非常受欢迎的著作。他是对20世纪70年代末期和80年代因特网的形成有杰出贡献的研究人员之一。他还供职于因特网体系结构委员会（负责指导因特网发展的团体），是美国计算机学会的会员。
PART I Introduction To Networking
Chapter 1 The Internet Has Arrived
The World Has Changed
Numbers Do Not Tell The Story
Learning About The Internet
Understanding The Big Picture
Terminology And Technology
Growth And Adaptability
The Impact Of The Internet
Organization Of The Book
A Personal Note
Chapter 2 Getting Started: Hands-On Experience
Introduction
The Web: Sites And Pages
Web Browsers and Browsing
Using A Browser
Examples Of Web Sites And Services
Internet Search
Summary
Chapter 3 Telephones Everywhere
Introduction
A Communication Service
Selling Communication
Limited Access
High Cost
The Difficult Transition
Ubiquitous Access
Relevance To The Internet
Chapter 4 The World Was Once Analog
Introduction
Sound, Vibrations, And Analog Recording
Analog Electronic Devices
Many Electronic Devices Are Analog
The First Analog Communication
Analog Is Simple But Inaccurate
Sending An Analog Signal Across A Wire
Digital Music
The Digital Revolution
Computers Are Digital
Digital Recording
Using Digital To Recreate Analog
Why Digital Music
Summary
Chapter 5 The Once And Future Digital Network
Introduction
The World Was Previously Digital
A Telegraph Is Digital
Morse Code
Letters And Digits In Morse Code
Users Did Not Encounter Morse Code
Virtually Instant Communication
Speed Is Relative
The Telephone Became Digital
Relevance To The Internet
Binary Encoding Of Data On The Internet
Why Use Two Symbols
Summary
Chapter 6 Basic Communication
Introduction
Communication Using Electricity
Signals On Wires
Information Coding
Modems Allow Two-Way Traffic
A Character Code For Digital Information
Detecting Errors
Summary
Chapter 7 The Local Area Network Arrives
Introduction
Motivation
Interchangeable Media
A Computer Consists Of Circuit Boards
Circuit Boards Plug Into A Computer
Connecting One Computer To Another
LAN Technologies
Connecting A Computer To A LAN
The Importance Of LAN Technology
Relationship To The Internet
PART II A Brief History Of The Internet
Chapter 8 Internet: The Early Years
Many Independent Networks
The Proliferation Of LANs
Facts About LANs
LANs Are Incompatible
Wide Area Technologies Exist
Few WANs, Many LANs
WANs and LANs Are Incompatible
The Desirability Of A Single Network
The Department Of Defense Had Multiple Networks
Connecting Disconnected Machines
The Internet Emerges
The ARPANET Backbone
Internet Software
The Name Is TCP/IP
The Shock Of An Open System
Open Systems Are Necessary
TCP/IP Documentation Is Online
The Military Adopts TCP/IP
Summary
A Personal Note
Chapter 9 Two Decades Of Incredible Growth
Introduction
Disseminating The Software
Meanwhile, Back In Computer Science
The Internet Meets UNIX
The U.S. Military Makes A Commitment
The Internet Doubles In Size In One Year
Every Computer Science Department
Graduate Students Volunteer Their Time
The IAB evolves
The IETF
Doubling Again In A Year
The Internet Improves Science
NSF Takes A Leadership Role
Target: All Of Science And Engineering
NSF’s Approach
The NSFNET Backbone
The ANS Backbone
Exponential Growth
A Commercial Assessment
The End Of Growth
Chapter 10 The Global Internet
Introduction
Early ARPA Netwos
Electronic Mail Amng Computers
BITNET And FIDONET
Networks In Europe
EBONE: The Internet In Europe
Backbones And Internet Hierarchy
Internet On All Continents
The World Of Internet after 1998
A Personal Note
Chapter 11 A Global Information Infrastructure
Introduction
Existing Infrastructure
Communication Infrastructure
The Internet Infrastructure
The Internet Offers Diverse Information Services
TCP/IP Provides Communication Facilities
A Personal Note
PART III How The Internet Works
Chapter 12 Packet Switching
Introduction
Sharing Saves Money
Sharing Introduces Delays
Sharing Wires
Selectable Channels
Sharing By Taking Turns
Packet Switching Avoids Delays
Each Packet Must Be Labeled
Computers Have Addresses
Packets Are Not All The Same Size
Packet Transmission Seems Instantaneous
Sharing Is Automatic
Network Hardware Handles Sharing
Many Devices Can Use Packet Switching
Relevance To The Internet
Summary
Chapter 13 Internet: A Network Of Networks
Introduction
Network Technologies Are Incompatible
Coping With Incompatibility
Two Fundamental Concepts
Using A Computer To Interconnect Networks
Interconnecting Computers Pass Packets
Interconnecting Computers Are Called Routers
Routers Are The Building Blocks Of The Internet
The Internet Includes Multiple Types Of Networks
Routers Can Interconnect WANs And LANs
The Hierarchical Structure Of The Internet
Where Packets Travel
Interconnecting Networks Was Revolutionary
Summary
Chapter 14 ISPs: Broadband And Wireless Access
Introduction
Internet Service Providers And Fees
Customer Connections Form The Last Mile
Leased Circuits Are Expensive
Dial-up Access Is Inexpensive, But Slow
Broadband Connections Offer High Speed
The Important Concept Of Continuous Connectivity
Instantaneous Access Changes Use
Modern Technologies Offer Inexpensive Dedicated Access
Wireless Access Is Available
Wi-Fi And 3G Wireless Technologies
A Personal Note
Chapter 15 IP: Software To Create A Virtual Network
Introduction
Protocol: An Agreement For Communication
Basic Functionality: The Internet Protocol
IP Software On Every Machine
Internet Packets Are Called Datagrams
The Illusion Of A Giant Network
The Internet’s Internal Structure
Datagrams Travel In Packets
Every Computer Is Assigned A Unique Address
Internet Addresses
An Odd IP Address Syntax
IP Addresses Are Not Random
A Trip Through An Example Internet
How Fast Is Your Connection
Summary
Chapter 16 TCP: Software For Reliable Communication
Introduction
A Packet Switching System Can Be Overrun
TCP Helps IP Guarantee Delivery
TCP Provides A Connection Between Computer Programs
The Magic Of Recovering Lost Datagrams
TCP Retransmission Is Automatic
TCP And IP Work Together
Summary
Chapter 17 Clients + Servers = Distributed Computing
Introduction
Large Computers Use Networks For Input And Output
Small Computers Use Networks To Interact
Distributed Computing On The Internet
A Single Paradigm Explains All Distributed Computing
Communicating Programs Are Clients Or Servers
A Server Must Always Run
Summary
Chapter 18 Names For Computers
Introduction
People Prefer Names To Numbers
Naming A Computer Can Be Challenging Or Fun
Computer Names Must Be Unique
Suffixes On Computer Names
Names With Many Parts
Domain Names Outside The US
Translating A Name To An Equivalent IP Address
Domain Name System Works Like Directory Assistance
Computer Name Lookup Is Automatic
IP Addresses And Domain Names Are Unrelated
Summary
Chapter 19 NAT: Sharing An Internet Connection
Introduction
High Capacity And Multiple Computers
It Is Possible To Share A Single IP Address
A Device For Connection Sharing Is Called A NAT Box
A NAT Box Acts Like A Miniature ISP
NAT Changes The Address In Each Datagram
Computer Software Can Perform The NAT Function
NAT Can Use A Wireless Network
Summary
Chapter 20 Why The Internet Works Well
Introduction
The Internet Works Well
IP Provides Flexibility
TCP Provides Reliability
TCP/IP Software Was Engineered For Efficiency
TCP/IP Research Emphasized Practical Results
The Formula For Success
Summary
PART IV Services Available On The Internet
Chapter 21 Electronic Mail
Introduction
Description Of Functionality
The Best Of All Worlds
Each User Has A Mailbox For Email
Sending An Email Message
Notification That Email Has Arrived
Reading An Email Message
A Browser Can Be Used To Send And Receive Email
Email Messages Look Like Interoffice Memos
Email Software Fills In Header Information
How Email Works
Using Email From A Personal Computer
Mailbox Address Format
Abbreviations Make Email Friendly
Aliases Permit Arbitrary Abbreviations
Aliases Shared By All Users Of A Computer System
Sending To Multiple Recipients
Mailing List: An Alias for Multiple Recipients
Public Mailing Lists And Mail Exploders
Exchanging Email With Non-Internet Sites
Access To Services Via Email
Speed, Reliability, And Expectations
Impact And Significance Of Electronic Mail
A Convention For Joining A Mailing List
Chapter 22 Bulletin Board Service (Newsgroups)
Introduction
Description Of Functionality
Many Bulletin Boards With Diverse Topics
Network News
Categories
Obtaining Network News And The Software To Read Articles
How Network News Appears To A User
Checking For News Articles
Reading Network News
Submission Of An Article
Moderated Newsgroups
Size Of Network News
Impact And Significance Of Newsgroups And Mailing Lists
Hints And Conventions For Participating In Discussions
Summary
Chapter 23 Browsing The World Wide Web
Introduction
Description Of Functionality
Browsing Vs. Information Retrieval
Early Browsing Services Used Menus
A Menu Item Can Point To Another Computer
How A Browser Works
An Example Point-And-Click Interface
Combining Menu Items With Text
The Importance Of Integrated Links
Embedded Links In Text Are Called Hypertext
Multimedia
Video And Audio References Can Be Embedded In Text
The World Wide Web
Browser Software Used To Access The Web
An Example Hypermedia Display
Control Of A Browser
External References
Recording The Location Of Information
Bookmarks Or Favorites
How The World Wide Web Works
A URL Tells A Browser Which Computer To Contact
A URL Tells A Browser Which Server To Contact
Use Of The Name www In URLs
A Browser Provides Access To Multiple Services
Inside A Browser Program
Summary
An Observation About Hypermedia Browsing
Chapter 24 World Wide Web Documents (HTML)
Introduction
Display Hardware Varies
A Browser Translates And Displays A Web Document
A Consequence Of The Web Approach
HTML, The Language Used For Web Documents
Instructions In A Web Page Control The Output
A Web Page Is Divided Into Two Main Sections
Indentation Can Make HTML Readable
The Body Of A Web Page Can Contain Text
Indentation Can Make Paragraphs Easier To Find
A Web Page Can Link To Another Page
HTML Allows Numbered And Unnumbered Lists
Images On A Web Page Are Digital
HTML Allows A Web Page To Include An Image
Text Can Appear Adjacent To An Image
Images Can Link To Another Web Page
Some Browsers Can Stretch Or Shrink Images
The Background Can Be Controlled
Other Features Of HTML
Importance Of HTML
GUI Tools Help With Web Page Creation
Summary
Chapter 25 Advanced Web Technologies (Forms, Frames, Plugins, Java, JavaScript, Flash)
Introduction
Conventional Web Pages Are Static
How A Server Stores Static Web Pages
Fetching Items One At A Time
Conventional Web Pages Use The Entire Screen
A Web Page Can Change Part Of the Screen
The Web, Advertising, And Frames
Pop-Ups And Pop-Up Blockers
Static Documents Have Disadvantages
Controlling How A Browser Processes Data
Plugins Allow Variety
A Server Can Compute A Web Page On Demand
How Server-Side Scripting Works
Professional Programmers Build Server Scripts
Personalized Web Pages
Personalized Advertisements
Web Pages Can Interact
Shopping Carts
Cookies
Should You Accept Cookies
A Web Page Can Display Simple Animations
Active Documents Are More Powerful
Java Is An Active Document Technology
JavaScript Is An Active Document Technology
Flash And Real Technologies
The Importance Of Advanced Web Technologies
Chapter 26 Group And Personal Web Pages (Wikis And Blogs)
Introduction
The Disadvantage Of A Bulletin Board System
Shared Pages
Shared Pages Are Called Wikis
Sharing And Consensus Building
The Disadvantage Of Wikis
Wikipedia Is An Experiment
Should You Trust Wikipedia
Publication Of A Personal Diary
A Personal Note
Chapter 27 Automated Web Search (Search Engines)
Introduction
Description Of Functionality
Browsing Vs. Automated Searching
A Search Engine Helps Users Get Started
A Search Tool Can Help Recover From Loss
How An Automated Search Service Operates
Gathering Information In Advance
Modern Systems Search Web Page Contents
How A Web Search Appears To A User
How A Search Engine Returns Results
Automated Search Services Use String Matching
The Advantages And Disadvantages Of String Matching
Automated Search Programs That Use Multiple Keys
Advanced Services Offer More Sophisticated Matching
Personalized Search Results
More Details About How Content Searching Works
Searches Are Restricted
Advertising Pays For Searching
Examples Of Automated Search Services
Significance Of Automated Web Search
Chapter 28 Text, Audio, And Video Communication (IM, VoIP)
Introduction
Instant Messaging Provides Textual Communication
Audio And Video Functionality
Audio And Video Require Special Facilities
An Audio Clip Resembles An Audio CD
Real-Time Means No Delay
Internet Audio In Real-Time
Radio Programs On The Internet
Real-Time Audio Transmission Is Called Webcasting
Internet Telephone Service Is Possible
Internet Telephone Service Is Known As VoIP
Audio Teleconferencing
A Cooperative Document Markup Service
Marking A Document
The Participants Discuss And Mark A Document
Video Teleconferencing
Video Teleconference Among Groups Of People
A Combined Audio, Video, Whiteboard, And IM Service
Summary
A Personal Note
Chapter 29 Faxes, File Transfer, And File Sharing (FTP)
Introduction
Sending A Fax
The Internet Can Be Used To Copy Files
Data Stored In Files
Copying A File
FTP Is Invoked From A Browser
FTP Allows A User To View Directory Contents
FTP Allows A User To Upload Files
FTP Transfers Must Be Authorized
How FTP Works
Impact And Significance Of FTP
Peer-To-Peer File Sharing
Summary
Chapter 30 Remote Login And Remote Desktops (TELNET)
Introduction
Early Computers Used Textual Interfaces
A Timesharing System Requires User Identification
Remote Login Resembles Conventional Login
How Remote Login Works
Escaping From Remote Login
The Internet Remote Login Standard Is TELNET
Remote Access Can Display A Desktop
How Remote Desktops Operate
Assessment Of Remote Login And Desktops
Generality Makes Remote Login And Desktops Powerful
Remote Access Accommodates Multiple Types Of Computers
Unexpected Results From Remote Access
Summary
Chapter 31 Facilities For Secure Communication
Introduction
The Internet Is Unsecure
Lack Of Security Can Be Important
Authentication And Privacy Are Primary Problems
Data Can Be Changed
Encoding Keeps Messages Private
Computer Encryption Uses Mathematics
No Network Is Absolutely Secure
Encryption Makes Email Private
Encryption Software Needs A Key
Two Keys Means Never Having To Trust Anyone
Secure Email In Practice
Secure Wireless Networks
Firewalls Protect Networks From Unwanted Packets
A Firewall Filters Packets
Firewalls Guard Against Trojan Horses
Residential And Individual Firewalls
Systems Exist To Detect Intrusion
Service Can Be Denied
Summary
Chapter 32 Secure Access From A Distance (VPNs)
Introduction
Organizations Grant Employees Special Privileges
Traveling Employees Lose Privilege
Telecommuters Do Not Have Privilege
Dedicated Leased Circuits Allow Secure Telecommuting
Standard Internet Connections Are Low-Cost
Can A Technology Combine Advantages
A Virtual Private Network Solves The Problem
How A VPN Works
The Illusion Of A Direct Connection
Significance Of VPNs
Chapter 33 Internet Economics And Electronic Commerce
Introduction
Who Pays For The Internet
E-commerce Is Big Business
Security Technology Made E-commerce Possible
Secure Sockets
Public Key Encryption Provides Authenticity
Digital Signatures
Certificates Contain Public Keys
What Is Digital Money
Digital Cash Is Not Widely Available
Business And E-commerce
Chapter 34 The Global Digital Library
Introduction
A Cornucopia Of Services
New Services Appear Regularly
Flexibility Permits Change
A Digital Library
Card Catalogs And Search Tools
Internet Services Can Be Integrated
Mr. Dewey, Where Are You
Information In The Digital Library
What Is The Internet
