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USER'S GUIDE & CATALOG
A Nl'TSHELL
IS1)1
HANOF!OOI<..
En KROL
O'REILLY & ASSOCIATES, Il'\c.
THE WHOLE INTERNET
USER'S GUIDE & CATALOG
The Whole Internet Catalog & User's Guide
by Ed Krol
Copyright @ 1992 O'Reilly & Associates, Inc. All rights reserved.
Printed in the United States of America.
Editor: Mike Loukides
Printing History:
September 1992: First Edition.
Many of the designations used by manufacturers and sellers to distinguish their products
are claimed as trademarks. Where those designations appear in this book, and O'Reilly and
Associates, Inc. was aware of a trademark claim, the designations have been printed in caps
or initial caps.
While every precaution has been taken in the preparation of this book, the publisher
assumes no responsibility for errors or omissions, or for damages resulting from the use of
the information contained herein.
@
This book is printed on acid-free paper with 50% recycled content, 10-15% post-consumer
waste. O'Reilly & Associates is committed to using paper with the highest recycled content
available consistent with high quality.
ISBN: 1-56592-025-2
PREFACE
TABLE OF CONTENTS
xix
Audience
Approaching This Book
Conventions
Acknowledgements
CHAPTER ONE
WHAT IS THIS BOOK ABOUT?
xxi
xxii
x.xiii
xxiii
1
Something for Everyone
What You Will Learn
What If I Don't Know UNIX?
What You Need
What an Internet Connection Means
Getting Connected?
How This Book Is Organized
CHAPTER 1WO
WHAT IS THE INTERNET?
2
3
5
6
7
9
10
11
What Makes Up the Internet?
Who Governs the Internet?
Who Pays for It?
What Does This Mean for Me?
What Does the Future Hold?
New Standard Protocols
International Connections
Commercialization
Privatization
13
13
15
]5
]e;
15
]6
16
1""'
l'
CHAPTER THREE
HOW THE INTERNET WORKS
19
19
20
20
23
24
25
25
25
26
28
29
Moving Bits from One Place to Another
Packet Switch Networks
The Internet Protocol (IP)
The Transmission Control Protocol (TCP)
Other Transmission Protocols
Making the Network Friendly
Applications
The Domain Name System
The Domain System Structure
Domain Name Lookup
Domain Name System Hints
CHAPTER FOUR
WHAT'S ALLOWED ON THE INTERNET?
31
31
32
32
33
34
35
35
36
36
38
39
40
41
42
42
Legal Implications
Research, Education, and the Federal Dollar
Commercial Use
Export Laws
Property Rights
Politics and the Internet
Network Ethics
Individualism
Protecting the Internet
Security Consciousness
Passwords
Importing Software
Misconfigured Software
System Software Flaws
What If My Computer Is Violated?
vi
CHAPTER FIVE
REMOTE LOGIN
45
46
47
48
51
52
54
54
Simple Telnet
What's Really Going On
Telnet Command Mode
Non-standard Telnet Servers
Telnet to Non-standard Ports
Mimicking Alternate Clients
Telnetting to IBM Mainframes
CHAPTER SIX
MOVING FILES: FrP
59
60
62
63
66
67
70
72
74
76
76
78
81
81
82
82
85
86
88
89
Getting Started with FTP
Common Problems
Browsing on a Remote Machine
Directories in FTP
ASCII and Binary Transfers
Transferring Multiple Files
FTP Command Summary
Anonymous FTP
Handling Large Files and Groups of Files
Compressed Files
Moving a Whole Directory
Shell Archives
Other Archival Utilities
Special Notes on Various Systems
Target: Digital Equipment VMS Systems
Target: IBM/PC DOS Systems
Target: IBM/VM Systems
Target: Macintosh
Last Words: Some Practical Advice
vii
CHAPTER SEVEN
ELECTRONIC MAIL
91
91
93
95
96
99
100
101
101
103
105
105
105
106
107
108
109
109
110
110
111
111
112
112
112
112
113
113
115
115
118
118
119
120
120
When Is Electronic Mail Useful?
Hints for W'riting Electronic Mail
How Electronic Mail Works
It's All in the Address
Acquiring Electronic Mail Addresses
Choosing a System
The UNIX Mail Program
Reading Your Mail
Sending Messages
A Shopping List of Features
Universally Supported Features
Aliasing
Folders
Forwarding
Inclusion of Text Files
Mailing Lists
Reply
Locally Supported Features
Carbon Copies
Blind Carbon Copies
Signature Files
Unusual and Non-standard Features
Attaching Documents
Notification of Receipt
Notification of Reading
Message Cancel
Sending Binary Data as ASCII
When Electronic Mail Gets Returned
Unknown Hosts
Unknown Recipients
Mail Can't Be Delivered
Failures Involving Multiple Recipients
Last Ditch Help
Mail Lists and Reflectors
viii
File Retrieval Using Electronic Mail
Specialized Servers
Listserv Requests
The Ftpmail Application Gateway
123
124
124
125
CHAPTER EIGHT
NETWORK NEWS
127
News Groups and News System Organization
Getting Started
Setting Up nn
Reading News
What Is a News Item?
Using a News Reader
Steering a News Reader
Saving News Items
Controlling What You Read
Subscribing and Unsubscribing
Killing and Auto-selecting Items
Catching Up
rot13
Posting Your Own Articles
Adding to an Existing Discussion
Starting a New Discussion
Replying Via E-mail
Other Hints and Conventions
Summary of Commands and Features
Command-line Options
Some Selection Mode Commands
Some Reading Mode Commands
128
133
133
135
135
136
139
139
140
140
141
144
145
146
146
147
149
150
151
151
153
154
CHAPTER NINE
FINDING SOFTWARE
155
156
157
158
159
How Archie Works
Contacting Archie
Using Archie with Telnet
Searching by Filename
ix
Searching Using the Descriptive Index
Other Archie Commands
Archie Configuration Variables
Using Archie by Electronic Mail
Archie Using a Client
162
163
163
164
166
CHAPTER TEN
FINDING SOMEONE
169
Why Isn't There One?
Mobile Users
Standards
Security and Privacy
What Is There?
Finding a User on a Specific System
Finger as a General Information Server
When Finger Fails
Whois
The USENET User List
The Future: X.500 Directory Services
Native X.500
Fred Via Telnet
Fred Via E-mail
Fred as an Application
Knowbot Information Service
169
170
170
171
171
171
173
174
174
178
179
179
181
185
186
186
CHAPTER ELEVEN
TuNNELING THROUGH THE INTERNET: GOPHER
189
190
192
193
194
195
197
200
201
204
The Internet Gopher
Finding a Gopher Client
How Gopher Works
Finding Internet Resources
Looking at Text Files
White Pages Servers
Moving to Other Servers
Index Searches
FfP Through Gopher
x
Using Telnet Through Gopher
Gopher Development
A Last Word
208
209
210
CHAPTER 1WEL VE
SEARCHING INDEXED DATABASES: W AIS
211
How WAIS Works
Getting Access
Formulating a W AIS Search
Refining a Search
When Searches Don't Go as Planned
Adding Sources
New Sources That Aren't in the Directory-of-Servers
Building Your Own Sources
212
214
215
221
222
223
224
225
CHAPTER THIRTEEN
HYPERTEXT SPANNING THE INTERNET: WWW
227
Getting Started
The Web and Gopher
Using WAIS Resources
The W AIS Directory of Servers
Other Internet Resources
FTP Resources
T elnet Resources
USENET News
White Pages
Navigating the Web
Creating Your Own Home Page
Where the Web Is Going
Other Kinds of Documents
Making Your Own Links
Collaborating with Others
229
231
233
235
236
236
237
238
238
238
2'10
2'11
2'11
2--i1
2'11
xi
Hypertext Editors
How Can I help?
242
242
CHAPTER FOURTEEN
OTHER APPLICATIONS
243
243
244
245
247
247
249
251
252
254
255
256
256
256
257
259
259
The R Commands
Security and Validation
Remote Login
Escape Sequences
Moving Files
Distributing Files
X Windows
Disk and File Sharing
Time Services
Fax Over the Internet
Diversions
Conversations with Others
Talking
Chat
Multi-person Games
Robotic Librarians
CHAPTER FIFTEEN
DEALING WITH PROBLEMS
261
262
264
265
265
266
267
268
268
269
269
270
270
The Ground Rules
Gather Baseline Information
The Battleplan
Know Hours of Operation
Read the Error Message
Did You Change Anything?
Try a Different Destination
Try Your Neighbor's System
Try to Reach a Local System
Look Around Your Office
Check Your Local Connection
Dial-up Connections
xii
LAN, PPP, or SLIP Connections
Some Consolation
Talking to Operations Personnel
Dealing with Coaxial Ethernets
Token Ring Notes
272
272
272
273
275
RESOURCES ON THE INTERNET
279
279
279
280
280
281
281
281
282
282
283
283
284
285
Stalking the Wild Resource
Friends
Network News and Mailing Lists
Archie
Gopher
WAIS
The world-Wide Web
How We Did It
What Is a Resource?
Accuracy and Permissions
Using the Catalog
Topics Covered
The Whole Internet Catalog
APPENDIX A
GETIING CONNECfED TO THE INTERNET
333
334
334
335
336
336
337
337
338
Different Grades of Service
Dedicated Internet Access
SLIP and PPP
Dial-up Access
UUCP Access
Access Via Other Networks
Telephone Connections
Service Providers
xiii
APPENDIX B
INTERNATIONAL NETWORK CONNECTMTY
349
350.
350
Summary of International Connectivity
Country Codes and Connectivity
APPENDIX C
ACCEPTABLE USE
353
353
The NSFNET Backbone Services Acceptable Use Policy
GLOSSARY
355
INDEX
365
xiv
FIGURES
CHAPTER ONE: WHAT IS THIS BOOK ABOUT?
1-1 A true Internet connection
1-2 A dzal-up Internet connection
1
8
8
19
21
21
24
27
59
78
91
122
127
129
130
155
156
169
180
181
211
216
217
217
218
220
220
221
225
CHAPTER THREE: HOW THE INTERNET WORKS
3-1 Internet hardware
3-2 IP envelopes
3-3 rcp packet encapsulatlOn
3-4 Domain authority
CHAPTER SIX: MOVING FILES: FTP
6-1 Moving many files
CHAPTER SEVEN: ELECTRONIC MAIL
7-1 Local mail reflectors
CHAPTER EIGHT: NETWORK NEWS
8-1 User's view of the news system
8-2 Implementation of the news system
CHAPTER NINE: FINDING SOFIW ARE
9-1 How archie works
CHAPTER TEN: FINDING SOMEONE
10-1 Phone book structure
10-2 X.500 tree structure
CHAPTER TWELVE: SEARCHING INDEXED DATABASES: WAIS
12-1 Main window
12-2 Directory-of-servers query
12-3 Selecting a source
12-4 Results of directory search
12-5 Behaviorproblems result
12-6 Article you retrieved
12-7 Feedback search setup
12-8 Source maintenance window
xv
CHAPTER THIRTEEN: HYPERTEXT SPANNING THE INTERNET: WWW 227
13-1 CERN home page, using Viola 230
13-2 Academic infonnation, using Viola 231
CHAPTER FIFTEEN: DEALING WITH PROBLEMS 261
15-1 The Internet cloud 262
15-2 Network schematic 264
15-3 Typical thin Ethernet 274
15-4 Thin Ethernet-tap and tenninator 274
APPENDIX B: INTERNATIONAL NETWORK CONNECTIVITY 349
B-1 Key to connectivity table 350
xvi
CHAPTER THREE: HOW THE INTERNET WORKS
3-1 Original High-level Domains
CHAPTER SIX: MOVING FILES: FrP
6-1 Common File Types and Modes
CHAPTER SEVEN: ELECTRONIC MAIL
7-1 Comparison of Communication Techniques
CHAPTER EIGHT: NETWORK NEWS
8-1 Common Distribution Keywords
CHAPTER NINE: FINDING SOFlWARE
9-1 Available Archie Servers
CHAPTER lWELVE: SEARCHING INDEXED DATABASES: WAIS
12-1 Waisindex Input Fonnats
CHAPTER FIFTEEN: DEALING WITH PROBLEMS
1 Internet Topic Areas
APPENDIX A: GElTING CONNECTED TO THE INTERNET
A -1 Telephone Line options
A-2 Nationwide and International Service Providers
A-3 Regional Service Providers
APPENDIX B: INTERNATIONAL NETWORK CONNECTIVITY
B-1 International Connectivity Summary
TABLES
19
28
59
69
91
92
127
148
155
157
211
226
261
284
333
337
340
342
349
350
xvii
PREFACE
Audience
Approaching I1Jis Book
Conventions
Acknowledgements
T his is a book about the Internet, the world's largest computer network. It's
aimed at the "garden variety" computer user: not the expert or the computer
afficionado, just someone who has a job to get done. To those of us who
have been using the Internet for a long time, a lot of what we discuss has become
commonplace. But to get a sense for what the Internet is, and why this book is
important, we need to take a few steps back.
Ten or twelve years ago, a minor revolution occurred when personal computers
became common. Within a few years everyone had a computer at home, or in the
office. And, to be honest, most people thought that was adequate: a little help doing
budget planning, a nice word processor for writing letters, and we were satisfied.
Some visionaries talked about computers as "information appliances": you could use
your home or office computer to connect to the national news services, get stock
reports, do library searches, even read professional journals or literary clas-
sics-but, at the time, these were far-reaching ideas.
Well, time has passed since computers first moved from behind the "glass wall" into
our offices and homes. In those dozen or so years, another revolution, arguably
more important than the first, has taken place. And that revolution was computer
networking. Personal computers are great, but computers become something spe-
cial when they're connected to each other.
With the Internet, networking has "come "of age." The information re
ources that
visionaries talked about in the early 80's are not just "research realities" that a few
advanced thinkers can play with in some lab-they're "real life" realities that you
can tap into from your home. Once you're connected to the Internet, you have
instant access to an almost indescribable wealth of information. You have to pay for
xL^{
17Je
'hole Internet Catalog & User's Guide
some of it, sure-but most of it is available for free. Through electronic mail and
bulletin boards (called "news groups" in Internet-lingo), you can use a different kind
of resource: a worldwide supply of knowledgeable people, some of whom are cer-
tdin to share your interests, no matter how obscure. It's easy to find a discussion
group on almost any topic, or to find some people interested in forming a new dis-
cussion group. While free advice is often worth what you pay for it, there are also
lots of well-informed experts who are more than willing to be helpful.
Well, then, where do you start? Getting a handle on the Internet is a lot like grab-
bing a handful of Jello-the more firm you think your grasp is, the more oozes
down your arm. You don't need to deal with Jello in this manner to eat it, you just
need the right tool: a spoon. And you need to dig in and start eating. The same is
true of the Internet. You don't need to be an expert in telephone lines, data commu-
nications, and network protocols for it to be useful. And no amount of gushing
about the Net's limitless resources will make the Internet useful. You just need to
know how to use some tools, and to start working with them.
As for uses, we've got millions of them. They range from the scholarly (you can read
works analyzing Dante's Divine Comedy); to the useful (you can look at agricultural
market reports); to the recreational (you can get ski reports for Aspen); to the
humorous ("How do I cook Jello?"). It is also an amazing tool for collaboration:
working with other people on your own "magnum opus."
In a sense, the existence of this book is a tribute to the power and usefulness of the
Internet. Mike Loukides, the editor, and I met via electronic mail. Network users
were clamoring to get me to update a help guide I wrote a long time ago, "The
Hitchikers Guide to the Internet." I was about to volunteer when Mike sent me an
electronic mail message and asked "How about doing it as a book?" This spurred a
number of messages about outlines and time frames until both were finalized. The
legalities and contracts were handled by the Postal Service; electronic contracts
were too commercial for the Internet at the time, and are still too high-tech for
courts to deal with. And we were on our way.
Shortly thereafter, I was shipped macro libraries to use in production, and began
shipping chapters to Mike, all bye-mail. He would annotate, change and ship them
back to me by the same means. Occasionally, we would trade file directories,
screen images, and illustrations. Except for the final review copies and illustrations,
everything was handled via the Internet. The whole process was accomplished with
less than ten telephone calls.
Think for a minute about what this medns. Traditional Post Office service between
Illinois (where I live) and Connecticut (where Mike lives) takes three days. If you
want to PdY extra, you can use a courier service and cut the time down to one day.
But I can ship the entire book to Mike over the Internet in a few minutes.
I also gathered the information in the Resource Catalog without having to leave
home. I watched news groups, followed e-mail discussions, and used various tools
to acquire the information for the catalog, all of which are explained in the book.
xx
Preface
Before including any of the resources, I verified that they really existed by reaching
out acros
the network and touching them.
Now, a year after it all began, there is this book. I still have not met anyone who
works for O'Reilly and Associates, in person. I'd certainly like to some day-they
are an amazingly professional group helping me through my first book.
Audience
This book is intended for anyone who wants access to the Internet's tremendous
resources. It's a book for professionals, certainly, but not computer professionals.
It's designed for those who want to use the network, but who don't want to become
a professional networker in order to use it. If you're a biologist, or a librarian, or a
lawyer, or a clergyman, or a high school teacher, or (fill in your profession
here), there's a lot of material and data available that will help you do your job. At
the same time, you'll probably find recent Supreme Court opinions or chromosome
maps much more interesting than the network itself. You want to use the network
as a tool; you don't want to make the network your life. If this description fits you,
you need this book. It will get you started and point you towards some interesting
resources. If, after this, you find that networking becomes your life-well, that's
your decision. The Internet has a way of becoming habit forming.
Although I've based our examples on UNIX, this book does not assume that you're a
UNIX user. We had to choose some common ground; UNIX systems are prevalent on
the Internet, so it was a logical choice. However, the same utilities are available for
virtually any operating system; and, with minor variations, you'll find that they work
the same way. If you're using DOS, a Macintosh, VAX/VMS, or some other kind of
computer, please pardon the UNIX bias-but you really shouldn't find it a problem.
Very specifically: while writing this book, my model audience was a new graduate
student in some non-technical discipline (i.e., not computer science or any form of
engineering) who needed to use the Internet to do research. Of course, this
presumes an audience ranging from Italian scholars to sociologists to physicists,
with a correspondingly wide range qf computer experience. I do assume that you're
computer literate-if you weren't you probably wouldn't even be looking at this
book-and that you are familiar with some computer and its operating system, but
not necessarily UNIX.
This book is also intended for the experienced network administrator: the guy
whose job it is to keep a company's or campus's networks working reasonably well.
No, you're not supposed to read it; you probably know everything in here already.
(Maybe not, though. Check out the chapters on WAIS, gopher, and the World-Wide
Web, three of the newest services.) If you have this job, you probably spend most
of your time answering the same fifty questions. When a new crop of students or
employees arrives, you might not get any work done for weeks. With any luck, this
book answers most of their questions. From the beginning, we were trying to write
a book that would answer as many questions as possihle. If you are a network
administrator, this book is intended for you-so you can give it away, or post a
xxi
The Jf1Jole Internet Catalog & User's Guide
note on your door saying, "go to the bookstore, buy this book, and read it before
bugging me!"
A
with all Nutshell handbooks. O'Reilly and Associates is interested in hearing
from readers. If you have any comments or suggestions, please send them to
nuts@ora.com. (If you don't know what this means. read Chapter 7, Electronic
.Hail.)
Approaching This Book
Of course, there are many ways to approach the Internet; likewise, there are many
ways to read this book. Here are a few suggestions. If you:
Are completely neu' to the Internet
Start at the beginning and read to the end. You might want to pay particu-
lar attention to the Resource Catalog, which tells you what you'll find, and
Appendix A, Getting Connected to the Internet, which tells you how to get
connected. But, basically, you ought to read the entire book. If you want,
you can skim Chapters 3 and 4, which explain how the Internet works,
and what's allowed; but please revisit these later.
Are familiar with the Internet, but not a user
Skip to Chapter 5; in this chapter, we start discussing the basic utilities that
you use on the Internet.
Are an experienced Internet user
Skip to Chapter 9. Chapters 9 through 13 discuss the newest tools to come
on the scene: Archie, some newer "white pages" services, Gopher, WAIS,
and the World-Wide Web. Even if you've been around for a while, you
may want to brush up on these. If you're not familiar with these tools, you
really should be.
Have used the Internet casually
Read the first four chapters to get the background you may have missed;
and then scan the Table of Contents for chapters whose topics are unfa-
miliar to you. If you do this, read the chapters in order because many of
the newer facilities (Chapter 9 and above), build on each other.
Want to get connected to the Internet
Look at Appendix A, which discusses various ways of getting a connec-
tion.
Want to know what's available before committing yourself
Look at the Resource Catalog.
Are only interested in electronic mail and network news
Read Chapters 7 and 8, which discuss the e-mail and news services.
But-please, read the rest of the book, too. You don't know what you're
missing.
xxii
Preface
Conventions
In this book, we use the following conventions:
· Command names are printed in bold; for example, telnet or archie.
· Names of services or protocols are printed in uppercase or with the initial letter
capitalized; for example, TELNET or Archie.
· Input typed literally by the user is printed in bold; for example, get host-
table.txt.
· Imernet names and addresses are primed in bold: for eXdmple. ora.com.
· Filenames are printed in italic; for example, /etc/hosts.
· Names of USENET news groups are printed in italic; for example, rec.musicfolk
· "Variables"-placeholders that the reader will replace with an actual value-are
printed in italic. For example, in the command ftp hostname, you mu
t substi-
tute hostname for the name of some computer on the Internet.
· Within examples, output from the computer is primed in cons tant width
type.
· Within examples, text typed literally by the user is primed in constant bold
type.
· Within examples, variables are printed in constant italic type.
· Within examples, explanatory comments are often placed in italic type.
Acknowledgements
A whole host of people helped with this book. First and foremost is my wife
Margaret. Without her support and help, it never would have come to pass. She
read and corrected most of it, searched Gopher for resources, and tried things to see
if my explanations really were sufficient for a computer professional to use the
Internet. Also, she took over enough of the running of our home to give me time to
devote to the project.
Next comes my daughter Molly, who did without me in many ways for the better
part of a year while I was writing. (This is Molly's second experience with comput-
ing fame-she was the toddler with a penchant for emergency-off switches. after
whom "Molly-guards" are named in the "Hackers Dictionary.'")
Then there is Mike loukides, the editor, project leader, confidence builder and
cheerleader, who dragged me, sometimes kicking and screaming, to the finish line.
Next are all the people at the University of Illinois who helped. George Bddger. the
head of the Computing and Communications Service Office, for the support I
needed with the project. Beth Scheid for picking up some pieces of my real job
while I was preoccupied with book-related problems. The real technical people,
who answered some bizarre questions and made
ome of the examples possible:
Charley Kline, Paul Pomes, Greg German, Lynn \X'ard, Albert Cheng, Sandy
x,-iii
The Whole Intenlet Catalog & User's Guide
Seehusen, Bob Booth, Randy Cotton, and Ed Kubaitis. The faculty of the Graduate
School of Library Science was also involved, especially Greg Newby, who had a
number of suggestions about how to approach the searching tools of the Internet.
Two people were my test audience: Lisa Gennan, a library science graduate stu-
dent, and Pat King, a then-neophyte system administrator. They knew little about
the Internet when they began reading the book as it was written, chapter by chap-
ter. They pointed out all the things that were used before explained or were just
plain explained too technically. Lisa also spent many hours visiting most of the
notable anonymous FIP servers on the Internet searching for resources. It's pretty
amazing what someone with a knowledge of common cataloging words and
phrases can do with Archie, * but I guess that's what librarians are trained to do.
A large group of people read the book checking for technical errors, inconsisten-
cies, and "useful stuff that I left out. n These included Eric Pearce, Robin Peek, Jerry
Peek, Mitch Wright, Rick Adams, Tim Berners-Lee, Martyne Hallgren, and Jim
Williams. The book would not be anywhere near as useful without their help.
I also owe thanks to the Production and Art departments at O'Reilly and Associates,
particularly Edie Freedman, who designed the book's format and selected all of the
engravings; Lenny Muellner, who implemented the fonnat in troff, something no
sane person should he asked to do; Chris Reilley, who drew the illustrations; and
Rosanne Wagger, who copy-edited the book, corrected more typos than I thought
exis ted, and in general turned this into a finished book. Finally, I'd like to thank
Karen Kolling for permission to reprint her recipe for Loubia (posted on the Net) in
the Resource Catalog.
* A file search [001 explained in Chapter 9, Finding Software.
x.-.;;iv
CHAPTER ONE
WHAT Is THIS
BOOK ABOUT?
SomethIng for Everyone
What You Will Learn
What You Need
What an Internet Connection Means
How This Book Is Organized
I n the early 1900's, if you wanted to tinker with horseless carriages, you fell in
with other tinkerers and learned by doing. There were no books about auto-
mobiles, no schools for would-be mechanics, no James Martin courses. The
market was too small for these training aids. In addition, there were good reasons to
fall in with a group of experts: early cars were so unreliable that they could hardly
be called transportation. When your car broke down, you needed to fix it yourself,
or have some good friends who could come to the rescue. You fiddled and asked
questions of others. Soon you could answer questions for a novice. Eventually, you
might become a highly regarded mechanic (in computing referred to as a "guru").
When you got to this level, your car might actually be useful transportation, not just
an expensive hobby.
Seven years ago, the Internet was in much the same state. The network only had a
few thousand users. All of its users either had ready access to experts, or were
experts themselves. And they needed expertise-the network was slow and unreli-
able. Its major purpose was not to do anything useful, but to help people learn how
to build and use networks.
In the past seven years, the number of Internet users has increased a thousand-fold.
These people use the network for their daily work and play. They demand reliabil-
ity, and don't want to be mechanics. They want to be chemists, librarians, meteorol-
ogists, kindergarten teachers..., who happen to use the network. So now they
demand documentation. Something to read on the train to work to improve their job
skills. They are computer-literate, but not network-literate. This book is about net-
work literacy.
1
The Whole blternet Catalog & User's Guide
So In ethil1g for Everyol1e
The usefulness of the Internet parallels the history of computing with a lag of about
ten years. About ten years ago, personal computers brought computing from the
realm of technical gurus to the general puhlic: "the rest of us," as Apple said in their
advertisements. The Internet is currently making the same transition.
As with personal computers (or, for that matter, automohiles), the Internet made the
transition from an expert's plaything to an everyday tool through a "feedback loop."
The network started to become easier to use-in part hecause the tools were bet-
ter, in part because it was faster and more reliable. Of the people who were previ-
ously scared away from the Internet, the more venturesome started to use it. These
new users created a demand for new resources and better tools. The old tools were
improved. and new tools were developed to access new resources, rr.aking the net-
work easier to use.
ow another group of people starts finding the Internet useful.
The process repeats itself; and it's still repeating itself.
Whatever their sophistication, Internet users are, as a whole, looking for one thing:
information. They find information from two general classes of sources: people and
computers. It's easy to forget about the Internet's "people" resources, but they're just
as important (if not more so) as the computers that are available. Far from being a
machine-dominated wasteland, where antisocial misfits sporting pocket protectors
flail away at keyboards, the Internet is a friendly place to meet people just like your-
self. You're a potential network user if you are:
· A science teacher in an area who needs to remain current and develop curricula
· A Unitarian-Universalist minister in a town of fundamentalists, looking for some
spiritual comraderie
· A criminal lawyer who needs to discuss a case with someone who has a particu-
lar kind of legal expertise
· An eighth grader looking for others whose parents don't understand real music
And so on. For all of these people, the Internet provides a way of meeting others in
the same boat. It's possible-in fact, it's usually easy-to find an electronic discus-
sion group on almost any topic, or to start a new discussion group if one doesn't
already exist.
The Internet also provides these people with access to computer resources. The sci-
ence teacher can access a NASA-funded computer that provides information, past,
present. and future, about space science and the space program. The minister can
find the Bible, the Koran, and the Torah, waiting to be searched for selected pas-
sages. The lawyer can find timely transcriptions of U.S. Supreme Court opinions in
Project Hermes. * The eighth grader can discuss musical lyrics with other eighth
graders, or can appear to be an expert among adults. After all, he is the only one
who understands the lyrics.
*Mead Data'" Lexis is heing 'test marketed' to law schools across the Internet.
2
What Is Ibis Book About?
This is just the beginning. Sure, you will still find a lot of things about computer
internals and the network itself, but this is quickly being eclipsed by information
about non-computer related fields. A large part of this book is a catalog of informa-
tion sources you can access through the Internet. In creating this catalog, we picked
as broad a range of sources as possible, to show that the Net really does have some-
thing for everyone. If we cataloged every resource on the Internet, the book would
be huge-and most of it would be telling you about different software repositories.
While we cover our share of software repositories, anyone can find software (if you
can't this book will show you how). What's harder is finding the other gems half-
buried in the muck. Since one person's gem is another's muck, we grouped the cata-
log by subject.
The nice thing about all this is that you play on your terms. When trying something
new in person, you're likely to be plagued by doubts. You hear about a bridge gath-
ering at the community center, and think "Am I good enough?", "Am I too good?",
"Will my ex-wife be there?" On the network, you can:
· Devote as much or as little time as you like
· Become casual acquaintances or fast friends with someone
· Observe discussions or take part
· Walk away from anything you find objectionable, or fight every wrong
If you'd like, you could make your collected works of poetry available to anyone
who would like to read them. There is very little risk, so you might as well try.
What You Will Learn
Just as there is no one use for the network, there is no one way to use the network.
If you learn everything in this book, you will become a competent network user.
You will knoV\ how to access every common thing on the network, and you'll know
how to get the software needed to do the uncommon things. But it will still be only
one way. There are different software packages and philosophies of use which you
may like better-there is nothing wrong with them.
Many people view the Internet as the Interstate Highway System for information.
You can drive cross-country in a Porsche, a pick-up truck, or a Yugo-they all get
you there. (Well, maybe not the Yugo.) This book takes you on a tour in a 1985
Chevy Impala. A Chevy may not be as sexy or fast as a Porsche, but it does offer
you a comfortable ride to your destination. Also, you won't get stuck in Outback,
Montana because the one mechanic in [Own has never seen a metric wrench.
In particular, here's what we will cover:
· How to log on to other computers on the Internet (telnet). Many computers clre
"publicly available" for various kinds of work. Some of these computers allow
anyone to use them; for some, you have to arrange for an account in advance.
Some of these computers can be used for "general purpose" work; others pro-
vide some special service, like access to a library catalog or a database.
3
Tbe Wbole Internet Catalog & User's &uide
· How to move files from one computer to ,mother (ftp>. There are many public
archives scattered around the network. providing files that are free for the tak-
ing. Many of these archives provide source code for various computer programs,
but other archives hold recipes. short stories, demographic information, and so
on. You ndme it, you can prohably find it (or something reasonably close).
· How to send electronic mail to other people who use the Internet. The Internet
provides worldwide electronic mail delivery.
· How to read and pdrticipate in group discussions (CSFNET news). There are dis-
cussion groups for topics rdnging from the obscure to the hizarre to the practical.
· Ho\v to find where various network resources, ranging from people to software
to general databases, are located ("white pages," archie, gopher, W AI
. World-
W'ide Weh). One of the Internet's problems is that it's too rich; there are so many
resources available, it's hard to find what you wdnt, or to remember where what
you want is located. A few years ago, the network was like a library without a
catalog. The "cataloging" tools are just now being put into place. We'll tell you
how to use some new and exciting tools (and some older, less-exciting tools) to
locate almost anything you might possibly want, ranging from people and soft-
ware to sociological abstracts and fruit-fly stocks.
With these tools, you'll have the network at your fingertips. There is one problem,
though. There are many different versions of all of these tools. I had to pick one
configuration to discuss in this book. I typically chose basic software, on which you
type commands to make it do your bidding, running on UNIX for the examples. I did
this for a couple of reasons. First, people who are going to have the most trouble
dealing with the network probably have the least sophisticated computer setup.
They are more likely to have a PC with two floppy drives than a high-end computer
with a graphics monitor and a mouse. With the software I'm discussing, a lower-end
computer will work fine. Second, when you start using the Internet, you may not be
connected to it directly, You may access the network by using a modem to "dial-up"
a computer that is connected, Most of the time, that computer will be running UNIX;
it's a fact of Internet life. Well, under those conditions you either are using a real ter-
minal (like a Digital Equipment VT100) or some emulation program, like Procomm,
Versatenn, or Kermit, that makes the fanciest computer act like a VT100 terminal. In
either case you are stuck with characters and commands.
For the most pdrt, what you can do on the Internet is defined by the network itself,
not by the software you run on your computer to gain access. Using a mouse and
pull-down menus may make the network easier to use, hut it really doesn't let you
do anything you couldn't do with a character-oriented dbplay and keyboard, So, by
making this choice, we're not limiting what you can do. Nor are we limiting the
book. If you go out and buy some mouse-bdsed software, you'll find that all the
concepts in this book are still applicable. You'll just be pushing buttons rather than
typing commands.
4
What Is This Book About?
What If I Don't Know UNIX?
It doesn't matter if you don't know UNIX. The Internet is not UNIX There are two
parts to using the network: running programs on your computer to access the Inter-
net, and using those programs to do things across the network. For a PC/DOS user
the program that lets you connect to another system for an interactive terminal ses-
sion is no different from any other PC/DOS program. The program's name is telnet,
so you type:
A: telnet
This looks just like starting WordPerfect or Lotus. The same is true for any other
brand of computer.
For your edification, let me show you the comparable UNIX command:
% telnet
Still think you need to know UNIX?
Once you get the program running, it will look just like every other program you
run on your computer: if you normally use commands, it will have commands; if
you use pull-down menus, it will have menus. Regardless of how you do things, the
things you can do will be the same. Think about how the network works (a subject
we'll discuss more in Chapter 3). Cooperating computers send precisely defined
messages back and forth. These messages only allow certain things to happen. If
those messages allow something to happen, it can. If they don't, it can't. It doesn't
matter whether your computer is a PC, a Macintosh, a VAX, or a UNIX workstation;*
the messages it sends to other Internet computers are the same.
So, the examples in this book were all done on UNIX systems-it shouldn't matter.
The commands you use may be slightly different, to make them more like a "nor-
mal" command on your computer sys tem, but when and why you use which com-
mand will remain the same. If an example shows that you start the ftp program
(you use this to move files), connect to a file archive on some computer, and
retrieve a certain file; then on an PC/DOS computer, you would need to do those
same steps in the same order. If you know how to run standard software on a com-
puter and read this book, you should be able to use the Internet.
At times, you may find that this discussion briefly descends into UNIX details, like
"uses the PAGER environment variable." I tried to be very explicit in explaining
examples, and this is the price I paid. If you're not interested in UNIX, skip the
details, but look at the explanation of what's going on. If the UNIX version of the
program has to deal with some condition, like the screen filling up, the PC/DOS or
Macintosh program will have to do it, too. They will do it in a manner that is
*This is not strictly true. The programs may be limited hy what a particular computer's operating system
may allow. Or the software for your computer may he an older (or newer) version than the correspond-
ing program on another computer.
5
The Whole Internet Catalog & User's Guide
unormal": Le., the way PC/DO
or a Macintosh handles similar events in other pro-
grams.
o, you might even be able to guess what you should do in an emergency
What You Need
You need three things to explore and use the Internet: a desire for information, the
ahility to use a computer, and access to the Internet. Desire for information is the
most important. That's what the Internet offers: the infonnation you want, when
\-ou want it-not "details at noon, six and ten, stay tuned." Without that desire, this
hook's contents won't impress you. If I say, "let's check the agricultural markets, the
special nutritional requirements of AIDS sufferers, ski conditions, and home beer
recipes," and you reply, "so what?" then you're not ready. If your response was,
u\XTow," then the Internet is for you.
You use the Internet with a computer. You don't have to be a computer scientist to
use it. You do need to be able to operate one, run existing programs, and under-
stand what files are. Some computer jargon might help, but mostly you need a
couple of very basic buzzwords:
bit The smallest unit of information. A bit can have the value 1 or the value
O. Everything in computing is based on collecting hunks of hits together,
manipulating them, and moving them from place to place. For example,
it takes eight bits to represent a standard alphabetic character.
K A suffix meaning "about 1000," derived from the Greek kilo. For
example, 8.6K characters meaning 8600 characters. In computing, K
may refer to 1000 or 1024 depending on the context, hut who cares? For
our purposes, "about 1000" is good enough.
click A verb meaning "to select something with a mouse." I did have to talk
about one interface which required a mouse. Sliding a mouse around on
the desk moves an arrow on the screen. Programs that use a mouse fre-
quently display simulated "push-buttons" on the screen. You activate
those buttons by positioning the arrow on the button you want to push,
and pressing the button on the mouse. This is commonly called "click-
ing" on that button.
If I did my job in writing this book, you will learn what you need to know along the
way. How's that for going out on a limb?
Finally, you need an Internet connection. This book is oriented towards someone
who has a connection and needs to know how to use it. That connection can take a
variety of flavors, ranging from a full connection via a local area network (IAN), to
limited dial-up connections using a terminal emulation package. If you already have
a connection, you can skip the next section. If you don't have a connection, Appen-
dix A discusses how to get one.
6
What Is This Book About?
What an Internet Connection Means
If you ask someone, "Are you connected to the Internet?" you might get some
strange answers. The question has a good, precise answer, but that's not what many
people think about. For many people, the question, "Are you connected" is similar
to the question "Do you shop at Sears?* Shopping at Sears means different things to
different people. To some, Sears is a store at the mall; to others, it is a catalog.
Whether the dnswer to the question is "yes" or "no" probably depends on whether
the respondent has been able to get what he or she wanted at Sears, not the means
by which the purchases were made, The same is true of Internet connections. If I
ask, "Are you connected?", the question you will likely hear is, "Can I do the Inter-
net things I want to do from my terminal?" For example, many people who only use
electronic mail think they are connected to the Internet when, in fact, they aren't.
Before you get started, it's important to know what a connection means. Once you
know what a connection means, you can figure out whether or not you already
have one; if you don't have one, you can determine what kind of connection service
you want to buy and how much you should pay.
The Internet offers a wide range of services. We've already seen a partial list of
these services: electronic mail, bulletin boards, file transfer, remote login, index pro-
grams, and so on. To get the complete set of services, you must have a TCP/IP style
connection (treat this as a buzzword right now-we'll get to what it means in a
while). A TCP/IP connection to the Internet is like a Vulcan mind meld on Star Trek.
Your computer is part of the network: your computer knows how to contact every
computer service on the Internet, though it may need some special software to use
some of them. Anything which can happen between networked computers can
occur. For example, if you want a file, you can move it directly to your workstation
as in Figure 1-1.
If you are only interested in some limited services, you don't necessarily need a full
connection to the Internet. That is: you can beg, borrow, or buy an account on a
computer that is connected to the Internet. Then you can use some terminal emula-
tor to dial in from your computer to the Internet machine; log in; read mail, fetch
files, and do whatever you want (Figure 1-2). In this situation it's fair to say, "I have
access to the Internet" or, "1 have an Internet connection" because you can do any-
thing the Internet will allow you to do-on the remote machine.t
But you can't say, "My home computer is connected to the Internet," because it isn't.
What's the difference? Well, once you've dialed in to your remote system, you can
read and write electronic mail. But you can't send or receive electronic mail from
your home system directly; you have to log in to some remote access point first. If
you want to save an important mail message, you can save it on the remote system.
But you can't save it on your own computer's disk directly; you'll have to first save
*Sears is, by the way. connected to the Internet
tOf course. the remote (Internet) computer might not have some useful program installed. You'll have
to talk that system's manager into finding it and installing it. Installing it on your home PC won't do any
good.
7
17Je
7Jole Internet Catalog & User's Guide
I
:
l
-
-
-
I
T
......
your computer
Flf!,ure 1-1: A tme hztenlet connection
.-
-
-
--
-
-
r
-
te/
.
\
Internet
\..
.... Access 1
,. System 1
....... "your computer
Figure 1-2: A dial-up Internet connectiun
the file on the remote system's disk then use your communications program to
move files from the remote system back to your desktop computer. Likewise, you
can fetch a file from any of the Internet's public archives; but you still need to go
8
What Is This Book About?
through an extr.l step of moving that file from the access computer to your personal
computer.
One step further away, you can get a kind of limited access to the Internet. If you're
a Compuserve or Bitnet user, you can send mail to the Internet, and (with the right
software) read Internet bulletin boards (known as news). A UNIX user who uses
UUCp* for electronic mail and news is in the same boat. Although it's common for
people in this situation to say that they're "connected to the Internet," they aren't in
any real sense. With this kind of connection, you can use a few popular Internet
services-but you can't use most of them. The fact that I can send a postcard to my
friends in Paris doesn't make me a citizen of France.
Getting Connected?
Here's the big surprise: You may already have an Internet connection and not know
it. Most Internet users have a connection through work or school: their corporation
or university is connected to the Internet, and they use it for work or for pleasure. If
your company has an Internet connection, and you have a computer in your office,
getting on the Net should be simple. Ask a system administrator whether or not the
company is on the Internet, and (if so) how you can get your office system hooked
up. If you're lucky, you may not have to do anything at all-you might be able to sit
down, type teInet, and go to work. Don't think this is unrealistic: there are a lot of
people who are this lucky. If you're unlucky and the administrator says that your
company or school is not on the Internet, ask the obvious question: "why not?" For
a small company, some relatively inexpensive Internet connections can give you the
kind of worldwide corporate network that, previously, only companies like EXXON
or IBM could afford.
If you're not already connected, there are many ways to get connected, These range
from large, fairly expensive solutions that are appropriate for large corporations or
universities to relatively low-cost solutions that are appropriate for very small
businesses or home use. No matter what level you're at, Internet access always
comes via an "access provider": an organization whose job it is to sell Internet
access. There are access providers for every level of service: from expensive dedi-
cated Internet connections, to inexpensive dial-up connections for home users.
Appendix A, Getting Connected to the Internet, lists many (though not all) access
providers and the types of service they provide. It also gives you some hints as to
how an individual may be able to get connected for little personal cost.
*uucp is an ancient way of configuring a UNIX computer to autom.uically dial-up another UNIX com-
puter and transfer files. This is the hasis for a vel)' popular mail service
9
The lf7Joie Internet Catalog & ('ser's Guide
How This Book Is Organized
This hook is organized like a class in high school woodshop. First, you talk ahout
the history and theory of carpentry. You then discuss (001 use and safety, one tool at
a time. On the last day of class, you go on a field trip to the lumber yard to get a feel
for what you hdve to work with.
In Chapters 2 through 4, we'll start with some history and theory. We'll keep the
background material to a minimum-just enough so you can understand why the
Internet is like it is. \Ve'll discuss a little hit ahout how the Internet works: not a lot
of "this bit moves here," hut mostly handwaving and conceptual explanations. This
isn't really required reading, and Cdn usually be skipped over safely. It's fairly short,
and I think it's important. If you get into a bind, and have to guess at what is going
on, or what (0 do next, nothing helps more than a feel for how things work. If you
would like to know more dhout the history of the Internet or its technology, there
are other books which go into a lot more detail. *
Most of the book (Chapters 5 to 15) discusses how to use the tools that allow your
computer to do things on the Internet. I've tried to focus on what you're likely to do,
and why: not just which knob to turn and which button to push, hut why you need
them. A lot of attention is paid to some relatively "fuzzy," but ultimately practical,
issues: what's allowed and what isn't? What's polite and what isn't? What's the best
way to find the kind of information you want?
The final large section of this book is a Resource Catalog: a list of things we (I had
some helpers) found on the Internet. It's organized by subject, so you shouldn't
have trouble finding topics that interest you. We found these resources by using the
tools explained in this book, and just looking around. The list is not complete, but
no list is. Pere Marquette didn't throw a dart at a map of the world and decide to
look for Indians to convert where the dart landed. He started in a place where he
knew there were Indians and began walking from there. This is your place to start.
Start at some place interesting and begin to look and wander. It's amazing what you
will find.
If you still think this thing called the Internet is for you, press on and you can find
out what it is.
*The best of these is probably Douglas Comer's book, Internetworking with TCPIIP: Principles, Proto-
cols, and Architectures (Prentice-Hall>. Technically. it's quite Ltdvanced, but it's the standard work on the
topic.
10
CHAPTER TWO
WHAT Is THE
INTERNET?
'What Makes Up the Internet?
'Who Governs the Internet?
Who Pays for It?
What Does This Mean for Me?
What Does the Future Hold?
T he Internet was born about 20 years ago, as a U.S. Defense Department net-
work called the ARPAnet. The ARPAnet was an experimental network
designed to support military research-in particular, research about how to
build networks that could withstand partial outages (like bomb attacks) and still
function. (Think ahout this when I describe how the network works; it may give
you some insight into the design on the Internet.) In the ARPAnet model, commu-
nication always occurs between a source and a destination computer. The network
itself is assumed to be unreliable; any portion of the network could disappear at any
moment (pick your favorite catastrophe-these days backhoes cutting cables are
more of a threat than bombs). It was designed to require the minimum of informa-
tion from the computer clients. To send a message on the network, a computer only
had to put its data in an envelope, called an Internet Protocol (IP) packet, and
"address" the packets correctly. The communicating computers-not the network
itself-were also given the responsibility to ensure that the communication was
accomplished. The philosophy was that every computer on the network could talk,
as a peer, with any other computer.
These decisions may sound odd, like the assumption of an "unreliable" network,
but history has proven that most of them were reasonably correct. Although the
International Standards Organization (ISO) was spending years designing the ulti-
mate standard for computer networking, people could not wait. Internet develop-
ers, responding to market pressures, began to put their IP software on every con-
ceivable type of computer. It became the only practical method for computers from
different manufacturers to communicate. This was attractive to the government and
universities, which didn't have policies saying that all computers must be bought
from the same vendor. Everyone bought whichever computer they liked, and
expected the computers to work together over the network.
11
17Je Whole Internet Catalog & User's Guide
Ahout ten years later, Ethernet local drea networks (IA.V) and workstations came on
the scene. Most of these workstations came with Berkeley UNIX, which came with
IP networking. Thb created a new demand: rather than connecting to a single large
timesharing computer per site, organizations wanted to connect the ARPAnet to
their entire local network. This would allow all the computers on that LAN to access
ARPAnet f.lCilities. About the same time, other organiz.:ltions started building their
own networks using the same communications protocols as the ARPAnet: namely,
IP and its relatives. It becdme obvious that if these networks could talk together,
users on one network could communicate with those on another; everyone would
benefit.
One of the most important of these newer networks was the I'\SFNET, run by the
National Science Foundation (NSF), an agency of the U.S. Government. In the late
80's the NSF created five supercomputer centers. Up to this point, the world's fastest
computers had only been available to weapons developers and a few researchers
from very large corpordtions. By creating supercomputer centers, the NSF was mak-
ing these resources available for any scholarly research. Only five centers were
created because they were so expensive-so they had to be shared. This created a
communicdtions problem: they needed a way to connect their centers together and
to allow the clients of these centers to access them. At first, the NSF tried to use the
ARPAnet for communications, but this strategy failed because of bureaucracy and
staffing problems.
In response, NSP decided to build its own network, based on the ARPAnet's IP tech-
nology. It connected the centers with 56,000 bit per second* (56k bps) telephone
lines. It was obvious, however, that if they tried to connect every university directly
to a supercomputing center, they would go broke. You pay for these telephone
lines by the mile. One line per campus with a supercomputing center at the hub,
like spokes on a bike wheel, adds up to lots of miles of phone lines. Therefore, they
decided to create regiondl networks. In each area of the country, schools would be
connected to their nearest neighbor. Each chain was connected to a supercomputer
center at one point, and the centers were connected together. With this configura-
tion, any computer could eventually communicate with any other by forwarding the
conversation through its neighbors.
This solution was successful-and, like any successful solution, a time came when
it no longer worked. Sharing supercomputers also allowed the connected sites to
share a lot of other things not related to the centers. Suddenly these schools had a
world of data and collaborators at their fingertips. The network's traffic increased
until, eventually, the computers controlling the network and the telephone lines
connecting them were overloaded. In 1987, a contract to manage and upgrade the
network was awarded to Merit Network Inc., which ran Michigan's educational net-
work, in partnership with IBM and MC!. The old network was replaced with faster
telephone lines (by a factor of 20), with faster computers to control it.
*This is roughly the ahility to transfer two full typewritten pages per second. That's slow hy modem
standards, but it was reasonahly fast in the mid 80's.
12
What Is tbe Internet?
The process of running out of horsepower and getting bigger engines and better
roads continues to this day. Unlike changes to the highway system, however, most
of these changes aren't noticed by the people trying to use the Internet to do real
work. You won't go to your office, log in to your computer, and find a message say-
ing that the Internet will be inaccessible for the next six months because of
improvements. Perhaps even more important: the process of running out of capacity
and improving the network has created a technology that's extremely mature and
practical. The ideas have been tested; problems have appeared, and problems have
been solved.
For our purposes, the most important aspect of the NSF's networking effort is that it
allowed everyone to access the network. Up to that point, Internet access had been
available only to researchers in computer science, government employees, and gov-
ernment contractors. The NSF promoted universal educational access by funding
campus connections only if the campus had a plan to spread the access around. So
everyone attending a four-year college could become an Internet user.
The demand keeps growing. Now that most four-year colleges are connected,
people are trying to get secondary and primary schools connected. People who
have graduated from college know what the Internet is good for, and talk their
employers into connecting corporations. All this activity points to continued growth,
networking problems to solve, evolving technologies, and job security for network-
ers.
What Makes Up the Internet?
What comprises the Internet is a difficult question; the answer changes over time.
Five years ago the answer would have been easy: "All the networks, using the IP
protocol, that cooperate to form a seamless network for their collective users." This
would include various federal networks, a set of regional networks, campus net-
works, and some foreign networks.
More recently, some non-IP-based networks saw that the Internet was good. They
wanted to provide its services to their clientele. So they developed methods of con-
necting these "strange" networks (e.g., Bitnet, DECnets, etc.) to the Internet. At first
these connections, called gateways, merely served to transfer electronic mail
between the two networks. Some, however, have grown to full service translators
between the networks. Are they part of the Internet? Maybe yes and maybe no. It
depends on whether, in their hearts, they want to be. If this sounds strange, read
on-it gets stranger.
Who Governs the Internet?
In many ways the Internet is like a church: it has its council of elders, every member
has an opinion about how things should work, and you can either take part or not.
It's your choice. The Internet has no president, chief operating officer, or Pope, The
constituent networks may have presidents and CEOs, but that's a different issue;
there's no single authority figure for the Internet as a whole.
13
17Je Uhole Internet Catalog & l'ser's Guide
The ultimate duthority for where the Internet is going rests with the Internet Society,
or ISac. Isac is a volunt.lry memhership organization whose purpose is to promote
glohal information exchange through Internet technology. * It appoints a council of
elders, which has responsihility for the technical management and direction of the
Internet.
The council of elders is a group of invited volunteers called the Intenlet Architec-
ture Board, or the lAB. The lAB meets regularly to "hless" stanùards and allocate
resources, like addresses. The Internet works hecause there are standard ways for
computers and software applications to talk to each other. This allows computers
from different vendors to communicate without prohlems. It's not an IBM-only or
Sun-only or Macintosh-only network. The lAB is responsible for these standards; it
decides when a standard is necessary, and what the standard should be. When a
standard is required, it considers the problem, aùopts a standard, and announces it
via the network. (Vou were expecting stone tablets?) The lAB also keeps track of
various numbers (and other things) that must remain unique. For example, each
computer on the Internet has a unique 32-hit address; no other computer has the
same address. How does this address get assigned? The lAB worries about these
kinds of prohlems. It doesn't actually assign the addresses, but it makes the rules
about how to assign addresses.
As in a church, everyone has an opinion how things ought to run. Internet users
express their opinions through meeting
of the Internet Engineering Task Force
(IETF). The IETF is another volunteer organization; it meets regularly to discuss oper-
ational and near-term technical problems of the Internet. When it considers a prob-
lem important enough to merit concern, the IETF sets up a "working group" for fur-
ther investigation. (In practice, "important enough" usually means that there are
enough people to volunteer for the working group.) Anyone can attend IETF meet-
ings and be on working groups; the important thing is that they work. Working
groups have many different functions, ranging from producing documentation, to
deciding how networks should cooperate when problems occur, to changing the
meaning of the bits in some kind of packet. A working group usually produces a
report. Depending on the kind of recommendation, it could just be documentation
and made availahle to anyone wanting it, it could be accepted voluntarily as a good
idea which people follow, or it could be sent to the lAB to he declared a standard.
If you go to a church and accept its teachings and philosophy, you are accepted by
it, and receive the benefits. If you don't like it, you can leave. The church is still
there, and you get none of the benefits. Such is the Internet. If a network accepts
the teachings of the Internet, is connected to it, and considers itself part of it, then it
is part of the Internet. It will find things it doesn't like and can address those con-
cerns through the IETF. Some concerns may be considered valid and the Internet
may change accordingly. Some of the changes may run counter to the religion, and
be rejected. If the network does something that cau
es damage to the Internet, it
could be excommunicated until it mends its evil ways,
*If you'd like more infonn.uion, or if you would like to join, see "Network Orgdnizations" in the Re-
source Catalog
14
What Is tbe Internet?
Who Pays for It?
The old rule for when things are confusing is "follow the money." Well, this won't
help you to understand the Internet. No one pays for "it"; there is no Internet, Inc.
that collects fees from all Internet networks or users. Instead, everyone pays for
their part. The NSF pays for NSF.:'JET. NASA pays for the NASA Science Internet. Net-
works get together and decide how to connect themselves together and fund these
interconnections. A college or corporation pays for their connection to some
regional network, which in turn PdYS a national provider for its access.
What Does This Mean for Me?
The concept that the Internet is not a network, but a collection of networks, means
little to the end user. You want to do something useful: run a program, or access
some unique data. You shouldn't have to worry about how it's all stuck together.
Consider the telephone system-it's an internet, too. Pacific Bell, AT&T, MCI,
British Telephony, Telefonos de Mexico, and so on, are all separate corporations
that run pieces of the telephone system. They worry about how to make it all work
together; all you have to do is dial. If you ignore cost and commercials, you
shouldn't care if you are dealing with MCI, AT&T, or Sprint. Dial the number and it
works.
You only care who carries your calls when a problem occurs. If something goes out
of service, only one of those companies can fix it. They talk to each other about
problems, but each phone carrier is responsible for fixing problems on its own part
of the system. The same is true on the Internet. Each network has its own network
operations center CNOC). The operations centers talk to each other and know how
to resolve problems. Your site has a contract with one of the Internet's constituent
networks, and its job is to keep your site happy. So if something goes wrong, they
are the ones to gripe at. If it's not their problem, they'll pass it along.
What Does the Future Hold?
Finally, a question I can answer. It's not that I have a crystal ball (if I did I'd spend
my time on Wall Street instead of writing a book). Rather, these are the things that
the lAB and the IETF discuss at their meetings. Most people don't care about the long
discussions; they only want to know how they'll be affected. So, here are highlights
of the networking future.
New Standard Protocols
When I was talking about how the Internet stdrted, I mentioned the International
Standards Organization (ISO) and their set of protocol standards. Well, they finally
finished designing it. Now it is an international standard, typically referred to as the
ISO or OSI COpen Systems Interconnect) protocol suite. Many of the Internet's com-
ponent networks allow use of OSI today. There isn't much demand, yet. The U.S.
Government has taken a position that government computers should be able to
speak these protocols. Many have the software, but few are using it now.
15
The \f7Jole Internet Catalog & User's Guide
It's really unclear how much demand there will be for OSI, notwithstanding the gov-
ernment backing. Many people feel that the current approach isn't broke, so why fix
it? They are just becoming comfortahle with what they have, why should they have
to learn a new set of commands and terminology just because it is the standard?
Currently there are no real advantages to moving to as!. It is more complex and less
mature than IP, and hence doesn't work as efficiently. OSI does offer hope of some
additional features, but it also suffers from some of the same problems which will
plague IP as the network gets much bigger and faster. It's cledr that some sites will
convert to the OSI protocols over the next few years. The question is: how many?
International Connections
The Internet has been an international network for a long time, hut it only extended
to the United States' allies and overseas military bases. Now, with the less paranoid
world environment, the Internet is spreading everywhere. It's currently in over 40
countries, and the number is rapidly increasing. Eastern European countries longing
for Western scientific ties have wdnted to pdrticipate for a long time, but were
excluded by government regulation. This ban has been relaxed. Third world coun-
tries that formerly didn't have the means to participate now view the Internet as a
way to raise their education and technology levels.
The ability of the Internet to speak OSI protocols should help the Internet to expand
into more countries. Except for the Scandinavian countries, which embraced the
Internet protocols long ago and are already well-connected, most of Europe regards
IP as a cultural threat akin to EuroDisney. Networks based on the OSI protocols are
much more palatable for them. If the two protocols could co-exist, everyone would
be happy.
At present, the Internet's international expansion is hampered by the lack of a good
supporting infrastructure, namely a decent telephone system. In both Eastern
Europe and the third world, a state-of-the-art phone system is nonexistent. Even in
major cities, connections are limited to the speeds available to the average home
anywhere in the U.S., 9600 bits/second. Typically, even if one of these countries is
"on the Internet," only a few sites are accessihle. Usually, this is the major technical
university for that country. However, as phone systems improve, you can expect
this to change too; more and more, you'll see smaller sites (even individual home
systems) connecting to the Internet.
Commercialization
Many big corporations have been on the Internet for years. For the most part, their
participation has been limited to their research and engineering departments. The
same corporations used some other network (usually a private network) for their
business communications. After all, this IP stuff was only an academic toy. The IBM
mainframes that handled their commercial data processing did the "real" networking
using a protocol suite called System Network Architecture (SNA)
16
What Is the Internet?
Businesses are now discovering that running multiple networks is expensive. Some
are beginning to look to the Internet for "one-stop" network shopping They were
scared away in the past by policies which excluded or restricted commercial use.
Many of these policies are under review and will change. As these restrictions drop,
commercial use of the Internet will become progressively more common,
This should be especially good for small businesses. Motorola or Standard Oil can
afford to run nationwide networks connecting their sites, but Joe's Custom Software
couldn't. If Joe's has a San Jose office and a Washington office, all it needs is an
Internet connection on each end. For all practical purposes, they have a nationwide
corporate network, just like the big boys.
Privatization
Right behind commercialization comes privatization. For years, the networking com-
munity has wanted the telephone companies and other for-profit ventures to pro-
vide "off the shelf" IP connections. That is, you could order an Internet connection
just like you order a telephone jack for your house. You order, the telephone
installer leaves, and you plug your computer into the Internet. Except for Bolt,
Beranek and Newman, the company that ran the ARPAnet, there weren't any takers.
The telephone companies have historically said, "We'll sell you phone lines, and
you can do whatever you like with them." By default, the Federal government
stayed in the networking business.
Now that large corporations have become interested in the Internet, the phone com-
panies have started to change their attitude. Now they and other profit-oriented net-
work purveyors complain that the government ought to get out of the network busi-
ness. After all, who best can provide network services but the "phone companies"?
They've got the ear of a lot of political people, to whom it appears to be a reason-
able thing. If you talk to phone company personnel, many of them still don't really
understand what the Internet is about, They ain't got religion, but they are studying
the Bible furiously. *
Although most people in the networking community think that privatization is a
good idea, there are some obstacles in the way. Most revolve around the funding
for the connections that are already in place. Many schools are connected because
the government pays part of the bill. If they had to pay their own way, some schools
would probably decide to spend their money elsewhere. Major research institutions
would certainly stay on the Net; but some smaller colleges might not, and the costs
would probably be prohibitive for most secondary schools (let alone grade
schools). What if the school could afford either an Internet connection or a science
lab? It's unclear which one would get funded. The Internet has not yet become a
"necessity" in many people's minds. When it does, expect privatization to come
quickly.
* Apologies to those telephone company employees who saw the light years ago and have heen trying
to drag their employers into church.
17
The \H.Jole Internet Catalog & User's Guide
Well, enough questions about the history of the information highway system. It's
time to walk to the edge of the road, try and hitch a ride, and be on your way.
18
CHAPTER THREE
How THE
INTERNET WORKS
Moving Bits from One Place to Another
Making the Network Friendly
I t's nice to know a bit about how things work. It allows you to make sense out of
some of the hints you will see in this book. They will make sense, rather than
seeming like capricious rules to be learned by rote. Lest you be scared away, we
will explore this with a maximum amount of handwaving. We'll never say "this field
is 3 bits long. . . "; we won't even think about it! If you want to know more, several
books on the Internet's implementation are available. *
In this chapter, we will look at packet switching networks and how, by putting
TCP/IP on top of such a network, something useful happens. We will talk about the
basic protocols that govern how the Internet communicates: TCP and its poor
cousin, UDP. These are the network's building blocks. At this point the Internet is
fairly boring (frustrating and hard to use). When you put the Domain Name System
and a few applications on top of it, it becomes something useful.
If you decide this isn't your cup of tea, feel free to skip the beginning of this chap-
ter. Do read the section on the Domain Name System. It is something that you will
be using indirectly for your entire Internet career.
Moving Bits from One Place to Another
Modern networking is built around the concept of "layers of service." You start out
trying to move bits from here to there, losing some along the way. This level con-
sists of wires and hardware, and not necessarily very good wires. Then you add a
layer of basic software to shield yourself from the problems of hardware. You add
another layer of software to give the basic software some desirable features. You
continue to add functionality and smarts to the network, one layer at a time, until
*Comer, Douglas, /nternetworking with TCP//P: Principles, Protocols, and Architecture, Volumes I and II
(Prentice Hall).
19
The Whole Internet Catalog & ['ser's Guide
you have something that'
friendly and useful. \Vell, let's start at the hottom and
work our way up.
Packet Su'itch Networks
\Vhen you try to imagine what the Internet is and how it operates, it is natural to
think of the telephone system. After .111, they" are hoth electronic, they both let you
open a connection and transfer information, and the Internet is primarily composed
of dedicated telephone lines. Unfortunately, this is the wrong picture, and causes
mJny misunderstandings about ho\\ the Internet operates. The telephone network
is what is known as a circuit sll'itched net\vork. When you make a call, you get a
piece of the net\vork dedicated to you. Even if you aren't using it (for example, if
you are put on hold), your piece of the network is unavailable to others wishing to
do real work. This leads to underutilization of a very expensive resource, the net-
work.
A hetter model for the Internet, which may not instill confidence in you, is the u.s.
Postal Service. The Postal Service is a packet switched network. You have no dedi-
cated piece of the network. What you want to send is mixed together with everyone
else's stuff, put in a pipe, trJnsferred to another Post Office, and sorted out again.
Although the technologies are completely different, the Postal Service is a surpris-
ingly accurate analogy; we'll continue to u
e it throughout this chapter.
The Internet Protocol (IP)
A wire can get data from one place to another. However, you already know that the
Internet can get data to many different places, distributed all over the world. How
does that happen?
The different pieces of the Internet are connected by a set of computers called
routers, which connect networks together. These networks are sometimes Ether-
nets; sometimes token rings, and sometimes telephone lines, as shown in Figure
3-1.
The telephone lines and Ethernets are equivalent to the trucks and planes of the
Postal Service. They are means by which mail is moved from place to place. The
routers are postal substations; they make decisions about how to route data ("pack-
ets"), just like a postal suhstation decides how to "route" envelopes containing mail.
Each suhstation or router does not have a connection to every other one. If you put
an envelope in the mail in Dixville Notch, New Hampshire, addressed to Boonville,
California, the Post Office doesn't reserve a plane from New Hampshire to
California to carry it. The local Post Office sends it to a substation; the substation
sends it to another suhstation; and so on, until it reaches the destination. That is,
each sub-station only needs to know what connections are available, and what is
the best "next hop" to get a packet closer to its destination. Similarly, with the Inter-
net: a router looks at where your data is going and decides where to send it next. It
just decides which pipe is best and uses it.
20
How the Internet Works
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How does the Net know where your data is going? If you want to send a letter, you
can't just drop the typed letter into the mailbox and expect delivery. You need to
put the paper in an envelope, write an address on it, and stick a stamp on it. Just as
the Post Office has rules about how to use its network, the Internet has rules about
how to use it. The rules are called protocols. The Internet Protocol (IP) takes care of
addressing, or making sure that the routers know what to do with your data when it
arrives. Sticking with our Post Office analogy, the Internet Protocol works just like
an envelope (Figure 3-2).
Figure 3-2: IP envelopes
i From: 192.112.36.5
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IP Packet
21
The \f-1Jole Internet Catalog & User's Guide
Some addressing information goes at the beginning of your me:,sage; this informa-
tion gives the network enough information to deliver the packet of data.
Internet addresses consist of four numbers less than 256. When written out, the
numbers are sep,lfated by periods like this:
192.112.36.5
128.174.5.6
(Don't worry; you don't need to remember numbers like these to use the network.)
The address is actually made up of multiple parts. Since the Internet is a network of
networks, the beginning of the address tells the Internet routers what network you
are part of. The right end of the address tells that network which computer or host
should receive the packet. * Every computer on the Internet has a unique address
under this scheme. Again, the Postal Service provides a good analogy. Consider the
address "50 Kelly Rd., Harnden, CT." The "Harnden, CT" portion is like a network
address; it gets the envelope to the right local Post Office, the Post Office that
knows about streets in a certain area. "50 Kelly Rd." is like the host address; it iden-
tifies a particular mailbox within the Post Office's service area. The Postal Service
has done its job when it has delivered the mail to the right local office, and when
that local office has put it into the right mailbox. Similarly, the Internet has done its
job when its routers have gotten data to the right network. and when that local net-
work has given the datd. to the right computer, or host, on the network.
For a lot of practical reasons (notably hardware limitations), information sent across
IP networks is broken up into bite-sized pieces, called packets. The information
within a packet is usually between 1 and about 1500 characters long. This prevents
anyone user of the network from monopolizing the network and allows everyone
to get a fair shot. It also means that if the network isn't fast enough, as more people
try to use it, it gets slower for everyone.
One of the amazing things about the Internet is that, on a basic level. IP is all YOli
need to participate. It wouldn't be very friendly but, if you were clever enough, you
could get some work done. As long as your data is put in an IP envelope, the net-
work has all the information it needs to get your packet from your computer to its
destination. Now, however, we need to deal with several problems:
· Most information transfers are longer than 1500 characters. You would be disap-
pointed, indeed, if the Post Office would only carry postcards, but refused any-
thing larger.
· Things can go wrong. The Post Office occasionally loses a letter; networks
sometimes lose packets, or damage them in transit. Unlike the Post Office, we'll
see that the Internet can deal with these problems successfully.
*Where the network portion ends and the host portion hegins is a bit complicated. It varies from ad-
dress to address based on an agreement hetween adjacent routers. Fortunately, as a user you II never
need to wony ahout this; it only makes a difference when you're setting up a network.
22
How the Internet Works
. Packets may arrive out of sequence. If you mail two letters to the same place on
successive days, there's no guarantee that they will take the same route or arrive
in order. The same is true of the Internet.
So, the next layer of the network will give us a way to transfer bigger chunks of
information, and will take care of the many "distortions" that can creep in because
of the network.
The Transmission Control Protocol (TCP)
TCP is the protocol, frequently mentioned in the same breath as IP, that is used to
get around these problems. What would happen if you wanted to send a book to
someone, but the Post Office only accepted letters? What could you do? You could
rip each page out of the book, put it in a separate envelope, and dump them all in a
mailbox. The recipient would then have to make sure the pages all arrived and
paste them together in the right order. This is what TCP does.
TCP takes the information you want to transmit and breaks it into pieces. It numbers
each piece so receipt can be verified and the data can be put back in the proper
order. In order to pass this sequence number across the network, it has an envelope
of its own which has the information it requires "written on it" (Figure 3-3). A piece
of your data is placed in a TCP envelope. The TCP envelope is, in turn, placed
inside an IP envelope and given to the network. Once you have something in an IP
envelope, the network can carry it.
On the receiving side, a TCP software package collects the envelopes, extracts the
data, and puts it in the proper order. If some are missing, it asks the sender to
retransmit them. Once it has all the information in the proper order, it passes the
data to whatever application program is using its services.
This is actually a slightly utopian view of TCP. In the real world not only do packets
get lost, they can also be changed by glitches on telephone lines in transit. TCP also
handles this problem. As it puts your data into an envelope, it calculates something
called a checksum. A checksum is a number that allows the receiving TCP to detect
errors in the packet. * When the packet arrives at its destination, the receiving TCP
calculates what the checksum should be and compares it to the one sent by trans-
mitter. If they don't match, an error has occurred in the packet. The receiving TCP
throws that packet away and requests a retransmission.
* Here's a simple example, if you're interested. Ler's assume that you're transmiuing raw compurer data in
8-bit chunks, or bytes. A vel)' simple checksum would be ro add all of these bytes together. Then stick
an extra byte onto the end of your data that contains the sum. (Or, at least, as much of the sum as fits
into 8 hits.) The receiver makes the same calculation. If any byte was changed during transmission, the
checksums will disagree. and you'll know there was an error. Of course, if there were two errors, they
might cancel each other out. But more complicated computations can handle multiple errors.
23
The Whule Internet Catalug & User's Guide
#7
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Other Transmission Protocols
TCP creates the appearance of a dedicated wire between the two applications, guar-
anteeing that what goes in one side comes out the other. You don't have a dedi-
cated link between the sender and receiver Cother people can use the same routers
and network wires in the gaps between your packets); but, for all practical pur-
poses, it looks like you do.
Ideal as this may sound, it is not the best approach for every program to use. Setting
up a TCP connection requires a fair amount of overhead and delay; if this machinery
isn't needed, it's better not to use it. If all the data you want to send will fit in one
packet and you don't particularly care to guarantee delivery, TCP may be overkill.
It turns out that there is another standard protocol that does away with this over-
head. This protocol is called the user datagram protocol or UDP. It is used instead
of TCP in some applications; that is, instead of wrapping your data in a TCP enve-
lope and putting that inside an IP envelope, the application puts your data into a
UDP envelope, which goes in the IP envelope.
UDP is a lot simpler than TCP because it doesn't worry about missing packets,
keeping data in the right order, or any of those niceties. UDP is used for programs
that only send short messages, and can just resend the me:':'age if a response does
24
How the Internet Works
not come in a short time. For example, assume that you're writing a program that
looks up phone numbers in a database somewhere else on the network. There is no
reason to set up a TCP connection to transmit 20 or so characters in each direction.
You can just put the name into one UDP packet, stick that into an IP packet, .and
send it. The other side of the application gets the packet, reads the name, looks up
the phone number, puts that into another UDP packet, and sends it back. What hap-
pens if the packet gets lost along the way? Your program has to handle that: if it
waits too long without getting a response, it justs sends another request.
Making the Network Friendly
Now that we have the ability to transfer information between places on the net-
work, we can start working on making the Internet more friendly. This is done by
having software tailored to the task at hand, and using names rather than addresses
to refer to computers.
Applications
Most people don't get really excited about having a guaranteed bit stream between
machines, no matter how fast the lines or exotic the technology that creates it. They
want to use that bit stream to do something useful, whether that is to move a file,
access some data, or playa game. Applications are pieces of software that allow this
to happen easily. They are yet another "layer" of software, built on top of the TCP or
UDP services. Applications give you, the user, a way to do the task at hand.
What an application is varies greatly. Applications can range from home-grown pro-
grams to proprietary programs supplied by a vendor. There are three "standard"
Internet applications: remote login, file transfer, and electronic mail, as well as other
commonly used but not standardized applications. Chapters 5 through 14 of this
book describe how to use most of the common Internet applications.
One problem with talking about applications is that the application's appearance to
you is determined by your local system. The commands, messages, prompts, etc.,
may be slightly different on your screen than in the book or on someone else's
screen. So, don't worry because the book says the message is "connection refused"
and the error message you receive is "Unable to connect to remote host: refused";
they are the same. Try and distill the essence of the message, rather than matching
the exact wording. And don't worry if some of the commands are named slightly
differently; most of the applications have reasonable "help" facilities that will let
you figure out the right command.
The Domain Name System
Fairly early on, people realized that addresses were fine for machines communicat-
ing with machines, but humans preferred names. It is hard to talk using addresses
(who would say, "I was connected to 192.112.36.5 yesterday and. . . "?), and even
harder to remember them. Therefore, computers on the Internet were given names
for the convenience of their human users. The preceding conversation becomes "I
25
The Whole Internet Catalog & User's Guide
was connected to the NIC* yesterday and. . . ". All of the Internet applications let
you use system names, rather than host dddresses.
Of course, naming introduces problems of its own. For one thing, you have to make
sure that no two computers that are connected to the Internet have the same name.
You also have to provide a way to convert names into numeric addresses. After all,
names are just fine for people; but the computers really prefer numbers, thank you.
You can give a program a name, but it needs some way to look that name up and
convert it into an address. (Y Oll do the same thing whenever you look someone up
in the phone book.)
In the beginning, when the Internet was a small folksy place, dealing with names
was easy. The NIC (Network Information Center) set up a registry. You would send
in a fonn, electronically of course, and they would maintain a file of names and
addresses. This file, called the hosts file, was distrihuted regularly to every machine
on the network. The names were simple words, every one chosen to be unique. If
you used a name, your computer would look it up in the file and substitute the
dddress. It was good.
Unfortunately, when the Internet went forth and multiplied, so did the size of the
file. There were significant delays in getting a name registered, and it became diffi-
cult to find names that weren't already used. Also, too much network time was
spent distributing this large file to every machine contained in it. It was obviollS that
a distrihuted, online system was required to cope with the rate of change. This sys-
tem is called the Domain Name System or DNS,
The Domain System Structure
The Domain Name System is a method to administer names by giving different
groups responsibility for subsets of the names. Each level in this system is called a
domain. The domains are separated by periods:
ux.cso.uiuc.edu
nic.ddn.mil
yoyodyne. com
There can be a variable number of domains within the name but practicdlly there
are usually five or less. As you proceed left to right through the domains, the num-
ber of names contained in the group gets bigger.
In the first line above (ux.eso.uiue.edu), ux is the name of a host, a real computer
with an IP address (Figure 3-4). The name for that computer is created and main-
tained by the eso group, which happens to be the department where the computer
resides. The department eso is a part of the University of Illinois at Urbana
Champdign (uiue). uiue is a portion of the national group of educational institu-
tions (edu). So the zone edu contains all computers in all U.S. educational institu-
tions; the zone uiue.edu contains all computers at the University of Illinois; and so
on.
* A Network Informarion Cemer is a repositOl)' for information about a network.
26
How the Internet Works
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Each group can create or change whatever lies within it. If uiue decided to create
another group called nesa, it could do so without asking anyone's permission. All it
has to do is add the new names to its part of the worldwide database, and sooner or
later everyone who needs to know will find out about the new name. Similarly, eso
can buy a new computer, assign it a name, and add it to the network without asking
anyone's permission. If every group from edu on down plays by the rules and
makes sure that the names it assigns are unique, then no two systems anyv.rhere on
the Internet will have the same name. You could have two machines named fred,
but only if they are in different domains (for example, fred.eso.uiue.edu and
fred.ora.eom) .
In practice, being the name administrator for a group requires certain skills, and is
not fun. Therefore, at some level around the enterprise level (uiue) or one level
below it, there is a person who is responsible for maintaining all lower levels. There
is some locally defined procedure for requesting that a name get created or
changed.
It's easy to see where domains and names come from within an organization like a
university or a business. However, where do the "top level" domains like edu come
from? They were created by fiat when the domain system was invented. Originally,
there were six highest level domains (see Table 3-1).
27
Tbe \f1Jole Internet Catalog & User's Guide
Table 3-1: Origil1al High-level Domains
Domain
Usage
For commercial organizations (Le., businesses)
Educational organizations (universities, secondary schools, etc.)
Governmental organizations, non
military
Military (army, navy, etc.)
Other organizations
Network resources
com
edu
gov
mil
or;g
net
As the Internet was a worldwide network, there needed to be a way to give foreign
countries responsibility for their own names. To this end, there are a set of two
letter domains which correspond to the highest level domains for countries. Since
ca is the country code for Canada, a Canadian computer might be named:
hockey. guelph. ca
There are almost 300 country codes, about 100 of which have some kind of com-
puter networking. There is a list of the country codes in Appendix B, International
Network Connectivity, in case you want to see where mail you received came from.
It's worth noting that the u.S. has its own country code, although it isn't used too
often; in the U.S., most network sites use the "organizational" domains (like edu) ,
rather than the "geographical" domains (like va.us- Virginia). However, you will
see both kinds of names. One computer may even have both kinds of names just for
completeness. There's no way to "convert" between organizational names and geo-
graphical names. For example, even though uxc.cso.uiuc.edu happens to be in
Urbana, Illinois, U.S.A., there is not necessarily a name uxc.urbana.il.us. Even if
there is, they aren't necessarily the same computer.
Domain Name Lookup
Now you know how domains relate to each other and how a name gets created.
Now you might just wonder how to use this marvelous system. You use it automati-
cally, whenever you use a name on a computer that knows about it. You never
need to look a name up "by hand," or give some special command to find out about
some name, although you can if you want. All computers on the Internet can use
the domain system, and most do.
When you use a name like ux.cso.uiuc.edu, the computer needs to turn it into an
address. To do so, it starts asking DNS servers for help, starting at the right end and
working left. First, it asks the local DNS servers to look up the address. At this point,
there are three possibilities:
· The local server knows the address, because the address is in the local server's
part of the worldwide database. For example, if you're in the computer science
department of the University of Illinois, your local server probably has informa-
tion about the computers in your department.
28
How tbe Internet W'orks
· The local "erver knows the address because someone else has asked for the
same address recently. Whenever you ask for an address. the DNS server keeps
it on hand for a while. just in case someone else wants the same address later;
this makes the system a lot more efficient.
· The local server doesn't know the address. but it knows how to find out.
How does the local server find out? Its software knows how to contact a root server.
This is the server that knows the addresses of name servers for the highest level
(rightmost) zone (edu). It asks the root server for the address of the computer
responsible for the edu zone. Having that information, it contacts that server and
asks that server for the address of the uiue server. Your software then contacts that
computer and asks for the address of the server for eso. Finally. it contacts that
machine and gets the address of ux, the host that was the target of the application.
A few computers are still configured to use the old-style hosts file. If you find your-
self on one of these, you may have to ask its administrator to look up the address
you need by hand (or look it up yourselO; then the administrator will have to add
the machine you want to contact to the local hosts file. While you're doing this. YOll
can hint that the administrator really ought to install the DNS software so YOll won't
have to do this again.
Domain Name System Hints
There are a few common misconceptions that you may encounter dealing with
names. Here are a few we can dispel now:
· The pieces of a domain-style name tell you who is responsible for maintaining
the name. It may not tell you anything about who maintains the computer corre-
sponding to that IP address, or even (despite the country codes) where that
machine is located. It would be perfectly legal for me to have the name
oZ.eso.uiue.edu (part of the University of Illinois' name space) point to a
machine in Australia. It isn't normally done, but it could be.
· The pieces of a domain name don't even necessarily tell you what network a
computer is located on. Domain names and networking often overlap, but
there's no necessary connection between them; two machines in the same
domain may not be on the same network. For example. the systems
uxe.eso.uiuc.edu and uxl.cso.uiuc.edu may be on different networks. Once
again, domain names only tell you who is responsible for the domain.
· A machine can have multiple names. This is especially true of machines that
offer services, where the service may be moved to a different computer in the
future. My Sun workstation may be known by ek.eso.uiuc.edu. It also might be
the computer where you can go to get publicly available files at the University of
Illinois. So it might also have the name ftp.uiuc.edu (ftp being the name of the
file moving program). Some time in the future, this service might he moved to
some other computer. When this happens, the name ftp.uiuc.edu would move
along with the service (my computer gets to keep its old name
ek.cso.uiuc.edu). People wanting the particular service use the same n
lme
regardless of which computer is providing the service. Names that symbolically
29
The Whole Internet Catalog & User's Guide
refer to a service are called "canonical names" or cnames. You will see them fre-
quently as you wander about the Internet.
· Names aren't necessdry for communication. Unless the error message you
receive is "host unknown," the name worked fine. A message like "host
unknown" means your system could not translate the name you gave into an
dddress. Once your system has the address in hand, it never uses the name
again.
· It is better to remember names than addresses. Some people feel that the name
system is "just one more thing to go wrong." The problem is that an address is
tied to a network. If the computer providing a service is moved from one build-
ing to another, its network and hence its address will likely change. The name
needn't change. \Vhen the administrator assigns the new address, he only needs
to update the name record so that the name points to the new address. Since the
name still works, you don't particularly care if the computer or function has
changed locations.
The Domain Name System may sound complicated, but it's one of the things that
make the Internet a comfortable place to live. If you don't like the periods wander-
ing around. forget about what they mean: they're just names. However, pretty soon
you'll start realizing, "yes, this resource is at the University of Virginia; this person
works for IBM in Germany; this is the address for reporting bugs in Nutshell Hand-
books (nuts@ora.com)" and so on. The real advantage of the domain system is
that it breaks the gigantic worldwide Internet into a bunch of manageable pieces.
Although hundreds of thousands of computers are "on the Net," they're all named;
and the names are organized in a convenient, perhaps even rational way, making it
easier for you to remember the ones you need.
30
CHAPTER FOUR
WHAT'S ALLOWED
ON THE INTERNET?
Legal Implications
Politics and the Internet
Network Ethics
Security Consciousness
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I n earlier chapters, I told you very generally what the Internet is good for, where
it came from, and how it works. Now it's time to get to the real nitty-gritty. We
will talk about what you are allowed to do on the network; in the next chapter,
we will start discussing "how to do it."
What you are allowed to do is a very complex issue. It is influenced by law, ethics,
and politics. How these inter-relate and which is paramount vary from place to
place. The Internet isn't a network-it's a network of networks-and each network
may have its own policies and rules. Lest you should give up before starting, the
rules are reasonably uniform, and you'll be safe if you keep a few guidelines in
mind. Fortunately, these guidelines aren't terribly restrictive. As long as you stay
within those guidelines, you can do whatever you want. If you feel yourself getting
near the edges, contact your network provider to determine exactly what is allowed
and what isn't. It may be possible to do what you want, but it's your responsibility
to find out. Let's look at the issues so you can see where the borders are.
Legal Implications
Thïee areas of the law affect the Internet:
· Federal subsidies pay for large sections of the Internet. These subsidies exclude
purely commercial use.
· The Internet is not just a nationwide network, but a true global network. When
shipping anything across a national boundary, including bits, export laws come
into effect and local laws change.
· Whenever you are shipping software (or, for that matter, ideas) from one place
to another, you must consider intellectual property and license issues
First, let's deal with the federal dollars.
31
The W1Jole Internet Catalog & User's Guide
Research, Education, and the Federal Dollar
Many of the networks in the Internet are sponsored by federal agencies. Under
federal law, an agency may only spend its budget on things that it is charged to do.
For example, the Air Force can't secretly increase its budget by ordering rockets
through :--JASA. These same laws apply to the network-if NASA funds a network, it
must be used for space science. As a user, you may have no idea which networks
your packets are traversing, but they better fall within the scope of each network's
funding agency. If they don't, it's off to Leavenworth.
Actually, it is not as bad as it sounds. A couple of years ago, the folks in Washington
realized that multiple parallel IP networks (NSFNET, NASA Science Internet,
etc.-one network per federal agency) was a waste of money (a radical idea). Leg-
islation was passed to create the National Research and Education Network, or
J\REN. This was to be a portion of the Internet dedicated to supporting research and
education that was common to all federal agencies. This means that you can use the
NREN* to do basic research and education, or in support of research and education.
The importance of the clause "in support of research or education" cannot be over-
emphasized. This provision legitimizes important ways to use the network that
don't, at first glance, seem appropriate. For example, if a vendor distributes soft-
ware that is used in research or education, it can distribute updates and answer
questions through electronic mail. This usage is considered "in support of research
or education" (RE). The vendor can't use the NREN for business functions, like mar-
keting, billing, or accounting. For this, it must use a commercial part of the Inter-
net.t
Commercial Use
When your site arranged for its Internet connection, someone needed to tell the net-
work provider whether the connection would be used for research and education,
or for commercial purposes. If your site decided it was "RE," your network traffic is
routed to prefer subsidized NREN routes. If you are a commercial site, your traffic is
routed over private routes. As you'd expect, your site's network access fees depend
on these decisions; "commeïcial" use is generally more expensive than "RE"
because it isn't subsidized. Only someone in your network administration can tell
you whether commercial dealings are allowed over your connection. Check before
you do.
Of course, many corporations join the Internet as "research and education"
sites-and this is appropriate, since the motivation for joining the Internet is often
research. For example, a seed company may wish to do joint soybean research with
a university. Yet many corporate legal departments decide to declare their
* Acrually, the NREN is a real network that hasn't yet been built. The bill also authorizes this traffic on ex-
bting federal networks. The correct tenn for what we have now is the Imerim Imer.lgency NREN.
t A copy of the official NSFNET acceptable use policy is included in Appendix C, Acceptahle Use. It is
one of the most restrictive with regard to commercial use. If your usage is acceptahle to NSFNET, it is
likely acceptahle to the other networks as well.
32
What's Allowed on the Internet?
connections commercial. This ensures there will not be a legal liability in the future,
when some uninformed employee uses the research connection for commercial
work. To many businesses, the added fees are well worth the comfort.
There are a number of commercial Internet providers: Advanced Networking Ser-
vices CANS), Performance Systems International cpsn, and UUnet are a few of them.
Each of these companies has its own market niche and its own national network to
provide commercial Internet services. In addition, state and regional networks carry
commercial traffic for their members. There are connections between each of these
and the federally supported networks. Using these connections and some nifty
accounting agreements, all of these networks inter-operate legally.
Export Laws
Whether you know it or not, exporting bits falls under the auspices of the Depart-
ment of Commerce export restrictions. * The Internet, being a virtually seamless glo-
bal network, makes it very easy to export things without your knowledge. Because
I'm not a lawyer I won't get very technical, but I will try to sketch what is required
to stay legal. If you think you might run afoul of the law after reading this, seek
competent legal help.
Export law is based on two points:
1. Exporting anything requires a license.
2, Exporting a service is roughly equivalent to exporting the pieces necessary to
provide that service.
The first point is fairly obvious: if you ship, carry, transfer a file, or electronically
mail anything out of the country it needs to be covered by an export license. Luck-
ily, there is a loophole called a genera/license that covers most things. The general
license allows you to export anything that is not explicitly restricted, and is readily
available in public forums in the United States. So anything you can learn from
walking into a conference or classroom that does not have security restrictions is
probably covered by the general license.
However, the list of restricted items has a lor of surprises, and does cover things
that you can learn as a student in any university. Networking code and encryption
code might be restricted, based upon their capabilities. Many times, one little item
is of concern, but by the time the regulations are written, they cover a much wider
area. For example, during the Persian Gulf War, it was a lot harder to knock out
Iraq's command and control network than anticipated. It turned out they were using
commercial IP routers which were very good at finding alternative routes quickly.
Suddenly, exporting any router that could find alternate routes was restricted.
The second point is even simpler. If exporting some hardware, say a supercom-
puter, is not allowed, then remote access to that hardware within this country is pro-
hibited as well. So, be careful about granting access to "special" resources (like
*This is a strictly u.S.-centric discussion. Other laws apply to selVers in other countries.
33
]be Whole Internet Catalog & úser's Guide
supercomputers) to people in foreign countries. The exact ndture of these restric-
tions depends, of course, on the foreign country and (as you Cdn probably imagine,
given the events of the last few years) can change quickly.
When investigating their potential for legal liability, the consortium that runs the
Bitnet (Educom) came to the following conclusions:* A network operator is respon-
sible for illegal export only if the operator was aware of the violation and failed to
inform proper duthorities; the network operator isn't responsible for monitoring
your usage and determining whether or not it's within the law. So network person-
nel nationwide probably aren't snooping through your packets to see what you are
shipping overseas (although who knows what the National Security Agèncy looks
at). However, if a network technician sees your packets, and if the packets are obvi-
ously in violation of some regulation, then the technician is obliged to inform the
government.
Property Rights
Property rights can also become an issue when you ship something to someone
else. The problem gets even more confusing when the communication is across
national borders. Copyright and patent laws vary greatly from country to country.
You might find on the network a curious volume of forgotten lore whose copyright
has expired in the U.S. Shipping these files to England might place you in violation
of British law. Know who has the rights to anything you give away across the net-
work. If it is not yours, make sure you have permission before giving something
away.
The law surrounding electronic communication has not kept pace with the technol-
ogy. If you have a book, journal, or personal letter, you can ask almost any lawyer
or librarian if you can copy or use it in a pdrticular manner. They can tell you if you
can, or whose permission you need to obtain. Ask the same question regarding a
network bulletin board posting, an electronic mail message, or a report in a file
available on the network, and they will throw up their hands. Even if you knew
whose permission to obtain, and obtained that permission via electronic mail, it's
not clear whether an e-mail message offers any useful protection. Just be aware that
this is a murky part of law which will likely be hammered out in the next decade.
Please note that property rights can be a problem even when using publicly avail-
able files. Some software available for public retrieval through the Internet must be
licensed from the vendor. For example, a workstation vendor might make updates
to its operating system software available via anonymous FTP. So you can easily get
the software, but in order to use it legally you must hold a valid software mainte-
nance license. Just because a file is there for the taking doesn't mean that taking it is
legal.
*The actual legal opinions are availahle on the network; see the Resource Catalog Law - Legal Opinions
on International Networking
34
What's Allowed on tbe Internet?
Politics and the Internet
Many network users view the political process as both a blessing and a curse. The
blessing is money. Suhsidies provide many people a utility they could not afford
otherwise. The curse is that their individual actions are under constant scrutiny.
Someone in Washington may decide, after the fact, that something you have done
can be exploited for political gain. The digitized centerfold you had on your
machine can suddenly become the center of an editorial entitled "Tax Dollars Fund
Pornogrdphy Distrihution."* This causes everyone responsible for the Internet's
funding no end of grief.
It's important to realize that the Internet has many political supporters, including
congressmen, presidential advisors, educational leaders, and federal agency heads.
They support the Internet because it benefits the country: it increases the U.S. 's abil-
ity to compete in international research and trade. Speeding communications allows
the research and educational process to speed up; because of the Net, our research-
ers and their students can develop better solutions to technical problems.
As is typical in the political world, there are also those people who see these bene-
fits as drivel. The millions of dollars spent on the network could be better spent
buying pork barrels in their own congressional district.
The bottom line in the politics of networking is that political support for the net-
work is broad, but relatively thin. Any act that can cause political waves might radi-
cally change it, probably for the worse.
Network Ethics
For the novice network user, the apparent lack of ethics on the network is fairly
disquieting. In actuality, the network is a very ethical place; the ethics are just a h 
