- T H E -

 

 

- H A C K E R ' S -

 

 

- H A N D B O O K -

 

 

 

 

Copyright (c) Hugo Cornwall

 

 

All rights reserved

 

 

First published in Great Britain in 1985 by Century Communications Ltd

Portland House, 12-13 Greek Street, London W1V 5LE.

 

 

Reprinted 1985 (four times)

 

 

ISBN 0 7126 0650 5

 

 

Printed and bound in Great Britain by Billing & Sons Limited, Worcester.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

CONTENTS

 

 

Introduction vii

 

 

First Principles

 

 

2 Computer-to-computer communications 7

 

 

3 Hackers' Equipment 15

 

 

4 Targets: What you can find on mainframes 30

 

 

5 Hackers' Intelligence 42

 

 

6 Hackers' Techniques 57

 

 

7 Networks 69

 

 

8 Viewdata systems 86

 

 

9 Radio computer data 99

 

 

10 Hacking: the future 108

 

 

Appendices

 

 

I troubleshooting 112

II Glossary 117

III CCITT and related standards 130

IV Standard computer alphabets 132

V Modems 141

VI Radio Spectrum 144

VII Port-finder flow chart 148

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

INTRODUCTION

 

 

The word 'hacker' is used in two different but associated

ways: for some, a hacker is merely a computer enthusiast of any kind,

who loves working with the beasties for their own sake, as opposed to

operating them in order to enrich a company or research project --or

to play games.

 

 

This book uses the word in a more restricted sense: hacking is a

recreational and educational sport. It consists of attempting to make

unauthorised entry into computers and to explore what is there. The

sport's aims and purposes have been widely misunderstood; most

hackers are not interested in perpetrating massive frauds, modifying

their personal banking, taxation and employee records, or inducing

one world super-power into inadvertently commencing Armageddon in the

mistaken belief that another super-power is about to attack it. Every

hacker I have ever come across has been quite clear about where the

fun lies: it is in developing an understanding of a system and

finally producing the skills and tools to defeat it. In the vast

majority of cases, the process of 'getting in' is much more

satisfying than what is discovered in the protected computer files.

 

 

In this respect, the hacker is the direct descendant of the phone

phreaks of fifteen years ago. Phone phreaking became interesting as

intra-nation and international subscriber trunk dialling was

introduced, but when the London-based phreak finally chained his way

through to Hawaii, he usually had no one there to speak to except the

local weather service or American Express office, to confirm that the

desired target had indeed been hit. One of the earliest of the

present generation of hackers, Susan Headley, only 17 when she began

her exploits in California in 1977, chose as her target the local

phone company and, with the information extracted from her hacks, ran

all over the telephone network. She 'retired' four years later, when

friends started developing schemes to shut down part of the phone

system.

 

 

There is also a strong affinity with program copy-protection

crunchers. Most commercial software for micros is sold in a form to

prevent obvious casual copying, say by loading a cassette, cartridge

or disk into memory and then executing a 'save' on to a

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

** Page VII

 

 

blank cassette or disk. Copy-protection devices vary greatly in

their methodology and sophistication and there are those who, without

any commercial motive, enjoy nothing so much as defeating them. Every

computer buff has met at least one cruncher with a vast store of

commercial programs, all of which have somehow had the protection

removed--and perhaps the main title subtly altered to show the

cruncher's technical skills--but which are then never actually used

at all.

 

 

Perhaps I should tell you what you can reasonably expect from this

handbook. Hacking is an activity like few others: it is semi-legal,

seldom encouraged, and in its full extent so vast that no individual

or group, short of an organisation like GCHQ or NSA, could hope to

grasp a fraction of the possibilities. So this is not one of those

books with titles like Games Programming with the 6502 where, if the

book is any good and if you are any good, you will emerge with some

mastery of the subject-matter. The aim of this book is merely to give

you some grasp of methodology, help you develop the appropriate

attitudes and skills, provide essential background and some

referencing material--and point you in the right directions for more

knowledge. Up to a point, each chapter may be read by itself; I have

compiled extensive appendices, containing material which will be of

use long after the main body of the text has been absorbed.

 

 

It is one of the characteristics of hacking anecdotes, like those

relating to espionage exploits, that almost no one closely involved

has much stake in the truth; victims want to describe damage as

minimal, and perpetrators like to paint themselves as heroes while

carefully disguising sources and methods. In addition, journalists

who cover such stories are not always sufficiently competent to write

accurately, or even to know when they are being hoodwink- ed. (A note

for journalists: any hacker who offers to break into a system on

demand is conning you--the most you can expect is a repeat

performance for your benefit of what a hacker has previously

succeeded in doing. Getting to the 'front page' of a service or

network need not imply that everything within that service can be

accessed. Being able to retrieve confidential information, perhaps

credit ratings, does not mean that the hacker would also be able to

alter that data. Remember the first rule of good reporting: be

sceptical.) So far as possible, I have tried to verify each story

that appears in these pages, but hackers work in isolated groups and

my sources on some of the important hacks of recent years are more

remote than I would have liked. In these

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

** Page VIII

 

 

cases, my accounts are of events and methods which, in all the

circumstances, I believe are true. I welcome notes of correction.

 

 

Experienced hackers may identify one or two curious gaps in the

range of coverage, or less than full explanations; you can chose any

combination of the following explanations without causing me any

worry: first, I may be ignorant and incompetent; second, much of the

fun of hacking is making your own discoveries and I wouldn't want to

spoil that; third, maybe there are a few areas which are really best

left alone.

 

 

Nearly all of the material is applicable to readers in all

countries; however, the author is British and so are most of his

experiences.

 

 

The pleasures of hacking are possible at almost any level of

computer competence beyond rank beginner and with quite minimal

equipment. It is quite difficult to describe the joy of using the

world's cheapest micro, some clever firmware, a home-brew acoustic

coupler and find that, courtesy of a friendly remote PDP11/70, you

can be playing with Unix, the fashionable multitasking operating

system.

 

 

The assumptions I have made about you as a reader are that you own a

modest personal computer, a modem and some communications software

which you know, roughly, how to use. (If you are not confident yet,

practise logging on to a few hobbyist bulletin boards.) For more

advanced hacking, better equipment helps; but, just as very tasty

photographs can be taken with snap-shot cameras, the computer

equivalent of a Hasselblad with a trolley- load of accessories is not

essential.

 

 

Since you may at this point be suspicious that I have vast

technical resources at my disposal, let me describe the kit that has

been used for most of my network adventures. At the centre is a

battered old Apple II+, its lid off most of the time to draw away the

heat from the many boards cramming the expansion slots. I use an

industry standard dot matrix printer, famous equally for the variety

of type founts possible, and for the paper-handling path, which

regularly skews off. I have two large boxes crammed full of software,

as I collect comms software in particular like a deranged

philatelist, but I use one package almost exclusively. As for

modems--well, at this point the set-up does become unconventional; by

the phone point are jack sockets for BT 95A, BT 96A, BT 600 and a

North American modular jack. I have two acoustic couplers, devices

for plunging telephone handsets into so that the computer can talk

down the line, at operating speeds of 300/300 and 75/1200. I also

have three heavy, mushroom coloured 'shoe-boxes', representing modem

technology of 4 or 5 years ago and operating at various speeds and

combinations of duplex/half- duplex. Whereas the acoustic coupler

connects my computer to the line by audio, the modem links up at the

electrical level and is more accurate and free from error. I have

access to other equipment in my work and through friends, but this is

what I use most of the time.

 

 

 

 

 

 

 

 

** Page IX

 

 

Behind me is my other important bit of kit: a filing cabinet.

Hacking is not an activity confined to sitting at keyboards and

watching screens. All good hackers retain formidable collections of

articles, promotional material and documentation; read on, and you

will see why.

 

 

Finally, to those who would argue that a hacker's handbook must be

giving guidance to potential criminals, I have two things to say:

First, few people object to the sports of clay-pigeon shooting or

archery, although rifles, pistols and crossbows have no 'real'

purpose other than to kill things--and hackers have their own code of

responsibility, too. Second, real hacking is not as it is shown in

the movies and on tv, a situation which the publication of this book

may do something to correct. The sport of hacking itself may involve

breach of aspects of the law, notably theft of electricity, theft of

computer time and unlicensed usage of copyright material; every

hacker must decide individually each instance as it arises.

 

 

Various people helped me on various aspects of this book; they

must all remain unnamed--they know who they are and that they have my

thanks.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

** Page X

 

 

 

 

 

 

CHAPTER 1

 

 

 

 

First Principles

 

 

The first hack I ever did was executed at an exhibition stand run

by BT's then rather new Prestel service. Earlier, in an adjacent

conference hall, an enthusiastic speaker had demonstrated view-

data's potential world-wide spread by logging on to Viditel, the

infant Dutch service. He had had, as so often happens in the these

circumstances, difficulty in logging on first time. He was using one

of those sets that displays auto-dialled telephone numbers; that was

how I found the number to call. By the time he had finished his third

unsuccessful log-on attempt I (and presumably several others) had all

the pass numbers. While the BT staff were busy with other visitors to

their stand, I picked out for myself a relatively neglected viewdata

set. I knew that it was possible to by-pass the auto-dialler with its

pre-programmed phone numbers in this particular model, simply by

picking up the the phone adjacent to it, dialling my preferred

number, waiting for the whistle, and then hitting the keyboard button

labelled 'viewdata'. I dialled Holland, performed my little by-pass

trick and watched Viditel write itself on the screen. The pass

numbers were accepted first time and, courtesy of...no, I'll spare

them embarrassment...I had only lack of fluency in Dutch to restrain

my explorations. Fortunately, the first BT executive to spot what I

had done was amused as well.

 

 

Most hackers seem to have started in a similar way. Essentially

you rely on the foolishness and inadequate sense of security of

computer salesmen, operators, programmers and designers.

 

 

In the introduction to this book I described hacking as a sport;

and like most sports, it is both relatively pointless and filled with

rules, written or otherwise, which have to be obeyed if there is to

be any meaningfulness to it. Just as rugby football is not only about

forcing a ball down one end of a field, so hacking is not just about

using any means to secure access to a computer.

 

 

On this basis, opening private correspondence to secure a password

on a public access service like Prestel and then running around the

system building up someone's bill, is not what hackers call hacking.

The critical element must be the use of skill in some shape or form.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

** Page 1

 

 

Hacking is not a new pursuit. It started in the early 1960s when

the first "serious" time-share computers began to appear at

university sites. Very early on, 'unofficial' areas of the memory

started to appear, first as mere notice boards and scratch pads for

private programming experiments, then, as locations for games.

(Where, and how do you think the early Space Invaders, Lunar Landers

and Adventure Games were created?) Perhaps tech-hacking-- the

mischievous manipulation of technology--goes back even further. One

of the old favourites of US campus life was to rewire the control

panels of elevators (lifts) in high-rise buildings, so that a request

for the third floor resulted in the occupants being whizzed to the

twenty-third.

 

 

Towards the end of the 60s, when the first experimental networks

arrived on the scene (particularly when the legendary

ARPAnet--Advanced Research Projects Agency network-- opened up), the

computer hackers skipped out of their own local computers, along the

packet-switched high grade communications lines, and into the other

machines on the net. But all these hackers were privileged

individuals. They were at a university or research resource, and they

were able to borrow terminals to work with.

 

 

What has changed now, of course, is the wide availability of home

computers and the modems to go with them, the growth of public-access

networking of computers, and the enormous quantity and variety of

computers that can be accessed.

 

 

Hackers vary considerably in their native computer skills; a basic

knowledge of how data is held on computers and can be transferred

from one to another is essential. Determination, alertness,

opportunism, the ability to analyse and synthesise, the collection of

relevant helpful data and luck--the pre-requisites of any

intelligence officer--are all equally important. If you can write

quick effective programs in either a high level language or machine

code, well, it helps. A knowledge of on-line query procedures is

helpful, and the ability to work in one or more popular mainframe and

mini operating systems could put you in the big league.

 

 

The materials and information you need to hack are all around

you--only they are seldom marked as such. Remember that a large

proportion of what is passed off as 'secret intelligence' is openly

available, if only you know where to look and how to appreciate what

you find. At one time or another, hacking will test everything you

know about computers and communications. You will discover your

abilities increase in fits and starts, and you must

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

** Page 2

 

 

be prepared for long periods when nothing new appears to happen.

 

 

Popular films and tv series have built up a mythology of what

hackers can do and with what degree of ease. My personal delight in

such Dream Factory output is in compiling a list of all the mistakes

in each episode. Anyone who has ever tried to move a graphics game

from one micro to an almost-similar competitor will already know that

the chances of getting a home micro to display the North Atlantic

Strategic Situation as it would be viewed from the President's

Command Post would be slim even if appropriate telephone numbers and

passwords were available. Less immediately obvious is the fact that

most home micros talk to the outside world through limited but

convenient asynchronous protocols, effectively denying direct access

to the mainframe products of the world's undisputed leading computer

manufacturer, which favours synchronous protocols. And home micro

displays are memory-mapped, not vector-traced... Nevertheless, it is

astonishingly easy to get remarkable results. And thanks to the

protocol transformation facilities of PADs in PSS networks (of which

much more later), you can get into large IBM devices....

 

 

 

 

The cheapest hacking kit I have ever used consisted of a ZX81, 16K

RAMpack, a clever firmware accessory and an acoustic coupler. Total

cost, just over ú100. The ZX81's touch-membrane keyboard was one

liability; another was the uncertainty of the various connectors.

Much of the cleverness of the firmware was devoted to overcoming the

native drawbacks of the ZX81's inner configuration--the fact that it

didn't readily send and receive characters in the industry-standard

ASCII code, and that the output port was designed more for instant

access to the Z80's main logic rather than to use industry-standard

serial port protocols and to rectify the limited screen display.

 

 

Yet this kit was capable of adjusting to most bulletin boards;

could get into most dial-up 300/300 asynchronous ports,

re-configuring for word-length and parity if needed; could have

accessed a PSS PAD and hence got into a huge range of computers not

normally available to micro-owners; and, with another modem, could

have got into viewdata services. You could print out pages on the ZX

'tin-foil' printer. The disadvantages of this kit were all in

convenience, not in facilities. Chapter 3 describes the sort of kit

most hackers use.

 

 

It is even possible to hack with no equipment at all. All major

banks now have a network of 'hole in the wall' cash machines-- ATMs

or Automatic Telling Machines, as they are officially

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

** Page 3

 

 

known. Major building societies have their own network. These

machines have had faults in software design, and the hackers who

played around with them used no more equipment than their fingers and

brains. More about this later.

 

 

Though I have no intention of writing at length about hacking

etiquette, it is worth one paragraph: lovers of fresh-air walks obey

the Country Code; they close gates behind them, and avoid damage to

crops and livestock. Something very similar ought to guide your

rambles into other people's computers: don't manipulate files unless

you are sure a back-up exists; don't crash operating systems; don't

lock legitimate users out from access; watch who you give information

to; if you really discover something confidential, keep it to

yourself. Hackers should not be interested in fraud. Finally, just

as any rambler who ventured past barbed wire and notices warning

about the Official Secrets Acts would deserve whatever happened

thereafter, there are a few hacking projects which should never be

attempted.

 

 

On the converse side, I and many hackers I know are convinced of one

thing: we receive more than a little help from the system managers of

the computers we attack. In the case of computers owned by

universities and polys, there is little doubt that a number of them

are viewed like academic libraries--strictly speaking they are for

the student population, but if an outsider seriously thirsty for

knowledge shows up, they aren't turned away. As for other computers,

a number of us are almost sure we have been used as a cheap means to

test a system's defences...someone releases a phone number and

low-level password to hackers (there are plenty of ways) and watches

what happens over the next few weeks while the computer files

themselves are empty of sensitive data. Then, when the results have

been noted, the phone numbers and passwords are changed, the security

improved etc etc....much easier on dp budgets than employing

programmers at £150/man/ day or more. Certainly the Pentagon has been

known to form 'Tiger Units' of US Army computer specialists to

pin-point weaknesses in systems security.

 

 

Two spectacular hacks of recent years have captured the public

imagination: the first, the Great Prince Philip Prestel Hack, is

described in detail in chapter 8, which deals with viewdata. The

second was spectacular because it was carried out on live national

television. It occurred on October 2nd 1983 during a follow-up to the

BBC's successful Computer Literacy series. It's worth reporting here,

because it neatly illustrates the essence of hacking as a sport...

skill with systems, careful research, maximum impact

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

** Page 4

 

 

with minimum real harm, and humour.

 

 

The tv presenter, John Coll, was trying to show off the Telecom

Gold electronic mail service. Coll had hitherto never liked long

passwords and, in the context of the tight timing and pressures of

live tv, a two letter password seemed a good idea at the time. On

Telecom Gold, it is only the password that is truly confidential;

system and account numbers, as well as phone numbers to log on to the

system, are easily obtainable. The BBC's account number, extensively

publicised, was OWL001, the owl being the 'logo' for the tv series as

well as the BBC computer.

 

 

The hacker, who appeared on a subsequent programme as a 'former

hacker' and who talked about his activities in general, but did not

openly acknowledge his responsibility for the BBC act, managed to

seize control of Coll's mailbox and superimpose a message of his own:

 

 

Computer Security Error. Illegal access. I hope your television

PROGRAMME runs as smoothly as my PROGRAM worked out your passwords!

Nothing is secure!

 

 

 

 

 

 

Hackers' Song

 

 

"Put another password in,

Bomb it out and try again

Try to get past logging in,

We're hacking, hacking, hacking

 

 

Try his first wife's maiden name,

This is more than just a game,

It's real fun, but just the same,

It's hacking, hacking, hacking"

 

 

The Nutcracker (Hackers UK)

 

 

HI THERE, OWLETS, FROM OZ AND YUG

(OLIVER AND GUY)

 

 

After the hack a number of stories about how it had been carried

out, and by whom, circulated; it was suggested that the hackers had

crashed through to the operating system of the Prime computers upon

which the Dialcom electronic mail software

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

** Page 5

 

 

resided--it was also suggested that the BBC had arranged the whole

thing as a stunt, or alternatively, that some BBC employees had fixed

it up without telling their colleagues. Getting to the truth of a

legend in such cases is almost always impossible. No one involved has

a stake in the truth. British Telecom, with a strong commitment to

get Gold accepted in the business community, was anxious to suggest

that only the dirtiest of dirty tricks could remove the inherent

confidentiality of their electronic mail service. Naturally, the

British Broadcasting Corporation rejected any possibility that it

would connive in an irresponsible cheap stunt. But the hacker had no

great stake in the truth either--he had sources and contacts to

protect, and his image in the hacker community to bolster. Never

expect any hacking anecdote to be completely truthful.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

** Page 6

 

 

 

 

 

 

CHAPTER 2

 

 

 

 

Computer-to-Computer

Communications

 

 

Services intended for access by microcomputers are nowadays

usually presented in a very user-friendly fashion: pop in your

software disc or firmware, check the connections, dial the telephone

number, listen for the tone...and there you are. Hackers, interested

in venturing where they are not invited, enjoy no such luxury. They

may want to access older services which preceded the modern 'human

interface'; they are very likely to travel along paths intended, not

for ordinary customers, but for engineers or salesmen; they could be

utilising facilities that were part of a computer's commissioning

process and have been hardly used since.

 

 

So the hacker needs a greater knowledge of datacomms technology than

does a more passive computer user, and some feeling for the history

of the technology is pretty essential, because of its growth pattern

and because of the fact that many interesting installations still use

yesterday's solutions.

 

 

Getting one computer to talk to another some distance away means

accepting a number of limiting factors:

 

 

* Although computers can send out several bits of information at

once, the ribbon cable necessary to do this is not economical at any

great length, particularly if the information is to be sent out over

a network--each wire in the ribbon would need switching separately,

thus making ex- changes prohibitively expensive. So bits must be

transmitted one at a time, or serially.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

** Page 7

 

 

* Since you will be using, in the first instance, wires and networks

already installed--in the form of the telephone and telex

networks--you must accept that the limited bandwidth of these

facilities will restrict the rate at which data can be sent. The data

will pass through long lengths of wire, frequently being

re-amplified, and undergoing de- gradation as it passes through dirty

switches and relays in a multiplicity of exchanges.

 

 

* Data must be easily capable of accurate recovery at the far end.

 

 

* Sending and receiving computers must be synchronised in their

working.

 

 

* The mode in which data is transmitted must be one understood by

all computers; accepting a standard protocol may mean adopting the

speed and efficiency of the slowest.

 

 

* The present 'universal' standard for data transmission used by

microcomputers and many other services uses agreed tones to signify

binary 0 and binary 1, the ASCII character set (also known as

International Alphabet No 5), and an asynchronous protocol, whereby

the transmitting and receiving computers are locked in step every

time a character is sent, not just at the beginning of a transmission

stream. Like nearly all standards, it is highly arbitrary in its

decisions and derives its importance simply from the fact of being

generally accepted. Like many standards, too, there are a number of

subtle and important variations.

 

 

To see how the standard works, how it came about and the reasons

for the variations, we need to look back a little into history.

 

 

 

 

The Growth of Telegraphy

 

 

The essential techniques of sending data along wires has a history

of 150 years, and some of the common terminology of modern data

transmission goes right back to the first experiments.

 

 

The earliest form of telegraphy, itself the earliest form of

electrical message sending, used the remote actuation of electrical

relays to leave marks on a strip of paper. The letters of the

alphabet were defined by the patterns of 'mark' and 'space'.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

** Page 8

 

 

The terms have come through to the present, to signify binary

conditions of '1' and '0' respectively. The first reliable machine

for sending letters and figures by this method dates from 1840; the

direct successor of that machine, using remarkably unchanged

electromechanical technology and a 5-bit alphabetic code, is still

widely used today, as the telex/teleprinter/teletype. The mark and

space have been replaced by holes punched in paper-tape: larger holes

for mark, smaller ones for space. Synchronisation between sending and

receiving stations is carried out by beginning each letter with a

'start' bit (a space) and concluding it with a 'stop' bit (mark). The

'idle' state of a circuit is thus 'mark'. In effect, therefore, each

letter requires the transmission of 7 bits:

 

 

. * * . . . * (letter A: . = space; * = mark)

 

 

of which the first . is the start bit, the last * is the stop bit and

* * . .. is the code for A.

 

 

This is the principle means for sending text messages around the

world, and the way in which news reports are distributed globally.

And, until third-world countries are rich enough to afford more

advanced devices, the technology will survive.

 

 

 

 

Early computer communications

 

 

When, 110 years after the first such machines came on line, the

need arose to address computers remotely, telegraphy was the obvious

way to do so. No one expected computers in the early 1950s to give

instant results; jobs were assembled in batches, often fed in by

means of paper-tape (another borrowing from telex, still in use) and

then run. The instant calculation and collation of data was then

considered quite miraculous. So the first use of data communications

was almost exclusively to ensure that the machine was fed with

up-to-date information, not for the machine to send the results out

to those who might want it; they could wait for the 'print-out' in

due course, borne to them with considerable solemnity by the computer

experts. Typical communications speeds were 50 or 75 baud. (The baud

is the measure of speed of data transmission: specifically, it refers

to the number of signal level changes per second and is thus not the

same as bits-per-second.)

 

 

These early computers were, of course, in today's jargon,

single-user/single-task; programs were fed by direct machine coding.

Gradually, over the next 15 years, computers spawned multi-user

capabilities by means of time-sharing techniques, and their human

interface became more 'user-friendly'.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

** Page 9

 

 

With these facilities grew the demand for remote access to

computers, and modern data communications began.

 

 

Even at the very end of the 1960s when I had my own very first

encounter with a computer, the links with telegraphy were still

obvious. As a result of happenstance, I was in a Government-run

research facility to the south-west of London, and the program I was

to use was located on a computer just to the north of Central London;

I was sat down in front of a battered teletype--capitals and figures

only, and requiring not inconsiderable physical force from my

smallish fingers to actuate the keys of my choice. As it was a

teletype outputting on to a paper roll, mistakes could not as readily

be erased as on a VDU, and since the sole form of error reporting

consisted of a solitary ?, the episode was more frustrating than

thrilling. VDUs and good keyboards were then far too expensive for

'ordinary' use.

 

 

 

 

The telephone network

 

 

But by that time all sorts of changes in datacomms were taking

place. The telex and telegraphy network, originally so important, had

long been overtaken by voice-grade telephone circuits (Bell's

invention dates from 1876). For computer communication, mark and

space could be indicated by different audio tones, rather than by

different voltage conditions. Data traffic on a telex line can

operate in only one direction at a time, but, by selecting different

pairs of tones, both 'transmitter' and 'receiver' could speak

simultaneously--so that in fact, one has to talk about 'originate'

and 'answer' instead.

 

 

Improved electrical circuit design meant that higher speeds than

50 or 75 baud became possible; there was a move to 110 baud, then 300

and, so far as ordinary telephone circuits are concerned, 1200 baud

is now regarded as the top limit.

 

 

The 'start' and 'stop' method of synchronising the near and far

end of a communications circuit at the beginning of each individual

letter has been retained, but the common use of the 5-bit Baudot code

has been replaced by a 7-bit extended code which allows for many more

characters, 128 in fact.

 

 

Lastly, to reduce errors in transmission due to noise in the

telephone line and circuitry, each letter can be checked by the use

of a further bit (the parity bit), which adds up all the bits in the

main character and then, depending on whether the result is odd or

even, adds a binary 0 or binary 1.

 

 

The full modern transmission of a letter in this system, in this

case, K, therefore, looks like this:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

** Page 10

 

 

START-STOP TRANSMISSION OF A DATA CHARACTER

 

 

TIME

INTERVAL_____________9___0___1___2___3___4___5___6___7___8___9___

NUMBER

1 1 1 1 1 1

Mark +---+ +---+ +---+ +---+---+ +---+

LINE | | 0 | | 0 0 | | 0 | | 0 | |

CONDITION Space-+ +---+ +---+---+ +---+ +---+ +-

 

 

^ ^

| |

BINARY STOP-+ START 1 0 0 1 0 1 1 0

DIGIT

 

 

The first 0 is the start bit; then follows 7 bits of the actual

letter code (1001011); then the parity bit; then the final 1 is the

stop code.

 

 

This system, asynchronous start-stop ASCII (the common name for

the alphabetic code), is the basis for nearly all micro-based

communications. The key variations relate to:

 

 

bit-length; you can have 7 or 8 databits (*)

 

 

parity; (it can be even or odd, or entirely absent),

 

 

Tones - The tones used to signify binary 0 and binary 1, and which

computer is in 'originate' and which in 'answer', can vary according

to the speed of the transmission and also to whether the service is

used in North America or the rest of the world. (Briefly, most of

the world uses tones and standards laid down by the Geneva-based

organisation, CCITT, a specialised agency of the International

Telecommunications Union; whereas in the United States and most parts

of Canada, tones determined by the telephone utility, colloquially

known as Ma Bell, are adopted.) The following table gives the

standards and tones in common use.

 

 

(*) There are no 'obvious explanations' for the variations commonly

found: most electronic mail services and viewdata transmit 7 data

bits, even parity and I stop Bit; Telecom Gold and most hobbyist

bulletin boards transmit 8 data bits, odd parity and 1 stop bit.

Terminal emulator software--see chapter 3--allows users to adjust for

these differing requirements.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

** Page 11

 

 

Service Speed Duplex Transmit Receive Answer

Designator 0 1 0 1

 

 

V21 orig 300(*) full 1180 980 1850 1650 -

V21 ans 300(*) full 1850 1650 1180 980 2100

V23 (1) 600 half 1700 1300 1700 1300 2100

V23 (2) 1200 f/h(**) 2100 1300 2100 1300 2100

V23 back 75 f/h(**) 450 390 450 390 -

Bell 103 orig 300(*) full 1070 1270 2025 2225 -

Bell 103 ans 300(*) full 2025 2225 1070 1270 2225

Bell 202 1200 half 2200 1200 2200 1200 2025

 

 

(*)any speed up to 300 baud, can also include 75 and 110 baud

services

 

 

(**)service can either be half-duplex at 1200 baud or asymmetrical

full duplex, with 75 baud originate and 1200 baud receive (commonly

used as viewdata user) or 1200 transmit and 75 receive (viewdata

host)

 

 

 

 

Higher Speeds

 

 

1200 baud is usually regarded as the fastest speed possible on an

ordinary voice-grade telephone line. Beyond this, noise on the line

due to the switching circuits at the various telephone exchanges,

poor cabling, etc. make accurate transmission difficult. Indeed, at

higher speeds it becomes increasingly important to use transmission

protocols that include error correction.

 

 

Error correction techniques usually consist of dividing the

transmission stream into a series of blocks which can be checked, one

at a time, by the receiving computer. The 'parity' system mentioned

above is one example, but obviously a crude one. The difficulty is

that the more secure an error-correction protocol becomes, the

greater becomes the overhead in terms of numbers of bits transmitted

to send just one character from one computer to another. Thus, in the

typical 300 bit situation, the actual letter is defined by 7 bits,

'start' and 'stop' account for another two, and the check takes a

further one--ten in all. After a while, what you gain in the speed

with which each actual bit is transmitted, you lose, because so many

bits have to be sent to ensure that a single character is accurately

received!

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

** Page 12

 

 

Although some people risk using 2400 baud on ordinary telephone

lines--the jargon is the PTSN (Public Telephone Switched

Network)--this means using expensive modems. Where higher speeds are

essential, leased circuits, not available via dial-up. become

essential. The leased circuit is paid for on a fixed charge, not a

charge based on time-connected. Such circuits can be conditioned',

for example by using special amplifiers, to support the higher data

rate.

 

 

For really high speed transmissions, however, pairs of copper

cable are inadequate. Medium speed is obtainable by the use of

coaxial cable (a little like that used for tv antenna hook-ups) which

have a very broad bandwidth. Imposing several different channels on

one cable-length is called multiplexing and, depending on the

application, the various channels can either carry several different

computer conversations simultaneously or can send several bits of one

computer conversation in parallel, just as though there were a ribbon

cable between the two participating computers. Either way, what

happens is that each binary 0 or binary 1 is given, not an audio

tone, but a radio frequency tone.

 

 

 

 

Synchronous Protocols

 

 

In the asynchronous protocols so far described, transmitting and

receiving computers are kept in step with each other every time a

character is sent, via the 'start' and 'stop' bits. In synchronous

comms, the locking together is done merely at the start of each block

of transmission by the sending of a special code (often SYN). The SYN

code starts a clock (a timed train of pulses) in the receiver and it

is this that ensures that binary 0s and 1s originating at the

transmitter are correctly interpreted by the receiver; clearly, the

displacement of even one binary digit can cause havoc.

 

 

A variety of synchronous protocols exist, such as the length of

block sent each time, the form of checking that takes place, the form

of acknowledgement, and so on. A synchronous protocol is not only a

function of the modem, which has to have a suitable clock, but also

of the software and firmware in the computers. Because asynchronous

protocols transmit so many 'extra' bits in order to avoid error,

savings in transmission time under synchronous systems often exceed

20-30%. The disadvantage of synchronous protocols lie in increased

hardware costs.

 

 

One other complication exists: most asynchronous protocols use the

ASCII code to define characters. IBM ('Big Blue'), the biggest

enthusiast of synchronous comms, has its own binary code to define

characters. In Appendix IV, you will find an explanation and a

comparison with ASCII.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

** Page 13

 

 

The hacker, wishing to come to terms with synchronous comms, has

two choices: the more expensive is to purchase a protocol convertor

board. These are principally available for the IBM PC, which has been

increasingly marketed for the 'executive workstation' audience, where

the ability to interface to a company's existing (IBM) mainframe is a

key feature. The alternative is to see whether the target mainframe

has a port on to a packet- switched service; in that event, the

hacker can use ordinary asynchronous equipment and protocols--the

local PAD (Packet Assembler/Disassembler) will carry out the

necessary transformations.

 

 

 

 

Networks

 

 

Which brings us neatly to the world of high-speed digital networks

using packet-switching. All the computer communications so far

described have taken place either on the phone (voice-grade) network

or on the telex network.

 

 

In Chapter 7 we will look at packet-switching and the

opportunities offered by international data networks. We must now

specify hackers' equipment in more detail.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

** Page 14

 

 

 

 

 

 

CHAPTER 3

 

 

 

 

Hackers' Equipment

 

 

You can hack with almost any microcomputer capable of talking to

the outside world via a serial port and a modem. In fact, you don't

even need a micro; my first hack was with a perfectly ordinary

viewdata terminal.

 

 

What follows in this chapter, therefore, is a description of the

elements of a system I like to think of as optimum for

straight-forward asynchronous ASCII and Baudot communications. What

is at issue is convenience as much as anything. With kit like this,

you will be able to get through most dial-up ports and into

packet-switching through a PAD -- a packet assembler/ disassembler

port. (It will not get you into IBM networks, because these use

different and incompatible protocols; we will return to the matter of

the IBM world in chapter 10.) In other words, given a bit of money, a

bit of knowledge, a bit of help from friends and a bit of luck, what

is described here is the sort of equipment most hackers have at their

command.

 

 

You will find few products on the market labelled 'for hackers';

you must select those items that appear to have 'legitimate' but

interesting functions and see if they can be bent to the hacker's

purposes. The various sections within this chapter highlight the sort

of facilities you need; before lashing out on some new software or

hardware, try to get hold of as much publicity and documentation

material as possible to see how adaptable the products are. In a few

cases, it is worth looking at the second-hand market, particularly

for modems, cables and test equipment.

 

 

Although it is by no means essential, an ability to solder a few

connections and scrabble among the circuit diagrams of 'official'

products often yield unexpectedly rewarding results.

 

 

 

 

The computer

 

 

Almost any popular microcomputer will do; hacking does not call

upon enormous reserves of computer power. Nearly everything you hack

will come to you in alphanumeric form, not graphics. The computer

you already have will almost certainly have the essential qualities.

However the very cheapest micros, like the ZX81, whilst usable,

require much more work on the part of the operator/hacker, and give

him far less in the way of instant facilities.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

** Page 15

 

 

(In fact, as the ZX81 doesn't use ASCII internally, but a

Sinclair-developed variant; you will need a software or firmware fix

for that, before you even think of hooking it up to a modem.)

 

 

Most professional data services assume the user is viewing on an

80-column screen; ideally the hacker's computer should be capable of

doing that as well, otherwise the display will be full of awkward

line breaks. Terminal emulator software (see below) can some- times

provide a 'fix'.

 

 

One or two disc drives are pretty helpful, because you will want

to be able to save the results of your network adventures as quickly

and efficiently as possible. Most terminal emulators use the

computer's free memory (i.e. all that is not required to support the

operating system and the emulator software itself) as store for the

received data, but once the buffer is full, you will begin to lose

the earliest items. You can, of course, try to save to cassette, but

normally that is a slow and tedious process.

 

 

An alternative storage method is to save to a printer, printing

the received data stream not only to the computer screen, but also on

a dot matrix printer. However, most of the more popular (and cheaper)

printers do not work sufficiently fast. You may find you lose

characters at the beginning of each line. Moreover, if you print

everything in real-time, you'll include all your mistakes, false

starts etc., and in the process use masses of paper. So, if you can

save to disc regularly, you can review each hack afterwards at your

leisure and, using a screen editor or word processor, save or print

out only those items of real interest.

 

 

 

 

Serial ports

 

 

The computer must have a serial port, either called that or marked

RS232C (or its slight variant RS423), or V24, which is the official

designator of RS232C used outside the USA, though not often seen on

micros.

 

 

The very cheapest micros, like the ZX81, Spectrum, VIC20, do not

have RS232C ports, though add-on boards are available. Some of the

older personal computers, like the Apple or the original Pet, were

also originally sold without serial ports, though standard boards are

available for all of these.

 

 

You are probably aware that the RS232C standard has a large number

of variants, and that not all computers (or add-on boards) that claim

to have a RS232C port can actually talk into a modem.

 

 

Historically, RS232C/V24 is supposed to cover all aspects of

serial communication, including printers and dumb terminals as well

as computers. The RS232C standard specifies electrical and physical

requirements.

 

 

 

 

 

 

 

 

 

 

 

 

** Page 16

 

 

Everything is pumped through a 25-pin D-shaped connector, each pin

of which has some function in some implementation. But in most cases,

nearly all the pins are not used. In practice, only three connections

are essential for computer to modem communication:

 

 

Pin 7 signal ground

 

 

Pin 2 characters leaving the computer

 

 

Pin 3 characters arriving at the computer

 

 

The remaining connections are for such purposes as feeding power

to an external device, switching the external advice on or off,

exchanging status and timing signals, monitoring the state of the

line, and so forth. Some computers and their associated firmware

require one or other of these status signals to go 'high' or 'low' in

particular circumstances, or the program hangs. Check your

documentation if you have trouble.

 

 

Some RS232C implementations on microcomputers or add-on boards are

there simply to support printers with serial interfaces, but they can

often be modified to talk into modems. The critical two lines are

those serving Pins 2 and 3.

 

 

A computer serving a modem needs a cable in which Pin 2 on the

computer is linked to Pin 2 on the modem.

 

 

A computer serving a printer, etc, needs a cable in which Pin 3 on

the: computer is linked to Pin 2 on the printer and Pin 3 on the

printer is linked to Pin 2 on the computer.

 

 

If two computers are linked together directly, without a modem,

then Pin 2 on computer A must be linked to Pin 3 on computer B and

Pin 3 on computer B linked to Pin 2 on computer A: this arrangement

is sometimes called a 'null modem' or a 'null modem cable'.

 

 

There are historic explanations for these arrangements, depending

on who you think is sending and who is receiving--forget about them,

they are confusing. The above three cases are all you need to know

about in practice.

 

 

One difficulty that frequently arises with newer or portable

computers is that some manufacturers have abandoned the traditional

25-way D-connector, largely on the grounds of bulk, cost and

redundancy. Some European computer and peripheral companies favour

connectors based on the DIN series (invented in Germany), while

others use D-connectors with fewer pin-outs.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

** Page 17

 

 

There is no standardisation. Even if you see two physically

similar connectors on two devices, regard them with suspicion. In

each case, you must determine the equivalents of:

 

 

Characters leaving computer (Pin 2)

Characters arriving at computer (Pin 3)

Signal ground (Pin 7)

 

 

You can usually set the speed of the port from the computer's

operating system and/or from Basic. There is no standard way of doing

this; you must check your handbook and manuals. Most RS232C ports can

handle the following speeds:

 

 

75, 110, 300, 600, 1200, 2400, 4800, 9600

 

 

and sometimes 50 and 19200 baud as well. These speeds are selectable

in hardware by appropriate wiring of a chip called a baud-rate

generator. Many modern computers let you select speed in hardware by

means of a DIL switch. The higher speeds are used either for driving

printers or for direct computer-to-computer or computer-to-peripheral

connections. The normal maximum speed for transmitting along phone

lines is 1200 baud.

 

 

 

 

Depending on how your computer has been set up, you may be able to

control the speed from the keyboard--a bit of firmware in the

computer will accept micro-instructions to flip transistor switches

controlling the wiring of the baud-rate generator. Alternatively,

the speeds may be set in pure software, the micro deciding at what

speed to feed information into the serial port.

 

 

In most popular micro implementations the RS232C cannot support

split-speed working (different speeds for receive and transmit). If

you set the port up for 1200 baud, it has to be 1200 receive and

transmit. This is a nuisance in Europe, where 75/1200 is in common

use both for viewdata systems and for some on-line services. The

usual way round is to have special terminal emulator software, which

requires the RS232C hardware to operate at 1200 /1200 and then slows

down (usually the micro's transmit path) to 75 baud in software by

means of a timing loop. An alternative method relies on a special

modem, which accepts data from the computer at 1200/1200 and then

performs the slowing-down to 75 baud in its own internal firmware.

 

 

 

 

Terminal emulators

 

 

We all need a quest in life. Sometimes I think mine is to search

for the perfect software package to make micros talk to the outside

world.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

** Page 18

 

 

As in all such quests, the goal is occasionally approached but

never reached, if only because the process of the quest causes one to

redefine what one is looking for.

 

 

These items of software are sometimes called communications

packages, or asynchronous comms packages, and sometimes terminal

emulators, on the grounds that the software can make the micro appear

to be a variety of different computer terminals. Until recently, most

on-line computer services assumed that they were being examined

through 'dumb' terminals--simply a keyboard and a screen, with no

attendant processing or storage power (except perhaps a printer).

With the arrival of PCs all this is slowly changing, so that the

remote computer has to do no more than provide relatively raw data

and all the formatting and on-screen presentation is done by the

user's own computer. Terminal emulator software is a sort of

half-way house between 'dumb' terminals and PCs with considerable

local processing power.

 

 

Given the habit of manufacturers of mainframe and mini- computers

to make their products as incompatible with those of their

competitors as possible (to maximise their profits), many slight

variants on the 'dumb' computer terminal exist--hence the

availability of terminal emulators to provide, in one software

package, a way of mimicking all the popular types.

 

 

Basic software to get a computer to talk through its RS232C port,

and to take in data sent to it, is trivial. What the hacker needs is

software that will make his computer assume a number of different

personalities upon command, store data as it is collected, and print

it out.

 

 

Two philosophies of presenting such software to the user exist:

first, one which gives the naive user a simple menu which says, in

effect, 'press a key to connect to database' and then performs

everything smoothly, without distracting menus. Such programs need an

'install' procedure, which requires some knowledge, but most

'ordinary' users never see this. Normally, this is a philosophy of

software writing I very much admire: however, as a hacker you will

want the precise opposite. The second approach to terminal emulator

software allows you to re configure your computer as you go on--there

is plenty of on-screen help in the form of menus allowing you to turn

on and off local echo, set parity bits, show non-visible control

codes and so on. In a typical hack, you may have only vague

information about the target computer, and much of the fun is seeing

how quickly you can work out what the remote computer wants to 'see'

- and how to make your machine respond.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

** Page 19

 

 

Given the numbers of popular computers on the market, and the

numbers of terminal emulators for each one, it is difficult to make a

series of specific recommendations. What follows there- fore, is a

list of the sort of facilities you should look for:

 

 

On-line help You must be able to change the software

characteristics while on-line--no separate 'install' routine. You

should be able to call up 'help' menus instantly, with simple

commands --while holding on to the line.

 

 

Text buffer - The received data should be capable of going into the

computer's free memory automatically so that you can view it later

off-line. The size of the buffer will depend on the amount of memory

left after the computer has used up the space required for its

operating system and the terminal software. If the terminal software

includes special graphics, as in Apple Visiterm or some of the ROM

packs used with the BBC, the buffer space may be relatively small.

The software should tell you how much buffer space you have used and

how much is left, at any time. A useful adjunct is an auto-save

facility which, when the buffer becomes full, stops the stream of

text from the host computer and automatically saves the buffer text

to disc. A number of associated software commands should let you turn

on and off the buffer store, clear it or, when off-line, view the

buffer. You should also be able to print the buffer to a 'line'

printer (dot-matrix or daisy wheel or thermal image). Some terminal

emulators even include a simple line editor, so that you can delete

or adjust the buffer before printing. (I use a terminal emulator

which saves text files in a form which can be accessed by my

word-processor and use that before printing out.)

 

 

Half/full Duplex (Echo On/Off) - Most remote services use an echoing

protocol: this means that when the user sends a character to the host

computer, the host immediately sends back the same character to the

user's computer, by way of confirmation. What the user sees on his

computer screen, therefore, has been generated, not locally by his

direct action on the keyboard, but remotely by the host computer.

(One effect of this is that there may sometimes be a perceptible

delay between keystroke and display of a letter, particularly if you

are using a packet-switched connection--if the telephone line is

noisy, the display may appear corrupt). This echoing protocol is

known as full duplex, because both the user's computer and the host

are in communication simultaneously.

 

 

However, use of full duplex/echo is not universal, and all

terminal emulators allow you to switch on and off the facility. If,

for example, you are talking into a half-duplex system (i.e. no

echo), your screen would appear totally blank. In these

circumstances, it is best if your software reproduces on the screen

your keystrokes.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

** Page 20

 

 

However, if you have your computer set for half-duplex and the host

computer is actually operating in full duplex. each letter will

appear twice--once from the keyboard and once, echoing from the host,

ggiiwiinngg tthhiiss ssoorrtt ooff eeffffeecctt. Your terminal

emulator needs to able to toggle between the two states.

 

 

Data Format/Parity Setting - In a typical asynchronous protocol, each

character is surrounded by bits to show when it starts, when it ends,

and to signify whether a checksum performed on its binary equivalent

comes out even or odd. The character itself is described, typically,

in 7 bits and the other bits, start, stop and parity, bringing the

number up to 10. (See chapter 2.) However, this is merely one very

common form, and many systems use subtle variants -- the ideal

terminal emulator software will let you try out these variants while

you are still on line. Typical variants should include:

 

 

Word length Parity No stop bits

 

 

7 Even 2

7 Odd 2

7 Even 1

7 Odd 1

8 None 2

8 None 1

8 Even 1

8 Odd 1

 

 

 

 

(NB although the ASCII character set is 7 bit, 8 bits are sometimes

transmitted with a ~padding~ bit; machine code instructions for 8-bit

and 16-bit machines obviously need 8-bit transmissions.)

 

 

Show Control Characters - This is a software switch to display

characters not normally part of the text that is meant to be read but

which nevertheless are sent by the host computer to carry out display

functions, operate protocols, etc. With the switch on, you will see

line feeds displayed as ^J, a back-space as ^H and so on; see

Appendix IV for the usual equivalents.

 

 

Using this device properly you will be able, if you are unable to

get the text stream to display properly on your screen, to work out

what exactly is being sent from the host, and modify your local

software accordingly.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

** Page 21

 

 

Control-Show is also useful for spotting 'funnies' in passwords and

log-on procedures--a common trick is to include ^H (backspace) in the

middle of a log-on so that part of the full password is overwritten.

(For normal reading of text, you have Control-Show switched off, as

it makes normal reading difficult.)

 

 

Macros - This is the US term, now rapidly being adopted in the UK,

for the preformatting of a log-on procedure, passwords etc. Typical

connecting procedures to US services like The Source, CompuServe, Dow

Jones etc are relatively complicated, compared with using a local

hobbyist bulletin board or calling up Prestel. Typically, the user

must first connect to a packet- switched service like Telenet or

Tymnet (the US commercial equivalents of BT's PSS), specify an

'address' for the host required (a long string of letters and

numbers) and then, when the desired service or 'host' is on line,

enter password(s) to be fully admitted. The password itself may be in

several parts.

 

 

The value of the 'macro' is that you can type all this junk in

once and then send off the entire stream any time you wish by means

of a simple command. Most terminal emulators that have this feature

allow you to preformat several such macros.

 

 

From the hacker's point of view, the best type of macro facility

is one that can be itself addressed and altered in software:

supposing you have only part of a password: write a little routine

which successively tries all the unknowns; you can then let the

computer attempt penetration automatically. (You'll have to read the

emulator's manual carefully to see if it has software-addressable

macros: the only people who need them are hackers, and, as we have

often observed, very few out-and-out hacker products exist!)

 

 

Auto-dial - Some modems contain programmable auto-diallers so that

frequently-called services can be dialled from a single keyboard

command.

 

 

Again the advantage to the hacker is obvious--a partly- known

telephone number can be located by writing some simple software

routine to test the variables.

 

 

However, not all auto-dial facilities are equally useful. Some

included in US-originated communications software and terminal

emulators are for specific 'smart' modems not available

elsewhere--and there is no way of altering the software to work with

other equipment. In general, each modem that contains an auto-dialler

has its own way of requiring instructions to be sent to it. If an

auto-dialling facility is important to you, check that your software

is configurable to your choice of auto-dial modem.

 

 

Another hazard is that certain auto-diallers only operate on the

multi-frequency tones method ('touch-tone') of dialling used in large

parts of the United States and only very slowly being introduced in

other countries. The system widely used in the UK is called 'pulse'

dialling. Touch-tone dialling is much more rapid than pulse dialling,

of course.

 

 

 

 

 

 

** Page 22

 

 

Finally, on the subject of US-originated software, some packages

will only accept phone numbers in the standard North American format

of: 3-digit area code, 3-digit local code, 4-digit subscriber code.

In the UK and Europe the phone number formats vary quite

considerably. Make sure that any auto-dial facility you use actually

operates on your phone system.

 

 

Format Screen - Most professional on-line and time-share services

assume an 80-column screen. The 'format screen' option in terminal

emulators may allow you to change the regular text display on your

micro to show 80 characters across by means of a graphics 'fiddle';

alternatively, it may give you a more readable display of the stream

from the host by forcing line feeds at convenient intervals, just

before the stream reaches the right- hand margin of the micro's

'natural' screen width.

 

 

Related to this are settings to handle the presentation of the

cursor and to determine cursor movement about the screen-- normally

you won't need to use these facilities, but they may help you when

on-line to some odd-ball, non-standard service. Certain specific

'dumb' terminals like the VT52 (which has become something of a

mainframe industry standard) use special sequences to move the cursor

about the screen--useful when the operator is filling in standard

forms of information.

 

 

Other settings within this category may allow you to view

characters on your screen which are not part of the normal character

set. The early Apples, for example, lacked lower case, presenting

everything in capitals (as does the ZX81), so various ingenious

'fixes' were needed to cope. Even quite advanced home computers may

lack some of the full ASCII character set, such oddities as the tilde

~ or backslash \ or curly bracket { }, for example.

 

 

Re-assign - keyboard A related problem is that home micro keyboards

may not be able to generate all the required characters the remote

service wishes to see. The normal way to generate an ASCII character

not available from the keyboard is from Basic, by using a Print

CHR$(n) type command. This may not be possible when on-line to a

remote computer, where everything is needed in immediate mode. Hence

the requirement for a software facility to re-assign any little-used

key to send the desired 'missing' feature. Typical requirements are

BREAK~ ESC, RETURN (when part of a string as opposed to being the end

of a command) etc. When re-assigning a series of keys, you must make

sure you don't interfere with the essential functioning of the

terminal emulator.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

** Page 23

 

 

For example, if you designate the sequence ctrl-S to mean 'send a DC1

character to the host', the chances are you will stop the host from

sending anything to you, because ctrl-S is a common command (some-

times called XOF) to call for a pause--incidentally, you can end the

pause by hitting ctrl-Q. Appendix IV gives a list of the full ASCII

implementation and the usual 'special' codes as they apply to

computer-to-computer communications.

 

 

File Protocols - When computers are sending large files to each

other, a further layer of protocol, beyond that defining individual

letters, is necessary. For example, if your computer is automatically

saving to disk at regular intervals as the buffer fills up, it is

necessary to be able to tell the host to stop sending for a period,

until the save is complete. On older time-share services, where the

typical terminal is a teletypewriter, the terminal is in constant

danger of being unable mechanically to keep up with the host

computer's output. For this reason, many host computers use one of

two well-known protocols which require the regular exchange of

special control characters for host and user to tell each other all

is well. The two protocols are:

 

 

Stop/Start - The receiving computer can at any time send to the host

a Stop (ctrl-S) signal, followed by, when it is ready a Start,

(ctrl-Q).

 

 

EOB/ACK - The sending computer divides its file into a blocks (of any

convenient length); after each block is sent, an EOB (End of Block)

character is sent (see ASCII table, Appendix IV). The user's computer

must then respond with a ACK (Acknowledge) character.

 

 

These protocols can be used individually, together or not at all.

You may be able to use the 'Show Control Codes' option to check

whether either of the protocols are in use. Alternatively, if you

have hooked on to a service which for no apparent reason, seems to

stop in its tracks, you could try ending an ACK or Start (ctrl-F or

ctrl-S) and see if you can get things moving.

 

 

File transmission - All terminal emulators assume you will want to

send, as well as receive, text files. Thus, in addition to the

protocol settings already mentioned, there may be additional ones for

that purpose, e.g. the XMODEM protocol very popular on bulletin

boards. Hackers, of course, usually don't want to place files on

remote computers.....

 

 

Specific terminal emulation - Some software has pre-formatted sets of

characteristics to mimic popular commercial 'dumb' terminals. For

example, with a ROM costing under £60 fitted to a BBC micro, you can

obtain almost all of the features of DEC's VT100 terminal, which

until recently was regarded as something of an industry-standard and

costing just under £1000.

 

 

** Page 24

 

 

Other popular terminals are the VT52 and some Tektronix models, the

latter for graphics display. ANSI have produced a 'standard'

specification.

 

 

Baudot characters - The Baudot code, or International Telegraphic

Code No 2, is the 5-bit code used in telex and telegraphy -- and in

many wire-based news services. A few terminal emulators include it as

an option, and it is useful if you are attempting to hack such

services. Most software intended for use on radio link-ups (see

Chapter 10) operates primarily in Baudot, with ASCII as an option.

 

 

Viewdata emulation - This gives you the full, or almost full,

graphics and text characters of UK-standard viewdata. Viewdata tv

sets and adapters use a special character-generator chip and a few,

mostly British-manufactured, micros use that chip also-- the Acorn

Atom was one example. The BBC has a teletext mode which adopts the

same display. But for most micros, viewdata emulation is a matter of

using hi-res graphics to mimic the qualities of the real thing, or to

strip out most of the graphics. Viewdata works on a screen 40

characters by 24 rows, and as some popular home micros have 'native'

displays smaller than that, some considerable fiddling is necessary

to get them to handle viewdata at all.

 

 

In some emulators, the option is referred to as Prestel or

Micronet--they are all the same thing. Micronet-type software usually

has additional facilities for fetching down telesoftware programs

(see Chapter 10).

 

 

Viewdata emulators must attend not only to the graphics

presentation, but also to split-speed operation: the usual speeds are

1200 receive from host, 75 transmit to host. USA users of such

services may get them via a packet-switched network, in which case

they will receive it either at 1200/1200 full duplex or at 300/300.

 

 

Integrated terminal emulators offering both 'ordinary'

asynchronous emulation and viewdata emulation are rare: I have to use

completely different and non-compatible bits of software on my own

home set-up.

 

 

 

 

Modems

 

 

Every account of what a modem is and does begins with the classic

explanation of the derivation of the term: let this be no exception.

Modem is a contraction of modulator-demodulator.

 

 

A modem taking instructions from a computer (pin 2 on RS232C)

converts the binary 0's and 1's into specific single tones, according

to which 'standard' is being used. In RS232C/V24, binary 0 (ON)

appears as positive volts and binary 1 (OFF) appears as negative

volts.

 

 

** Page 25

 

 

The tones are then fed, either acoustically via the telephone

mouth-piece into the telephone line, or electrically, by generating

the electrical equivalent direct onto the line. This is the

modulating process.

 

 

In the demodulating stage, the equipment sits on the phone line

listening for occurrences of pre-selected tones (again according to

whichever 'standard' is in operation) and, when it hears one,

delivers a binary 0 or binary 1 in the form of positive or negative

voltage pulses into pin 3 of the computer's serial port.

 

 

This explanation holds true for modems operating at up to 1200

baud; above this speed, the modem must be able to originate tones,

and detect them according to phase as well, but since higher-speed

working is unusual in dial-up ports--the hacker's special interest,

we can leave this matter to one side.

 

 

The modem is a relatively simple bit of kit: on the transmit side

it consists of a series of oscillators acting as tone generators, and

on receive has a series of narrow band-pass filters. Designers of

modems must ensure that unwanted tones do not leak into the telephone

line (exchanges and amplifiers used by telephone companies are

sometimes remotely controlled by the injection of specific tones) and

also that, on the receive side, only the distinct tones used for

communications are 'interpreted' into binary 0s or 1s. The other

engineering requirements are that unwanted electrical currents do not

wander down the telephone cable (to the possible risk of phone

company employees) or back into the user's computer.

 

 

Until relatively recently, the only UK source of low-speed modems

was British Telecom. The situation is much easier now, but

de-regulation of 'telephone line attachments', which include modems,

is still so recent that the ordinary customer can easily become

confused. Moreover, modems offering exactly the same service can vary

in price by over 300%. Strictly speaking, all modems connected to

the phone line should be officially approved by BT or other

appropriate regulatory authority.

 

 

At 300 baud, you have the option of using direct-connect modems

which are hard-wired into the telephone line, an easy enough

exercise, or using an acoustic coupler in which you place the

telephone hand-set. Acoustic couplers are inherently prone to

interference from room-noise, but are useful for quick lash-ups and

portable operation. Many acoustic couplers operate only in

'originate' mode, not in' answer'. Newer commercial direct- connect

modems are cheaper than acoustic couplers.

 

 

** Page 26

 

 

At higher speeds acoustic coupling is not recommended, though a

75/1200 acoustic coupler produced in association with the Prestel

Micronet service is not too bad, and is now exchanged on the

second-hand market very cheaply indeed.

 

 

I prefer modems that have proper status lights--power on, line

seized, transmit and receive indicators. Hackers need to know what is

going on more than most users.

 

 

The table below shows all but two of the types of service you are

likely to come across; V-designators are the world-wide 'official'

names given by the CCITT; Bell-designators are the US names:

 

 

Service Speed Duplex Transmit Receive Answer

Designator 0 1 0 1

 

 

V21 orig 300(*) full 1180 980 1850 1650 -

V21 ans 300(*) full 1850 1650 1180 980 2100

V23 (1) 600 half 1700 1300 1700 1300 2100

V23 (2) 1200 f/h(**) 2100 1300 2100 1300 2100

V23 back 75 f/h(**) 450 390 450 390 -

Bell 103 orig 300(*) full 1070 1270 2025 2225 -

Bell 103 ans 300(*) full 2025 2225 1070 1270 2225

Bell 202 1200 half 2200 1200 2200 1200 2025

 

 

(*)any speed up to 300 baud, can also include 75 and 110 baud

services

 

 

(**)service can either be half-duplex at 1200 baud or asymmetrical

full duplex, with 75 baud originate and 1200 baud receive (commonly

used as viewdata user) or 1200 transmit and 75 receive (viewdata

host)

 

 

The two exceptions are:

V22 1200 baud full duplex, two wire

Bell 212A The US equivalent

These services use phase modulation as well as tone.

 

 

British Telecom markets the UK services under the name of

Datel--details are given in Appendix V.

 

 

BT's methods of connecting modems to the line are either to

hard-wire the junction box (the two outer-wires are the ones you

usually need)--a 4-ring plug and associated socket (type 95A) for

most modems, a 5-ring plug and associated socket (type 96A) for

Prestel applications (note that the fifth ring isn't used)--and, for

all new equipment, a modular jack called type 600. The US also has a

modular jack, but of course it is not compatible.

 

 

** Page 27

 

 

Modern modem design is greatly aided by a wonder chip called the

AMD 7910. This contains nearly all the facilities to modulate and

demodulate the tones associated with the popular speed services, both

in the CCITT and Bell standards. The only omission--not always made

clear in the advertisements--are services using 1200/1200

full-duplex, ie V22 and Bell 212A.

 

 

Building a modem is now largely a question of adding a few

peripheral components, some switches and indicator lights, and a box.

In deciding which 'world standard' modem to purchase, hackers should

consider the following features:

 

 

Status lights you need to be able to see what is happening on the

line.

 

 

Hardware/software switching - cheaper versions merely give you a

switch on the front enabling you to change speeds, originate or

answer mode and CClTT or Bell tones. More expensive ones feature

firmware which allows your computer to send specially formatted

instructions to change speed under program control. However, to make

full use of this facility, you may need to write (or modify) your

terminal emulator.

 

 

Auto-dial - a pulse dialler and associated firmware are included in

some more expensive models. You should ascertain whether the

auto-dialer operates on the telephone system you intend to hook the

modem up to--some of the US 'smart' modems present difficulties

outside the States. You will of course need software in your micro to

address the firmware in the modem --and the software has to be part

of your terminal emulator, otherwise you gain nothing in convenience.

However, with appropriate software, you can get your computer to try

a whole bank of numbers one after the other.

 

 

D25 connector - this is the official 'approved' RS232CN24 physical

connection--useful from the point-of-view of easy hook-up. A number

of lower-cost models substitute alternative DIN connectors. You must

be prepared to solder up your own cables to be sure of connecting up

properly.

 

 

Documentation I always prefer items to be accompanied by proper

instructions. Since hackers tend to want to use equipment in

unorthodox ways, they should look for good documentation too.

 

 

** Page 28

 

 

Finally, a word on build-your-own modems. A number of popular

electronics magazines and mail-order houses have offered modem

designs. Such modems are not likely to be approved for direct

connection to the public telephone network. However, most of them

work. If you are uncertain of your kit-constructing skills, though.

remember badly-built modems can be dangerous both to your computer

and to the telephone network.

 

 

 

 

Test Equipment

 

 

Various items of useful test equipment occasionally appear on the

second-hand market--via mail-order, in computer junk shops, in the

flea-market section of exhibitions and via computer clubs.

 

 

It's worth searching out a cable 'break-out' box. This lets you

restrap a RS232C cable without using a soldering iron--the various

lines are brought out on to an accessible matrix and you use small

connectors to make (or break) the links you require. It's useful if

you have an 'unknown' modem, or an unusually configured computer.

 

 

Related, but much more expensive, is a RS232C/V24 analyser --this

gives LED status lights for each of the important lines, so you can

see what is happening.

 

 

Lastly, if you are a very rich and enthusiastic hacker, you can

buy a protocol analyser. This is usually a portable device with a

VDU, full keyboard, and some very clever firmware which examines the

telephone line or RS232C port and carries out tests to see which of

several popular datacomms protocols is in use. Hewlett Packard do a

nice range. Protocol analysers will handle synchronous transmissions

as well as synchronous. Cost: £1500 and up...and up.

 

 

** Page 29

 

 

 

 

 

 

CHAPTER 4

 

 

 

 

Targets

 

 

Wherever hackers gather, talk soon moves from past achievements

and adventures to speculation about what new territory might be

explored. It says much about the compartmentalisation of computer

specialities in general and the isolation of micro- owners from

mainstream activities in particular that a great deal of this

discussion is like that of navigators in the days before Columbus:

the charts are unreliable, full of blank spaces and confounded with

myth.

 

 

In this chapter I am attempting to provide a series of notes on

the main types of services potentially available on dial-up, and to

give some idea of the sorts of protocols and conventions employed.

The idea is to give voyagers an outline atlas of what is interesting

and possible, and what is not.

 

 

 

 

On-line hosts

 

 

On-line services were the first form of electronic publishing: a

series of big storage computers--and on occasion, associated

dedicated networks -- act as hosts to a group of individual databases

by providing not only mass data storage and the appropriate 'search

language' to access it, but also the means for registering, logging

and billing users. Typically, users access the on-line hosts via a

phone number which links into a a public data network using packet

switching (there's more on these networks in chapter 7).

 

 

The on-line business began almost by accident; large corporations

and institutions involved in complicated technological developments

found that their libraries simply couldn't keep track of the

publication of relevant new scientific papers, and decided to

maintain indices of the papers by name, author, subject-matter, and

so on, on computer. One of the first of these was the armaments and

aircraft company, Lockheed Corporation.

 

 

In time the scope of these indices expanded and developed and

outsiders -- sub-contractors, research agencies, universities,

government employees, etc were granted access. Other organisations

with similar information-handling requirements asked if space could

be found on the computer for their needs.

 

 

** Page 30

 

 

Eventually Lockheed and others recognised the beginnings of a quite

separate business; in Lockheed's case it lead to the foundation of

Dialogue, which today acts as host and marketing agent for almost 300

separate databases. Other on-line hosts include BRS (Bibliographic

Retrieval Services), Comshare (used for sophisticated financial

modelling), DataStar, Blaise (British Library) I P Sharp, and

Euronet-Diane.

 

 

On-line services, particularly the older ones, are not especially

user-friendly by modern standards. They were set up at a time when

both core and storage memory was expensive, and the search languages

tend to be abbreviated and formal. Typically they are used, not by

the eventual customer for the information, but by professional

intermediaries--librarians and the like-- who have undertaken special

courses. Originally on-line hosts were accessed by dumb terminals,

usually teletypewriters like the Texas Whisperwriter portable with

built-in acoustic modem, rather than by VDUs. Today the trend is to

use 'front-end' intelligent software on an IBM PC which allows the

naive user to pose his/her questions informally while offline; the

software then redefines the information request into the formal

language of the on-line host (the user does not witness this process)

and then goes on-line via an auto-dial modem to extract the

information as swiftly and efficiently as possible.

 

 

On-line services require the use of a whole series of passwords:

the usual NUI and NUA for PSS (see chapter 7), another to reach the

host, yet another for the specific information service required.

Charges are either for connect-time or per record retrieved, or

sometimes a combination.

 

 

The categories of on-line service include bibliographic, which

merely indexes the existence of an article or book--you must then

find a physical copy to read; and source, which contains the article

or extract thereof. Full-text services not only contain the complete

article or book but will, if required, search the entire text (as

opposed to mere keywords) to locate the desired information. An

example of this is LEXIS, a vast legal database which contains nearly

all important US and English law judgements, as well as statutes.

 

 

 

 

News Services

 

 

The vast majority of news services, even today, are not, in the

strictest sense, computer-based, although computers play an important

role in assembling the information and, depending on the nature of

the newspaper or radio or tv station receiving it, its subsequent

handling.

 

 

** Page 31

 

 

The world's big press agencies--United Press, Associated Press,

Reuters, Agence France Presse, TASS, Xinhua, PAP, VoA -- use telex

techniques to broadcast their stories. Permanent leased telegraphy

lines exist between agencies and customers, and the technology is

pure telex: the 5-bit Baudot code (rather than ASCII) is adopted,

giving capital letters only, and 'mark' and space' are sent by

changing voltage conditions on the line rather than audio tones.

Speeds are 50 or 75 baud.

 

 

The user cannot interrogate the agency in any way. The stories

come in a single stream which is collected on rolls of paper and then

used as per the contract between agency and subscriber. To hack a

news agency line you will need to get physically near the appropriate

leased line, tap in by means of an inductive loop, and convert the

changing voltage levels (+80 volts on the line) into something your

RS232C port can handle. You will then need software to translate the

Baudot code into the ASCII which your computer can handle internally,

and display on screen or print to a file. The Baudot code is given in

Appendix IV.

 

 

None of this is easy and will probably involve breaches of several

laws, including theft of copyright material! However a number of news

agencies also transmit services by radio, in which case the signals

can be hijacked with a short-wave receiver. Chapter 9 explains.

 

 

Historic news, as opposed to the current stuff from agencies, is

now becoming available on-line. The New York Times, for example, has

long held its stories in an electronic 'morgue' or clippings library.

Initially this was for internal use, but for the last several years

it has been sold to outsiders, chiefly broadcasting stations and

large corporations. You can search for information by a combination

of keyword and date-range. The New York Times Information Bank is

available through several on-line hosts.

 

 

As the world's great newspapers increasingly move to electronic

means of production--journalists working at VDUs, sub-editors

assembling pages and direct-input into photo-typesetters--the

additional cost to each newspaper of creating its own morgue is

relatively slight and we can expect to see many more commercial

services.

 

 

In the meantime, other publishing organisations have sought to

make available articles, extract or complete, from leading magazines

also. Two UK examples are Finsbury Data Services' Textline and

Datasolve's d Reporter, the latter including material from the BBC's

monitoring service, Associated Press, the Economist and the Guardian.

Textline is an abstract service, but World Reporter gives the full

text. In October 1984 it already held 500 million English words.

 

 

** Page 32

 

 

In the US there is NEXIS, which shares resources with LEXIS; NEXIS

held 16 million full text articles at that same date. All these

services are expensive for casual use and are accessed by dial-up

using ordinary asynchronous protocols.

 

 

Many electronic newsrooms also have dial-in ports for reporters

out on the job; depending on the system these ports not only allow

the reporter to transmit his or her story from a portable computer,

but may also (like Basys Newsfury used by Channel Four News) let them

see news agency tapes, read headlines and send electronic mail. Such

systems have been the subject of considerable hacker speculation.

 

 

 

 

Financial Services

 

 

The financial world can afford more computer aids than any other

non-governmental sector. The vast potential profits that can be made

by trading huge blocks of currency, securities or commodities--and

the extraordinary advantages that a slight 'edge' in information can

bring--have meant that the City, Wall Street and the equivalents in

Hong Kong, Japan and major European capitals have been in the

forefront of getting the most from high-speed comms.

 

 

Ten years ago the sole form of instant financial information was

the ticker tape--telegraphy technology delivering the latest share

price movements in a highly abbreviated form. As with its news

equivalents, these were broadcast services (and still are, for the

services still exist) sent along leased telegraph lines. The user

could only watch, and 'interrogation' consisted of back-tracking

along a tape of paper. Extel (Exchange Telegraph) continues to use

this technique, though it is gradually upgrading by using viewdata

and intelligent terminals.

 

 

However, just over ten years ago Reuters put together the first

packages which gave some intelligence and 'questioning power' to the

end user. Each Reuters' Monitor is intelligent, containing (usually)

a DEC PDP-8 series mini and some firmware which accepts and selects

the stream of data from the host at the far end of the leased line,

marshalls interrogation requests and takes care of the local display.

Information is formatted in 'pages' rather like viewdata frames, but

without the colour. There is little point in eavesdropping into a

Reuters line unless you know what the terminal firmware does. Reuters

now face an aggressive rival in Telerate, and the fight is on to

deliver not only fast comprehensive prices services but international

screen-based dealing as well. The growth of Reuters and its rivals is

an illustration of technology creating markets--especially in

international currency--where none existed before.

 

 

** Page 33

 

 

The first sophisticated Stock Exchange prices 'screens' used

modified closed circuit television technology. London had a system

called Market Price Display Service--MPDS--which consisted of a

number of tv displays of current prices services on different

'channels' which could be selected by the user. But London now uses

TOPIC, a leased line variant on viewdata technology, though with its

magazine-like arrangement and auto-screen refresh, it has as much in

common with teletext as Prestel. TOPIC carries about 2,500 of the

total 7,500 shares traded in London, plus selected analytical

material from brokers. Datastream represents a much higher level of

sophistication: using its £40,000 plus pa terminals you can compare

historic data-- price movements, movements against sector indices

etc--and chart the results.

 

 

The hacker's reward for getting into such systems is that you can

see share and other prices on the move. None of these prices is

confidential; all could be obtained by ringing a stockbroker.

However, this situation is likely to change; as the City makes the

change from the traditional broker/jobber method of dealing towards

specialist market making, there will then be electronic prices

services giving privileged information to specialist share dealers.

All these services are only available via leased lines; City

professionals would not tolerate the delays and uncertainties of

dial-up facilities. However dial-up ports exist for demonstrations,

exhibitions, engineering and as back-up--and a lot of hacking effort

has gone into tracking them down.

 

 

In the United States, in addition to Reuters, Telerate and local

equivalents of official streams of stock exchange and over-the-

counter data, there is Dow Jones, best known internationally for its

market indices similar to those produced by the Financial Times in

London. Dow Jones is in fact the owner of the Wall Street Journal and

some influential business magazines. Its Dow Jones News/Retrieval

Service is aimed at businesses and private investors. It features

current share prices, deliberately delayed by 15 minutes, historic

price data, which can be charted by the user's own computer

(typically an Apple or IBM PC) and historic 'morgue' type company

news and analysis. Extensions of the service enable customers to

examine accounts of companies in which they are interested. The bulk

of the information is US-based, but can be obtained world-wide via

packet-switching networks. All you need are the passwords and special

software.

 

 

** Page 34

 

 

 

 

Business Information

 

 

Business information is usually about the credit-worthiness of

companies, company annual reports, trading opportunities and market

research. The biggest electronic credit data resource is owned by the

international company Dun & Bradstreet: during 1985-86 it is due to

spend £25m on making its data available all over Europe, including

the UK. The service, which covers more than 250,000 UK businesses, is

called DunsPrint and access is both on-line and via a viewdata

front-end processor. Another credit agency, CNN Services, extensively

used already by the big clearing banks, and with 3000 customers

accessing information via viewdata sets, has recently also announced

an extended electronic retrieval service for its own called Guardian

Business Information A third UK credit service available

electronically is called InfoLink.

 

 

In addition, all UK companies quoted on the London Stock Exchange

and many others of any size who are not, have a report and analysis

available from ICC (InterCompany Comparisons) who can be accessed via

on--line dial--up, through a viewdata interface and also by

Datastream customers. Dun & Bradstreet also have an on--line service

called KBE covering 20,000 key British enterprises.

 

 

Prodigious quantities of credit and background data on US

companies can be found on several of the major on--line hosts. A

valid phone number, passwords and extracts from the operations manual

of one of the largest US services, TRW--it has credit histories on 90

million people--sat on some hackers' bulletin boards (of which much

more later) for over twelve months during 1983 and 1984 before the

company found out. No one knows how many times hackers accessed the

service. According to the Washington Post, the password and manual

had been obtained from a Sears Roebuck national chain store in

Sacramento; some hackers claimed they were able to alter credit

records, but TRW maintain that telephone access to their systems is

designed for read-only operations alone, updating of files taking

place solely on magnetic tape.

 

 

US market research and risk analysis comes from Frost Sullivan.

Risk analysis tells international businessmen which countries are

politically or economically unstable, or likely t become so, and so

unsafe to do business with. I once found myself accessing a

viewdata-based international assessment service run b a company

called Control Risks, which reputedly has strong link to the Special

Air Service. As so often happens when hacker think they are about to

uncover secret knowledge, the actual data files seemed relatively

trivial, the sort of judgements that could be made by a bright sixth

former who read posh newspapers and thoughtful weekly magazines.

 

 

** Page 35

 

 

 

 

University facilities

 

 

In complete contrast to computers that are used to store and

present data are those where the value is to deliver processing power

to the outside world. Paramount among these are those installed in

universities and research institutes.

 

 

Although hackers frequently acquire phone numbers to enter such

machines, what you can do once you are there varies enormously. There

are usually tiers and banks of passwords, each allowing only limited

access to the range of services. It takes considerable knowledge of

the machine's operating system to break through from one to another

and indeed, in some cases, the operating system is so thoroughly

embedded in the mainframe's hardware architecture that the

substantial modifications necessary to permit a hacker to roam free

can only be done from a few designated terminals, or by having

physical access to the machine. However, the hobbyist bulletin board

system quite often provides passwords giving access to games and the

ability to write and run programs in exotic languages--my own first

hands--on experience of Unix came in exactly this way. There are

bulletin boards on mainframes and even, in some cases, boards for

hackers!

 

 

Given the nature of hacking, it is not surprising that some of the

earliest japes occurred on computers owned by universities. Way back

in the 1970s, MIT was the location of the famous 'Cookie Monster',

inspired by a character in the then-popular Rowan & Martin Laugh-in

television show. As someone worked away at their terminal, the word

'cookie' would appear across their screen, at first slowly wiping out

the user's work. Unless the user moved quickly, things started to

speed up and the machine would flash urgently: "Cookie, cookie, give

me a cookie". The whole screen would pulse with this message until,

after a while, the hacking program relented and the 'Monster' would

clear the screen, leaving the message: "I didn't want a cookie

anyway." It would then disappear into the computer until it snared

another unsuspecting user. You could save yourself from the Monster

by typing the word "Cookie", to which it replied "Thank you" and then

vanished.

 

 

In another US case, this time in 1980, two kids in Chicago,

calling themselves System Cruncher and Vladimir, entered the computer

at DePaul University and caused a system crash which cost $22,000 to

fix. They were prosecuted, given probation and were then made a movie

offer.

 

 

** Page 36

 

 

In the UK, many important university and research institution

computers have been linked together on a special data network called

SERCNET. SERC is the Science and Engineering Research Council.

Although most of the computers are individually accessible via PSS,

SERCNET makes it possible to enter one computer and pass through to

others. During early 1984, SERCNET was the target of much hacker

attention; a fuller account appears in chapter 7, but to anticipate a

little, a local entry node was discovered via one of the London

University college computers with a demonstration facility which, if

asked nicely, disgorged an operating manual and list of 'addresses'.

One of the minor joys of this list was an entry labelled "Gateway to

the Universe", pure Hitch-hiker material, concealing an extensive

long-term multi-function communications project. Eventually some

hackers based at a home counties university managed to discover ways

of roaming free around the network....

 

 

 

 

Banking

 

 

Prominent among public fantasies about hackers is the one where

banks are entered electronically, accounts examined and some money

moved from one to another. The fantasies, bolstered by

under-researched low-budget movies and tv features, arise from

confusing the details of several actual happenings.

 

 

Most 'remote stealing' from banks or illicit obtaining of account

details touch computers only incidentally and involve straight-

forward fraud, conning or bribery of bank employees. In fact, when

you think about the effort involved, human methods would be much more

cost-effective for the criminal. For hackers, however, the very

considerable effort that has been made to provide security makes the

systems a great challenge in them- selves.

 

 

In the United Kingdom, the banking scene is dominated by a handful

of large companies with many branches. Cheque clearing and account

maintenance are conducted under conditions of high security with

considerable isolation of key elements; inter-bank transactions in

the UK go through a scheme called CHAPS, Clearing House Automatic

Payments System, which uses the X.25 packet switching protocols (see

chapter 7). The network is based on Tandem machines; half of each

machine is common to the network and half unique to the bank. The

encryption standard used is the US Data Encryption Standard. Certain

parts of the network, relating to the en- and de-cryption of

messages, apparently auto-destruct if tampered with.

 

 

** Page 37

 

 

The service started early in 1984. The international equivalent

is SWIFT (Society for Worldwide Interbank Financial Transactions);

this is also X.25- based and it handles about half-a-million messages

a day. If you want to learn someone's balance, the easiest and most

reliable way to obtain it is with a plausible call to the local

branch. If you want some easy money, steal a cheque book and cheque

card and practise signature imitation. Or, on a grander scale, follow

the example of the £780,000 kruggerand fraud in the City. Thieves

intercepted a telephone call from a solicitor or bank manager to

'authenticate' forged drafts; the gold coins were then delivered to a

bogus company.

 

 

In the United States, where federal law limits the size of an

individual bank's operations and in international banking, direct

attacks on banks has been much easier because the technology adopted

is much cruder and more use is made of public phone and telex lines.

One of the favourite techniques has been to send fake authorisations

for money transfers. This was the approach used against the Security

National Pacific Bank by Stanley Rifkin and a Russian diamond dealer

in Geneva. $10.2m moved from bank to bank across the United States

and beyond. Rifkin obtained code numbers used in the bilateral Test

Keys. The trick is to spot weaknesses in the cryptographic systems

used in such authorisations. The specifications for the systems

themselves are openly published; one computer security expert, Leslie

Goldberg, was recently able to take apart one scheme--proposed but

not actually implemented--and show that much of the 'key' that was

supposed to give high level cryptographic security was technically

redundant, and could be virtually ignored. A surprisingly full

account of his 'perfect' fraud appears in a 1980 issue of the journal

Computer Fraud and Security Bulletin.

 

 

There are, however, a few areas where banking is becoming

vulnerable to the less mathematically literate hacker. A number of

international banks are offering their big corporation customers

special facilities so that their Treasury Departments (which ensure,

among other things, that any spare million dollars are not left doing

nothing over night but are earning short-term interest) can have

direct access to their account details via a PC on dial-up. Again,

telebanking is now available via Prestel and some of its overseas

imitators. Although such services use several layers of passwords to

validate transactions, if those passwords are mis-acquired, since no

signatures are involved, the bank account becomes vulnerable.

 

 

** Page 38

 

 

Finally, the network of ATMs (hole-in-the-wall cash machines) is

expanding greatly. As mentioned early in this book, hackers have

identified a number of bugs in the machines. None of them,

incidentally, lead directly to fraud. These machines allow card-

holders to extract cash up to a finite limit each week (usually

£100). The magnetic stripe contains the account number, validation

details of the owner's PIN (Personal Identity Number), usually 4

digits, and a record of how much cash has been drawn that week. The

ATM is usually off-line to the bank's main computer and only goes

on-line in two circumstances--first, during business hours, to

respond to a customer's 'balance request'; and second, outside

regular hours, to take into local memory lists of invalid cards which

should not be returned to the customer, and to dump out cheque book

and printed statement requests.

 

 

Hackers have found ways of getting more than their cash limit each

week. The ATMs belonging to one clearing bank could be 'cheated' in

this way: you asked for your maximum amount and then, when the

transaction was almost completed, the ATM asked you 'Do you want

another transaction, Yes/No?' If you responded 'yes' you could then

ask for--and get--your credit limit again, and again, and again. The

weakness in the system was that the magnetic stripe was not

overwritten to show you had had a transaction till it was physically

ejected from the machine. This bug has now been fixed.

 

 

A related but more bizarre bug resided for a while on the ATMs

used by that first bank's most obvious High Street rivals. In that

case, you had to first exhaust your week's limit. You then asked for

a further sum, say £75. The machine refused but asked if you wanted a

further transaction. Then, you slowly decremented the amounts you

were asking for by £5...70, 65, 60...and so on, down to £10. You then

told the ATM to cancel the last £5 transaction...and the machine gave

you the full £75. Some hackers firmly believe the bug was placed

there by the original software writer. This bug too has now been

fixed.

 

 

Neither of these quirks resulted in hackers 'winning' money from

the banks involved; the accounts were in every case, properly

debited. The only victory was to beat the system. For the future, I

note that the cost of magnetic stripe reader/writers which interface

to PCs is dropping to very low levels. I await the first inevitable

news reports.