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CHAPTER 3 - Hackers' Equipment
------------------------------

     You  can  hack  with  almost  any  microcomputer capable of talking to the
outside would 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
they use different and incompatible protocols; we will return to the matter  of
the IBM world in chapter  10.) In other works, given  a bit of money, a  bit of
knowledge, a bit of help from friends and a bit of luck (RAD: that's 4 bits,  I
do belive that makes a NIBBLE - hehehe), 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' (RAD:  You
may find some labelled  'for Anti-hackers' - heaven  forbid! - It appears  Case
have what  they call  a HACKER  CRAKER! I  think it's  any advanced  version of
their dial-guard!  More later!);  you must  select those  items that  appear to
have 'legitimate' bit interesting functions and see if they can be bent to  the
hacker's  purposes.  The  various  sections  within  this chapter highlight the
sorts of  facilities you  need; before  lashing out  on some  new software  and
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 scramble among the circuit diagram of 'offical' products  often
yield unexpectedly rewarding results.


THE COMPUTER

Almost  any  popular  microcomputer  will  do;  hacking  does  not call upon an
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.
(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 awkard line breaks.
Terminal emulator software (see below) can sometimes provide a 'fix'.

     One or two  disk drives are  pretty helpful, because  you will want  to ba
able to save the results of your network adventures as quickly and  efficiently
as possible. Most  terminal emulators use  the computer's free  memory (ie. 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 ptinter,  printing 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 ot work fast
enough.  You  may  find  you  lose  characters  at  the beggining of each line.
Moreover, if you print-everything  in real-time, you'll include  mistaks, 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 (it
its slight variant RS423), or V24,  which is the official designator of  RS232C
used outside the USA, though not often seen on micros.

     The vert  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 those.

     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  supported  to  cover  all aspects of serial
communications, including  printers and  dumb terminals  as well  as computers.
The RS232 standard specifies  electrical and physical requirements.  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 practise,  only three  connections are  essential for computer to
modem communication:

Pin 7    signal ground
Pin 2    character leaving the computer
Pin 3    character arriving at the computer

The  remainging  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 cirsumstances, 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 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 all you need to know about in practise.

     One difficulty that frequently arises with newer or portable computers  is
that  some  manufacturers  have  abondoed  the  tradional  25-way  D-connector,
largely on the grouds of bulk, cost and redundancy. Some European computer  and
peripheral companies  favour connectors  based on  the DIN  series (inverted in
Germany), while others use D-connector with fewer pin-outs.

     There  is  no  standardization.  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 the 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 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:

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

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 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. (RAD: That may be
normal, but faster speeds are used all the time.)

     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   implmentations  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  2100 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
emulators software, which requires the RS232C hardware to operate at  1200/1200
and then slows down (usually the  micro's tranmit 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. 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 of  software are sometimes called  communications packages,
or  asynchronous  comms  packages,  and  sometimes  terminal  emulators, on the
grounds that  software can  make a  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  'dumd'
terminals and PCs with considerable local processing power.

     Given the habit  of manufacturers of  mainframe and minicomputers  to make
their products as  imcompatible with those  of their competitors  as possible (
to maximize their profits ), many slight variants on the 'dumb' 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 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 in 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  any
key to  connect to  database' and  then performs  evertything smoothly, without
distracting menus.  Such programs  need a  '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  reconfigure  your  computer  as you go on - there is
plenty of on screen help in tthe 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 want to 'see' - and how to make your machine respond.

     Given the number  of popular computers  on the market,  and the number  of
terminal emulators  for each,  it is  difficult to  make a  series of  specific
recomendations. What  follows therefore,  is a  list of  the sort of facilities
you should look for:

On-line help, Text buffer,  Half/Full Duplex (Echo on/off),  Data Format/Parity
Setting,  Show  Control  Characters,  Macros/Keystroke  Multipliers, Auto-dial,
Format  screen,  Re-assign  keyboard,   File  protocols,  File   transmissions,
Specific terminal emulations, Bauddot characters, Viewdata emulation.


MODEMS

Every account of what a modem  is and does begins with the  classic explanation
of  the  ferivation  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 0s and 1s 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.  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 occurences 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
consits 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 amplifers
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  te
ordinary  customer  can  easily  become  confused.  Moreover,  modems  offering
exactly the same  serivce can vary  in price by  over 300%. Strictly  speaking,
all modems connected to the phone  line should be officially approved by  BT or
other appopriate regulatory authority.

     At 300 baud, you have the option of using direct-connect modems whcih  are
hard-wired  into  the  telephone  line,  an  easy  enough  exercise, or using a
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.

     At higher speeds  acoustic coupling is  not recommended, though  a 75/1200
acoustic  coupler  produced  in  asociation  with  the Prestel Micronet service
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.

     British Telecom markets the UK service  under the name of Datel -  details
are given in Appendix V.

     BT's (RAD:  If you  have forgotten,  BT is  not Blue  Thunder!) 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 asociated socket  (type
96A) for Prestel applications (note that the fifth ring isn't used) - and,  for
all new equipment, a modular jack, but of course it is not compatible.

---- End of Chapter 3 ---------------------------------------------------------------------------------
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