"Hugo Cornwall "The Hacker's handbook"" - читать интересную книгу автора

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.
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 г40,000 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