208 lines
10 KiB
Plaintext
208 lines
10 KiB
Plaintext
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[][][][][][][][][][][][][][][][][][][]
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[] []
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[] THE INS AND OUTS []
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[] OF []
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[] PACKET SWITCHING []
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[] []
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[] by: The Seker []
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[] Tribunal of Knowledge! []
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[][][][][][][][][][][][][][][][][][][]
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[] Written (c) June 23, 1986 []
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[][][][][][][][][][][][][][][][][][][]
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'TRIBUNAL COMMUNICATIONS LTD'
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""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
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Not many people are quite aware how complex packet switched networks are.
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In this file I hope to clear up all confusion and answer all questions
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concerning packet switching and making international datacalls via packet
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switched networks.
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HISTORY
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=======
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Using normal phone lines, computers can only transmit data at speeds up to
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1200 bps efficiently. This is very slow compared to the inner workings of even
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the slowest computer. If computers could transmit across phone lines at higher
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speeds, 9600 bps for example, there would still be the problem of using a
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compatible protocol. Packet switched networks take care of these and other
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problems dealing with communications.
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The idea of developing a completely computerized network for computers was
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first discussed in the mid 1960's..probably someplace like Bell Labs, MIT, or
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the like. But it wasn't until a decade later that the theory was put into
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construction.
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The first packet network was a project of the Defense Department. They
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labeled it ArpaNet. It was and still is a boon for advanced hackers, as it is
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host to over 300 government related computers. (See 'Hacking ArpaNet' written
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by the Wizard of ArpaNet for an indepth look at breaching this system.)
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Today there are over five commercial packet networks in the United States
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alone (Telenet, Tymnet, CompuServe, etc), and many more throughout the world.
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HOW IT WORKS
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============
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In essence, packet switching services operate at 4800 bps full duplex
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(both direction simulstaneously) and use a form of TDM (Time Division
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Multiplexing), a transmission which is basis for most of the world's voice
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communications. Transmission streams are separated into convenient sized
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blocks or 'packets', each one of which contains a head and tail signifying the
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origination and destination of the data. The packets are assembled by either
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the originating system or by a special facility supplied by the packet switch
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system. Packets in a single transmission may follow the same physical path
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(same cable) or may use an alternate route (ie. a detour cable) depending on
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the congestion of the system. The packets from one 'conversation' are very
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likely to be interleaved with packets from other 'conversations'. The
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originating and receiving computers see none of this mixing. At the receiving
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end, the various packets are stripped of their routing information, and
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re-assembled in correct order before presentation to the computer terminal.
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All public networks that use packet switching have installed a standard
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protocall to try and be compatible with each other. (good luck) The standard,
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which is called CCITT X.25 (Developed at the Geneva conferences.), is
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implemented on all international datacalls. This is a complex system for
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interface between data terminal equipment and data circuit-terminating
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equipment.
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ACCESSING
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=========
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Users (hackers) can access packet switching in a variety of ways. Special
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terminals called Packet Terminals, which are usually hard wired to the nearest
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PSS (Packet Switch Stream), that are able to create and arrange data into the
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correct format are often used. This is very expensive, a reason why you will
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only be likely to see these type of terminals within large company office
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buildings. The average person will probably access a packet network using an
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ordinary ascii terminal (computer and modem), and connect to a special PSS
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facility called a PAD (Packet Assembler/Disassembler) which will handle the
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formatting for them.
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USING
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=====
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To use a public packet network it is usually required for one to have a
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NUI (Network User Identity) which is registered at your local PSE (Packet
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Switch Exchange) for billing purposes...or a way around this.
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Dial into your local PAD (often called port) and enter your NUI. If a
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valid ID is not given, the port will usually throw you off. (There are a few
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exceptions which we will discuss later.) Then one enters the NUA (Network User
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Address) or call name of the computer he/she wants to access. Each computer on
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a network has one given to them. This is usually in the form of numbers or
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somtimes letters. (As in Tymnet's case.) After the correct information is
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entered, the network will connect you via its private sattelite system to the
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local phone system of your destination and then onto the computer you wish
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to access.
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BILLING
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=======
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Billing on networks is done to either the user or reversed and charged to
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the designated computer. Charging is not done according to the distance of the
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call or by the time passed, rather by how many packets exchanged and sometimes
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a small fee for CPU (Centeral Processing Unit) time.
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Many packet networks do not require you to have an NUI at all. One of
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these that many of you probably have worked with is Telenet. It is a leading
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public network throughout the continent. Billing on there is a variation of
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the norm. There is only a charge to a user when he/she wants to access a
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computer internationally or one which doesn't accept the charges of the
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datacall. (ie. REFUSE COLLECT CONNECT 00 AA) Billing like this will probably
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disappear soon due to the greed of big business.
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INTERNATIONAL DATACALLS
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=======================
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If a person wishes to call a computer located on a foreign network, there
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is a little procedure which must be done. As I said earlier, each computer on
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a network has its own address. (NUA) Networks also have their own 'address',
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which is called a DNIC. (Data Network Identification Code) This code is four
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numerical digits long. The first three numbers in this code represent which
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country the network is located in. The fourth digit is which service in that
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particuliar country, as some countries have more than one network. (For
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example, 5052 is Australia's Auspac DNIC. 505 is the country code. 2 is the
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service code.) A list follows:
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COUNTRY NETWORK DNIC
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------------------------------------------------------
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Australia Auspac 5052
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Australia Midas 5053
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Belgium Euronet 2062/2063
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Canada Datapac 3020
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Canada Globedat 3025
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Canada Infoswitch 3029
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Denmark Euronet 2383
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France Transpac 2080
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France Antilles Euronet 3400
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Germany (West) Datex P 2624
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Germany (West) Euronet 2623
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Great Britain IPSS 2342
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Hong Kong IDAS 4542
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Irish Republic Euronet 2723
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Italy Euronet 2223
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DDX-P 4401
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Japan Venux-P 4408
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Luxembourg Euronet 2703
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Netherlands Euronet 2043
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Norway Norpak 2422
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Singapore Telepac 5252
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South Africa Saponet 6550
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Spain TIDA 2141
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Sweden Telepak 2405
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Switzerland Datalink 2289
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Switzerland Euronet 2283
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USA Autonet 3126
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USA CompuServe 3132
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USA ITT (UDTS) 3103
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USA RCA (LSDS) 3113
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USA Telenet 3110
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USA Tymnet 3106
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USA Uninet 3125
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USA WUI (DBS) 3104
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As you can see, the the United States has many services. But their DNIC
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doesn't follow the pattern I described earlier. (ie. first three digits
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represent country, last is service) I am not quite sure why this is, but I
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think it may be because each of the US services listed are privately owned.
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As I was saying earlier, there is a little extra bit of information you
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must give the network when making an international call. Instead of just
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emtering the NUA like on a domestic call, you have to enter the DNIC and append
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the NUA or you will not complete you call and probably will get an error code.
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Here is what a call from Telenet to Cambridge University's port selector in
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England, which is located on Euronet (In Britain they call it IPSS.) would
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look like:
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TELENET
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714A
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TERMINAL= d1
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ID EXAMPLE
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PASSWORD?
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ID VALID
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c 234222339399
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CONNECTED TO 234 222339399
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What I just did was connect to a Telenet port. Enter my NUI. Then enter
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the DNIC for IPSS in Britain (2342) and appended the NUA for Cambridge
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University. (22339399) Then I was connected.
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REFERENCES
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==========
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For more detailed info on packet switching and its uses, etc, I recommend
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the following two books:
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'Data Communications: Facilities, Networks, and Systems Design'
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Doll, Dixon R., New York, Wiley, c1978
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'Packet Radio'
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Rouleau, Robert and Ian Hodgson, Blue Ridge Summit, Pa., Tab Books, c1981
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ACKNOWLEDGEMENTS
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================
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Much of the imformation within was provided by:
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Cyclone II
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Slave Driver
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NOTE: This document was written for informational purposes only. Any
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application of what was provided within is responsibility of the user,
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not the author.
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>>>>>>>>>>>>>>> (c) 1986 TRIBUNAL OF KNOWLEDGE! <<<<<<<<<<<<<<<
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