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Unix - Frequently Asked Questions (4/7) [Frequent posting]
Section - Is it possible to "spy" on a terminal ... ?

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4.11) Is it possible to "spy" on a terminal, displaying the output
      that's appearing on it on another terminal?

      There are a few different ways you can do this, although none
      of them is perfect:

      * kibitz allows two (or more) people to interact with a shell
        (or any arbitary program).  Uses include:

        - watching or aiding another person's terminal session;
        - recording a conversation while retaining the ability to
          scroll backwards, save the conversation, or even edit it
          while in progress;
        - teaming up on games, document editing, or other cooperative
          tasks where each person has strengths and weakness that
          complement one another.

        kibitz comes as part of the expect distribution.  See question 3.9.

        kibitz requires permission from the person to be spyed upon.  To
        spy without permission requires less pleasant approaches:

      * You can write a program that rummages through Kernel structures
        and watches the output buffer for the terminal in question,
        displaying characters as they are output.  This, obviously, is
        not something that should be attempted by anyone who does not
        have experience working with the Unix kernel.  Furthermore,
        whatever method you come up with will probably be quite
        non-portable.

      * If you want to do this to a particular hard-wired terminal all
        the time (e.g. if you want operators to be able to check the
        console terminal of a machine from other machines), you can
        actually splice a monitor into the cable for the terminal.  For
        example, plug the monitor output into another machine's serial
        port, and run a program on that port that stores its input
        somewhere and then transmits it out *another* port, this one
        really going to the physical terminal.  If you do this, you have
        to make sure that any output from the terminal is transmitted
        back over the wire, although if you splice only into the
        computer->terminal wires, this isn't much of a problem.  This is
        not something that should be attempted by anyone who is not very
        familiar with terminal wiring and such.

      * The latest version of screen includes a multi-user mode.
        Some details about screen can be found in question 4.10.

      * If the system being used has streams (SunOS, SVR4), the advise
        program that was posted in volume 28 of comp.sources.misc can
        be used.  AND it doesn't requirethat it be run first (you do
        have to configure your system in advance to automatically push
        the advise module on the stream whenever a tty or pty is opened).

------------------------------

End of unix/faq Digest part 4 of 7
**********************************

-- 
Ted Timar - tmatimar@isgtec.com
ISG Technologies Inc., 6509 Airport Road, Mississauga, Ontario, Canada L4V 1S7

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Top Document: Unix - Frequently Asked Questions (4/7) [Frequent posting]
Previous Document: Is it possible to reconnect a process to a terminal ... ?

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Last Update March 27 2014 @ 02:12 PM