Free Knowledge Resources


Linux Manual Pages


Free Software * Books

Source Code

Free Media

Linux

ttysnoop(8)


NAME

     ttysnoop --- snoop on a user's tty

SYNOPSIS

     ttysnoop [pty]
     ttysnoops

DESCRIPTION

     The ttysnoop / ttysnoops client-server combo can be used to snoop (watch)
     on a user's login tty.  The server (ttysnoops) is usually started by
     getty(8) or telnetd(8) and reads the file /etc/snooptab to find out which
     tty's should be cloned and which programs to run on them (usually
     /bin/login). A tty may be snooped through a pre-determined (ie.  fixed)
     device, or through a dynamically allocated pseudo-tty (pty). This is also
     specified in the /etc/snooptab file. To connect to the pty, the client
     ttysnoop should be used. The available pseudo terminals pty are present
     as sockets in the directory /var/spool/ttysnoop/.

   Format of /etc/snooptab
     The /etc/snooptab file may contain comment lines (starting with a '#'),
     empty lines, or entries for tty's that should be snooped upon. The format
     of such an entry is as follows:

       tty   snoop-device   type   program

     where tty is the leaf-name of the tty that should be snooped upon (eg.
     ttyS2, not /dev/ttyS2) OR the wildcard '*', which matches ANY tty.
     snoop-device is the device through which tty should be snooped (eg.
     /dev/tty8) OR the literal constant "socket". The latter is used to tell
     ttysnoops that the snoop-device will be a dynamically allocated pty.
     type specifies the type of program that should be run, currently
     recognized types are "init", "user" and "login" although the former two
     aren't really needed. Finally, program is the full pathname to the
     program to run when ttysnoops has cloned tty onto snoop-device.

EXAMPLE

     The following example /etc/snooptab file should illustrate the typical
     use of ttysnoop / ttysnoops:

        #
        # example /etc/snooptab
        #
        ttyS0    /dev/tty7    login    /bin/login
        ttyS1    /dev/tty8    login    /bin/login
        #
        # the wildcard tty should always be the last one in the file
        #
        *        socket       login    /bin/login
        #
        # example end
        #

     With the above example, whenever a user logs in on /dev/ttyS0 or
     /dev/ttyS1, either tty will be snooped through /dev/tty7 or /dev/tty8
     respectively. Any other tty's will be snooped through a pty that will be
     allocated at the time of login. The system-administrator can then run
     ttysnoop pty to snoop through the pty. Note that it is up to the system-
     administrator to setup getty and/or telnetd so that they execute
     ttysnoops instead of /bin/login.

SEE ALSO

     getty(8), telnetd(8)

FILES

     /etc/snooptab

BUGS

     The program is unable to do any terminal control-code translations for
     the original tty and the snoop-device. I doubt it will ever do this.

AUTHOR

     Carl Declerck, carl@miskatonic.inbe.net



Opportunity


Personal Opportunity - Free software gives you access to billions of dollars of software at no cost. Use this software for your business, personal use or to develop a profitable skill. Access to source code provides access to a level of capabilities/information that companies protect though copyrights. Open source is a core component of the Internet and it is available to you. Leverage the billions of dollars in resources and capabilities to build a career, establish a business or change the world. The potential is endless for those who understand the opportunity.

Business Opportunity - Goldman Sachs, IBM and countless large corporations are leveraging open source to reduce costs, develop products and increase their bottom lines. Learn what these companies know about open source and how open source can give you the advantage.



Free Software


Free Software provides computer programs and capabilities at no cost but more importantly, it provides the freedom to run, edit, contribute to, and share the software. The importance of free software is a matter of access, not price. Software at no cost is a benefit but ownership rights to the software and source code is far more significant.

Free Office Software - The Libre Office suite provides top desktop productivity tools for free. This includes, a word processor, spreadsheet, presentation engine, drawing and flowcharting, database and math applications. Libre Office is available for Linux or Windows.



Free Books


The Free Books Library is a collection of thousands of the most popular public domain books in an online readable format. The collection includes great classical literature and more recent works where the U.S. copyright has expired. These books are yours to read and use without restrictions.

Source Code - Want to change a program or know how it works? Open Source provides the source code for its programs so that anyone can use, modify or learn how to write those programs themselves. Visit the GNU source code repositories to download the source.



Education


Study at Harvard, Stanford or MIT - Open edX provides free online courses from Harvard, MIT, Columbia, UC Berkeley and other top Universities. Hundreds of courses for almost all major subjects and course levels. Open edx also offers some paid courses and selected certifications.

Linux Manual Pages - A man or manual page is a form of software documentation found on Linux/Unix operating systems. Topics covered include computer programs (including library and system calls), formal standards and conventions, and even abstract concepts.


birds banner