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