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TTYSNOOP(8) BSD System Manager’s Manual TTYSNOOP(8)

NAME

ttysnoop — snoop on a user’s tty

SYNOPSIS

ttysnoop [pty]
ttysnoops
[loginname]

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 ttysnoop client should be used.

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" altough 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 AT miskatonic DOT inbe DOT net

BSD August 8 1994 BSD

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