Looking for Software to Lock T

[CARLA BAZEMORE]

Does anyone know of any software that runs on an UNIX system that
will guard an unattended terminal against unauthorized use.  This
software should clear the terminal screen and not reactivate the
terminal screen until the correct password is entered.  

If anybody has any knowledge of any software that will do the above,
please let me know.

Thank you,
Carla Bazemore 
bazemore at ccf.nrl.navy.mil