Utmpd

I got the idea of implementing a user access-control
daemon. I coded a simple program called utmpd which 
role is to force logout users violating a defined rule.

Eg.: We set the configuration file to kill user "test",
every time he logs in to the system from Monday to Friday.
Every time the user "test" tries to log in at these days
(Mon,Thu,...Fri) he receives a message on his terminal:

        "You are not allowed to log in on this day!"

and got killed.

Other options that utmpd supports are :

        DENY_TIME (denied access at predefined time,
                   time ranges...)

        WDENY_TIME (explained above)

        HOST_DENY (killing users loged from certain
                   hosts (eg. microsoft.com !sorceforge.net ))

        MAX_IDLE  (sets the maximum idle a user can reach)

For download and other info look at:

        http://utmpdix.sourceforge.net/