[K12OSN] User stays logged on after terminal is turned off [FIX]

["Tim Thorpe" <tim cleanyourdirt com>]

Issue with users failing to log out and their sessions continuing when the
terminal is turned off, reaching the max users limit on the server. 

It's a problem with GDM
GDM has been fixed, 

find the gdm.conf file, probably /etc/X11/gdm/gdm.conf

in that file, search for the word 'Ping'

if the line is commented out un-comment it. It should be set to something
like 15.

now, you need to restart GDM. but if you do, you'll lose your current
session

COMMAND restarts GDM and kills ALL current connections.
gdm-restart

COMMAND sets file config but DOES NOT kill current connections
gdm-save-restart