You may want to check out ltsp---packages for it are available. I believe it can be configured to set time limits on sessions. You might also take a look at the Howard County Library [1] [2]. They cooked up their own distribution, and it appears they're more Red Hat, but if you contact them they might be able to pass along a tip or two. [1] http://webjunction.org/do/DisplayContent?id=11058 [2] http://www.libraryjournal.com/article/CA406008.html