Hi fvdw, hi Jocko,
I've seen a firmware plug-in on Openmediavault which I used on my self-build NAS which is called "Autoshutdown".
This is a nice background task which has a look on active IP addresses in you home network. You can configure the IP adresses (or ranges) which should be watched and if not available the NAS closed down.
I think this is quite a usefull plug.in / script to be implemented in the firmware.
Link
https://bintray.com/openmediavault-plug ... tdown/view
http://adomatp.de/index.php/homeservern ... toshutdown