Saving power by turning off clients at night
============================================

It is possible to save power by turning off clients at night, and turn
them automatically on in the morning.

There are some considerations to make when doing this:

 - The clients should not be shut down when someone is using them.
   This is done by checking the output from who', and as a special
   case, checking for the LDM ssh connection command to work with LTSP
   thin clients.

 - To avoid breaking fuses, it is a good idea to make sure all clients
   do not start at the same time.

 - There are two different methods available to wake up clients.  One
   uses the BIOS feature and require a working and correct hardware
   clock, as well as a supported motherboard and BIOS version
   (nvram-wakeup), The other require a server with knowledge about all
   the clients to wake up and for all the clients to have support for
   wake-on-lan.

How to set it up
----------------

On clients that should turn off at night, touch
/etc/shutdown-at-night/shutdown-at-night, or add the hostname to the
netgroup "host-shutdown-at-night".  The clients might need to have
wake-on-lan configured in the BIOS.  It is also important that the
switches and routers used between the wake-on-lan server and the
clients will pass the WOL packages to the clients even if the clients
are turned off.

To enable wake-on-lan on the server, add the clients to
/etc/shutdown-at-night/clients, with one line per client, IP address
first, and MAC address (ethernet address) next, with space between
them, or create a script /etc/shutdown-at-night/clients-generator to
generate the list of clients on the fly.

License
-------

This package is licensed using GNU General Public License v2 or later.

Bugreporting
------------

Report issues to the debian-edu@lists.debian.org mailing list.
