"Recent pushes for "green" technology focus mostly on
talk, with little action for the typical home- or small-office
environment. Many users leave their systems online continuously
through laziness or ignorance, resulting in a significant source of
power consumption, as well as an additional vector for malware
propagation. The tools and code presented here allow you to find
those inactive systems and securely start the shutdown process.
With a Linux® box monitoring your network connections using
Argus and some custom Perl code, any system that supports Perl can
be set to be remotely shut down when a centralized set of
inactivity rules are met."