Remote Power Cycling with "Whack-on-LAN"

by
Grant Ayers

Advised by
Jay Lepreau

Hardware and software lockups pose a serious problem for remotely deployed PCs. They require on-site human intervention which can yield excessive downtime and unavailability. The best way to cope with this issue is to introduce a mechanism that enables remote hardware reset, irrespective of the remote node's hardware/software state. Commercial solutions exist, such as "management processors" built into server-class machines or separate serial or network controlled power-cycle units, but are prohibitively expensive and require additional infrastructure (external power, and/or a separate, external communications link).

We have developed a lightweight, cost-effective (as little as $5 per machine) hardware modification to the Magic Packet technology implemented in many commodity ethernet adapters that diverts a Wake on Lan (WOL) event into a hardware reset. A significant issue with Magic Packets is their lack of security provisioning; any packet with the correct contents will trigger a WOL event. In the usual context of waking a machine, this is mostly a non-issue, but can have disasterous consequences when coupled with hardware reset. To address this, we are exploring mechanisms for authenticating or filtering Whack-on-LAN packets.