Today I started using some technology that has proven to be surprisingly useful: Wake On LAN. Computers equipped with this feature provide a very small power source to the Ethernet card, and it watches the wire for a magic packet containing (among other things) the card's hardware address. When it sees this magic packet, it pretends that the system's power button has been pressed and turnes on the computer. It boots normally.

I'm using this at a customer that's a 30 minute drive away: I make a list in advance of all the MAC addresses in the place, and with a simple bit of perl code I can wake up any of the machines. This is going to be really helpful when I remotely "shutdown" a key server instead of "reboot". I've done this before.

I used the wakeonlan software by José Pedro Oliveira, and this was utterly plug and play. No special drivers required, it "just worked" on a Red Hat Linux 7.2 system. What a joy.