Author: Mohannad Hussain (9 Articles)
If you have ready my post on the new, power efficient power supplies for computers, you may start to notice a trend here! I have a desktop machine that, once upon a time, was doing quite a bit for me (web server, SVN repo, MySQL, PosgtreSQL, Samba shares, UPnP streaming, CUPS print server…etc), which required it to be on at all times. However, my needs have changed and these days I only need this machine turned on occasionally.
I had previously connected that machine to an LCD energy meter and figured it was probably costing me $5/month. Not too much, but not too little either. I wanted to find an easy, convenient way to turn this machine on and off (i.e. without having to physically push the power button). The turning off part was pretty easy, since I can do that over SSH or VNC, so it was just a matter of figuring out a way to turn it on remotely.
I started my search in the wrong direction, looking at power bars with wireless switches (Belkin makes one), or even Bluetooth connected power bars. All of which would be too expensive and an overkill for my simple purpose.
Eventually, a light bulb went on in my head! An old technology that I knew about for years, but never explored it, was the solution! It is called Wake-on-LAN (WOL) and it allows the network adapter, upon the reception of a “magical” trigger packet, to turn on the whole machine.
Sounds too good to be true? That’s what I thought, too. Then I Googled for examples of how to configure it and found an excellent guide at Life Hacker. It turned out to be even easier than I thought! In my case, all the configuration was perfectly lined up out of the box, so it worked on the first attempt without having to change anything.
As for where or what to use to send that magic packet, there are at least three very easy choices:
- Your router, especially if you’re running an aftermarket firmware like DD-WRT or Tomato
- A smartphone app
- Websites offering it as a free service, although, you’d have to be OK with opening UDP ports 7 or 9 – or both if you don’t feel like searching!
I am surprised that I don’t hear much chatter about WOL in the IT circles. Personally, I think it is a great technology that can save a lot of energy and money, and it has been around for a while so most computers out there should have it built-in. It certainly has worked quite well for me!