Technology.Life.Insight.

Wake On LAN

Happy New Year!!

While I wait for the work I’ve been doing for the past 6 months to be publicly released (so I can talk about it), here is a quick post about WOL. WOL technologies have been around for awhile and are used to wake a computer from sleep by sending a magic packet or pattern to the sleeping PC. The best analogy I’ve seen for this is a bunch of people in a room together and one person across the room shouting out another’s name. Everyone but the person with the name called ignores the call. Sleep mode shuts down all major processing on the PC but keeps active tasks (documents, etc) alive in RAM which continues to be energized during sleep. This allows the PC to be quickly awakened and resume normal operation, right where the user left off.

Use Case

I have 6 Windows7 PCs in my house, all of which are connected to a HomeGroup, along with a NAS, a LAN-enabled TV, an XBOX360 and a PS3, all capable of delivering and consuming content via DLNA. I let my PCs sleep after 2 hours of inactivity which saves power consumption. Sometimes I want to access content or simply RDP to a PC that is sleeping. Instead of walking around and physically waking up a sleeping PC, why not leverage WOL? This can be useful in corporate environments as well if you don’t already have tools in place.

Set Up

First you need to enable WOL in the properties of your NIC, most of which these days should be supported. In the advanced properties tab look for “Wake-Up Capabilities.” The important thing to enable in the values here is the Magic Packet. Enabling Pattern is ok too.

Wake Up

Now when the PC sleeps it can be awakened remotely. There are a few different tools out there that can do this. I’ll be working with Depicus’ tools which has, among others, command line and GUI versions: Wake On LAN GUI/ Command Line. Both are free and dead simple executables that require no install and can be easily stored in your Dropbox for portability. They also have apps for Android and IOS. Each version accomplishes the same thing ultimately and can target a host over the internet if need be. All that is needed is the MAC address of the PC to wake up, its IP, subnet and port. For LAN wake up use port 7, if using across the internet you will need to specify a port that is allowed through your firewall as well as a public IP.

The GUI provides a dropdown to specify local subnet or internet. In my tests the GUI required the dashes in the MAC address, it gave an error without them. The cmd version will accept either.

Here you can see the PC I’m waking up is 10.10.1.19. It is fully asleep when the Ping starts, times out to unreachable, then comes back alive when the magic packet was sent.

That’s it! Another reason to stay seated. :)

References:

Power Management for Network Devices in Windows 7

Depicus

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