WOL – Wake up On LAN – How to set it up

A very interesting feature to set up on the client computers that you manage is Wake up On LAN, or WOL. It can be very useful to be able to power on a client in a remote location, or to be able to power on all clients at once. Also, with WOL, you don’t even have to leave your desk to power on a client before working on it with VNC or Remote Desktop… (I’m quite sure some people here will appreciate that !)

Related post: Remotely Shutdown client computers

 

How does it work ?

It is quite simple: a computer, with a dedicated software, sends a signal across the network called a magic packet. The client to which this “magic packet” is sent then powers on by itself.

Not all computers can be powered on this way. You need a computer with a network card that accepts Magic packets and that is able to manage the computer power status. Most of computers that are less than 5 years old have nowadays such a network card. Have a look at the network card : if you can see some LED blinking on it while the computer is powered off, it is certainly able to manage the computer power status.

Try it !

The best thing to do is to try first to power on a computer through WOL to see if it works.

For that, you will need an already powered on computer (yours !) connected to the network.

Then, get the MC-WOL free software from here. This is the software that send the magic packet. Save it on your computer.

Get the MAC address of the computer that you want to power on, and, from the command line, launch the following command:

<Path to MC-WOL.exe>\mc-wol MAC_address

or <Path to MC-WOL.exe>\mc-wol MAC_address /a subnet_broadcast_address

if the computer is on a subnet different from yours.

If the computer powers on, then it’s all good ! If not, well, it is not over. You have to look at the settings of the computer that you want to wake up.

Setup on the client computer

You first need to set up the BIOS. Enter the BIOS, and look for a setting called “WOL, “Wake up ON LAN”, “Remote wake up”… Set this setting to “enable”.

On some computers, if fast boot is enabled, it disables WOL. Check this.

Then, you need to set up the network adapter options in Windows to enable WOL. Boot Windows and log on as an administrator. Launch Device Manager, select the network adapter used for WOL, open the properties and click the “advanced” tab.

Check the list of options displayed. They are different from computer to computer, of course, but the ones to enable are usually easy to identify. They generally include, in their names, words like “WOL”, “Magic packet”, “power management”…

On a Dell Optiplex computer, it looks like this:



Enable the options and click “OK”.

Firewall restrictions

As explained above, you can use MC-WOL to wake up a computer on a subnet different from yours. If the 2 subnets are linked by a firewall type device than prevent broadcast of packet to the whole subnet, then MC-WOL is not going to work, because MC-WOL broadcasts the magic packet to the whole subnet.

Script it

Here is a little script I wrote to wake up one specific client on my network from its host name (because a MAC address is a pain to remember and type…), or all the clients at once.

Download it from here.

Extract it, then run the executable and specify that you want the files copied to your “Program Files” folder, then:

1- in “RemoteClientWakeUp.bat”, set up the broadcast addresses of your subnets.

2- in “Clientlist.txt”, put the hostname and Mac address of each client, separated by a tab.

Included in this download, there is also a module to remotely shutdown client computers. Check the related post.