Sonntag, 2. September 2012

Mac OS X Wake On LAN (WOL)

Manny Mac user have problems getting WOL to work properly.
You often read, that WOL is only possible if a „Magic Packet“ is sent via LAN. Apparently this wont work via WLAN.
However some of us would like to wake up our Mac connected via WLAN with any Network access: A web request or a VNC connection. Not just by using special software like (the very good iPhone App) iNET.

Actually i didn‘t even manage to wake up my Mac Min with iNET, after it had went to sleep (slow flashing LED). When my Mac was sleeping iNET didn‘t even find it with a network scan.

Well, there is a solution to this, with a small drawback. I‘l get back to the drawback later.

If you have a look in the system information, you will find astonishing parameters, that you can change if you know where to find them.

Open the system information e.g. by clicking on the Apple in the upper left corner of your monitor. Then click „About this Mac“. Go on by clicking on „further information“ and then „System profiler.“
In the left pane under „Harwdare“, click on „Power“. On the right pane you find a parameter  „PrioritizeNetworkReachibilityOverSleep“, which is set to 0 (zero). You also find a parameter which tell in how many minutes the hard disk will go to sleep.

You wont find this settings on the GUI (System Preferences). You find them in the file
„/Library/Preferences/SystemConfiguration/com.apple.PowerManagement.plist“ which you can edit with a text editor. You do have to have root rights to do that however.
A very convenient editor for this type of work it TextWrangler, as it prompts you to „unlock“ the file, as you go.

I use my Mac Mini as a test web server, so i set the „PrioritizeNetworkReachibilityOverSleep“ as well as the „Disk Sleep Timer“ to 1.

After editing this file, you have to enter the system preferences clicking on „energy saver“ in the „Hardware“ section, checking „wake for network access“.

That‘s it!
Now my Mac shuts down the monitor and the hard dis after 1 minute and i can wake it up with any network access. In this type of sleep mode the LED is not slow flashing any more. Its solid. The Mac still appears when i do a network scan (with iNET).

The drawback is, that the cooling fan doesn‘t go to sleep.

When making a web request e.g. the Mac Mini fires up the hard disk at no time and everything is up and running. Note: This works over (W)LAN as well as internet using a port forwarding.

This is my configuration: internet -> router (FritzBox with port forwarding) -> WLAN -> Mac mini.

Have fun!