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Posts Tagged ‘UDP’

Apple Airport Extreme Basestation and Wake On Lan

Monday, September 15th, 2008

In order to cut down on energy usage I wanted my allwayson windows XP server to hibernate when not in use. My network adapter supports wakeOnLan and I also had it configured in a minute. Make sure Wake on Lan is activated in your Bios as well as in the configuration menu of the networking card.

Wake On Lan settings on the server

Wake On Lan settings on the server

wake on land settings - energy management

be sure to check all three boxes. The last box makes sure your pc does not wake up from random networking traiffc.

this is what it looks like on a mac

this is what it looks like on a mac

Then I go to my macbook pro and fire up this tool http://gsd.di.uminho.pt/jpo/software/wakeonlan/ which is a small free but fully functional wake on lan tool for macs that is able to send the so called magic packets that wake up a computer in standby or hibernation mode. There are a ton of tools like this for windows as well. google is your friend.

wake550

So within the network everything works just fine. I put in the mac address and the broadcasting IP which usually is something like 192.168.x.255 and hit go. seconds later my server is booting up. very nice.

Wake on Lan over the internet through a Airport Extreme basestation is a different story. In theory all you had to do is forward the UDP port 9 to the broadcasting IP of 192.168.x.255. So any magic package that hits your router on the wan port is automatically broadcasted over your local network in order to find the machine that needs to be powered up. pretty simple in theory.

1. Update 4.5.2009

2. Update 20.5.2009

Wake on lan over the internet

It is possible to do it over the internet on the long run. The important thing to understand is that the Airport extreme basestation still will not allow any broadcasting of outside traffic. It can be done however if you manually specifiy the ip address for the computer that should wake up. your are very likely to have your Airport Extreme Basestation hand out IP addresses to devices using DHCP. Your computer needs an IP reservation that will give it the same Ip every time it is on, so the magic package will always reach the correct machine. you can make such a reservation in the Airport utility at internet –> DHCP. The AEBS will only remeber the computer with the IP reservation for a short amount of time so it is not a long term solution.

Ip reservation

You need the computers mac address to make this reservation, usually something like this xx:xx:xx:xx:xx:xx. Then head over to you computer’s network settings and asign the same IP you just reserverd manually to the computer.

manual ip

Now you have to forward the UDP 9 port in the airport utility. Unlike previously assumed you do not want to forward it to the broadcasting IP but to the specific IP you asigned to the computer.

forwarding the udp 9 port

forwarding the udp 9 port

http://ifatwww.et.uni-magdeburg.de/wol/

http://stephan.mestrona.net/wol/

here is a really good german explaination of the entire issue.

Bottom Line:

it is possible to use wake on lan within your local network/subnet if you have an Apple Airport Extreme Basestation, but it is not possible to wake up your machine over the internet since the AEBS will not forword the magic packages coming in at the UDP 9 Port.

It is possible to do wake on lan over the internet and on your local lan with your airport extreme basestation. Thanks a bunch for the commenter who came up with this idea!

It is possible to do wake a lan over the internet but after a short time the AEBS “forgets” the link to the computer and it will not work any more. Sry for the messy post, I will clean it up once I have figuered the damn problem out!