Wake on Lan

Wake on Lan is technique to power on a computer over the network by sending a specific data paket ("Magic paket"). This does not require administrative privileges. You only need access to computer on the same network.

Our computers have an IDLE Timeout, which turns them off when they are not used (no user processes are running). In former times it was possible to request a flag which disabled this feature. To save power we no longer support this.

With a little bit of information you can wake up your computer from the login node. The information you need is the hardware address (mac) of the computer. This can be read, when you are logged in to the computer.

Open a terminal windows an type "ip a". This shows all network interfaces. The important interface starts with "en" (enp0s31f6 in the example). The screen shot show the output of the ip command with the mac addresses marked by the circle.

The mac address is a 48 bit hexadecimal encoded number.

To wake up the machine, you need to login to "iota". Kappa does not work, because it's on a different network then the clients computers.

Run the command

wakeonlan RECORDED-MAC-ADDRESS
 

With RECORDED-MAC-ADDRESS replaced by the numbers recorded from the "ip a" output.

After some minutes you should be able to ssh to your machine.