Enabling Wake On Lan Feature on Ubuntu

Posted on February 1, 2021

Intro

Recently, I decided to make an old desktop machine to a server like resource, which meant to remove any input or output peripherals except for the internet connectivity means (Ethernet cable) as to be able to access it via ssh.

Of course, a 24/7 available machine is not a very cost-effective and environment-friendly solution in a home setup, so the Wake-On-Lan feature was the right choice. This feature enables you to turn on your machine using the local network. (Wake-on-Lan)

The desktop at hand runs Ubuntu 20.04.1 LTS (GNU/Linux 5.8.0-40-generic x86_64) as OS (not a server oriented one) and has an ASUS P5Q-SE parentboard with an integrated network interface controller (NIC). The network interface controller must support the Wake-On-Lan feature in order to enable it.

Install ssh server

As a zero step, I installed the openssh-server in order to be able to access the machine after the configuration.

To check if the ssh server is installed and/or active I issued the below command:

If the ssh server is not in place, one can download it by issuing the below command:

Use ssh client

After ssh server was in place and active, I performed an ssh connection as a health check (in order to avoid plugging/unplugging input/output devices for debugging).

To perform the health check I used the MobaXterm.

MobaXTerm is a user-friendly toolbox for remote computing, which includes a colorful ssh client

Enable WOL in BIOS

A good guide for the steps can be found at: WakeOnLan Ubuntu Help

Next step was to enter the BIOS and find the much-desired flag(s). In the aforementioned parentboard I had to enter the BIOS, go under Power section, next to APM Configuration menu and enable both Power by PCI Devices and Power by PCIE Devices. For reasons unknown to me, both flags should be enabled in order to work.

Enable WOL in software

After that, I had to get the name of my NIC in order to check if it supports and has enabled the WOL feature. Issuing ifconfig gave me the info I needed. In my case the NIC was called enp2s0

Next command in line was sudo ethtool enp2s0 which revealed its secrets:

The g in Supports Wake-on meant that I was lucky and my machine actually supported the WOL feature and the d in Wake-on meant that the feature was disabled at the time.

One command kept me away from fulfilling the configuration (or so I thought..).

I issued an sudo ethtool -s enp2s0 wol g to enable the feature.

After that I got a reassuring:

when I issued the sudo ethtool enp2s0 command again.

Then, I shut down the machine.

Wake-On-Lan Client program

In order to perform the Wake-On-Lans to this machine I got a portable Wake-On-Land program for my other Windows machine (which would be the client for the desktop machine).

The program fitted to my needs was WakeMeOnLan for Windows which can be downloaded at:

Nirsoft WakeMeOnLan

It is a simple program to hold and awake your Wake-On-Lan machines.

Persisting setting

So, I stored my machine and performed an awakening. All played well, until I shut down again the server after the session and tried to awake it again.

No response.

The cause was (maybe for security reasons, maybe not) that the enable flag was reset after shutdown. It was not persisted across boots.

Solution to this incident, was brought by this site: Wake-on-LAN ArchLinux Wiki

What I read and did was to make a new file at /etc/systemd/system/wol@.service and append the below content:

What this script does is to enable the Wake-On-Lan feature in every boot after the network initializes. This is done by systemd automatically, so you end up with a persistent setting of the feature.

Conclusion

Lines above, documented a walkthrough for enabling Wake-On-Lan feature for the specific system. Many parts may vary when enabling the feature to another machine, but the concept remains as described and summarized to the next list: