Enabling Wake-on-Lan (and WAN) on Ubuntu 24.04ravig31

For lot of the projects I do I need a dedicated Linux environment to use tools like perf. But personally daily driving Ubuntu is not really suitable for me and I enjoy using my M1 Mac too much xd. I wanted a way to wake up my Linux machine when I wasn’t home, as I didn’t want to leave it running 24/7. This is where I came across Wake-on-LAN (WOL), which allowed me to remotely power on my PC and SSH into it from anywhere. Here is a little guide.

Enable Wake-on-LAN in the BIOS

The first and most fundamental step is to enable WOL in your motherboard’s BIOS/UEFI settings. The exact location of this setting can vary, but you’ll typically find it under a menu like “Power Management,” “Advanced,” or “PME (Power Management Events).” Look for an option like “Wake on LAN,” “Wake on PCI-E,” or similar and enable it.

Make sure to save your changes and exit the BIOS.

Configure WOL in Ubuntu

Next, we need to ensure that the network interface in Ubuntu is configured to listen for the magic packet.

Install and ese `ethtool`

We’ll use ethtool to check if our network interface supports WOL and to configure it. If you don’t have it installed, you can get it with:

sudo apt install ethtool

Before we configure anything, we need to identify the name of our network interface and its MAC address. Run the following command:

ip a

The output will list your network interfaces. In my case, the Ethernet interface is named enp4s0. Make a note of this and especially the MAC address, as you’ll need it to send the magic packet later.

Now, let’s check if the interface supports and is configured for WOL. Running ethtool as root is necessary to see the full settings:

sudo ethtool enp4s0

Look for the “Supports Wake-on” and “Wake-on” lines in the output. If it supports WOL, it will look something like this:

Supports Wake-on: pumbg
Wake-on: d

The pumbg string indicates that the interface supports different types of wake-on events. The letter g is the most important for us, as it signifies support for the MagicPacket protocol. The d on the Wake-on line means it’s currently disabled. We need to change that.

Persist the WOL setting with NetworkManager

For the WOL setting to survive a reboot, we need to configure NetworkManager. Ubuntu 24.04 uses NetworkManager to manage network connections, and it’s the recommended way to persist these settings.

Check for Active Connections: First, find the name of your active network connection.

Bash
```
nmcli connection show
```
You’ll get a list of connections. Identify the one for your wired Ethernet interface. Mine’s named "netplan-enp4s0".
Modify the Connection Profile: Use nmcli to set the wake-on-lan property to magic.

Bash
```
sudo nmcli connection modify "netplan-enp4s0" 802-3-ethernet.wake-on-lan magic
```
Replace “netplan-enp4s0” with the actual name from the previous step.
Apply and Verify Changes: Restart NetworkManager to apply the new settings, and then verify that they’ve been successfully applied.

Bash
```
sudo systemctl restart NetworkManager
nmcli connection show "netplan-enp4s0" | grep 802-3-ethernet.wake-on-lan
```
The output should show 802-3-ethernet.wake-on-lan: magic.

Double check if Wake on: g is set using sudo ethtool enp4s0. If this works your Ubuntu machine is now configured to respond to magic packets. Hooray!

Problem with dual-booting Windows 11

If you shut down your PC from Windows, you might find that WOL doesn’t work. I learnt that this is because Windows’ “Fast Startup” feature (or similar power management settings) can sometimes interfere with WOL functionality. Here’s how to fix it:

Open the Device Manager.
Expand the “Network adapters” section and find your Ethernet adapter.
Right-click the adapter and go to Properties.
In the “Advanced” tab, adjust these settings:
- “Energy Efficient Ethernet”: Turn this off.
- “Wake on Magic Packet”: Set this to on or Enabled.
- “Wake on Pattern Match”: Set this to on or Enabled.
- “Wake on Link Settings”: Set this to Forced.
- “Wait on Link”: Turn this on.
In the “Power Management” tab, make sure the following are checked:
- “Allow this device to wake the computer”
- “Allow only a magic packet to wake the computer”

This configuration ensures the network card remains in a low-power state, but with the necessary listening capabilities active. Additionally, I also disabled hibernation with powercfg /hibernate off as this was another fix i found online.

Sending the magic packet

Now that your PC is configured, you need a way to send the magic packet. I use a MacBook, so I used wakeonlan with Homebrew.

Install wakeonlan:

Bash
```
brew install wakeonlan
```
Send the Packet: Use the MAC address you noted earlier to send the magic packet.

Bash
```
wakeonlan a8:5e:45:53:45:a6
```
Your PC should now power on.

WoWww (Wake-on-Wan)

Waking your PC from outside your local network (WAN) is a bit trickier. Directly port-forwarding the WOL packet from your router to your PC often didn’t work for me. This is because WOL packets are a broadcast protocol, and routers typically don’t allow broadcast traffic to be forwarded from the public internet for security reasons. Here is a reddit post on it.

My solution for this is to use a low-power device that’s always on, such as an old Raspberry Pi or a mini PC like a NUC.

I have a NUC that’s always on and acts as a server.
From my MacBook, I can SSH into the NUC.
Once connected, I run the wol command (for Linux) from the NUC, which is on the same local network as my main PC. The magic packet is sent locally, anddd magically Wake-on-Wan.

I think this is this is the most secure method that avoids exposing your network to potential security risks. While there may be other workarounds, this is a very common and effective approach.

Hope this helped!

- ravi

ravig31

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