What Is Wake-on-LAN

What Is Wake-on-LAN, and How Do I Enable It?

by YatriTrivedi 

Technology often yields ridiculous conveniences, like being able to turn on your computer from miles away without pushing the power button. Wake-on-LAN has been around for a while, so let’s see how it works and how we can enable it.

What Is Wake-on-LAN?

Wake-on-LAN (sometimes abbreviated WoL) is an industry standard protocol for waking computers up from a very low power mode remotely. The definition of “low power mode” has changed a bit over time, but we can take it to mean while the computer is “off” and has access to a power source. The protocol also allows for a supplementary Wake-on-Wireless-LAN ability as well.

This is useful if you plan to access your computer remotely for any reason: it allows you to retain access to your files and programs, while keeping the PC in a low-power state to save electricity (and of course, money). Anyone who uses a program like VNC or TeamViewer, or keeps a file server or game server program available, should probably have the option enabled for the sake of convenience.

Wake-on-LAN is dependent on two things: your motherboard and your network card. Your motherboard must be hooked up to an ATX-compatible power supply, as most computers in the past decade or so are. Your Ethernet or wireless card must also support this functionality. Because it is set either through the BIOS or through your network card’s firmware, you don’t need specific software to enable it. Support for Wake-on-LAN is pretty universal nowadays, even when it’s not advertised as a feature, so if you have a computer built in the past decade or so, you’re covered.

For those of you who build your own rigs, take care when buying an Ethernet card. While most built-in cards on motherboards don’t need this step, discrete network cards often need a 3-pin cable attached to the motherboard to support Wake on LAN. Do your research online before you buy, so you’re not disappointed later on down the line.

The Magic Packet: How Wake-on-LAN Works

Wake-on-LAN-enabled computers essentially wait for a “magic packet” to arrive that includes the network card’s MAC address in it. These magic packets are sent out by professional software made for any platform, but can also be sent by routers and internet-based websites. The typical ports used for WoL magic packets are UDP 7 and 9. Because your computer is actively listening for a packet, some power is feeding your network card which will result in your laptop’s battery draining faster, so road warriors should take care to turn this off when you need to eke out some extra juice.

Magic packets are usually sent over the entirety of a network and contain the subnet information, network broadcast address, and the MAC address of the target computer’s network card, whether Ethernet or wireless. The above image shows the results of a packet sniffer tool used on magic packet, which brings into question exactly how secure they are when used in unsafe networks and over the internet. On a secure network, or for basic home use, there shouldn’t be any practical reason to worry. Many motherboard manufacturers often implement software along with Wake-on-LAN capabilities to offer hassle-free or largely configuration-free usage scenarios.

How to Enable Wake-on-LAN on Your System

To get started using Wake-on-LAN, you’ll have to enable it in a few places—usually your BIOS and from within Windows. Let’s start with the BIOS.

In the BIOS

Most older computers and many modern ones have their Wake-on-LAN settings buried in the BIOS. To enter the BIOS, you’ll need to press a key as you boot your computer—usually Delete, Escape, F2, or something else (your boot screen will give you instructions on what key to press to enter setup). Once you’re in, check under Power Management or Advanced Options or something of that sort.

On this HP computer’s BIOS, the setting is found near the “resume after power failure” option. Some aren’t so obvious: on my ASUS motherboard (below), the Wake on LAN option is buried two layers deep in the menu system, under “Power on by PCIE/PCI”, because the built-in network controller is behind the PCI controller—it’s only visible that this is the right option in the description text.

The point is, it isn’t always easy or obvious to find the relevant option, since BIOS menu systems vary so widely. If you’re having trouble, check your computer or motherboard’s manual or do a quick Google search. Remember that most manufacturers offer PDF versions of documentation online.

In Windows

You’ll also need to enable Wake-on-LAN in your operating system. Here’s how it goes in Windows. Open the Start menu and type “Device Manager”. Open the Device Manager and expand the “Network Adapters” section. Right click on your network card and go to Properties, then click on the Advanced tab.

Scroll down in the list to find “Wake on Magic Packet” and change the Value to “Enabled.” You can leave the other “Wake on” settings alone. (Note: one of our test rigs didn’t have this option, but Wake-on-LAN still worked fine with the other settings in this guide enabled properly—so don’t fret if it isn’t there.)

Now click the Power Management tab, and make sure the “Allow this device to wake the computer” and “Only allow a magic packet to wake the computer” boxes are enabled. Click OK when you’re done.

In macOS

Open up your System Preferences and choose Energy Saver. You should see “Wake for Network Access” or something similar. This enables Wake-on-LAN.

In Linux

Ubuntu has a great tool that can check to see if your machine supports Wake-on-LAN, and can enable it. Open up a terminal and install ethtool with the following command:

sudo apt-get install ethtool

You can check your compatibility by running:

sudo ethtool eth0

If your default interface is something else, substitute it for eth0 .

Look for the “Supports Wake-on” section. As long as one of the letters listed is g , you can use magic packets for Wake-on-LAN. To enable this option, use the following command.

sudo ethtool -s eth0 wol g

This should take care of it. You can run the command to check and see if it’s enabled now. Look for the “Wake on” section. You should see a g instead of a d now.

How to Wake Your Computer with Wake-on-LAN Magic Packets

To send out Wake-on-LAN requests, you have a cornucopia of options available.

Depicus has an excellent series of lightweight tools to get the job done, including a GUI-based one for Windows and command-line-based one for both Windows and macOS. Wiki.tcl.tk has a great cross-platform lightweight script that handles the requests as well.

DD-WRT has great WoL support, so if you don’t feel like downloading software to do it, you really don’t have to. Or, if you’re out and about, you can use your Android device to wake your computers.

In addition, many applications support Wake-on-LAN within them. For example, if you’re trying to access your computer from afar with a remote desktop program, you can wake the sleeping computer with TeamViewer’s built-in “Wake Up” button, which uses Wake-on-LAN.

You may need to tweak other settings in that program for it to work, so refer to the program’s manual for more info on Wake-on-LAN.

In addition, depending on the program, Wake-on-LAN may only work if you send the magic packet from a computer on your existing network. If your program doesn’t automatically handle the network connections for Wake-on-LAN, you’ll need to set up your router to forward UDP ports number 7 and 9, specifically for the MAC address of the PC you’re connecting to. If you’re not sure how to do this, check out our guide on forwarding ports from the router. You may also want to set up a dynamic DNS address so you don’t need to check your remote computer’s IP address every time.