Wake On Lan – What Exactly Is It?

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 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.

WoL 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 NIC’s firmware, you don’t need specific software to enable it. Support for WoL 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. If, however, you have a more modern computer, you may find that you have advanced BIOS options for allowing the computer to power on via a time schedule. It’s not technically WoL, but in terms of functionality, it’s pretty close.

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 WoL. Do your research online before you buy so you’re not disappointed later on down the line.

The MagicPacket: How WoL Works

WoL-enabled computers essentially wait for a “magic packet” to arrive that includes the NIC’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 WoL capabilities to offer hassle-free or largely configuration-free usage scenarios.

Enabling WoL on Your System- BIOS

Most older computers and many modern ones have their WoL settings buried in the BIOS. Depending on your system, you need to hit Escape, F2, or Delete to get into the BIOS, but if you’re not sure then you should check your system’s documentation. Once you’re in, check under Power Management or Advanced Options or something of that sort.

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