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83 lines
7.1 KiB
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83 lines
7.1 KiB
Plaintext
Episode: 3684
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Title: HPR3684: Wake on Lan
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Source: https://hub.hackerpublicradio.org/ccdn.php?filename=/eps/hpr3684/hpr3684.mp3
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Transcribed: 2025-10-25 03:48:39
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---
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This is Hacker Public Radio Episode 3,684 for Thursday the 15th of September 2022.
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Today's show is entitled Wake on Land.
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It is hosted by JWP and is about 10 minutes long.
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It carries a clean flag.
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The summary is Wake on Land Motherboard Feature.
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Good day.
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I'm JWP and today I want to talk to you about the WOL support.
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First off, what does WOL stand for?
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WOL stands for Wake on Land.
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Your computer on computing, Wake on Land or capital W, little O, big L is a networking protocol
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that provides the ability to configure.
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It provides to be started from a lower power state using a special signal over the network
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also referred to as the magic packet.
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You can think of it as a remote power button for your computer.
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And if you go to the Wiki, it says it's either an Ethernet or token-ring computer networking
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standard that allows the computer to be awakened by network message.
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And this message is sent to the target computer by a program executed on a device connected
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to the same local area network.
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And it's possible to initiate the message from another network by using the subnet
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directly broadcast or a WOL gateway service.
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Equivalent terms include Wake on Land, which is a remote wake up power on power up by land,
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resume by land, resume on land, wake up on land.
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And this is all basically the same technology.
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If the computer is being awakened communicating via Wi-Fi, a supplementary standard called Wake on wireless land must be employed.
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So the WOL and WOL VLAN standards are supplemented by vendors to provide protocol transparent on-demand services.
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For example, Apple Bundrore, Wake on demand, Sweet Proxy feature is something that uses.
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So it all sort of works on the magic packet symbol.
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And so it's gone on for a really long time too.
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It started in 96 when Intel and IBM formed the Advanced Manageability Alliance,
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or the AMA, and then 97 the Alliance introduced the Wake on Land technology.
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So this is a very old technology.
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Ethernet connections including home and work, and networks, wireless data networks, and internet itself are based on frames between computers.
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WOL is implemented using a specifically designed frame called the Magic Packet,
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which is sent to all computers in a network, along with the computer to be awakened.
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And the Magic Packet contains a MAC address of the destination computer identifying the number of built into each network interface.
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And so, as you know, with the networking, everything has a MAC address.
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So it can be specific to there.
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And it's unique, because it's unique, the number of that's how it works.
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And Power Downer turned off the computers that are capable to Wake on Land will contain certain network devices available to listen to incoming packets in low power mode
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while the system is powered down.
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If a Magic Packet is received at the direct to device MAC address, then it signals the computer to supply the motherboard and initiate a system wake up.
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And in the same way as pressing a power button we do.
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The Magic Packet can be sent on a layer, on link layer layer 2 on the OSI mode, and when sent is broadcasted to attach devices on a given network using the network broadcast address.
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The IP address in the layer 3 of the OSI model is not used.
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The Magic Packet is sent on the data link layer 2 in the OSI mode.
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No, that's not it.
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Because Wake on Land is built upon a broadcasting technology, it can generally only be used in the current network subset.
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There are such and so, and Wake on Land can operate across a network and practice given the appropriate configuration hardware, including remote wake up across the internet.
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In order to wake on land to work, parts of the network interface need to stay on, and this consumes a small amount of power, a standby power, much less than normal operating power.
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And the link speed is usually reduced to the lowest possible speed as not to waste power.
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Gigabit internet, Nick only maintains a 10 NBS link.
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Dislaping Wake on land when not needed can slightly reduce power consumption on computers that are switched off but still plug into the power socket.
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The power drain comes in consideration when battery powered devices such as laptops can also deplete the battery even when the device is completely shut down.
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Okay, so let's talk a little bit more about the Magic Packet.
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The Magic Packet is a frame most often sent as a broadcast when it contains somewhere in its payload, six bytes of all, 255 parentheses, FFFF, FFFF, FFFF, FFFF, and the hexademo, followed by 16 repetitions of the target's 48-bit MAC address for a total of 102 bytes.
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Since the Magic Packet is only scanned for the string above and not actually passed by the FFFF protocol stack, it can be sent as a payload of any network and transport layer protocol.
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Although it's typically sent as a UDP datagram to port zero, which is a reserve port number, echo protocol or discord protocol or directly over the internet as a ether type OXO842.
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The connection is orientated in the transport layer like TCP and is less suited for this task as it requires establishing an active connection before sending user data.
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The Magic Packet has some limitations and its first limitation is it requires a MAC address and also may require a secure sign-on password.
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It does not provide delivery confirmation, so you don't know if it wakes up.
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It may not work outside of a local network. It requires hardware support of the wake on LAN on the destination of Peter.
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Most of the 802 11 wireless interfaces do not maintain a low power state and cannot receive the Magic Packet.
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If you're doing 802 11 on the wireless, it doesn't really happen.
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I mean, technically, there's all kinds of things to think about. You got security considerations on authorized access, interactions with networks, but in a home environment or even a small business environment, if they get past your router, you have more trouble.
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If he's in there and he can send the wake on LAN to a specific MAC address and you've messed up, he or she is already inside.
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What about the hardware? Your power supply has to be an ATX 201 and you have to have a network interface card that does it.
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Believe it or not, a lot of motherboards do out of the box. Just check your motherboard paperwork.
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Some operating systems control the wake on LAN behavior via NIC drivers.
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In other words, they have to have a PCI 22 standard with a compliant 22 network adapter and do not usually require a wake on LAN cable as required standby powers related through the PCI bus.
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If you want to support PME power events, you have to go into your BIOS and enable it.
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I hope you have a great day. This is JWP. Enjoy the podcast.
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You have been listening to Hecker Public Radio at HeckerPublicRadio.org. Today's show was contributed by a HPR listener like yourself.
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If you ever thought of recording podcasts, then click on our contribute link to find out how easy it really is.
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Hosting for HPR has been kindly provided by an honesthost.com, the internet archive and our sync.net.
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On the Sadois status, today's show is released under Creative Commons Attribution 4.0 International License.
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