wake on lan

7 Articles

Linux Server, Wakey, Wakey

April 21, 2023 by 39 Comments

We all know we should save energy and not leave computers on all the time. It is probably better for the computer, too. But when you operate a home server, it isn’t feasible to just turn it on when you want to use it and then turn it off again. Or is it? [Daniel] decided that was exactly what he wanted to do, and it was quite an adventure to get there.

The trick is to use a Raspberry Pi — they don’t draw nearly the power a big computer does — to stay awake to facilitate the process. The Pi watches for ARP requests for the sleeping machine and replies on its behalf so that other network nodes can find the machine even when it isn’t on.

The server itself detects if it is idle in a cron job. When it finds that there are no SSH or other service connections for a set period of time, it suspends the machine to RAM, putting it in a low-power mode. Waking a sleeping computer up over the network is a solved problem, and [Daniel] investigated several wake-on-lan solutions.

There were several oddities to work out, including a Mac pinging an unused network share, and a router that was making NetBIOS queries. However, [Daniel] found a $30 router that could do port mirroring and that helped a lot with troubleshooting.

This is one of those things where his recipe won’t exactly fit your situation. But the post has a lot of good information and some nice tricks for troubleshooting any kind of network bizarreness.

Wireshark is a great tool for this kind of work, too. Another useful technique is recording network traffic and playing it back.

The Terrible Devices Of The Internet Of Wrongs

June 15, 2016 by 22 Comments

Last week was Bsides London, and [Steve Lord] was able to give a talk about the devices that could pass for either a terrible, poorly planned, ill-conceived Internet of Things Kickstarter, or something straight out of the NSA toolkit. [Steve] built the Internet of Wrongs, devices that shouldn’t exist, but thanks to all this electronic stuff, does.

Continue reading “The Terrible Devices Of The Internet Of Wrongs” →

Remote PC Power Control Thwarts Button Pushers

December 19, 2015 by 21 Comments

Pervasive connectivity is a mixed blessing at best, especially when it creates the expectation that we’ll always have access to everything we need. When what you need is on your work or home PC, there are plenty of options for remotely accessing files using your phone. But if your roomie or the cleaning crew powers the machine down, you’ve got a problem – unless you’ve got a way to remotely power the machine back up.

[Ahmad Khattab]’s hack required getting up close and personal with his PC’s motherboard. A Particle Photon steals power from the always-on 3.3 volt line of the vacant Trusted Platform Module connector on his machine. Outputs from the Photon are connected to the motherboard’s power switch connection and a smartphone app drives the outputs and turns the machine on and off. As [Ahmad] admits, there are plenty of ways to attack this problem, including Wake-on-LAN. But there’s something to be said for the hardware approach, especially when a Photon can be had for $20.

Astute readers will note that we recently covered a very similar project using a Particle Core. Be sure to check that one out for a little more detail on using Particle’s cloud, and for some ideas on powering the module if your motherboard lacks a TPM port. In the meantime, enjoy [Ahmad]’s video.

Continue reading “Remote PC Power Control Thwarts Button Pushers” →

Unlock on LAN

Unlock On LAN Apartment Security

September 5, 2014 by 29 Comments

Here’s a cool little variation of that handy little function called Wake on LAN — [Jonathan] found himself locked out of his apartment one too many times, so he decided to add his own fail safe backup in order to get inside without a key — using a Raspberry Pi of course.

His apartment is one of those older style ones where the door is always locked and you use a buzzer to let someone in (or a key to get in yourself). This made it super easy to add some internet connectivity to the system. [Jonathan] tapped into the buzzer with a relay since the system uses medium voltage AC to operate. A Raspberry Pi triggers a transistor using its GPIO to click the relay on and off, effectively controlling the lock.

Using a WiFi dongle he’s connected the Pi to his home network and written a simple perl script to trigger the relay — all he has to do is visit a URL on his phone or computer and the door will unlock instantly!

Once the system worked [Jonathan] soldered all the components onto a breadboard and hooked it up. He still needs an enclosure for it, but it’s been working well since he installed it.

Another option would be to use an RFID tag system through the door, which could be pretty cool as well.

Wake On LAN With A Dev Board

May 19, 2014 by 23 Comments

Screen

At home, [Daniel] has an extremely powerful dual quad-core Xeon system with ECC RAM that he uses for heavy lifting tasks – compiling, CUDA processing, and actual computing. Of course the electric bill for running this box all the time would be crazy, so Wake on LAN it is. There’s only one problem: for some reason, the BIOS doesn’t have Wake on LAN. The solution, of course, was a microcontroller system that would listen for the magic WoL packet and turn the computer on when it was received. This project eventually turned into a great case mod with an integrated LCD that powers the computer up over Ethernet, shows the current running processes, CPU and memory usage, and is an excellent use of a TI dev board.

The dev board in question is a TI Sitara AM355x starter kit that runs Linux, has two Ethernet ports and a touch sensitive LCD, and more than enough power to handle something as simple as a system monitor. To power on his monster computer from the dev board, [Daniel] is using a LED on the board, an inverter, a ULN2003 driver chip, and a relay connected to the computer’s power button. It’s not exactly a masterpiece of craftsmanship, but the dev board looks good mounted in the case, and from the videos below, it’s a great way to get system information embedded right into a computer case.

Continue reading “Wake On LAN With A Dev Board” →

Power Strip Hack Reduces Standby Electricity Consumption

November 21, 2011 by 31 Comments

computer-standby-circuit

For years, [Rasmus] has left his computer connected directly to the mains power so that he can turn it on via Wake on Lan. While powered down, it would still continuously consume about 6W of electricity, but now that he didn’t need it to be on standby so often, he wanted to make it more energy efficient.

In Denmark, where he lives, many people use power strips that have an onboard USB cable. These strips are meant to reduce the standby power consumption of PC peripherals such as monitors by powering on the mains sockets only when the computer is active. He decided the easiest way to cut his standby energy consumption to 0W would be to power his computer via this strip as well.

While it sounds great in theory, it presented a sort of chicken/egg problem. If the computer needs to be turned on for the power strip to recognize it, then how could he also supply power to the computer from the same strip? His solution was a small circuit that would charge up while the computer was running, and still hold enough juice to kickstart the PC’s boot process, thus turning on the power strip.

It really is an ingenious way to go about things, nice job!