Hackaday Links: December 13, 2020

Our Sun is getting a bit frisky these days, and has rewarded us with perhaps the best screensaver image ever taken. The incredibly detailed photo of a sunspot was actually taken back in January by the Daniel K. Inouye Solar Telescope, a 4-meter instrument with adaptive optics that can image the sun from the near-infrared to visible wavelengths and resolve surface details down to 20 km. The photo, with a distinct “Eye of Sauron” look, shows the massive convection cells surrounding the dark sunspot; an accompanying animation shows the movement of plasmas along the tortured lines of magnetic flux that cause the sunspot to form. It’s fascinating to watch, and even more interesting to mull over the technology that went into capturing it.

With the dustup surrounding the youtube-dl DCMA takedown by GitHub fresh on the open-source community’s minds, GitHub Universe 2020 had an interesting discussion about maintaining open-source software projects that’s worth watching. They focused on the challenges that youtube-dl maintainers face in keeping the tool working, and the impact their effort has on the people and groups that rely on them. To underscore that point, they featured a researcher with Human Rights Watch who depends on youtube-dl in her work, and made it quite clear that keeping up with all the API changes that constantly break open source tools like youtube-dl make the role of the maintainers that much more critical.

Speaking of GitHub, here’s a frightening and fascinating new tool: Depix, the password de-pixelizer. Developer Sipke Mellema noticed that his company often used pixelization to obscure passwords in documentation, and wondered if he could undo the process. He wrote up an article describing the pixelization process using a linear box filter and his method for attacking it, which involves generating a De Bruijn sequence in the same font, text size, and colors as the original document and feeding a screenshot of that and the pixellated password into the tool. We suspect it’ll only work for a subset of obfuscated passwords, but it’s still pretty clever.

‘Tis the season for Advent calendars, and the folks at QEMU have posted theirs. Open each of 24 doors on the calendar and you’re rewarded with a downloadable QEMU disk image that implements something fun. Minesweeper, a ray tracer that fits into a boot loader, and of course Conway’s Game of Life. The GW-BASIC image on Day 3 caught our eye — brings back some memories.

For anyone who has ever watched a Pixar film and wondered how all that animation actually works, here’s a great lesson in making art with math. The video is by Inigo Quilez and goes through the basics of rendering images using raymarching SDFs, or signed distance functions. In the beginning, it seemed like it was going to be a little bit like drawing an owl, but his descriptions of the math involved and how each element of the animation is just another formula is fascinating. What’s more, there’s a real-time rendering tool where you can inspect the code and edit it. Alas, my changes only made things worse, but it was still fun and instructive to play with. Check out the video after the break!

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Remoticon Video: Firmware Reverse Engineering Workshop With Asmita Jha

Taking things apart to see how they work is an important part of understanding a system, and that goes for software as much as for hardware. You can get a jump start on your firmware reverse engineering skills with Asmita Jha’s workshop which was presented live at the Hackaday Remoticon. The video has just been published, and is found below along with a bit more on what she covered in her hands-on labs.

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Python Is All You’ll Ever Need In This Linux Distro

Choosing the perfect Linux distribution that satisfies your personal needs and likings can be an impossible task, and oftentimes requires a hint of Stockholm syndrome as compromise. In extreme cases, you might end up just rolling your own distro. But while frustration is always a great incentive for change, for [Josh Moore] it was rather curiosity and playful interest that led him to create snakeware, a Linux distribution where the entire user space not only runs on Python, but is Python.

Imagine you would boot your Linux system, and instead of the shell of your choice, you would be greeted by an interactive Python interpreter, and everything you do on the system will be within the realms of that interpreter — that’s the gist of snakeware. Now, this might sound rather limiting at first, but keep in mind we’re talking about Python here, a language known for its versatility, with an abundance of packages that get things done quick and easy, which is exactly what [Josh] is aiming for. To get an idea of that, snakeware also includes snakewm, a graphical user interface written with pygame that bundles a couple of simple applications as demonstration, including a terminal to execute Python one-liners.

Note that this is merely a proof of concept at this stage, but [Josh] is inviting everyone to contribute and extend his creation. If you want to give it a go without building the entire system, the GitHub repository has a prebuilt image to run in QEMU, and the window manager will run as regular Python application on your normal system, too. To get just a quick glimpse of it, check the demo video after the break.

Sure, die-hard Linux enthusiasts will hardly accept a distribution without their favorite shell and preferable language, but hey, at least it gets by without systemd. And while snakeware probably won’t compete with more established distributions in the near future, it’s certainly an interesting concept that embraces thinking outside the box and trying something different. It would definitely fit well on a business card.

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512 Bytes Ought To Be Enough For Dinosaurs

It’s said that slow internet is worse than no internet at all, which is mainly a matter of continuously crushing all hope and sanity vs. finding peace in accepting a fate out of your control. Plus, you can easily pass the time of being catapulted back to the prehistoric ages by navigating a jumpy little creature from that same age through a field of cacti — at least if you’re using Chrome or Chromium. But neither a browser nor actually an operating system are really necessary for that, as [franeklubi] shows with a boot sector implementation of the same game.

Sure, the graphics aren’t quite on par, but compared to the original’s 3000+ lines of JavaScript, [franeklubi] managed to implement it in a few hundred lines of assembly, and was of course constrained by the 512 bytes of the boot sector itself (well, 510 plus the signature). This constraint causes a few limitations, like a slight lack of randomness in the obstacle arrangements, and a constant running speed, but it also makes it the perfect playground and starting point to delve into the world of nifty knacks and hacks, trying to squeeze every last byte.

If you want to give it a try for yourself, all you need is NASM and QEMU — and while you’re at it, why not have some Tetris along the way? We could also see this nicely combined with the real-world jumping version from a few weeks back, and turn it into a standalone arcade game. Bounce Crouch Revolution anyone?

Learn About BGP With The Internet Of EvE

When we first saw [Ben Jojo’s] post about the Internet inside EvE Online, we didn’t think we’d be that interested. We don’t play EvE — a massively multiplayer game. But it turns out, the post is really about understanding BGP (Border Gateway Protocol) and how it helps route traffic in large networks. The best part? He actually simulates a network with 8,000 nodes to test out what he’s talking about.

Obviously, you wouldn’t want to fire up 8,000 Raspberry Pi computers for such an experiment. Using Buildroot, he set up a very small Linux image that had the bare minimum required to run the tests. The qemu provided virtualization, including an obscure feature that allows you to transfer data between virtual machines using UDP. The whole thing ran on some pretty beefy hardware in the cloud. Sure, you could have provisioned 8,000 cloud instances, but that would run into some serious money pretty fast, we imagine. As a wrap-up, he even uses BGP to model his local mass transit system.

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Pun Intended: Bare Metal Attracts Rust

Programming languages tend to polarize, and Rust is by far no exception. Whether it will stick around and grow as an alternative for the lower levels or not — time will tell. In the meantime, if you’re curious about the language and its low-level abilities yourself, [phil-opp] has written a series of blog posts on building your own little bare metal kernel in Rust.

Starting from the basics, [phil-opp] describes in detail the set-up and build process to create a standalone executable that won’t be linked against the Rust standard library. From here he proceeds to build a simple operating system kernel that prints a good old Hello World via VGA output — QEMU emulation included. And of course, there is a GitHub repository with all of the source code.

[phil-opp] has been working on this for a while already, and he is currently writing the second edition of the series. Some content is therefore still missing, but you may find more of it in his first edition. And in case you know absolutely nothing about Rust in the first place, let’s just take a step back and start with the basics. After all, we might see more of it in the future.

Roll Your Own Raspberry Pi OS

Writing an operating system is no small task, but like everything else it is easier than it used to be. [JSandler] has a tutorial on how to create a simple operating system for the Raspberry Pi. One thing that makes it easier is the development environment used. QEMU emulates a Raspberry Pi so you can do the development on a desktop PC and test in the virtual environment. When you are ready, you can set up a bootable SD card and try your work on a real device.

The operating system isn’t very complex, but it does boot, organize memory, displays on the screen, handles interrupts, and manages processes. What else do you need?

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