Program Guesses Your Regular Expression

April 22, 2020 by Al Williams 12 Comments

We aren’t sure how we feel about [pemistahl’s] grex program. On the one hand, we applaud a program that can take some input samples and produce a regular expression. On the other hand, it might be just as hard to gather example data that produces the correct regular expression. Still, it is an interesting piece of code.

Even the author suggests not to use this as an excuse to not learn regular expressions, since you’ll need to check the program’s output. It is certain that the results will match your test cases, but it isn’t certain that it won’t accept things you didn’t expect. Bad regular expressions have been the source of some deeply buried bugs.

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Reverse Engineering An RGB Keyboard Under Linux

April 14, 2020 by Tom Nardi 5 Comments

Hardware support under Linux is far better than it ever has been in the past. These days, most things “just work” out of the box, and you probably won’t have to compile any custom kernel modules. Certainly a far cry from where things were a decade ago. But that doesn’t mean everything will work to 100% of its abilities. Take for example, the Duck keyboard that [Cynthia Revström] has. Sure it works as a basic keyboard under any OS, but getting those fancy RGB LEDs working is another story entirely.

Don’t get the wrong idea here, [Cynthia] isn’t just trying to get the keyboard to flash along to music; the goal was to use the RGB lighting of the Ducky keyboard for notifications that the user can’t possibly ignore. Even the most laser-focused among us would have a hard time not noticing that the entire keyboard is blinking red. But the “DuckyRGB” software that you need to do something like that is Windows-only and apparently distributed via a sketchy Google Drive link. Yikes.

The first step to creating an alternative was to spin up a Windows VM and install DuckyRGB. From there, Wireshark could listen in between the virtual computer and the Ducky keyboard to see what the software was sending over the wire. After identifying a version number being sent in the clear, [Cynthia] was able to isolate the LED commands by searching for the hex color codes. From there, it was a relatively simple matter of writing some glue code to connect it up to an alert service and get notifications going.

There was only one problem; the keyboard didn’t work anymore. Turns out the tool that [Cynthia] wrote to control the keyboard’s LEDs was claiming the device so the kernel couldn’t access it for normal input. It took a detour with HIDAPI to get everyone playing together nicely, and now changing the color of your Ducky keyboard on Linux doesn’t turn it into a paperweight.

Even if you don’t have a Ducky keyboard, or aren’t particularly interested in having its LEDs blinked at you if you do, this project is a phenomenal example of practical USB reverse engineering. [Cynthia] says the inspiration for this project came from friend [Ben Cox], who’s write-up on creating USB userspace drivers we covered last year. If you’ve got and old USB gadget with Windows-only drivers, maybe it’s time you take a crack at unlocking it.

Software-Defined Radio Made Easy

April 11, 2020 by Bryan Cockfield 25 Comments

Just a few decades ago, getting into hobby radio meant lots of specialty hardware, and making changes to your setup to work on various frequencies wasn’t particularly easy. Since software-defined radio (SDR) came onto the scene in an accessible way for most of us, this barrier to entry was reduced significantly and made the process of getting on the air a lot easier. It goes without saying that it does require some software, but [Aaron]’s latest project makes even getting that software extremely simple.

What he has done is created a custom Linux distribution based on Debian, called DragonOS, with the entire suite of SDR programs needed to get up and running. Out of the box, it supports RTL-SDR, HackRF and LimeSDR packages and even includes other fun tools you’ll need like Kismet. There are several video demonstrations of his distribution, including using RTL-SDR for ADS-B reception, and also shows off several custom implementations of the OS in various scenarios on his YouTube channel. The video linked below also shows how to set up the distribution in a virtual machine, so you can run this even if you don’t have a computer to dedicate to SDR.

Getting into SDR has never been easier, and the odds of having something floating around in the junk drawer that you can use to get started are pretty high. The process is exceptionally streamlined with [Aaron]’s software suite. If you’re a little short on hardware, though, there’s no better place to get started than with the classic TV-tuner-to-SDR hack from a few years back.

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Linux Fu: Tracing System Calls

April 7, 2020 by Al Williams 11 Comments

One of the nice things about Linux and similar operating systems is that you can investigate something to any level you wish. If a program has a problem you can decompile it, debug it, trace it, and — if necessary — even dig into the source code for the kernel and most of the libraries the program is probably using. However, the tools to do this aren’t ones you use every day. One very interesting tool is strace. Using it you can see what system calls any program makes and that can sometimes give you important clues about how the program works or, probably more often, why it doesn’t work.

Let’s consider the least complex use of the command. Suppose you want to make symlink from testxmit.grc to the /tmp directory. That command is simple:

ln -sf testxmit.grc /tmp

But if you tell strace to run it, the command becomes:

strace ln -sf testxmit.grc /tmp

You might want to redirect the output to a file using the shell or the -o option, though. Some commands generate a lot and often the first page or two of output isn’t really what you care about anyway. Continue reading “Linux Fu: Tracing System Calls” →

A(nother) Minimalist Window Manager

March 3, 2020 by Bryan Cockfield 31 Comments

For however many Linux distributions there are to choose from, there are perhaps even more window managers that can be paired with them, and some have dramatically different features than the X window systems that most of us are familiar with. There’s a rabbit hole to fall down, as with most Linux-related topics, but while this tiling window manager from [caoluin], called sara, adds to the cacophony, it’s also representative of any pet project that lets us take a deep dive into something personally interesting.

What started as a desire to revive an abandoned window manager called catwm eventually evolved into a fork of sorts of another popular window manager called dwm. dwm is used as a basis or as building blocks for many other window managers, and while [caoluin] was writing sara he found that many of the solutions he found converged on the same things that dwm had already implemented. In a way, it’s reassuring if your solutions are similar to tried-and-true methods already in use. For other things he found interesting solutions, and other features that dwm has he found to be unnecessary and removed them.

Does the world need another window manager? Probably not. But we can all appreciate building something from scratch, just to see how it really works under the hood. As far as that goes, we’d consider sara a success for [caoluin], and if you’re really interested in window managers then you can take a look at his Github page or one of the more esoteric window managers we’ve seen.

Multiple 3D Printers, And One Pi To Rule Them All

February 24, 2020 by Tom Nardi 17 Comments

If you’ve got a desktop 3D printer, there’s an excellent chance you’ve heard of OctoPrint. This web front-end, usually running on a Raspberry Pi, allows you to monitor and control the printer over the network from any device that has a browser. But what if you’ve got two printers? Or 20? The logistics of each printer getting its own Pi can get uncomfortable in a hurry, which is why [Jay Doscher] has been working on a way to simplify things.

Leveraging the boosted processing power of the Raspberry Pi 4 and some good old fashioned Linux trickery, [Jay] is now controlling multiple printers from a single device. The trick is to run multiple instances of the OctoPrint backend and assign them to virtual network interfaces so they don’t interfere with each other. This takes some custom systemd unit files to get up and running on Raspbian, which he’s been kind enough to include them in the write-up.

But getting multiple copies of OctoPrint running on the Pi is only half the battle. There still needs to be a way to sort out which printer is which. Under normal circumstances, the printers would be assigned random virtual serial ports when the Pi booted. To prevent any confusion, [Jay] explains how you can use custom udev rules to make sure that each printer gets its own unique device node. Even if you aren’t trying to wrangle multiple 3D printers, this is a useful trick should you find yourself struggling to keep track of your USB gadgets.

If you’re wondering why [Jay] needs to have so many 3D printers going at the same time, we hear they’ve been keeping rather busy running off parts for commissioned copies of his popular projects. Something to consider the next time you’re wondering if there’s a way to make a happy buck out of this little hobby of ours, folks.

Hackaday Links: February 23, 2020

February 23, 2020 by Dan Maloney 19 Comments

If you think your data rates suck, take pity on New Horizons. The space probe, which gave us lovely pictures of the hapless one-time planet Pluto after its 2015 flyby, continued to plunge and explore other, smaller objects in the Kuiper belt. In January of 2019, New Horizons zipped by Kuiper belt object Arrokoth and buffered its findings on the spacecraft’s solid-state data recorders. The probe has been dribbling data back to Earth ever since at the rate of 1 to 2 kilobits per second, and now we have enough of that data to piece together a story of how planets may have formed in the early solar system. The planetary science is fascinating, but for our money, getting a probe to narrowly miss a 35-kilometer long object at a range of 6.5 billion km all while traveling at 51,500 km/h is pretty impressive. And if as expected it takes until September to retrieve all the data from the event at a speed worse than dialup rates, it’ll be worth the wait.

Speaking of space, if you’re at all interested in big data, you might want to consider putting your skills to work in the search for extraterrestrial intelligence. The Berkeley SETI Research Center has been feeding data from the Green Bank Telescope and their Automated Planet Finder into the public archive of Breakthrough Listen, a 10-year, $100 million initiative to scan the million closest stars in our galaxy as well as the 100 nearest galaxies for signs of intelligent life. They’re asking for help to analyze the torrents of data they’re accumulating, specifically by developing software and algorithms to process the data. They’ve set up a site to walk you through the basics and get you started. If you’re handy with Python and have an interest in astronomy, you should check it out.

Staying with the space theme, what’s the best way to get kids interested in space and electronics? Why, by launching a satellite designed to meme its way across the heavens, of course. The Mission for Education and Multimedia Engagement satellite, or MEMESat-1, is being planned for a February 2021 launch. The 1U cubesat will serve as an amateur radio repeater and slow-scan TV (SSTV) beacon that will beam down memes donated to the project and stored on radiation-hardened flash storage. In all seriousness, this seems like a great way to engage the generation that elevated the meme to a modern art form in a STEM project they might otherwise show little interest in.

It looks as though Linux might be getting a big boost as the government of South Korea announced that they’re switching 3.3 million PCs from Windows to Linux. It’s tempting to blame Microsoft’s recent dropping of Windows 7 support for the defenestration, but this sounds like a plan that’s been in the works for a while. No official word on which distro will be selected for the 780 billion won ($655 million) effort, which is said to be driven by ballooning software license costs and a desire to get out from under Microsoft’s thumb.

And finally, in perhaps the ickiest auction ever held, the “Davos Collection” headed to the auction block this week in New York. The items offered were all collected from the 2018 World Economic Forum in Davos, Switzerland, where the world’s elites gather to determine the fate of the 99.999%. Every item in the collection, ranging from utensils and glassware used at the many lavish meals to “sanitary items” disposed of by the billionaires, and even hair and fluid samples swabbed from restrooms, potentially holds a genetic treasure trove in the form of the DNA it takes to be in the elite. Or at least that’s the theory. There’s a whole “Boys from Brazil” vibe here that we find disquieting, and we flatly refuse to see how an auction where a used paper cup is offered for $8,000 went, but if you’d like to virtually browse through the ostensibly valuable trash of oligarchs, check out the auction catalog.