linux

631 Articles

This Tiny Router Could Be The Next Big Thing

February 1, 2019 by 22 Comments

It seems like only yesterday that the Linksys WRT54G and the various open source firmware replacements for it were the pinnacle of home router hacking. But like everything else, routers have gotten smaller and faster over the last few years. The software we run on them has also gotten more advanced, and at this point we’ve got routers that you could use as a light duty Linux desktop in a pinch.

But even with no shortage of pocket-sized Linux devices in our lives, the GL-USB150 “Microrouter” that [Mason Taylor] recently brought to our attention is hard to ignore. Inside this USB flash drive sized router is a 400 MHz Qualcomm QCA9331 SoC, 64 MB of RAM, and a healthy 16 MB of storage; all for around $20 USD. Oh, and did we mention it comes with OpenWRT pre-installed? Just plug it in, and you’ve got a tiny WiFi enabled Linux computer ready to do your bidding.

On his blog [Mason] gives a quick rundown on how to get started with the GL-USB150, and details some of the experiments he’s been doing with it as part of his security research, such as using the device as a remote source for Wireshark running on his desktop. He explains that the diminutive router works just fine when plugged into a USB battery bank, offering a very discreet way to deploy a small Linux box wherever you may need it. But when plugged into a computer, things get really interesting.

If you plug the GL-USB150 into a computer, it shows up to the operating system as a USB Ethernet adapter and can be used as the primary Internet connection. All of the traffic from the computer will then be routed through the device to whatever link to the Internet its been configured to use. Depending on how you look at it, this could be extremely useful or extremely dangerous.

For one, it means that something that looks all the world like a normal USB flash drive could be covertly plugged into a computer and become a “wiretap” through which all of the network traffic is routed. That’s the bad news. On the flip side, it also means you could configure the GL-USB150 as a secure endpoint that lets you quickly and easily funnel all the computer’s traffic through a VPN or Tor without any additional setup.

We’ve seen all manner of hacks and projects that made use of small Linux-compatible routers such as the TP-Link TL-MR3020, but we expect the GL-USB150 and devices like it will be the ones to beat going forward. Let’s just hope one of them doesn’t show up uninvited in your network closet.

Linux Fu: Easier File Watching

January 31, 2019 by 22 Comments

In an earlier installment of Linux Fu, I mentioned how you can use inotifywait to efficiently watch for file system changes. The comments had a lot of alternative ways to do the same job, which is great. But there was one very easy-to-use tool that didn’t show up, so I wanted to talk about it. That tool is entr. It isn’t as versatile, but it is easy to use and covers a lot of common use cases where you want some action to occur when a file changes.

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A Nexus 5 Smartphone Running PostmarketOS

PostmarketOS Turns 600 Days Old

January 17, 2019 by 18 Comments

PostmarketOS began work on a real Linux distribution for Android phones just over 600 days ago. They recently blogged about the state of the project and ensured us that the project is definitely not dead.

PostmarketOS’ overarching goal remains a 10 year life-cycle for smartphones. We previously covered the project on Hackaday to give an introduction. Today, we’ll concern ourselves with the progress the PostmarketOS team has made.

The team admits that they’re stuck in the proof-of-concept phase, and need to break out of it. This has required foundational changes to the operating system to enable development across a wide variety of devices and processor architectures. There’s now a binary package repository powered by builds.sr.ht which will allow users to install packages for their specific device.

Other updates include fixing support for the Nexus 5 and Raspberry Pi Zero, creating support for open source hardware devices including the Pine A64-LTS and Purism Librem 5. PostmarketOS now boots on a total of 112 different devices.

We’re excited to see the PostmarketOS project making progress. With the widespread move to mobile devices, users lose control over their computing devices. PostmarketOS gives us the ability to run code that we can read and modify on these devices. It’s no small feat though. Supporting the wide variety of custom hardware in mobile devices requires a lot of effort.

While it may be a while before PostmarketOS is your daily driver, the project is well suited to building task-specific devices that require connectivity, a touch screen, and a battery. We bet a lot of Hackaday readers have a junk drawer phone that could become a project with the help of PostmarketOS.

Linux Fu: The Kitchen Sync

January 10, 2019 by 12 Comments

One of the great things about Linux and similar operating systems is they are configurable. If you don’t like something, there’s a great chance you can change it easily with a few entries in a file somewhere. For example, take bash — a very popular shell by any measure. If you want a different style of command line editing, there’s an option. You want the tab key to match files regardless of case? Another option. Usually, these are set in one of your so-called profile files like .bashrc in your home directory.

As long as you are sitting in front of your single computer working, this is great. You customize your .bashrc and other files to your heart’s content and then you work in an environment that acts the way you want it to. The problem is when you have a lot of computers. Maybe you have a web server, a desktop, a firewall machine, and a few dozen Raspberry Pi computers. How do you keep all the configurations the same? Then once they are the same, how do you keep them up to date?

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35C3: Safe And Secure Drivers In High-Level Languages

December 31, 2018 by 12 Comments

Writing device drivers is always a good start for a journey into the Linux kernel code. Of course, the kernel is a highly complex piece of software, and if you mess up your code properly, you might take down the entire system with you. User-space drivers on the other hand might not look as good on your CV, but they can help to work around some of the dangers and complexity of the kernel space. Plus, you don’t necessarily have to limit yourself to C to write them, especially if you are concerned about the usual C pitfalls and the security issues they can lead to.

With that in mind, [Paul Emmerich] is researching the concept of Linux user-space drivers for Intel’s 10Gbit network cards using other high-level languages, and recruits his students to write their final theses about the implementation details of as many languages as possible.

At last year’s 34c3, [Paul] already demonstrated the basics of writing such a user-space network driver for Linux, which serves now as reference implementation for his students. We won’t see Bash or JavaScript here, but we will see a brief summary of what it generally means to develop user-space drivers in C#, Swift, OCaml, or Haskell, along a more detailed insight from [Sebastian Voit] and [Simon Ellmann] about Go and Rust. A collection of each language’s implementation can be found on GitHub.

Since some of these languages bring their own memory handling and perform unpredictable garbage collection, performance and latency are two big topics to cover here. But then, the general concept is language-independent, so even if nothing in the world could ever make you give up on C, you might at least take away some new ideas for driver development.
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Linux Fu: Share Terminal In Browser

December 21, 2018 by 20 Comments

The title of this post says it all: GoTTY is a program that lets you share Linux terminal applications into a web browser. It is a simple web server written in Go that runs a non-GUI program and can push it out a socket in such a way that a browser can display it and, optionally, let the user interact with it.

With the emphasis on security these days, that ought to alarm you. After all, why would you want a shell running in a browser? Hang on, though. While that is possible — and not always undesirable — the real value to this technique is to run a specific command line program in a browser window. Here’s a use case: You want users to remotely monitor a system using top (or htop, if you are fancy). But you don’t want users logging into the system nor do you want to require them to have ssh clients. You don’t want to install monitoring tools, just use what you already have.

If you could get the output from top to show up in a browser window — even if the users had no ability to input — that would be an easy solution. Granted, you could just run top in batch mode, collect the output, and write it somewhere that a web server could find it. Assuming you have a web server installed, of course. But then what if you did want some other features like taking command line options or having the option for (hopefully) authenticated users to interact with the software? Now that would be more complicated. With GoTTY, it is easy.

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The Space Station Has A Supercomputer Stowaway

December 10, 2018 by 59 Comments

The failed launch of Soyuz MS-10 on October 11th, 2018 was a notable event for a number of reasons: it was the first serious incident on a manned Soyuz rocket in 35 years, it was the first time that particular high-altitude abort had ever been attempted, and most importantly it ended with the rescue of both crew members. To say it was a historic event is something of an understatement. As a counterpoint to the Challenger disaster it will be looked back on for decades as proof that robust launch abort systems and rigorous training for all contingencies can save lives.

But even though the loss of MS-10 went as well as possibly could be expected, there’s still far reaching consequences for a missed flight to the International Space Station. The coming and going of visiting vehicles to the Station is a carefully orchestrated ballet, designed to fully utilize the up and down mass that each flight offers. Not only did the failure of MS-10 deprive the Station of two crew members and the experiments and supplies they were bringing with them, but also of a return trip which was to have brought various materials and hardware back to Earth.

But there’s been at least one positive side effect of the return cargo schedule being pushed back. The “Spaceborne Computer”, developed by Hewlett Packard Enterprise (HPE) and NASA to test high-performance computing hardware in space, is getting an unexpected extension to its time on the Station. Launched in 2017, the diminutive 32 core supercomputer was only meant to perform self-tests and be brought back down for a full examination. But now that its ticket back home has been delayed for the foreseeable future, NASA is opening up the machine for other researchers to utilize, proving there’s no such thing as a free ride on the International Space Station.

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