network

92 Articles

Portable Router Build: Finding An LTE Modem

August 19, 2024 by 8 Comments

Ever want your project equipped with a cellular interface for a data uplink? Hop in, I have been hacking on this for a fair bit! As you might remember, I’m building a router, I told you about how I picked its CPU board, and learned some lessons from me daily-driving it as a for a bit – that prototype has let me learn about the kind of extra hardware this router needs.

Here, let’s talk about LTE modems for high data throughput, finding antennas to make it all work, and give you a few tips that should generally help out.  I’d like to outline a path that increases your chances of finding a modem working for you wonderfully – the devices that we build, should be reliable.

Narrowing It Down

If you look at the LTE modem selection, you might be a little overwhelmed: Simcom, Qualcomm, uBlox, Sierra, Telit, and a good few other manufacturers package baseband chipsets into modules and adjust the chipset-maker-provided firmware. The modems will be available in many different packages, too, many of them solderable, and usually, they will be available on mPCIe cards too. If you want to get a modem for data connections for a project, I argue that you should go for mPCIe cards first, and here’s why.

Continue reading “Portable Router Build: Finding An LTE Modem” →

A Really Low Level Guide To Doing Ethernet On An FPGA

August 14, 2024 by 7 Comments

With so much of our day-to-day networking done wirelessly these days, it can be easy to forget about Ethernet. But it’s a useful standard and can be a great way to add a reliable high-throughput network link to your projects. To that end, [Robert Feranec] and [Stacy Rieck] whipped up a tutorial on how to work with Ethernet on FPGAs. 

As [Robert] explains, “many people would like to transfer data from FPGA boards to somewhere else.” That basically sums up why you might be interested in doing this. The duo spend over an hour stepping through doing Ethernet at a very low level, without using pre-existing IP blocks to make it easier. The video explains the basic architecture right down to the physical pins on the device and what they do, all the way up to the logic blocks inside the device that do all the protocol work.

If you just want to get data off an embedded project, you can always pull in some existing libraries to do the job. But if you want to really understand Ethernet, this is a great place to start. There’s no better way to learn than doing it yourself. Files are on GitHub for the curious. Continue reading “A Really Low Level Guide To Doing Ethernet On An FPGA” →

Portable Router Build: Picking Your CPU

August 13, 2024 by 23 Comments

I want to introduce you to a project of mine – a portable router build, and with its help, show you how you can build a purpose-built device. You might have seen portable routers for sale, but if you’ve been in the hacking spheres long enough, you might notice there are “coverage gaps”, so to speak. The Pi-hole project is a household staple that keeps being product-ized by shady Kickstarter campaigns, a “mobile hotspot” button is a staple in every self-respecting mobile and desktop OS, and “a reset device for the ISP router” is a whole genre of a hacker project. Sort the projects by “All Time” popularity on Hackaday.io, and near the very top, you will see an OpenVPN &Tor router project – it’s there for a reason, and it got into 2014 Hackaday Prize semifinals for a reason, too.

I own a bunch of devices benefitting from both an Internet connection and also point-to-point connections between them. My internet connection comes sometimes from an LTE uplink, sometimes from an Ethernet cable, and sometimes from an open WiFi network with a portal you need to click through before you can even ping anything. If I want to link my pocket devices into my home network for backups and home automation, I can put a VPN client on my laptop, but a VPN client on my phone kills its battery, and the reasonable way would be to VPN the Internet uplink – somehow, that is a feature I’m not supposed to have, and let’s not even talk about DNSSEC! Whenever I tried to use one of those portable LTE+WiFi[+Ethernet] routers and actively use it for a month or two, I’d encounter serious hardware or firmware bugs – which makes sense, they are a niche product that won’t get as much testing as phones.

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A Cute Sentry Scans Your Net For Scullduggery

July 4, 2024 by 9 Comments

As long as we get to make our own network security tools, why not make them look cute? Netgotchi may not be much more than an ESP8266 running network scans and offering up a honeypot service, but it smiles while sits on your desk and we think that’s swell.

Taking inspiration from a recent series of red-team devices that make hacking adorable, most obviously pwnagotchi (and arguably Flipper), Netgotchi lives on the light side of the Force. Right now, it enumerates the devices on your network and can alert you when anything sketchy joins in. We can totally imagine customizing this to include other network security or health checks, and extending the available facial expressions accordingly.

You might not always be thinking about your network, and if you’re like us, that’s probably just fine. But we love standalone displays that show one thing in an easily digestable manner, and this fits the bill, with a smile.

Accelerate Your Large Builds Locally With Distcc

March 4, 2024 by 19 Comments

The motto of Sun Microsystems back in the day was “The Network Is The Computer” which might be kind of relevant when CPUs were slower and single-core affairs, but lately to get a faster compile, you’d simply throw more cores and memory at the problem. The thing is, most of us don’t do huge compilations all that often, we can’t remember the last time we even attempted a Linux kernel build. However if you do find yourself with a sudden need to do so, and have access to a pile of machines hooked to a network, then why not check out distcc: the fast distributed C/C++ Compiler? We’ve seen a few mentions in comments and a HaD links article referencing it, but never explicitly covered the tool. So here we go.

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Modeling Network Latency

January 17, 2024 by 6 Comments

The selfhosting community is an interesting and useful part of the Internet dedicated to removing one’s own services and data from the cloud and hosting it on their own servers, often on hardware that can be physically touched. With that kind of network usage, it’s not uncommon for people to build their own routers, firewalls, and other network support systems from the ground up. And, if you go deep enough, maybe even a home lab dedicated to testing and improving the network’s various layers. This piece of software helps simulate network latency to more accurately assess quality of service, performance, and the optimization of one one’s own networks.

The tool, called Speedbump, allows a network administer to quickly build a test network where characteristics of the network such as base latency and wave shape and size can be set up. From there, a TCP proxy sends the network traffic through the virtual network, adding in a set amount of delay to anything traveling on the network. It can be installed (or built from source) on an existing installation or used from within a Docker terminal, so there are plenty of options depending on preference. It’s also available as a library for any programs written in Go.

While this certainly has applications for home labs where self-hosting services is done at a high level, this could have professional applications as well. For troubleshooting simpler network issues we’d always recommend this tool which allows a more comprehensive network test than the standard “ping” command, and if you haven’t heard of selfhosting before it’s probably time to read this primer on it and build a hobby web server from scratch.

An exploded view render of a red 3D printed case with a green PCB is inside with visible USB-A connectors with a mouse and keyboard graphic above each and "A" and "B" labels above USB-C connectors on the other side.

Building A Better Keyboard And Mouse Switch

December 26, 2023 by 38 Comments

Switching inputs between desktops seems like something that should be simple but can prove to be a pain in reality. [Hrvoje Cavrak] decided to take matters into his own hands and build a better keyboard and mouse switch.

DeskHop is built from two Raspberry Pi Pico boards connected via UART and separated by an Analog Devices ADuM1201 dual-channel digital isolator. Through the magic of Pico-PIO-USB these RP2040s can be both host and device. To keep things simple, the PCB is single-sided, and the BOM only has five distinct components.

Once hooked up to your Windows, Mac, or Linux device, your mouse pointer “magically” goes from one screen to the other when dragged across the screen edge. Keyboard LEDs can be reprogrammed to indicate which device is active, and the real beauty of the device is that since it’s a hardware solution, you don’t have to install any software on a computer you might not have admin access to.

If you want to see some more ideas for keyboard and mouse switching, check out this Pi KVM with ATX signaling, this USB triplexer, or this Pi KVM on a PCIe card.