Ethernet History: Why Do We Have Different Frame Types?

August 23, 2024 by Maya Posch 9 Comments

Although Ethernet is generally considered to be a settled matter, its history was anything but peaceful, with its standardization process (under Project 802) leaving its traces to this very day. This is very clear when looking at the different Ethernet frame types in use today, and with many more historical types. While Ethernet II is the most common frame type, 802.2 LLC (Logical Link Control) and 802 SNAP (Subnetwork Access Protocol) are the two major remnants of this struggle that raged throughout the 1980s, even before IEEE Project 802 was created. An in-depth look at this history with all the gory details is covered in this article by [Daniel].

The originally proposed IEEE 802 layout, with the logical link control (LLC) providing an abstraction layer.

We covered the history of Ethernet’s original development by [Robert Metcalfe] and [David Boggs] while they worked at Xerox, leading to its commercial introduction in 1980, and eventual IEEE standardization as 802.3. As [Daniel]’s article makes clear, much of the problem was that it wasn’t just about Ethernet, but also about competing networking technologies, including Token Ring and a host of other technologies, each with its own gaggle of supporting companies backing them.

Over time this condensed into three subcommittees:

802.3: CSMA/CD (Ethernet).
802.4: Token bus.
802.5: Token ring.

An abstraction layer (the LLC, or 802.2) would smooth over the differences for the protocols trying to use the active MAC. Obviously, the group behind the Ethernet and Ethernet II framing push (DIX) wasn’t enamored with this and pushed through Ethernet II framing via alternate means, but with LLC surviving as well, yet its technical limitations caused LLC to mutate into SNAP. These days network engineers and administrators can still enjoy the fallout of this process, but it was far from the only threat to Ethernet.

Ethernet’s transition from a bus to a star topology was enabled by the LANBridge 100 as an early Ethernet switch, allowing it to scale beyond the limits of a shared medium. Advances in copper wiring (and fiber) have further enabled Ethernet to scale from thin- and thicknet coax to today’s range of network cable categories, taking Ethernet truly beyond the limits of token passing, CSMA/CD and kin, even if their legacy will probably always remain with us.

Portable Router Build: Finding An LTE Modem

August 19, 2024 by Arya Voronova 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 Lewin Day 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 Arya Voronova 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.

Continue reading “Portable Router Build: Picking Your CPU” →

Hacking Airline WiFi The Hard Way

July 10, 2024 by Al Williams 28 Comments

We’ve all been there. You are on a flight, there’s WiFi, but you hate to pay the few bucks just to watch dog videos. What to do? Well, we would never suggest you engage in theft of service, but as an intellectual exercise, [Robert Heaton] had an interesting idea. Could the limited free use of the network be coopted to access the general internet? Turns out, the answer is yes.

Admittedly, it is a terrible connection. Here’s how it works. The airline lets you get to your frequent flier account. When there, you can change information such as your name. A machine on the ground can also see that change and make changes, too. That’s all it takes.

It works like a drop box. You take TCP traffic, encode it as fake information for the account and enter it. You then watch for the response via the same channel and reconstitute the TCP traffic from the remote side. Now the network is at your fingertips.

There’s more to it, but you can read about it in the post. It is slow, unreliable, and you definitely shouldn’t be doing it. But from the point of view of a clever hack, we loved it. In fact, [Robert] didn’t do it either. He proved it would work but did all the development using GitHub gist as the drop box. While we appreciate the hack, we also appreciate the ethical behavior!

Some airlines allow free messaging, which is another way to tunnel traffic. If you can connect to something, you can probably find a way to use it as a tunnel.

A Cute Sentry Scans Your Net For Scullduggery

July 4, 2024 by Elliot Williams 10 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.

Raspberry Pi Saves Printer From Junk Pile

June 13, 2024 by Al Williams 53 Comments

Around here, printers have a life expectancy of about two years if we are lucky. But [techtipsy] has a family member who has milked a long life from an old Canon PIXMA printer. That is, until Microsoft or Canon decided it was too old to print anymore. With Windows 10, it took some hacking to get it to work, but Windows 11 was the death knell. Well, it would have been if not for [techtipsy’s] ingenuity with a Raspberry Pi.

The Pi uses Linux, and, of course, Linux will happily continue to print without difficulty. If you are Linux savvy, you can probably see where this is going.

Continue reading “Raspberry Pi Saves Printer From Junk Pile” →