Screenshot of Wireshark, showing that source and destination port for ArtNet packets are the same

ArtNet Not Going Through? Your Switch Might Be Protecting You

February 12, 2023 by Arya Voronova 12 Comments

Cool technology often comes at a cost, and it’s not always that this cost is justified. For instance, [Rainfay] tells us about how the the ArtNet protocol’s odd design choices are causing incompatibility with certain Ethernet switches. ArtNet is a protocol for lighting control over DMX-512 – simply put, it allows you to blink a whole ton of LEDs, even literally. Unlike DMX-512 which can use different physical mediums, ArtNet uses Ethernet, taking form of the usual kind of network packets – and it does seem to do a great job about that, if it weren’t for this one thing.

For some reason, ArtNet connections are required to use the same destination and source port – unlike the usual network traffic, where the destination port is protocol-dependent and the source port is randomized. This behaviour violates RFCs, and not just in an abstract manner – such behaviour is indicative of certain kinds of attacks, that switches on the smart side are able and are supposed to prevent. As a result, ArtNet traffic actually triggers some protections on switches at the fancier end, specifically, so-called BLAT protection.

In short, if your ArtNet stream is mysteriously not going through and your switch is on the fancier side, [Rainfay] says you might need to disable some security mechanisms. Sadly, as she points out, this problem isn’t even a direct consequence of some inherent property of ArtNet, but merely a consequence of a bizarre design choice. Once you’re done disabling protections, however, do check out some ArtNet projects for inspiration – it’s a genuinely useful protocol supported in a ton of fancy software, and it might be that you want to use it in the firmware of your RGB strip controller board!

Building A NAS That Really Looks Like A NAS

January 20, 2023 by Anool Mahidharia 19 Comments

Building your own network attached storage (NAS) for personal use isn’t all that difficult. A single board computer, a hard disk and a power supply in an enclosure is all the hardware you need. Then, choose from one of several open source NAS software solutions and you’re up and running. [tobychui] decided to notch things up by designing a NAS that really looks like a NAS. It’s tailored to his specific requirements and looks like a professional product to boot. The design features dual 3.5 inch HDD bays, a small footprint, is low cost, compatible with a variety of single board computers, and can handle high data transfer speeds by using RAM and SD card for buffering.

Not only has he done a great job with the hardware design, but he’s also developed a companion software for the NAS. “ArozOS” is a web desktop operating system that provides full-fledged desktop experience within a browser. ArozOS has a great user interface and features a lot of networking, file, disk management and security functions. He has also developed a launcher application to enable over-the-air (OTA) software updates.

Assembling the device will need some planning and preparation, even though most of the hardware is off the shelf. You will need a SATA to USB 2.0 adapter, a SBC (Orange Pi Zero, Raspberry Pi 4, Orange Pi Zero 2, etc) , three buck converters — one each to provide 12 V to the two hard disks and a third to provide 5 V to the SBC. You’ll also need a 12 V / 6 A or 24 V / 3 A external power brick, or a USB-C 65 W GaN charger with a triggering module to set the desired voltage and current.

There is also one custom power distribution board which is essentially a carrier board to mount the buck converters and connectors for power and USB data. For the 3D prints, [tobychui] recommends printing at the highest resolution for a nice finish.

The off the shelf SATA to USB adapter will need to be taken apart before it can be fixed to the 3D printed SATA adapter plate and might pose the most challenge during construction, but the rest of the assembly is fairly straightforward. Once assembly is complete, [tobychui] walks you through installation of the ArozOZ software, mounting the drives and making them accessible over the network.

Have you got your data backup act in order ? If not, it’s still not too late to make it a new Year’s resolution. And if you need help figuring things out, check out New Year Habits – What Do You Do For Data Storage?

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It’s Ethernet, From An SPI Interface

December 19, 2022 by Jenny List 37 Comments

Over the years as microcontrollers have become fast enough to do the heavy lifting, we have become used to 10 megabit Ethernet being bit-banged from interfaces it was never meant to emerge from. We think however that we’ve never seen one driven from an SPI interface, so this one from [Ivan] may be a first. With a cleverly designed transceiver using logic chips, it even offers a chance to understand something about the timing of an Ethernet interface, too.

The differential logic signals derived from a simple Ethernet transceiver can be read by an SPI bus, but for the lack of a clock line. The challenge was then to construct a circuit the would construct the required clock pulses from the state changes on the data line. This would become a monostable with XOR gate, and a shift register to handle the clock during the preamble phase.

The resulting circuitry fits neatly on a shield for the ST Nucleo 64 board, where while it might not be the obvious choice for an Ethernet shield it certainly does the job.

If unexpected Ethernet is your thing, how about the i2s peripheral on an ESP8266?

Magnetic jack version of the bit-bang ethernet peripheral for Raspberry Pi Pico

Bit-Banging Bidirectional Ethernet On A Pi Pico

December 3, 2022 by Dave Walker 38 Comments

These days, even really cheap microcontroller boards have options that will give you Ethernet or WiFi access. But what if you have a Raspberry Pi Pico board and you really want to MacGyver yourself a network connection? You could do worse than check out this project by [holysnippet] that gives you a bit-banged bidirectional Ethernet port using only scrap passive components and software.

This project is similar to one we shared back in August by [kingyo], but differs in that what [holysnippet] has achieved is a fully-functional (albeit only around 7 Mbps) Ethernet port, rather than a simple UDP transmit device. The Ethernet connection itself is handled by the lwip stack. Connection to the RJ45 socket can be made from any of the Pi Pico pins, provided TX_NEG is followed directly by TX_POS, but the really hacky part is in the hardware.

schematic of Pi Pico bit-banged ethernet peripheral — Schematic showing the empirically-determined passive component values required.

Rather than developing hardware that would protect the Pico, this design admits that it “shamefully relies on the Pico’s input protection devices” to limit the Ethernet voltages to 3.3 V.

You’ll need an isolation transformer from some old Ethernet-enabled gear (either standalone or as part of a magnetic jack), but then it’s only resistors and capacitors from there. There are warnings not to connect this to PoE networks for obvious reasons, and the component layout needs to keep in mind the ~20 MHz frequencies involved, but to get this working at all feels like quite a feat.

Normally, there’d be no reason to go to these lengths, but it’s always educational to see if it can be done and, with the current component shortages, this is another trick to keep up your sleeve for emergencies!

Putting ports where they shouldn’t belong is not a new idea, of course. Back in the day we even shared an inadvisable ATTINY implementation of bit-banged Ethernet with no protection at all.

Thanks to [biemster] for the tip-off

Pie Stop For Emergency DNS Needs

November 24, 2022 by Bryan Cockfield 37 Comments

The war on Internet ads rages on, as the arms race between ad blockers and ad creators continues to escalate. To make a modern Internet experience even remotely palatable, plenty of people are turning to DNS-level filters to stop the ads from coming into the network at all. This solution isn’t without its collateral damage though, as the black lists available sometimes filter out something that should have made it to the user. For those emergencies, [Kristopher] created the Pie Stop, a physical button to enact a temporary passthrough on his Pi-Hole.

While [Kristopher] is capable of recognizing a problem and creating the appropriate white list for any of these incidents, others in his household do not find this task as straighforward. When he isn’t around to fix the problems, this emergency stop can be pressed by anyone to temporarily halt the DNS filtering and allow all traffic to pass through the network. It’s based on the ESP-01S, a smaller ESP8266 board with only two GPIO pins. When pressed, it sends a custom command to the Pi-Hole to disable the ad blocking. A battery inside the case allows it to be placed conveniently anywhere near anyone who might need it.

With this button deployed, network snafus can be effectively prevented even with the most aggressive of DNS-level ad blocking. If you haven’t thought about deploying one of these on your own network, they’re hard to live without once you see how powerful they are. Take a look at this one which also catches spam.

MoCA Networking Is A Niche Solution For Coax Lovers

November 3, 2022 by Lewin Day 63 Comments

When it comes to networking these days, the vast majority of our devices are connected wirelessly. Beyond that, we’re all familiar with the Cat 5 and Cat 6 cables that form the high-capacity Ethernet networks in our homes, schools, and offices.

It’s only if you go back to the very dawn of Ethernet that coaxial cables are relevant… right? Wrong! MoCA networking is all about coaxial cables, designed to hook up devices over cable TV infrastructure!

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Building A Local Network With LoRaWAN

October 22, 2022 by Bryan Cockfield 40 Comments

At its core, the Internet is really just a bunch of computers networked together. There’s no reason that there can’t be other separate networks of computers, or that we all have to tie every computer we have to The One Internet To Rule Them All. In fact, for a lot of embedded systems, it doesn’t make much sense to give them a full network stack and Cat6e Ethernet just to report a few details about themselves. Enter LoRaWAN, a wireless LAN that uses extremely low power for Internet-of-Things devices, and an implementation of one of these networks in an urban environment.

The core of the build is the LoRaWAN gateway which sits at the top of a tall building to maximize the wireless range of all of the other devices. It’s running ChirpStack on the software side and uses a Kerlink Wigrid station to broadcast. The reported range is a little over 9 km with this setup. Other gateways can also be added, and the individual LoRa modules can report to any available gateway. From there, the gateways all communicate back to the central server and the information can be sent out to the wider network, Internet or otherwise.

The project’s creator [mihai.cuciuc] notes that this sort of solution might not be best for everyone. There are other wide area networks available, but using LoRaWAN like this would be likely to scale better as more and more devices are added to the network. For some other ways that LoRa can be used to great effect, take a look at this project which builds an off-grid communications network with it.