Gigabit Ethernet Through the Air

There are a couple of really great things about transmitting data using light as the carrier. It can be focused so that it doesn’t spill all over the neighborhood like radio signals do — giving it both some security against eavesdropping and preventing one signal from stepping on another’s toes. And while you can modulate radio signals up nearly to the carrier frequency, the few gigahertz we normally use for radio just won’t cut it for really high bit rates. Light gets you terahertz.

The Koruza project is an open-source, “inexpensive” system that aims to transmit 1 Gb/sec over distances around 100 meters, using modulated infrared light. The intended use-case is urban building-to-building communication at speeds that would otherwise require laying fiber-optic cables. Indeed, the system piggy-backs on existing fiber-optic equipment to get the job done, but the hard part is aligning the units to get maximum signal from point A to point B.


Koruza does this by including motorized lenses on the 3D-printed chassis. You make a rough alignment with a visible green laser, and then fine-tune the IR beams from a web console where you get immediate feedback on how the received signal strength is changing. Both Koruza boxes have a Raspberry Pi inside and use normal networking for calibration and signal-strength statistics. It’s a really neat system, and it’s fully DIY’able except for the commodity fiber-optic bits.

We’ve always had a soft-spot in our heart for transmitting data over light beams. The Ronja project has been doing so since 2001, and over longer distances, with completely DIY hardware, if at a slower bitrate. And now that Li-Fi seems to be getting traction, we might see an unfocused equivalent running inside our homes.

Thanks [Pavel] for the tip!

Link Trucker is a Tiny Networking Giant



  • Is the link up? Is this cable connected?
  • Can it get a DHCP address?
  • Can it perform a DNS lookup?
  • Can it open a webpage?


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Hacking Old Ethernet Gear

Have you ever wanted a pocket-sized device that could tell you if a network jack was live or not? [TanzerGuy] did and he hacked a piece of old networking gear to do the job.

Today when you think of Ethernet, you probably think of CAT-5 cable or something similar. But it hasn’t always been like that. In the early days of Ethernet networking, an Ethernet cable was a big piece of coax. A media attachment unit (MAU) clamped to the cable and then connected to an attachment unit interface (AUI) that resided in the actual network card. Later standards used thinner coax that attached to the card using a Tee connector, but even these are rare today.

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Encoding Data in Packet Delays

If you’ve ever been to a capture the flag hacking competition (CTF), you’ve probably seen some steganography challenges. Steganography is the art of concealing data in plain sight. Tools including secret inks that are only visible under certain light have been used for this purpose in the past. A modern steganography challenge will typically require you to find a “flag” hidden within an image or file.

[Anfractuosus] came up with a method of hiding packets within a stream of network traffic. ‘Timeshifter’ encodes data as delays between packets. Depending on the length of the delay, each packet is interpreted as a one or zero.

To do this, a C program uses libnetfilter_queue to get access to packets. The user sets up a network rule using iptables, which forwards traffic to the Timeshifter program. This is then used to send and receive data.

All the code is provided, and it makes for a good example if you’ve ever wanted to play around with low-level networking on Linux. If you’re interested in steganography, or CTFs in general, check out this great resource.

Meshing Pis with Project Byzantium





VCF East X: The Quarternet Steering Committee

Today was the first day of the Vintage Computer Festival East X. As is the tradition, the first day was packed with talks and classes about various retrocomputing ephemera, with this year featuring a great talk from [David Riley] about 8-bit computer music, a class on system architecture from our own [Bil Herd] (video coming soon), and a talk about vintage teletypes. One of these talks was about creating new hardware: [Jim Brain]’s steering committee on a networking solution for vintage microcontrollers. It’s called Quarternet: a two-bit solution for an eight bit world.

While minicomputers are easily networkable, designed around multi-user operating systems, and have the hardware for a lot of networking hardware, 8-bit micros are the exact opposite. That doesn’t mean 8-bitters don’t have networking; you can get an Ethernet cart for a C64, and just about everything can connect to a BBS. [Jim]’s talk was about whittling down the use cases for the Quarternet to something that could be implemented easily, but still give the most capability.

During the talk, the audience settled on using a serial connection from the micro to the outside world; this makes sense, as everything has a serial port. A ‘lightweight API’ was suggested to take up the software side of the problem, but there wasn’t much agreement over what that API would actually do.

[Jim]’s idea is for a box that plugs into the serial port of any old microcomputer and would connect to the Internet somehow. Ethernet, WiFi, or even a modem isn’t out of the question here. That takes care of connecting to the Internet, but there’s also the question of the cooler side of networking – network drives, file sharing, and the like.

For this, [Jim] is imagining a box with a serial port on one end, and a network port on the other. In the middle would be a cartridge slot for any hardware imaginable. If you want to plug in an Apple II disk drive, just insert the right cartridge and you’re good to go. If you need network access to a Commodore 1541 drive, just insert another cartridge, and it’ll just work.

It’s an interesting idea, but [Jim] is really interested in getting even more feedback for a networking system for old microcomputers. If you have any ideas, leave a note for him in the comments.

Great Scott! A Flux Capacitor Notification Light

If you are into your social media, then you probably like to stay updated with your notifications. [Gamaral] feels this way but he wasn’t happy with the standard way of checking the website or waiting for his phone to alert him. He wanted something a little more flashy. Something like a flux capacitor notification light. This device won’t send his messages back in time, but it does look cool.

He started with an off-the-shelf flux capacitor USB charger. Normally this device just looks cool when charging your USB devices. [Gamaral] wanted to give himself more control of it. He started by opening up the case and replacing a single surface mount resistor. The replacement component is actually a 3.3V regulator that happens to be a similar form factor as the original resistor. This regulator can now provide steady power to the device itself, as well as a ESP8266 module.

The ESP8266 module has built-in WiFi capabilities for a low price. The board itself is also quite small, making it suitable for this project. [Gamaral] used just two GPIO pins. The first one toggles the flux circuit on and off, and the second keeps track of the current state of the circuit. To actually trigger the change, [gamaral] just connects to the module via TCP and issues a “TIME CIRCUIT ON/OFF” command. The simplicity makes the unit more versatile because an application running on a PC can actually track various social media and flash the unit accordingly.