Hackers extend Toslink audio cables to 143 kilometers, achieve IP data transmission

What just happened? Two hackers have successfully expanded Toslink’s range of optical audio cables, which allow data to be transmitted over unprecedented distances. Although practical applications may be limited, their efforts could pave the way for future advances in optical communications and networking technologies. Their ingenuity exemplifies the hacker spirit of constantly questioning, exploring, and pushing the boundaries of what technology can do.

Two hackers have challenged the boundaries of optical data transmission. demonstration that even outdated technologies can be repurposed in unexpected ways. At the 38th Chaos Communication Congress (38C3) in Germany, a gathering known for attracting tech enthusiasts and hackers, Benjojo presented his work on expanding Toslink traffic far beyond its intended range.

Toslink, a fiber optic connection used primarily for audio transmission, is typically limited to a distance of about 10 meters. However, Benjojo’s experiment increased this distance to an incredible 143 kilometers.

Building on Benjojo’s work, another hacker known as Manawyrm took the concept further. Just a day after Benjojo’s presentation, Manawyrm demonstrated the transmission IP data via Toslinkeffectively creating a core fiber optic network using audio cables.

Benjojo’s experiment involved a complex setup of data center equipment and various gadgets to achieve extended range. This included small form factor pluggable ports (SFPs), A/D and Toslink D/A converters, and an oscilloscope.

The long-distance test connected two data centers in London’s Docklands – Telehouse North and IP House – which are approximately 650 meters apart. The installation also featured a pair of fibers connecting the data centers, a CWDM multiplexer to maximize fiber connectivity between buildings, and a fiber loop installed at the Telehouse end to enable testing from a single location. Benjojo documented the whole process in a detailed blog post and YouTube video.

Although the speeds achieved were far from competitive with modern networking standards, the proof of concept was significant. Manawyrm’s IP-over-Toslink hack achieved a real-world data rate of approximately 1.47 Mbps (0.18 MB/s), just below Toslink’s theoretical maximum limit.

It is important to note that these experiments do not herald a revolution in networking technology. The speeds achieved are impractical for modern data transfer needs: the maximum speed over Toslink cables is approximately 1536 kbps (0.19 MB/s).

However, these experiments highlight an important principle: with the right modifications, cables designed for specific purposes can be adapted for uses far beyond their original purpose. This flexibility in optical data transmission can inspire new approaches to networking in non-traditional environments.

While Toslink’s experiments are unlikely to replace traditional network cables, they highlight the innovative potential hidden in seemingly outdated technology.