How to detect AirPlay activity?

[bendt.v.rasmussen]

Hi fellows

I want to have my ubuntu home server turn my amplifier on/off through an arduino board, whenever I use AirPlay to stream from my iPad to my AirPort Express router.

But how do I detect Airplay activity on my home network? I have been looking into nast, and I guess it has something to do with sniffing, but I have no idea how this works. I can detect, when I turn AirPlay on, but is there a way that I can see, that Airplay is currently streaming?

Thanks for reading

Bendt Rasmussen