Giacomo Vacca

 I'm a passionate runner, and always considered cycling as something fun, e.g. mountain-biking, but difficult to practice regularly. There's a lot of overhead in cycling, like the preparation, bike maintenance, dealing with city traffic, etc. Anyway about eight months ago I bought a road bike and felt in love with it. Soon after that I discovered Zwift and that gave an additional dimension to the sport: practice whenever you want from home, with accurate power measurements and a way to socialise with distant people. That was a game changer. In five months I cycled 1600 virtual Km and climbed almost 17 virtual Km. Meanwhile my running performance, instead of degrading, improved, and that surprised me. Anyway what I wanted to write about is a great article I read, "Physiological Differences Between Cycling and Running" . It's a review of articles published in that area. Some conclusions are very interesting. In general it seems sports medicine is still inconclusive...

 Since I needed to see a few details in the handling of attributes in STUN responses, I thought of going through the whole STUN protocol RFC again and take notes on the most important parts. I put my notes in some slides, and I'm sharing then in Slideshare in case somebody else may find them useful too: STUN protocol from Giacomo Vacca

I needed an efficient way to programmatically extract RTP streams from a network capture. In addition I wanted to: save each stream into a separate pcap file. extract SRTP-negotiated keys if present and available in the trace, associating them to the related RTP (or SRTP if the negotiation succeeded) stream. Some caveats: In normal conditions the negotiation of SRTP sessions happens via a secure transport, typically SIP over TLS, so the exchanged crypto information may not be available from a simple network capture. There are ways to extract RTP streams using Wireshark or tcpdump; it’s not necessary to do it programmatically. All this said I wrote a small tool ( https://github.com/giavac/pcap_tool ) that parses a network capture and tries to interpret each packet as either RTP/SRTP or SIP, and does two main things: save each detected RTP/SRTP stream into a dedicated pcap file, which name contains the related SSRC. print a summary of the crypto information exchanged, if available. With ...