How to use the Skype and P2P traffic blocker? Tapping into Skype Traffic with the traffictapper from Lyanda.

Give it a try. «Lyanda has made precompiled binaries for windows users. The Skype traffic identifier can be used directly. Try it out. Really interesting technology. Downlad this zip file and uncompress it anywhere. The traffic identifier is made of two distinct processes. First "TrafficTapDemo.exe", is the actual "Tap" program. It will record the network traffic in an in-memory database.
As you launch it, it will prompt you for a network device. Choose the device where you intend to tap the traffic from.»

Here is the brief explanation how it works.

«Lynanda's asynchronous filter is based on supervised/unsupervised machine learning. The main idea behind the classification methodology is that if packet payload is not a reliable indicator of application identification, packet timestamp is. In fact, it is very difficult for an application to control its response times. Therefore, most application leave specific correlations in the packet timestamp serie related to a given flow. These correlations are recorded into general bayesian networks and compared with flows taped on the wire. While the learning process is fairly slow, actual identification is very fast, accurate and universal, in the sense that it's not application dependent. At the time of writing, no application is known to hide its packet timestamp correlations. Clever analysis can actually show that it is pretty difficult, if possible, to hide these patterns on current processor architectures. It is thought to change however when CPU architectures will move towards instruction parallelization.
Such method can be used for any application flow. The accuracy of the filter can be improved by more learning. Though depending on what you do on the flow after detection, a 99% detection rate is usually sufficient. The process can be iterated to reduce false positives probability.»

Detailed explanation here.