Pictures from the Skype

This paper focuses on the characterization and classification of Skype traffic, a nowadays very popular and fashionable VoIP application. Building over previous work, we develop a software tool which can be used to examine the evolution of Skype call classification in an interactive fashion. The demonstrator software focuses on the main aspects of Skype traffic characterization and presents the traffic patterns Skype generates during a call or while idle. In addition, the demonstrator shows the evolution of the internal indexes the Skype classifiers use. After describing the classification process and the demonstrator software, we use the tool to demonstrate the feasibility of online Skype traffic identification, considering both accuracy and computational costs. Experimental results show that few seconds of observation are enough to allow the classifier engines to correctly identify the presence of Skype flows. Moreover, results indicate that the classification engine can cope with multi-Gbps links in real-time using common off-the-shelf hardware.