In this paper, leveraging a public dataset released in 2017, we provide classification results with the aim of investigating to which degree the specific anonymity tool (and the traffic it hides) can be identified, when compared to the traffic of other considered anonymity tools, using five machine learning classifiers. This process is impaired or prevented by privacy-preserving protocols and tools, that encrypt the communication content, and (in case of anonymity tools) additionally hide the source, the destination, and the nature of the communication. Traffic Classification (TC) is an important tool for several tasks, applied in different fields (security, management, traffic engineering, R&D). Finally, we report our experience in effectively crawling bridge nodes, supposedly revealed sparingly in Tor. We provide an efficient method allowing an exit node to detect such an abnormal usage. We also show that Tor usage is now diverted from the onion routing concept and that Tor exit nodes are frequently used as 1-hop SOCKS proxies, through a so-called tunneling technique. We do not only report such usage in terms of traffic size and number of connections but also depict how users behave on top of Tor. Furthermore, this paper provides a deep analysis of both the HTTP and BitTorrent protocols giving a complete overview of their usage. In particular, we quantify the BitTorrent traffic and show that the load of the latter on the Tor network is underestimated because of encrypted BitTorrent traffic (that can go unnoticed). Beyond providing global statistics on the typical usage of Tor in the wild, we show that Tor is actually being is-used, as most of the observed traffic belongs to P2P applications. Surprisingly, very few researches shed light on such an anonymizing network. Indeed, Tor an example of anonymizing networks based on onion routing concept attracts more and more volunteers, and is now popular among dozens of thousands of Internet users.

Anonymizing networks are then poised to become an important service to support anonymous-driven Internet communications and consequently enhance users' privacy protection. Users' anonymity and privacy are among the major concerns of today's Internet.

Tor network magic