Effectiveness of performance flag selection for enhancing Tor circuits

Tor is an open network that defends against network surveillance, preserving personal freedom and privacy on the Internet. The barrier to a more widespread use of Tor is a variety of performance problems. We focused on enhancing Tor circuits by selecting the relays on the basis of assigned performance flags, which are known as a guard, fast and stable flags. We observed that these simple strategies can improve the selection method for relays with high bandwidth and TCP advertised window sizes. In this work, we regard bandwidth as the key factor in Tor design and path selection. We determine a better method of circuit selection based on actively measuring RTTs, TCP throughput and the TCP advertised window sizes of the relays.