Increasing bandwidth in Tor paths with multiple inter-relay connections

Abstract

Tor is a well-known low-latency anonymous network for Tor users who surf the Internet to hide themselves. However, Tor transmission is usually considered slow for several reasons. One of them is that the connections from multiple Tor users are multiplexed into one TCP connection between each pair of adjacent onion routers in the Tor path. The overall throughput is limited because the available bandwidth of a connection is subject to congestion control and fairness with other non-Tor connections. In this work, we design and propose multiple-connection Tor (MCTor) to speed up the Tor network by allowing multiple connections between adjacent onion routers. MCTor will increase the overall throughput and is compatible with the Tor network. The emulation supports that MCTor can achieve our goal. We have two connection distribution mechanisms, uniform and hashing. We implement emulation to test both mechanisms in three experiments: Youtube, upload, and download. In the first experiment, we improve the throughput by 35% using the hashing mechanism. In the second, we improve the throughput by 17% using the uniform mechanism. In the third, we improve the throughput by 48% using the uniform mechanism.