Paper Info
Title
Never been KIST: Tor's congestion management blossoms with Kernel-informed socket transport
Abstract
Tor's growing popularity and user diversity has resulted in network performance problems that are not well understood. A large body of work has attempted to solve these problems without a complete understanding of where congestion occurs in Tor. In this paper, we first study congestion in Tor at individual relays as well as along the entire end-to-end Tor path and find that congestion occurs almost exclusively in egress kernel socket buffers. We then analyze Tor's socket interactions and discover two major issues affecting congestion: Tor writes sockets sequentially, and Tor writes as much as possible to each socket. We thus design, implement, and test KIST: a new socket management algorithm that uses real-time kernel information to dynamically compute the amount to write to each socket while considering all writable circuits when scheduling new cells. We find that, in the medians, KIST reduces circuit congestion by over 30 percent, reduces network latency by 18 percent, and increases network throughput by nearly 10 percent. We analyze the security of KIST and find an acceptable performance and security trade-off, as it does not significantly affect the outcome of well-known latency and throughput attacks. While our focus is Tor, our techniques and observations should help analyze and improve overlay and application performance, both for security applications and in general.
Year
Venue
Keywords
2014
USENIX Security
management,networks,circuits
Field
DocType
Citations 
Kernel (linear algebra),Congestion management,Computer security,Computer science,Latency (engineering),Scheduling (computing),Throughput,Overlay,Network performance
Conference
9
PageRank 
References 
Authors
0.53
39
5
Name
Order
Citations
PageRank
Rob Jansen128316.78
John Geddes2172.39
Chris Wacek31194.79
Micah Sherr462544.49
Paul Syverson54713457.55