Toward Understanding Congestion in Tor DC-area Anonymity, Privacy, and Security Seminar January 24 th, 2014 Rob Jansen U.S. Naval Research Laboratory *Joint.

Slides:

Advertisements

Similar presentations

Martin Suchara, Ryan Witt, Bartek Wydrowski California Institute of Technology Pasadena, U.S.A. TCP MaxNet Implementation and Experiments on the WAN in.

Advertisements

A Probabilistic Analysis of Onion Routing in a Black-box Model 10/29/2007 Workshop on Privacy in the Electronic Society Aaron Johnson (Yale) with Joan.

Reducing Latency in Tor Circuits with Unordered Delivery Michael F. Nowlan, David Wolinsky, and Bryan Ford Yale University Dedis Lab.

Onions for Sale: Putting Privacy on the Market Rob Jansen Aaron Johnson Paul Syverson U.S. Naval Research Laboratory Presented by: Alessandro Acquisti.

Tor: The Second-Generation Onion Router

LASTor: A Low-Latency AS-Aware Tor Client

PIR-Tor: Scalable Anonymous Communication Using Private Information Retrieval Prateek Mittal University of Illinois Urbana-Champaign Joint work with: Femi.

Computer Networks Performance Metrics Computer Networks Term B10.

Playback-buffer Equalization for Streaming Media using Stateless Transport Prioritization Dan Tan, HPL, Palo Alto Weidong Cui, UC Berkeley John Apostolopoulos,

The Sniper Attack: Anonymously Deanonymizing and Disabling the Tor Network Rob Jansen et. al NDSS 2014 Presenter: Yue Li Part of slides adapted from R.

LIRA: Lightweight Incentivized Routing for Anonymity Rob Jansen Aaron Johnson Paul Syverson U.S. Naval Research Laboratory 20th Annual Network & Distributed.

Trust-based Anonymous Communication: Models and Routing Algorithms Aaron Johnson Paul Syverson Roger Dingledine Nick Mathewson U.S. Naval Research Laboratory.

Memory-based DoS and Deanonymization Attacks on Tor DCAPS Seminar October 11 th, 2013 Rob Jansen U.S. Naval Research Laboratory

ExperimenTor: A Testbed for Safe and Realistic Tor Experimentation Kevin Bauer 1 Micah Sherr 2 Damon McCoy 3 Dirk Grunwald 4 1 University of Waterloo 2.

Onion Routing Security Analysis Aaron Johnson U.S. Naval Research Laboratory DC-Area Anonymity, Privacy, and Security Seminar.

Anonymity Analysis of Onion Routing in the Universally Composable Framework Joan Feigenbaum Aaron Johnson Paul Syverson Yale University U.S. Naval Research.

How Much Anonymity does Network Latency Leak? Paper by: Nicholas Hopper, Eugene Vasserman, Eric Chan-Tin Presented by: Dan Czerniewski October 3, 2011.

Message Splitting Against the Partial Adversary Andrei Serjantov The Free Haven Project (UK) Steven J Murdoch University of Cambridge Computer Laboratory.

On Traffic Analysis in Tor Guest Lecture, ELE 574 Communications Security and Privacy Princeton University April 3 rd, 2014 Dr. Rob Jansen U.S. Naval Research.

Location-Aware Onion Routing Aaron Johnson U.S. Naval Research Laboratory IEEE Symposium on Security and Privacy May 19, 2015.

Next Generation Networks Chapter 10. Knowledge Concepts QoS concepts Bandwidth needs for Internet traffic.

1 Congestion Control. Transport Layer3-2 Principles of Congestion Control Congestion: r informally: “too many sources sending too much data too fast for.

10 - Network Layer. Network layer r transport segment from sending to receiving host r on sending side encapsulates segments into datagrams r on rcving.

Data Communication and Networks

Efficient Internet Traffic Delivery over Wireless Networks Sandhya Sumathy.

Lecture 5: Congestion Control l Challenge: how do we efficiently share network resources among billions of hosts? n Last time: TCP n This time: Alternative.

Anonymizing Network Technologies Some slides modified from Dingledine, Mathewson, Syverson, Xinwen Fu, and Yinglin Sun Presenter: Chris Zachor 03/23/2011.

Preventing Active Timing Attacks in Low- Latency Anonymous Communication The 10 th Privacy Enhancing Technologies Symposium July 2010 Joan Feigenbaum Yale.

Aaron Johnson U.S. Naval Research Laboratory CSci 6545 George Washington University 11/18/2013.

4: Network Layer4b-1 Router Architecture Overview Two key router functions: r run routing algorithms/protocol (RIP, OSPF, BGP) r switching datagrams from.

Lecture 1, 1Spring 2003, COM1337/3501Computer Communication Networks Rajmohan Rajaraman COM1337/3501 Textbook: Computer Networks: A Systems Approach, L.

On the Anonymity of Anonymity Systems Andrei Serjantov (anonymous)

CSE 486/586, Spring 2012 CSE 486/586 Distributed Systems Case Study: TOR Anonymity Network Bahadir Ismail Aydin Computer Sciences and Engineering University.

Transport Layer3-1 Chapter 3 outline r 3.1 Transport-layer services r 3.2 Multiplexing and demultiplexing r 3.3 Connectionless transport: UDP r 3.4 Principles.

1 Kommunikatsiooniteenuste arendus IRT0080 Loeng 7 Avo Ots telekommunikatsiooni õppetool, TTÜ raadio- ja sidetehnika inst.

Shadow: Simple HPC for Systems Security Research Invited Talk Kansas State University September 25 th, 2013 Rob Jansen U.S. Naval Research Laboratory

High Performance Computing & Communication Research Laboratory 12/11/1997 [1] Hyok Kim Performance Analysis of TCP/IP Data.

Never Been KIST: Tor’s Congestion Management Blossoms with Kernel- Informed Socket Transport 23 rd USENIX Security Symposium August 20 th 2014 Rob JansenUS.

Computer Networks Performance Metrics. Performance Metrics Outline Generic Performance Metrics Network performance Measures Components of Hop and End-to-End.

Understanding the Performance of TCP Pacing Amit Aggarwal, Stefan Savage, Thomas Anderson Department of Computer Science and Engineering University of.

Prentice HallHigh Performance TCP/IP Networking, Hassan-Jain Chapter 8 TCP/IP Performance over Optical Networks.

Denial of Service DoS attacks try to deny legimate users access to services, networks, systems or to other resources. There are DoS tools available, thus.

1 Capacity Dimensioning Based on Traffic Measurement in the Internet Kazumine Osaka University Shingo Ata (Osaka City Univ.)

Modeling and Simulating Time- Sensitive Networking Harri Laine.

Victor Farbman and Maxim Trosman Under guidance of Amichai Shulman.

Tor and Timing Attacks An attack within the accepted attacker model.

LASTor: A Low-Latency AS-Aware Tor Client. Tor  Stands for The Onion Router  Goals: Anonymity ○ Each hop only knows previous and next hop on a path.

How Low Can You Go: Balancing Performance with Anonymity in Tor’ DC-Area Anonymity,Privacy, and Security Seminar May 10 th, 2013 Rob Jansen U.S. Naval.

Mix networks with restricted routes PET 2003 Mix Networks with Restricted Routes George Danezis University of Cambridge Computer Laboratory Privacy Enhancing.

Shadow: Scalable Simulation for Systems Security Research CrySP Speaker Series on Privacy University of Waterloo January 20 th, 2016 Rob Jansen U.S. Naval.

TCP Traffic Characteristics—Deep buffer Switch

-1- Georgia State UniversitySensorweb Research Laboratory CSC4220/6220 Computer Networks Dr. WenZhan Song Professor, Computer Science.

Studies of LHCb Trigger Readout Network Design Karol Hennessy University College Dublin Karol Hennessy University College Dublin.

A special acknowledge goes to J.F Kurose and K.W. Ross Some of the slides used in this lecture are adapted from their original slides that accompany the.

Aaron Johnson Rob Jansen Aaron D. Jaggard Joan Feigenbaum

Improving Tor’s Security with Trust-Aware Path Selection Aaron Johnson

Advanced Computer Networks

PeerFlow: Secure Load Balancing in Tor Aaron Johnson1 Rob Jansen1 Aaron Segal2 Nicholas Hopper3 Paul Syverson1 1U.S. Naval Research Laboratory 2Yale.

The Onion Router Hao-Lun Hsu

Shadow: Real Applications, Simulated Networks

Performance Enhancements for Tor

Chapter 4: Network Layer

Inside Job: Applying Traffic Analysis to Measure Tor from Within

Shadow: Scalable and Deterministic Network Experimentation

The Tor Network: Freedom and Privacy Online Aaron Johnson U. S

Privacy-Preserving Dynamic Learning of Tor Network Traffic

EE 122: Lecture 7 Ion Stoica September 18, 2001.

Chapter 4: Network Layer

Rob Jansen, U.S. Naval Research Laboratory

Presentation transcript:

Toward Understanding Congestion in Tor DC-area Anonymity, Privacy, and Security Seminar January 24 th, 2014 Rob Jansen U.S. Naval Research Laboratory *Joint with John Geddes, Chris Wacek, Micah Sherr, Paul Syverson

Tor for Awesomeness Anonymity

Tor is Slow!!! Research* ● PCTCP: Per-Circuit TCP-over-IPsec Transport for Anonymous Communication Overlay Networks (CCS ‘13) ● Reducing Latency in Tor Circuits with Unordered Delivery (FOCI ‘13) ● How Low Can You Go: Balancing Performance with Anonymity in Tor (PETS ‘13) ● The Path Less Travelled: Overcoming Tor's Bottlenecks with Traffic Splitting (PETS ’13) ● An Empirical Evaluation of Relay Selection in Tor (NDSS ‘13) ● LIRA: Lightweight Incentivized Routing for Anonymity (NDSS ‘13) ● Improving Performance and Anonymity in the Tor Network (IPCCC ‘12) ● Enhancing Tor's Performance using Real-time Traffic Classification (CCS ’12) ● Torchestra: Reducing interactive traffic delays over Tor (WPES ‘12) ● Throttling Tor Bandwidth Parasites (USENIX Sec ‘12) ● LASTor: A Low-Latency AS-Aware Tor Client (Oakland ‘12) ● Congestion-aware Path Selection for Tor (FC ‘12) *Not a comprehensive list

Tor is Slow!!! Research* ● PCTCP: Per-Circuit TCP-over-IPsec Transport for Anonymous Communication Overlay Networks (CCS ‘13) ● Reducing Latency in Tor Circuits with Unordered Delivery (FOCI ‘13) ● How Low Can You Go: Balancing Performance with Anonymity in Tor (PETS ‘13) ● The Path Less Travelled: Overcoming Tor's Bottlenecks with Traffic Splitting (PETS ’13) ● An Empirical Evaluation of Relay Selection in Tor (NDSS ‘13) ● LIRA: Lightweight Incentivized Routing for Anonymity (NDSS ‘13) ● Improving Performance and Anonymity in the Tor Network (IPCCC ‘12) ● Enhancing Tor's Performance using Real-time Traffic Classification (CCS ’12) ● Torchestra: Reducing interactive traffic delays over Tor (WPES ‘12) ● Throttling Tor Bandwidth Parasites (USENIX Sec ‘12) ● LASTor: A Low-Latency AS-Aware Tor Client (Oakland ‘12) ● Congestion-aware Path Selection for Tor (FC ‘12) *Not a comprehensive list Where?

Outline ● Where is Tor slow? – Understand Tor relay architecture – Measure and analyze relay congestion in realistic Tor networks ● Design focused solutions

Outline ● Where is Tor slow? – Understand Tor relay architecture – Measure and analyze relay congestion in realistic Tor networks ● Design focused solutions

The Tor Network

Relay Overview

Onion routing connections

Relay Overview TCP TCP Transport

Relay Overview TCP Multiplexed Circuits and Streams

Relay Overview TCP

Relay Internals Kernel InputKernel OutputTor InputTor Output Tor Circuits Network Input

Relay Internals Kernel InputKernel OutputTor InputTor Output Tor Circuits Split data into socket buffers

Relay Internals Kernel InputKernel OutputTor InputTor Output Tor Circuits Read data from sockets into Tor

Relay Internals Kernel InputKernel OutputTor InputTor Output Tor Circuits Process data (encrypt/decrypt)

Relay Internals Kernel InputKernel OutputTor InputTor Output Tor Circuits Split cells into circuit queues

Relay Internals Kernel InputKernel OutputTor InputTor Output Tor Circuits Circuits linked to outgoing connection

Relay Internals Kernel InputKernel OutputTor InputTor Output Tor Circuits Schedule cells

Relay Internals Kernel InputKernel OutputTor InputTor Output Tor Circuits Write data from Tor into sockets

Relay Internals Kernel InputKernel OutputTor InputTor Output Tor Circuits Schedule data for sending

Relay Internals Kernel InputKernel OutputTor InputTor Output Tor Circuits Opportunities for traffic management

Outline ● Where is Tor slow? – Understand Tor relay architecture – Measure and analyze relay congestion in realistic Tor networks ● Design focused solutions

Kernel Congestion: libkqtime Kernel InputKernel OutputTor InputTor Output Tor Circuits

Kernel Congestion: libkqtime Kernel InputKernel OutputTor InputTor Output Tor Circuits tag match

Kernel Congestion: libkqtime Kernel InputKernel OutputTor InputTor Output Tor Circuits tag match tag match

Kernel Congestion: libkqtime Kernel InputKernel OutputTor InputTor Output Tor Circuits tag match tag match track cells

Congestion Analysis

Analyzing the Design Kernel InputKernel OutputTor InputTor Output Tor Circuits

Analyzing the Design Kernel InputKernel OutputTor InputTor Output Tor Circuits Queuing delays in kernel output buffer

Analyzing the Design Kernel InputKernel OutputTor InputTor Output Tor Circuits Queuing delays in kernel output buffer Circuit scheduling design flaws

Outline ● Where is Tor slow? – Understand Tor relay architecture – Measure and analyze relay congestion in realistic Tor networks ● Design focused solutions

Ineffective Priority Kernel OutputTor Output Tor Circuits Circuit schedulers are ineffective at prioritization

Ineffective Priority Kernel OutputTor Output Tor Circuits Libevent schedules one connection at a time

Ineffective Priority Kernel OutputTor Output Tor Circuits Libevent schedules one connection at a time Tor only considers a subset of writable circuits

Ineffective Priority Kernel OutputTor Output Tor Circuits Libevent schedules one connection at a time Tor only considers a subset of writable circuits Circuits from different connections are not prioritized correctly

Scheduling Problems Scenario A Scenario B No Shared ConnectionShared Connection

Scheduling Problems Scenario A Scenario B

Global Circuit Scheduling Kernel OutputTor Output Tor Circuits Choose among ALL writable circuits

Kernel Buffer Bloat Kernel OutputTor Output Tor Circuits Queuing delays in kernel output buffer

Kernel Buffer Bloat Kernel OutputTor Output Tor Circuits Queuing delays in kernel output buffer ● Too many large kernel queues ● More data in kernel than it can send ● Circuit scheduler timing issues

Tor Output Auto-tuning ● Don’t write what the kernel can’t send ● Smartly write to kernel using – Socket queue lengths and sizes – TCP windows – Node bandwidth capacity ● Check again before kernel starvation Increase effectiveness of circuit scheduler

Questions? cs.umn.edu/~jansen think like an adversary

libkqtime