1. Monitoring Network Bias
Gergely Biczok, Whitney Young, and Aleksandar Kuzmanovic
Northwestern Networks Group (
Supported by NSF CAREER Award No
Motivation
Other probes
DNS hijacking of mistyped web addresses
Blocking HTTP download of *.torrent files
Can add newly discovered probes modularly
Net Neutrality
Openness vs. managing traffic
Debate in public, struggle in legislation, war in the Internet
ISPs are already installing middleboxes capable of degrading/changing/blocking popular applications
We do not take sides…
…but want to facilitate network accountability
System Design
Goal
Develop an end-host based measurement system for detecting and exposing biased network behavior
Methodology
Main idea
Collect reported/possible types of discriminatory ISP practices/middleboxes
Reverse-engineer their operation to create probes that will likely trigger them (approximately emulate desired traffic pattern)
Detect and locate biased network elements
Filtering
Port-based
Signature-based
Signature database compiled from open source tools, web search and packet traces
Flow-pattern-based
Spatial and temporal correlation of UDP and TCP flows specific to p2p applications
Shaping
Extensive shaping reported for p2p and encrypted traffic
Compare HTTP/FTP data rates to SSL and BitTorrent (emulated) rates
Back-to-back minute-long experiments
Significant and consistent (across hosts from the same ISP) difference in data rates indicate the presence of shapers
Locating middleboxes (filters and shapers)
Repeat the same measurements between the same end-host and multiple specifically selected PlanetLab nodes
Select servers that are “geographically” far away from each other minimizing the common segment of the paths
If same phenomena are observed, middlebox is in the shared path segments
Central Server
Serves the main website
Selects multiple PL nodes for given end-host
Coordinates probing PL nodes
Handles incoming reports and generate feedback to users
PlanetLab Node
If selected serves the Java applet to a Client
Sends and receives probes to/from a Client via applet
Sends a report to Central Server at the end of every measurement session
Client
Runs an applet in a web browser
Sends and receives probes from multiple PL nodes
Sends reports to PL nodes
Displays results to the user in a browser
Results and Future Work
Implementation is ongoing
Functions partly tested manually on small scale
Experienced BT shaping on well seeded torrents (D/U: 30 KBps/5 KBps) vs. HTTP download (200 KBps) at a given ISP
Signature-based filtering probes validated with open-source filtering software in a testbed
Large-scale live measurement in the near future
Upon collecting sufficient data we can draw a global map of biased network behavior