What it detects
- This aims at detecting a DPI device that does MITM for the traffic to certain destination addresses.
Inputs
- A list of addresses to be tested.
Experiment
- The round trip time to the target address is measured.
Control
- The round trip time of an address in the same geographical area is used to verify if such latency is realistic for that destination.
Output
- The RTT for packets going to the destination address.
Questions
- How do we understand what is the correct base latency when connecting to the target address?
Notes
If OONI were to run a chargen server on all ports (or, at least, commonly used ports), the output would be at a known rate in B/s. OONI clients connecting to this server could compare downlink rates for ports, as well as compare against the known optimal rate. This wouldn't work for comparing specific destinations, but it might help establish a baseline.
Also see Dan Kaminsky's work on N00ter, a network neutrality testing router which tunnels connections to hosts through a VPN to detect whether or not an ISP is prioritizing or throttling traffic. --isis