2020-vandersloot-running
findings extracted from this paper
-
Total hardware cost for four detector stations plus a central proxy was approximately $30,000 USD, with estimated annual operating costs of ~$13,000 for co-location and ~$24,000 for a 2 Gbps upstream connection, plus ~40% FTE of an ISP network engineer—costs that are structurally higher than endpoint-based circumvention due to mandatory network-operator co-location requirements.
-
During a major censorship event in April 2019, new censor techniques blocked many Psiphon transports while TapDance remained accessible, causing a 4× increase in the fraction of TapDance-enabled clients' traffic and daily users peaking above 25,000—with no measurable degradation in connection success rate or per-session throughput under the increased load.
-
Over 115 days of operation with 1,500–2,000 active decoys, the busiest decoy site averaged only 13.24 concurrent connections and 12.32 MB of traffic per day; only 2 of roughly 3,000 candidate decoy sites opted out via robots.txt over 18 months, and none reported operational problems, confirming that decoy websites are not meaningfully burdened at this deployment scale.
-
The first production Refraction Networking deployment used four TapDance stations at Merit Network observing 140 Gbps aggregate capacity and served up to 33,000 unique users per month across 559,000 Psiphon installations, proxying up to 500 Mbps of circumvention traffic during the first year of continuous operation.
-
Approximately 50% of TapDance client connection attempts failed to pass through any station due to routing variability at the ISP, producing an average of about one failed decoy per successful connection and time-to-first-byte exceeding five seconds in typical cases, even though median session RTT remained under one second.