What it detects
If a certain Tor bridge is being blocked and how.
Inputs
A list of Tor Bridges (either normal or obfs) described as IP, PORT pairs.
Experiment
- It attempts to do a TCP connect to the bridge IP:Port
- It attempts to make an SSL Handshake with the IP:Port pair
- It attempts to do a full Tor connection to the bridge
Control
Based on which one of the previous operations fail, the test will return through what means the bridge is being blocked.
Output
The list of bridges being blocked.
Questions
In what order and with what logic should we combine the experiment points to avoid being detected from the censor.
Notes
See Roger Dingledine's post on testing bridge reachability on the Tor Project blog for more ideas on how this test could be implemented.