A simple Tor connectivity tester.

Connects to a given IP address and port, does a TLS handshake with Tor's supported cipher suites, and exchanges versions cells.

Addresses and ports of Tor directory authorities can be found here:

https://github.com/OpenObservatory/ooni-resources/blob/master/bridge_reachability/tor-bridges-ip-port.csv

References:

https://trac.torproject.org/projects/tor/wiki/org/projects/Tor/TLSHistory

https://gitweb.torproject.org/torspec.git/tree/tor-spec.txt