tcis is short for ``Tor Connection Initiation Simulator''. The tool
partially simulates the initiation of a Tor connection to a given IP
address by sending a TLS client hello containing the Tor cipher list
(see [1]). After that, the program terminates. The TLS client hello is
hardcoded into the program and in order to make the client hello
appear like a real Tor connection, dynamic fields such as the
timestamp, the random value and the host name are initialized when the
program is started.

The tool is useful for analyzing the Great Firewall of China which is
known to search for the Tor cipher list and launches active scanning
after a cipher list was detected in a connection.

To run the program, you need to specify an IP address and a port where
a TCP daemon is listening. It does not have to be a Tor process. A
simple ``nc -l -p 1234'' is enough.

$ make
$ ./tcis <IP> <port>

[1] https://trac.torproject.org/projects/tor/ticket/4744