From README:

TSP is a control protocol used to establish and maintain static 
tunnels. The Gateway6 Client is used on the host computer to connect 
to a tunnel broker using the TSP protocol and to get the information 
for its tunnel. When it receives the information for the tunnel, the 
Gateway6 client creates the static tunnel on its operating system.

The Gateway6 Client code is mostly identical for all client platforms.
However, creating the static tunnel is operating system dependent and 
is done by a script called by the Gateway6 Client. These scripts are 
located under the template directory in the Gateway6 Client 
installation directory.

The script executed by the Gateway6 Client to configure the tunnel 
interface is customized for each type of supported operating system 
and takes care of all specifics for the target operating system. 
On Unix systems, it is a shell script. This separation of the binary 
and script enables fast and easy additions of new operating systems, 
as has been shown by the community contributions for many operating 
systems.

WWW: http://gogonet.gogo6.com/page/freenet6-services