This is great to for connect to MySQL server, which is not exposed to the internet. You connect to your web server via SSH and than forward port 3306 from your local machine to port 3306 on the remote machine. Once the tunnel runs, the SQL functions in our plugin can connect through the tunnel to the remove database server.
For details, please see the SSH.Tunnel.Run function to start the tunnel and SSH.Tunnel.Messages to see debug messages. Please don't do anything with the SSH session while the tunnel is running. But you can of course run multiple SSH sessions in parallel to run shell commands or several tunnels.
We had this implemented earlier this year for Xojo (see SSH2TunnelMBS class), but when I mentioned at the FileMaker conference that I have the code to do a tunnel, I was quickly asked to port this to the FileMaker plugin, so here it is.