What is the way of access to the training material? Through HTTPS, SFTP or any other way. If you have the choice to do that, then design your secure server's network interface so that the only IPs that can access to your training server is the ones you authorize and do the transfer with the most simplest way (e.g. TCP/IP sockets).
Actually, you can still develop a protocol for TCP/IP sockets so that even other can connect to your secure server, they can not login if they don't know the password for the server.