Secure VNC with IMIv2

This section describes the Secure VNC procedure, parts of which your custom VNC proxy has to implement.

1. The thin client sends its certificate to UMS on boot.

   
   

   For a thin client newly registered to the UMS, either

   • reboot the thin client once or

   • use UMS Console to send Settings UMS > TC and send Settings TC > UMS once

   
   

2. Via the IMIv2 REST API, the custom proxy asks UMS for the credentials necessary for shadowing the thin client:
   GET /umsapi/v2/thinclients/[thin client ID]?facets=shadow

3. The custom proxy receives the credentials:

   • the thin client certificate in Base64 encoding, or an empty string if UMS has not received a certificate

   • a one-time-password in the form of a Java UUID for logging in within the next 5 min.

4. The custom proxy initiates a SSL connection to the thin client's TCP port 5900.

5. The thin client sends its certificate.

6. The custom proxy checks the certificate against the one received from UMS and decides whether to accept it and proceed with the connection.

7. The custom proxy opens a TCP server socket for an external VNC viewer to connect to. The custom proxy must connect the network streams involved as follows:

   • write to the VNC viewer what it reads from the SSL connection with the thin client

   • write to the SSL connection with the thin client what it reads from the VNC viewer

   
   Make the external VNC viewer connect to the custom proxy's server socket.

8. On accepting the connection from the external VNC viewer, the custom proxy writes the String
   PROCYCMD PW_[one-time password]
   to the SSL connection with the thin client.

9. The thin client sends the password to UMS.

10. UMS checks the password.

11. If the password is correct, UMS tells the thin client to proceed. Otherwise the connection will be closed.

12. The thin client sends a string like RFB 003.008\n as a VNC hello which initiates the VNC session with the external VNC viewer.