How to Disable the "No Authentication" for Security Types on a VNC Server
The virtual network computing (VNC) remote desktop application features basic security measures to protect a VNC session. The client/server program includes optional security authentication via password.
To ensure only authorised client computers connect to a VNC Server, disable the "No Authentication" option and configure a password for remote access.
Select the "Start" or "Globe" button located in the lower left desktop corner of the Windows computer that has VNC Server installed. Click "Programs" or "All Programs." Choose the VNC program group. Point to the "VNC Server (Service-Mode)" program group. Select the "Configure VNC Service" icon.
Choose the "Authentication" tab in the "VNC Server Properties (Service-Mode)" window that appears. Click the "VNC Password Authentication" radio button.
Select the "Configure" button. Enter the same password in the "New Password" and "Confirm Password" boxes. Click the "OK" button. Click the "OK" button in the "VNC Server Properties (Service-Mode)" window. The "No Authentication" option is disabled.