VNC client gets "No matching security types" when connecting to display :0 on SLE 12

SUSE Linux Enterprise Desktop or Server 12

Vino server has been enabled by turning on Screen Sharing.

From the menu go to System Tools --> Settings --> Sharing and enable Screen Sharing.  This will run the Vino server which is the program that will allow a VNC connection to display :0 or the system console.

Once enabled Vino listens on port 5900 for a VNC client connection or 5800 for a connection from a browser.  When using vncviewer from a SUSE Linux Enterprise system or using a VNC client such as Tight VNC on Windows the connection will fail with the message, "No matching security types."

The Vino server included with SUSE Linux Enterprise 12 introduced the TLC encryption method and by default requires encryption from the client.  The vncviewer and Tight VNC clients do not support this encryption so they appropriately fail with the indicated message.

There are two possible solutions for this situation.

1.  Use a client that supports the encryption.  On SUSE Linux Enterprise 12 systems there are two supported programs, vinagre and virt-manager.

2.  Disable the encryption requirement for the Vino server.  This option is not displayed in the screen sharing setup so it must be modified using the "gsettings" command.  The following command must be run as the user that has enabled screen sharing:

gsettings set org.gnome.Vino require-encryption false

You can verify that the setting was changed properly by running this command and looking for the "require-encryption" setting:

gsettings list-recursively org.gnome.Vino

If there is still trouble connecting after modifying this setting restart the system or restart the xdm service by running "rcxdm restart".  This will kill all currently running desktops so be sure nobody is logged in.