XDMCP is not encrypted and is not secure outside of a firewall-protected LAN. If you are attempting to use XDMCP over the Internet, it should be used with VPN secure tunneling. Unfortunately, UDP port forwarding is not available with SSH, so XDMCP cannot be used with SSH.

 At the login screen:

• Options-->Remote Login via XDMCP

        Type in the host name or IP address (example: 192.168.0.2) of the remote computer.

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