VirtualBox has builtin RDP support, much like VMware's Remote View (VNC), however it does take some tinkering to get working on Ubuntu Desktop / Server.
The main issue is when trying to use PAM authentication, on the host system, to authenticate remote users who wish to RDP into a Virtual Machine. PAM needs to be configured to allow the VRDPAuth.so library access to PAM services. This can be done by
1. Creating a new PAM configuration file
sudo gedit /etc/pam.d/vrdpauth
and adding the following lines
auth required pam_unix.so account required pam_unix.so broken_shadow
Save the file
2. You now need to set an environment variable so that VRDPAuth.so uses the correct PAM Service instead of the /etc/pam.d/login service:
- You can alternately set this as part of your .bashrc to save retyping at each login.