Oracle VM VirtualBox can display virtual machines remotely, meaning that a virtual machine can execute on one computer even though the machine will be displayed on a second computer, and the machine will be controlled from there as well, as if the virtual machine was running on that second computer.

For maximum flexibility, Oracle VM VirtualBox implements remote machine display through a generic extension interface called the VirtualBox Remote Desktop Extension (VRDE). The base open source Oracle VM VirtualBox package only provides this interface, while implementations can be supplied by third parties with Oracle VM VirtualBox extension packages, which must be installed separately from the base package. See Installing Oracle VM VirtualBox and Extension Packs.

Oracle provides support for the VirtualBox Remote Display Protocol (VRDP) in such an Oracle VM VirtualBox extension package.

VRDP is a backwards-compatible extension to Microsoft's Remote Desktop Protocol (RDP). As a result, you can use any standard RDP client to control the remote VM.

Even when the extension is installed, the VRDP server is disabled by default. It can easily be enabled on a per-VM basis either from VirtualBox Manager in the Display settings, see Display Settings, or with the VBoxManage command, as follows:

$ VBoxManage modifyvm VM-name --vrde on

By default, the VRDP server uses TCP port 3389. You will need to change the default port if you run more than one VRDP server, since the port can only be used by one server at a time. You might also need to change it on Windows hosts since the default port might already be used by the RDP server that is built into Windows itself. Ports 5000 through 5050 are typically not used and might be a good choice.

The port can be changed either in the Display settings of the graphical user interface or with the --vrde-port option of the VBoxManage modifyvm command. You can specify a comma-separated list of ports or ranges of ports. Use a dash between two port numbers to specify a range. The VRDP server will bind to one of the available ports from the specified list. For example, VBoxManage modifyvm VM-name --vrde-port 5000,5010-5012 configures the server to bind to one of the ports 5000, 5010, 5011, or 5012. See VBoxManage modifyvm.

The actual port used by a running VM can be either queried with the VBoxManage showvminfo command or seen in VirtualBox Manager on the Runtime tab of the Session Information dialog, which is accessible from the Machine menu of the VM window.

Oracle VM VirtualBox supports IPv6. If the host OS supports IPv6 the VRDP server will automatically listen for IPv6 connections in addition to IPv4.