Virtual Box guest additions do not install per default. We do have to manually install them as outlined here:
In a non-GUI (server) guest we may not need the guest additions if we do not need additional features provided with them (e.g. support for USB2). Then we simply do not install the guest additions that come on an .iso image installed on the host after installing the virtualbox-guest-additions-iso package there with
user@host:$ sudo apt-get install virtualbox-guest-additions
When having installed the version from the Oracle repository (see this question) the guest additions .iso is installed on the host by default.
Installing guest additions is done from an install script on the .iso to compile and insert the kernel modules provided. Mounting the .iso image can be done from their location on the host, or alternatively by installing the guest additions .iso from the Ubuntu repository with
user@guest:$ sudo apt-get --no-install-recommends install virtualbox-guest-additions
We should not install recommends in the guest to avoid installing virtualbox-ose package too.
Note that the guest-additions version from the repositories may be of an earlier version than Virtual Box when installed from Oracle. This will likely work but it is not recommended.
After having installed the kernel modules guest additions .iso can be removed from the guest OS. To uninstall guest additions from the guest we may remove the kernel modules manually, or run the
uninstall.sh script located in