You didn’t read the magazine article carefully. As the magazine says,
Guest Additions need to be installed inside the VM, not on your host OS.
The scripts are to be run in the guest OS, and are included in the guest addition CD. Insert this CD to your guest OS by clicking Devices -> Insert Guest Additions CD image… in Virtual Box.
Also, the article’s method is outdated, just like the magazine’s comment says, install this on your guest OS
Another way to install the guest additions is to enable the rpmfusion-free repo and install them as any other package:
sudo dnf install https://download1.rpmfusion.org/free/fedora/rpmfusion-free-release-(rpm -E %fedora).noarch.rpm
$ sudo dnf install VirtualBox-guest-additions
What you really need for your host OS is Oracle’s VirtualBox Extension Pack, which is proprietary (subject to VirtualBox_PUEL – Oracle VM VirtualBox), and must be downloaded from VirtualBox’s website (not rpmfusion): Downloads – Oracle VM VirtualBox. This is not needed for basic function of VirtualBox, but as you said you want to connect hard disk through USB,
I can’t attach any external drive to my virtual machine (I have three connected, two HDDs and a thumbdrive), none are detected in the machine settings:
then it’s necessary because this Extension Pack provides USB 2.0 and USB 3.0 ability.
Is it mandatory to install
Extension Pack and
Guest Additions for the machine?
Yes, it is, for USB 2.0/USB 3.0 ability.
My suggestion: qemu/kvm. It is a trully FOSS alternative, and can be easily controlled by virtmanager (
sudo dnf install virt-manager). Also, you don’t have to insert out-of-tree kernel modules from virtualbox, it’s in the kernel main tree. One drawback is that virtmanager does not provide easy guest integration like sharing files between guest and host (well, at least for non-linux guest; you can share filesystem for linux guest), which is pretty inconvenient. But as for USB qemu/kvm does it pretty well, no extra packages needed.