The VirtualBox online-manual writes “Forwarding host ports < 1024 impossible…”. This tutorial shows that it is still possible. I know that there are several reasons not to do so, but there are also reasons where it is necessary.
Conditions
VirtualBox with VM configured (not running)
You know the root password
Example for Ubuntu
# become root
$ sudo su -
# start VirtualBox Manager
$ virtualbox
Now you probably need to import the VM. Attention! The acces rights will be changed!
Port Forwarding
Configure or just check the port forwarding. To do so, you can use the graphical port forwarding editor or even the command line (VBoxManage).
# switch into default VirtualBox directory
$ cd VirtualBox\ VMs/
# create new VirtualBox VM
$ VBoxManage createvm --name "Win10x64" --ostype Windows10_64 --register
# configure system settings of VM
$ VBoxManage modifyvm "Win10x64" --memory 2048 --cpus 2 --acpi on --pae on --hwvirtex on --nestedpaging on
# configure boot settings of VM
$ VBoxManage modifyvm "Win10x64" --boot1 dvd --boot2 disk --boot3 none --boot4 none
# configure video settings
$ VBoxManage modifyvm "Win10x64" --vram 128 --accelerate3d on
# configure audio settings
$ VBoxManage modifyvm "Win10x64" --audio coreaudio --audiocontroller hda
# configure network settings
$ VBoxManage modifyvm "Win10x64" --nic1 nat
# configure usb settings
$ VBoxManage modifyvm "Win10x64" --usb on
# create storage medium for VM
$ VBoxManage createhd --filename ./Win10x64/Win10x64.vdi --size 30000
# modify a storage controller
$ VBoxManage storagectl "Win10x64" --name "SATA" --add sata
# attache storage medium to VM
$ VBoxManage storageattach "Win10x64" --storagectl "SATA" --port 0 --device 0 --type hdd --medium ./Win10x64/Win10x64.vdi
# add windows iso
$ VBoxManage storageattach "Win10x64" --storagectl "SATA" --port 1 --device 0 --type dvddrive --medium /path/to/windows.iso
# add guest addition iso
$ VBoxManage storageattach "Win10x64" --storagectl "SATA" --port 2 --device 0 --type dvddrive --medium /path/to/VBoxGuestAdditions.iso
# start VM
$ VBoxManage startvm Win10x64
You can now begin the installation. Do not forget the Guest Additions! After successful installation and configuration, you can remove the unnecessary media.