Yes, you can run virtual box on liinux server, no issue. Please follow below steps -
1. You have to download the virtual box on your system and run the installer.
2. Once done then downoad the Ubuntu download page. You can install the long-term version or ltest version. It is recommended that you should install the long term version for the best result.
3. .iso file gets downloaded with the installation.
4. Next step is to setup the Virtual machine.
5. Launch the virtual box and after that proceed with the new configuration of new virtal box. You can keep all values as it is. Just you wll need to update the name,type and version.
6. Virytal box is ready now, you have to install the OS on it. Install Ubunt on it. Enter the correct details for the below values.
Hostname: hostcom†(or another all-lower-case network name for your server).
User full name: Your full name (e.g. Jay McGavrenâ€).
Username: Your user name, which should be short, one word, and all lower case (e.g. jayâ€).
Password: Enter and confirm a password. Remember it, because you'll need it to log in or run administrative commands on the virtual machine.
Write partition changes to disk: No†will be selected by default; choose Yesâ€.
Write to disk (again): No†will be selected by default; choose Yesâ€.
Software selection: standard system utilities†will be selected by default, so just hit Enter. Other packages you need should be installed using the apt-get program later.
GRUB boot loader: The default choice is actually the correct one on this screen, but to avoid confusion: The installer will confirm this is the only operating system on this computerâ€. And it is the only operating system on this virtual machine. So go ahead and choose Yesâ€.
7. Now, connect to your virtual box vai SSH using port 22.
Hope tis will help you.