virtualbox.org

I'm trying to run VirtualBox on a headless whitebox running Ubuntu Server, but there's one thing which has stumped me - the lack of bridged network settings under Preferences/Network. The only tabs available are 'NAT Networks' and 'Host-only Networks'.

Have I missed some configuration?

Post the guests log file ( as an attachment ). Compress if it is too large to post.

There's' no guest log file because I haven't configured any guests yet. Shouldn't I be able to configure the virtual network settings before that?

Sure but without a log to show why it is all but impossible to know why. Unless you have some other diagnostic information that we can look at.
Since you are running headless it may just be that you have not configured it to have one. Are you using some 3rd party application to configure this with?

APT to install VirtualBox from the repository, and X11 forwarding to run VirtualBox for the initial configuration.

If you think it'll help, I'll make a guest VM with a NAT network adaptor and send the log.

Which repository? The Ubuntu one or VirtualBox?

I also don't know how you can forward X11 from the server unless you installed Xorg.

Yes, the Ubuntu repository.

Then you need to ask Ubuntu because we don't support their fork. Or you can remove theirs and install the official version from virtualbox.org.