I have recently switched from Ubuntu to Win8 as my basic system. As RoR development under Win is a suicidal practice, I have decided to install Ubuntu on virtual machine (Oracle VM Box).
I want the guest Ubuntu network services (in particlar, LAMP&Rails server services) to be visible for host + guest OS should have access to the internet. Luckily, VirtualBox provides an easy method to accomplish this target in a few steps using secondary host-only network interface.
Install guest OS using default NAT network interface.
Keeping the VM turned off, configure according to your preferences the host-only network interface in VirtualBox (File->Preferences->Network in VirtualBox main window). Then add the host-only adapter as a secondary network interface for guest OS.
Configure guest OS to use static IP on secondary network interface.
Edit hosts file in host OS. In case of Windows 8, open notepad as administrator and edit %systemroot%\system32\drivers\etc\hosts appending the following line (GUEST_IP MOCK.DOMAIN) as in the example below:
Now you can easily access the guest network services (WWW, SSH, FTP etc.) from your host OS. You can find a comprehensive description of the host-only network layer provided by VirtualBox on slides published by Alex Hahn.