VirtualBox Host-Only Networking

VirtualBox allows one to configure a VM with host-only networking. This can be useful if you are connnecting a number of VMs together and need to put them on the same switch/bridge.

However, it's darn frustrating to figure out how to enable it as all of the googling and manuals indicate you just enable it by selecting settings within the VM.

What they fail to mention though (but is covered in the built-in help in VirtualBox), is that you must first create a device for this host-only networking to use. From the main VirtualBox window, choose Preferences (below the File) menu. That will bring up the global preferences for the VirtualBox hypervisor. Click "Network" and then the "+" sign to add a host-only network device (typically vboxnet0).

It's possible that some versions of VirtualBox create one of these at install time, but on Ubuntu, such is not the case. Now you can create a number of virtual machines and put them on the same nic. Your host OS will also now show that same nic. Here's an example from my laptop's OS:

medberry@handsofblue:~$ ip a show dev vboxnet0
6: vboxnet0: mtu 1500 qdisc pfifo_fast state UNKNOWN qlen 1000
    link/ether 0a:00:27:00:00:00 brd ff:ff:ff:ff:ff:ff
    inet 192.168.56.1/24 brd 192.168.56.255 scope global vboxnet0
    inet6 fe80::800:27ff:fe00:0/64 scope link 
       valid_lft forever preferred_lft forever
medberry@handsofblue:~$ 

and that same vboxnet0 is now an option when you select host-only networking in the vm: