Virtual LAN over Wireless LAN: Get the Wireless Routing Going in Virtualbox

Virtualbox definitely has it’s fair share of networking chaos that makes it rather difficult to quickly set up the networking options and get it right the first time. The various networking modes that it gives you are tailor made for very particular scenarios with very precise conditions that must be met – and not to mention, some very annoying exceptional circumstances to boot. It’s a big jumble and if you need a good primer to get you at least somewhere on the way, I suggest that you read this:

https://blogs.oracle.com/fatbloke/entry/networking_in_virtualbox1 [Very nice and easy read. With pics 🙂 …]

and, this:

http://www.virtualbox.org/manual/ch06.html [The manual itself – with almost all the gory details explained.]

To cut the long story short, I needed to test some security tools in a wireless environment where I need 2 virtual machines, the host machines and any other machine on the host machine (wireless) network to all be in communication at the same time, i.e, more or less on the same LAN, or at most one hop away through a single router.  I need to easily (and seamlessly) switch between communication with the virtual machines, the host itself and physical machines on the host’s LAN – and also get to the Internet. The physical LAN is actually a Wireless LAN, and well the Virtual LAN, is … well … virtual (Physical or Wireless, it’s hard to tell). Is that all too much to ask (even as an early Christmas present) from the almighty Virtualbox?

Well, it seems it’s more difficult that it actually seems. None of Virtualbox’s networking modes seems to support this scenario out of the box (No pun intended 😛 ). I’m pretty sure there are many people who are looking for this kind of thing to work: Virtual machines to talk to each other, the host and other devices on the host’s WLAN. The closest thing is using NAT with port-forwarding, but i didn’t like that solution because it’s rather limiting in terms of getting several things on several different ports to get through without having to manually configure the ports.

Something that could have been close to the ideal situation would have been if Virtualbox could support bridging with the physical host’s Wireless interface. (There are probably several other “almost” solutions, but none working yet).

The main problem it seems is that Virtualbox – on it’s own – does not support actual routing – or at least from the little testing done, it doesn’t seem to do any serious routing – whether in NAT, bridged adapter mode, host-only adapter or internal network mode. Routing between the physical LAN that the host is on

The Solution:

What worked for me was the luck that my Virtualbox environment was actually running on a Windows 7 host that supports a rather nifty tool called the Microsoft Virtual Miniport Adapter – something that seems to have hived off from a previous Virtual Router project. The idea is that it allows the Windows 7 user machine to easily act as a Wireless Router… and perhaps share the Internet connection also.

So the thing is that I shared the Internet Connection of the host machine (and thereby the connection to the Host Machine’s Wireless LAN, Wired Lan, etc) with the Microsoft Virtual Miniport Adapter (i.e Virtual Router). This creates a bridge between the physical wired/wireless LAN to this “Virtual Wireless Router.”

(Now comes the beautiful part …)

In Virtualbox, if one uses the Bridged Adapter mode and bridges the virtual machines to the respective “Microsoft Virtual Miniport Adapter”/ Virtual Router … Hey presto! Magic happens! Suddenly the virtual machines are able to route traffic towards the host itself as well as towards any other machine on the host’s network … and onwards to the Internet – if the host network is connected to the Internet.

Suddenly, the problem that Virtualbox cannot (as of  yet: Sept 2012) support bridging to the host’s Wireless Adapter, is suddenly alleviated. All the pent up tension is relieved  … absolute carthasis, and a sense of relaxation follows. It works!

🙂 A step-by-step “How-to” guide will follow in the next post. 🙂