VM in VirtualBox using unbound WiFi interface on host

I have a Linux host with 2 interfaces, a wired gigabit Ethernet and WiFi. Currently only the wired interface is connected. I wanted to experiment using WiFi interface by a VM guest in VirtualBox. There are various scenarios for this. I might want to test network routing by using the WiFi in conjunction with a smartphone offering tethering. Or access the Internet using from a VM on the desktop using the smartphone when the broadband connection is down.

The short answer is yes, this is eminently possible. The key points to take away are that, 1. the host has to configure the WiFi interface, i.e. load the appropriate driver and authenticate to the access point but not assign an IP address to it, and 2. the guest has to use bridging to access the host's WiFi interface. In fact it will appear to be a wired interface to the guest. All the usual IP configuration methods are available, static or DHCP, depending on what the access point allows. Also note that the MAC address seen by the gateway will be the MAC of the guest, not the MAC of the WiFi interface.

It's the wireless switch, stupid

A friend of mine asked to see why a HP Mini 5101 netbook with Ubuntu Karmic on it wouldn't connect to a WiFi AP. As far as I could see the best advice was to install bcmwl-kernel-source, which contains a non-GPLed driver and has to be compiled into a non-free kernel module. But I could not get it to see any APs.


Since the release of Ubuntu Lucid is imminent, I suggested trying Lucid Beta2 on it and then installing the official release after April 29. It would provide a netbook remix and LTS install too. (The Karmic install was a vanilla desktop install, not the best use of the small screen.) Installing off a USB memory stick was painless and fast. I connected it up to a wired network and did:

apt-get install bcmwl-kernel-source

That did all the setup required. But it still wouldn't connect to any APs. Wait a moment, I thought, how do I know if the RF transceiver is turned on or not? I remembered that many notebooks come with a RF kill switch. An examination of the keyboard showed no such function key. Time to do an Internet search. Sure enough, there is a RF kill switch, and it's on the front edge. See the first picture in this photo review. If the RF is on, the LED glows blue.


After flicking the switch on, all the neighbourhood APs were visible in NetworkManager. Duh, that will teach me to at least glance through the manual before installing.


And thank you HP for making a RF kill switch that looks so much like a lid latch. (Sarcasm.)