title: Cannot use Vagrant and Virtualbox in network namespace
body: <p>We have VMs defined in Vagrant that are used both for development (IDE etc) and for running integration tests. The integration tests take very long and can leave the VMs in a broken state. Also, Vagrant and Virtualbox's global state prevent me from running and debugging integration tests for different parameters in parallel.</p>
  <p>Thus I'm trying to create isolated environments for the integration tests. I created an isolated home folder and a network namespace and called <code>vagrant up</code> in that environment. I get</p>
  <pre><code>Command: [&quot;hostonlyif&quot;, &quot;ipconfig&quot;, &quot;vboxnet12&quot;, &quot;--ip&quot;, &quot;192.168.60.1&quot;, &quot;--netmask&quot;, &quot;255.255.255.0&quot;]
  
  Stderr: VBoxManage: error: The host network interface named 'vboxnet12' could not be found
  </code></pre>
  <p>When I open the VirtualBox GUI from the new namespace and then &quot;Host Network Manager&quot;, I see no interfaces. When I try to create one, it calls it <code>vboxnet13</code>. In my default network namespace, there exist <code>vboxnet1</code> to <code>vboxnet12</code>. So it seems my isolation is not good enough and virtualbox in the custom network namespace somehow seems to be aware of the interfaces in the default namespace, but cannot use them. I wonder what is missing to successfully isolate Vagrant + Virtualbox.</p>