Force VirtualBox VMs to use Tor.

Virtual machines are a great tool to run untrusted piece of software. Most of the time, the default networking configuration uses a bridge to allow VMs to communicate. One caveat about this approach is that both VMs and the host will be able to access the same network (like my personal trusted LAN for instance…), something that I definitely don’t want.

Multiple solutions exist to isolate the untrusted VMs from the host LAN. One of them uses VirtualBox, Tor and Whonix, and is pretty quick to set up.

Whonix_Logo.png

Whonix is an OS designed to run as a set of VMs with pre-installed and configured applications. Among other features, it also uses Tor for every network connection thanks to Whonix-Gateway, a VM used as a gateway from Whonix VMs to the Tor network.

However, please note that UDP traffic won’t work due to Tor limitations. DNS queries will use Tor DnsPort on the Whonix Gateway to avoid leaks.

  • Download Whonix-Gateway (look for Download Whonix-Gateway link),
  • Download the associated signature, and the SHA512 file (also provided with its signature),
  • Check them both,
  • On VirtualBox, simply import the .ova downloaded above with File > Import Appliance,
  • Leave the default settings untouched, read and agree the agreement,
  • Start Whonix-Gateway VM and follow the initial instructions,
  • You may want to activate the auto-update when prompted,
  • For the VMs you want to redirect the traffic, go to Settings, Network and select Internal Network. Set Whonix as name.

Once Whonix-Gateway has been configured, you get the following network configuration:

auto eth1
iface eth1 inet static
address 10.152.152.10
netmask 255.255.192.0

Thus, you can assign your VMs in the range 10.152.152.10 /18. For instance, the following configuration is used for my first VM:

IP: 10.152.152.11
Mask: 255.255.192.0
Gateway: 10.152.152.10
Primary DNS server: 10.152.152.10

All traffic will now be isolated from your host LAN, and will only use Tor (including DNS queries). In order for this setup to work, whenever you want to connect one of your VM, the Whonix-Gateway has to be up.
A visit on check.torproject.org from inside a VM using Whonix-Gateway tells that I am using Tor but not Tor Browser.

Please note that this setup should not be trusted to provide serious anonymity guarantees but only to isolate untrusted VMs from my LAN and hide my public facing IP from them.