From WSL2 to VirtualBox VM

Right now (April 2025) Microsoft permits to configure WSL2 in mirrored networking (and DNS Tunnelling) mode:

[wsl2]
networkingMode=mirrored
dnsTunneling=true

That's useful for access a webserver you run within your WSL2 instance in localhost from the host machine. E.g. a simple python webserver executed like this from the command line:

python -m http.webserver

it's accesible from a browser on the host machine at the address http://localhost:8000/.

But... What if you you are developing a webserver within your WSL2 instance and you needs to test this webserver within a VirtualBox VM?

A simple solution is:

1. check for the existance of a dedicated Host-Only Ethernet Adapter created by VirtualBox; its DHCP Server will use a IP/netmask and DNS configuration like this:

   IPv4 Address	192.168.99.1
   IPv4 Network Mask	255.255.255.0

   Server Address	192.168.99.50
   Server Mask	255.255.255.0
   Lower Address Bound	192.168.99.99
   Upper Address Bound	192.168.99.254

2. Install the Hyper-V Service, command line tool and GUI tools. Then following this guide we can create an external switch that use our existing VirtualBox Host-Only Ethernet Adapter.

3. that's the result with ipconfig from a powershell session:

   Ethernet adapter vEthernet (hyperv-to-virtualkbox):
   
   Connection-specific DNS Suffix  . :
   Link-local IPv6 Address . . . . . : fe80::aa:bb:cc:aaf%28
   IPv4 Address. . . . . . . . . . . : 192.168.99.1
   Subnet Mask . . . . . . . . . . . : 255.255.255.0
   Default Gateway . . . . . . . . . :

4. In the end it's possible the connect from the WSL2 instance to the VirtualBox VM like this:

   ssh [email protected]

Where 192.168.99.51 is the VM ip. See also this article about ssh forwarding.