WSL2 and Wireguard

[Jason A. Donenfeld]

Hi Ruben,

On Mon, Nov 23, 2020 at 5:43 PM Ruben Di Battista
<rubendibattista at gmail.com> wrote:
>
> Hello,
>
> I'm experiencing a problem with Wireguard and WSL2. If I activate my
> tunnel and then I ping a machine on the VPN IP range from WSL2, I
> don't get any response.
>
> However, if after activating Wireguard, I ping from cmd or PowerShell,
> I successfully get the ping back and I'm able then also to ping from
> WSL2.
>
> I'm not sure if this is related to Wireguard or WSL2, In any case I
> reported the bug here: https://github.com/microsoft/WSL/issues/5810
>
> Is it a problem of my machine, a problem from WSL2 or Windows Wireguard?

That's pretty weird. I've seen a few related bugs like that, where it
seems like WSL will drop packets that don't meet some unusual stateful
criteria. I don't know if they're trying to do some kind of connection
tracking, or if the routing logic is partially broken for NdisMediumIP
devices.

I assume you're experiencing this using the latest WireGuard 0.3 [1]?

To answer your direct question, though, I think this might be a WSL
problem rather than a WireGuard problem. If that Github issue doesn't
get any attention after some time, I can try to reverse engineer the
hyper-v networking drivers to see what's going on, but as always with
that kind of thing, no guarantees on its success.

Jason

[1] https://lists.zx2c4.com/pipermail/wireguard/2020-November/006075.html