WSL2 and Wireguard

WSL2 and Wireguard

[Ruben Di Battista]

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?

-- 
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-'       `'
https://rdb.is

Re: WSL2 and Wireguard

[Jason A. Donenfeld]

Hi Ruben,

On Mon, Nov 23, 2020 at 5:43 PM Ruben Di Battista
<rubendibattista@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

Re: WSL2 and Wireguard

[Ruben Di Battista]

Ehi Jason!

Thanks for the detailed answer. I just checked on the new 0.3 and the
problem still persists. I'm not a network engineer, but I think it
might be useful if you can provide more details in the Github issue
(or the one I link in the second comment) that could help speed up the
process...

I guess it's a problem with their hyper-v networking adapter...

On Mon, Nov 23, 2020 at 5:51 PM Jason A. Donenfeld <Jason@zx2c4.com> wrote:
>
> Hi Ruben,
>
> On Mon, Nov 23, 2020 at 5:43 PM Ruben Di Battista
> <rubendibattista@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



-- 
          _
-.     .´  |∞∞∞∞
  ',  ;    |∞∞∞∞∞∞
    ˜˜       |∞∞∞∞∞∞∞∞∞ RdB
    ,.,    |∞∞∞∞∞∞
  .'   '.  |∞∞∞∞
-'       `'
https://rdb.is

Re: WSL2 and Wireguard

[Jason A. Donenfeld]

On Mon, Nov 23, 2020 at 8:53 PM Ruben Di Battista
<rubendibattista@gmail.com> wrote:
>
> Ehi Jason!
>
> Thanks for the detailed answer. I just checked on the new 0.3 and the
> problem still persists. I'm not a network engineer, but I think it
> might be useful if you can provide more details in the Github issue
> (or the one I link in the second comment) that could help speed up the
> process...

If I can figure out more details, I'll post them. Right now I have
mostly speculation and haven't started dissecting WSL2's networking
quirks. I have subscribed to that issue though.