ssh over stunnel hangs on second connection
cygwin@kosowsky.org
cygwin@kosowsky.org
Fri Feb 16 23:46:17 GMT 2024
Andrew Schulman via Cygwin wrote at about 09:36:58 -0500 on Friday, February 16, 2024:
> Hi. I'm the stunnel maintainer for Cygwin. I don't know why stunnel would hang
> as you describe, but I'll try to help.
>
> I agree that your configuration of ssh over TLS is common - I used it myself for
> years. However as matthew patton suggests, there are other ways to get the same
> goal, that may let you work around this problem.
>
> One possibility that matthew didn't mention, is to run your ssh server on port
> 443, and connect directly to it with ssh - no TLS wrapper. Yes, that's
> non-standard, but if you can live with that, it might work fine for you and be
> simpler. My best understanding is that ssh and TLS are indistinguishable to an
> application firewall.
I actually ran SSHD over 443 (technically, had my router port forward
443 to 22 on my server) for about 15 years.
But then I started finding some corporate and airline networks would
use DPI to block non-ssl packets on 443 which would block SSH.
This is the reason I went to SSH over SSL/stunnel to get around such
DPI and it has worked fine for the past 5+ years.
I only noticed the current problem when I moved to a new Win11 laptop
along with upgraded Cygwin...
>
> But supposing you keep your current configuration. Can you please clarify how
> you're invoking stunnel? Do you have a ProxyCommand directive in your
> .ssh/config, like:
>
> ProxyCommand /usr/bin/stunnel stunnel.conf
No... I just ssh to 'localhost' on the port that per stunnel.conf is
listening for client connections.
This works fine in Ubuntu and has worked fine for me before on
Win7/Win10.
I don't use any fixed ProxyCommand to invoke stunnel because the vast
majority of the time I just use straight SSH -- I only use 'stunnel'
when SSH is blocked.
> or is it some other way? I ask this because with ProxyCommand as above, you
> should get a separate stunnel process for each new ssh connection, and I can't
> think why they would interfere with each other.
>
> Andrew
>
>
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