Fwd: SSHD not connecting from outside(real) IP

Adam Dinwoodie adam@dinwoodie.org
Mon Jan 4 23:12:00 GMT 2016


On Mon, Jan 04, 2016 at 06:05:32PM -0200, João Paulo wrote:
> Hello all,
> I have a mystery and I need help. I have openssh(Cygwin) installed
> and working just fine in here.
> I can connect normally from any of my machines to the server using
> local IPs. Ex: ssh localhost or ssh 192.168.0.2. BUT, when using my
> external IP(over internet->real IP) it times out.
> I can validate that the service is up and running on
> http://www.canyouseeme.org/ on the port FW I did for this service.
> Port 22 is correctly FW to my SSHD server. On windows, I can only
> see an entry on Security Events(attached) and nothing else after
> that. (Means it is reaching my machine)
> I have tried to reinstall Cygwin, change ports. sshd_config is in
> default, disable firewall, AV. I ran out of ideas......
> I had this working fine on previous window 7, now I am on Windows 10.
> Thanks.

To check I'm understanding you correctly: you're using Cygwin on your
Windows 10 machine to run an sshd service, you're attempting to connect
to this using SSH from another machine, this works when the other
machine is within your local network but not when the other machine is
external.

If that's the case, I think it's very unlikely that Cygwin is the
problem  -- if Cygwin were the problem, I would expect connections to
fail on your local network too.  To check that, can you run a packet
capture on the system running Cygwin sshd while you attempt to connect?
I expect it will show no received packets, which means the problem lies
elsewhere in your network.

For packet capture I normally use Wireshark, but alternatives are
available (doing it on your router would be ideal if it supports that).

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