Cygwin sshd broken by seemingly trivial network change

[Charles Russell]

On 12/17/2020 3:09 PM, Brian Inglis wrote:

> Have you checked your new router to see what default rules are enabled
> there?

The router firewall is disabled. (I have a another router serving as a 
firewall between it and the modem.) Besides, all hosts are on the local 
side of the new router, and disabling the Windows firewall eliminates 
the problem.
_____________________
On 12/17/2020 3:23 PM, Bill Stewart wrote:
>
> If it works when you disable the firewall, then (to state the obvious,
> sorry) there is a rule in the firewall that is blocking the traffic.

So far so good.

> I would suggest to examine all of the rules carefully. I say this
> because it is happened to me before, and I could have sworn that I
> looked at all of the rules.

I've looked at
   Advanced Settings; Incoming Rules
and I've looked at the output of
   netsh advfirewall firewall show rule name=all

What else is there to look at in Windows 7 Home?

This is doubly frustrating because Cygwin sshd has been running properly 
for 10 years on one of these computers and 8 years on the other. Perhaps 
I should reset the firewalls to default, but that will break other things.
____________

On 12/17/2020 3:24 PM, Erik Soderquist wrote:

> I've had weird instances where the Windows Firewall tools lied; I
> confirmed this by temporarily shutting down the Windows Firewall
> entirely, then restarting the service having problems and retesting.
> On retest, it worked fine, confirming it was the firewall causing the
> problem.

I didn't have to restart sshd; I could connect as soon as I disabled 
Windows Firewall.

>
> What exactly the problem was varied (this has happened many many times
> to me)...  In some cases it was the rule definition for the scope not
> matching the actual network, in some cases I could not find any real
> issue, but deleting and recreating the rules fixed the issue, in a few
> cases, I also found a deny rule that somehow matched the service
> having problems, and deny rules take precedence over allow rules.  One
> example of the conflict could be "sshd allowed" vs "port 22 denied";
> the deny would take precedence.

I don't see any way to set port rules in Windows 7 Home, and none are 
visible in the list of incoming rules.

I could not delete sshd, only disable it, even as administrator. (The 
delete button was grayed out).  I disabled it, rebooted, then enabled 
it. That didn't help.