On 12/26/2019 02:47 PM, Gordon Messmer wrote:> On 12/25/19 6:56 AM, H wrote:
>> I have tried to make sure the sshd configuration on all servers are
identical but still have this problem. I can rule out a general problem with the
router in my office since all connections are via that router, the only
difference is that the problematic server is in the same building and the
connection loops back via the same router but through an external IP address.
>
>
> When you say "external address," I assume you mean that your
office network is being NATed.? In that case, when you are connecting to systems
outside your network, the router is performing SNAT for your connections.? When
you connect to the system in your building, using an "external"
address, your router is probably performing both SNAT and DNAT for that
connection. Your router may have different timeouts on its SNAT and DNAT
tables.? More than likely, the timeout for DNAT is lower than the TCP keepalive
time, and you're seeing idle connections closed by the router.? You might be
able to prevent that by setting a ServerAliveInterval value in ~/.ssh/config.?
It is disabled by default, but should keep connections alive in your case, if it
is set lower than the timeout on the router.
>
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I now have additional information:
- I could not find any entries in /var/log/secure on the server either that
related to disconnections.
- I am also being disconnected while doing ssh transfers, thus not only when the
session is idle. No set time intervals but often as quickly as within 10 minutes
after establishing the ssh connection.
- Further - which I forgot to mention - when I connect from my workstation back
to server on the same router using Cisco AnyConnect software terminating far,
far away and then thus going back to same router, I have no problems with being
disconnected when the connection is idle. Thus no general problem with the
router or the hardware on the server itself.
- Finally, today I for the first time connected to the server using the internal
192.168.x.x. address and have after several hours of idle session not been
disconnected.
Are my observations above still consistent with your hypothesis?