ssh connection randomly times out

[SCOTT FIELDS]

Do you have keepalive configured in your base config? Matters if you have a stateful inspection firewall between your endpoints.
________________________________
From: openssh-unix-dev <openssh-unix-dev-bounces+scott.fields=kyndryl.com at mindrot.org> on behalf of Brian Candler <b.candler at pobox.com>
Sent: Friday, September 18, 2026 2:41 PM
To: James Moe <moe.james at sohnen-moe.com>; openssh-unix-dev at mindrot.org <openssh-unix-dev at mindrot.org>
Subject: [EXTERNAL] Re: ssh connection randomly times out

On 18/09/2026 19:12, James Moe via openssh-unix-dev wrote:
> opensuse tumbleweed
> OpenSSH_10.5p1, OpenSSL 3.5.3 16 Sep 2025
> linux 7.2.5-1-default x86_64
>
> I establish a connection to a remote host. After some random length of time
> (minutes, hours), the connection becomes unresponsive.

Idle time, or active time?


>   After a further period
> the connection is terminated:
>
> --[ termination text ]--
> Read from remote host sma-station12l: Connection timed out
> Connection to sma-station12l closed.
> client_loop: send disconnect: Broken pipe
> --[ end ]--
>
> This is a recent change. It would seem a timer has gotten involved in some way.
> Previously the connection stayed active forever. Obviously something changed.
> How do I diagnose the issue?

It's possible that something else has changed along the network path
which is interfering with the session, so could you first demonstrate
that the problem *doesn't* happen with an earlier version of OpenSSH?
What's the most recent release which is problem-free? Or if you're
really keen, do a git bisect to find the specific change (but I realise
this is tricky when the problem takes a long time to rear its head).

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