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Date:      Wed, 21 Jun 2023 15:26:52 -0400
From:      Cheng Cui <cc@freebsd.org>
To:        bob prohaska <fbsd@www.zefox.net>
Cc:        freebsd-net@freebsd.org, freebsd-arm@freebsd.org
Subject:   Re: -current dropping ssh connections
Message-ID:  <CAGaXuiKK7Zh2gFqtFGdZ_H%2BX-2y8CWZU2Jq1HOvc8b=CFy-Wiw@mail.gmail.com>
In-Reply-To: <ZJMyPquk32fXhT%2BI@www.zefox.net>
References:  <ZJMyPquk32fXhT%2BI@www.zefox.net>

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>
> There don't seem to be any error messages on the console at all, the
> client
> session simply reports
> client_loop: send disconnect: Broken pipe
>

Have you tried SSH keepalive?
https://stackoverflow.com/questions/25084288/keep-ssh-session-alive

Best Regards,
Cheng Cui


On Wed, Jun 21, 2023 at 1:24=E2=80=AFPM bob prohaska <fbsd@www.zefox.net> w=
rote:

> I've got a Pi4 running -current that seems to selectively drop ssh
> connections.
>
> Connections running a shell seem to stay up, but a session running tip to=
 a
> usb-serial adapter (FTDI TTL232R-3V3) seems go away within a few hours.
> There don't seem to be any error messages on the console at all, the
> client
> session simply reports
> client_loop: send disconnect: Broken pipe
>
> Searches through /var/log/sshd_debug.log find many transactions between
> the ssh client and the -current target host, but none seem to be error
> messages; all are either connection reports or disconnects by user.
>
> This sort of behavior has been intermittent with aarch64 among both
> the Pi4 and a pair of Pi3s for some time, but now only the Pi4 is
> dropping connections.
>
> I've tried searching /var/log/sshd_debug.log for the keywords tip,
> ucom, the IP address of the NAT client used to connect and cuaU0.
> Are there other things worth looking for?
>
> Right now I'm using in /etc/rc.conf the line
> sshd_flags=3D"-E /var/log/sshd_debug.log"
> which is already quite verbose. Is there a better
> option that emphasizes errors over normal traffic?
>
> Thanks for reading,
>
> bob prohaska
>
>
>
>

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<div dir=3D"ltr"><blockquote class=3D"gmail_quote" style=3D"margin:0px 0px =
0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir=
=3D"ltr">There don&#39;t seem to be any error messages on the console at al=
l, the client <br>
session simply reports <br>
client_loop: send disconnect: Broken pipe</div></blockquote><div dir=3D"ltr=
"><br></div><div>Have you tried SSH keepalive?</div><div dir=3D"ltr"><a hre=
f=3D"https://stackoverflow.com/questions/25084288/keep-ssh-session-alive">h=
ttps://stackoverflow.com/questions/25084288/keep-ssh-session-alive</a><div>=
<div dir=3D"ltr" class=3D"gmail_signature"><div dir=3D"ltr"><div><br></div>=
Best Regards,<div>Cheng Cui</div></div></div></div><br></div><br><div class=
=3D"gmail_quote"><div dir=3D"ltr" class=3D"gmail_attr">On Wed, Jun 21, 2023=
 at 1:24=E2=80=AFPM bob prohaska &lt;<a href=3D"mailto:fbsd@www.zefox.net">=
fbsd@www.zefox.net</a>&gt; wrote:<br></div><blockquote class=3D"gmail_quote=
" style=3D"margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);=
padding-left:1ex">I&#39;ve got a Pi4 running -current that seems to selecti=
vely drop ssh connections.<br>
<br>
Connections running a shell seem to stay up, but a session running tip to a=
<br>
usb-serial adapter (FTDI TTL232R-3V3) seems go away within a few hours. <br=
>
There don&#39;t seem to be any error messages on the console at all, the cl=
ient <br>
session simply reports <br>
client_loop: send disconnect: Broken pipe<br>
<br>
Searches through /var/log/sshd_debug.log find many transactions between<br>
the ssh client and the -current target host, but none seem to be error<br>
messages; all are either connection reports or disconnects by user.<br>
<br>
This sort of behavior has been intermittent with aarch64 among both<br>
the Pi4 and a pair of Pi3s for some time, but now only the Pi4 is<br>
dropping connections. <br>
<br>
I&#39;ve tried searching /var/log/sshd_debug.log for the keywords tip,<br>
ucom, the IP address of the NAT client used to connect and cuaU0.<br>
Are there other things worth looking for?<br>
<br>
Right now I&#39;m using in /etc/rc.conf the line<br>
sshd_flags=3D&quot;-E /var/log/sshd_debug.log&quot;<br>
which is already quite verbose. Is there a better<br>
option that emphasizes errors over normal traffic?<br>
<br>
Thanks for reading,<br>
<br>
bob prohaska<br>
<br>
<br>
<br>
</blockquote></div></div>

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