Date: Mon, 26 Jun 2023 19:00:08 -0700 From: bob prohaska <fbsd@www.zefox.net> To: Jamie Landeg-Jones <jamie@catflap.org> Cc: freebsd-net@freebsd.org, freebsd-arm@freebsd.org Subject: Re: -current dropping ssh connections Message-ID: <ZJpCqCVzcMGIruMU@www.zefox.net> In-Reply-To: <202306222238.35MMcoQm017939@donotpassgo.dyslexicfish.net> References: <ZJMyPquk32fXhT%2BI@www.zefox.net> <E84D47F1-4E75-4DA1-8EE2-3E2F36DF0EF1@yahoo.com> <ZJM7VXyWotSGwAtH@www.zefox.net> <202306212305.35LN5ITH069587@donotpassgo.dyslexicfish.net> <ZJR5FzEEFofoh8f1@www.zefox.net> <202306222238.35MMcoQm017939@donotpassgo.dyslexicfish.net>
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On Thu, Jun 22, 2023 at 11:38:50PM +0100, Jamie Landeg-Jones wrote: > bob prohaska <fbsd@www.zefox.net> wrote: > > > That seems worth a try. > > The notion of an ssh escape (~. in this case) finding its way into the data stream is new to me. > > Thinking again, that looks like corruption coming down the ssh connection. > For the ssh escape char to affect anything (note it needs to be preceeded > by a new line) it would have to be sent up the line. > > For an example, assuming ssh has the default escape char, look at the difference between: > > printf 'pwd;\n~.;echo sleeping.; sleep 5' | ssh -tt user@host > > and with the same printf, but no escape char: > > printf 'pwd;\n~.;echo sleeping.; sleep 5' | ssh -tt -e none user@host > > You can see how the former closes the connection due to the \n~. > > (The -tt forces a terminal/interactive session to be set up - normally, as we are > piping input to ssh in this case, the terminal isnt set up, and the escape character > isn't used - it's only recongnised in interactive sesions by default) > > I personally have "EscapeChar none" in my ssh_config, but I suspect this > is probably not the issue here, still, can't hurt to try it! Indeed, connection was dropped with escape character set to none. There does seem to be a some dependence on system load. Connections survive at light or no load and drop when the sshd side is busy. Thanks for writing! bob prohaska
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