Troubleshooting AutoSSH

Andrew Schulman schulman.andrew@epamail.epa.gov
Fri Jul 12 19:18:00 GMT 2013


> On Fri, 12 Jul 2013, Andrew Schulman wrote:
> 
> > Hi Lee.  Okay, that does seem to narrow it down.
> >
> > You're right that autossh doesn't have any ipv4 options.  It hasn't been
> > updated in a few years, and I think it's just not ipv6-aware yet.
> >
> Looks like it may not be autossh - if I start sshd with a default config,
> it works [ssh localhost], .. if I try ssh -4 localhost, nada!
> 
> It looks like *sshd* can only bind IPV6 - forcing it to bind IPV4 only
> prevents startup.

OK.  So does it work then to pass the -6 flag to ssh?

If sshd is only accepting ipv6, then it may be autossh's port monitoring
feature that's broken.  It uses ssh to forward some ports of its own, and
that feature might be ipv4-only.  You can turn it off by passing -M0 to
autossh.  Does that fix the problem?

If that does fix the problem, then it's not a very good solution, because
you've had to disable autossh's monitoring of your connection.  So it won't
know if your connection has stopped passing traffic, in order to restart
it.  But at least we'll have a well-defined bug to report upstream.

Andrew


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