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Re: cygwin sshd dumping stack trace when not allocating pseudo-tty


On 8/21/2013 6:42 AM, Thorsten Glaser wrote:
On Tue, 20 Aug 2013, Larry Hall (Cygwin) wrote:

On 8/20/2013 4:32 AM, Thorsten Glaser wrote:
On Mon, 19 Aug 2013, Larry Hall (Cygwin) wrote:

and to understand the method you're using to login.

SSH public-key auth, that is, RSA keys. (This is a requirement
because the process will run as batch job so we cannot use any
interactive auth method.)

Understood but method 2 and 3 allow for this as well.  They use a
very different way of "getting there".  One of these two methods
could work for you.

Hm. I must admit Iâm a bit confused here, but AIUI if thereâs a
problem with logging in (the auth method or that the home directory
is on the domain controller), then I should be unable to login with
SSH key, without password, interactively, too â right?

As things stands:

ssh-key interactive â works
password interactive â works
ssh-key batch â doesnât work (-T, running a command, scp, rsync)
password batch â works

There's definitely a different path being taken here and the authentication
isn't "keeping up" in the failing case.  Putting 'sshd' in debug mode may
shed some light on why this is a problem in this particular installation.
But to re-iterate my point, in case your main goal is just to find a
way that works, methods 2 and 3 use different techniques to accomplish
the same thing.  For method 2, you have a different token, so if
authenticating with a created token is causing a problem, this could help.
Method 3 avoids all impersonation token issues by simply using password
authentication.  So this one seems like it should work based on your
current testing.

It's telling you that cmd.exe doesn't understand UNC paths.  And that
actually gives me an idea.  Can you create a local home directory

Hmm. When I login using ssh-key interactively, I get this:

tglase@tglase:~ $ ssh cygbox
Last login: Tue Aug 20 10:21:46 2013 from tglase.lan.tarent.de
tglase@cygbox:~$ pwd
//dc/tglase

So why would it work interactively but not in batch mode?

I'm saying cmd.exe is complaining, not the shell.  But if you really want
to understand how you get the message you're seeing in the batch case, I
recommend setting up 'sshd' in debug mode, enabling verbosity on the SSH
session, and turning on echoing of all scripts run by the shell.  This
will give you allot of output but also provide more context for the
messages you see.  That should help you narrow down where the complaint
is coming from.

and run ssh-user-config again to see if that helps?  If so, you can
either continue to use this configuration or try method 3.

Other things I noted:

   1. You're running cygwin 1.7.9.  The current version is 1.7.24.  You
      should upgrade.

I cannot âjustâ change things like this on the system unless
itâs known that not doing so fixes a problem (actually, the
system isnât even normally mine to administer, Iâm just helping
out).

That's your choice but also it puts you into the category of an unsupported
installation.  Looking at it another way, how can you determine whether a
newer version helps address a problem if you don't try it?

   2. Your CYGWIN environment variable contains "sshd".  You should
      remove this.

Iâve got no idea where this is set; running a cygwin or CMD.EXE
doesnât set $CYGWIN or %CYGWIN%, respectively, at all.

Must be part of the service settings in the registry then.

--
Larry

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