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RE: Unable to run sshd under a domain sshd_server account [SOLVED]
On Mon, 12 May 2008, Igor Peshansky wrote:
> On Mon, 12 May 2008, Schutter, Thomas A. wrote:
>
> > > -----Original Message-----
> > > From: Igor Peshansky
> > > Sent: Monday, May 12, 2008 4:30 PM
> > > To: Schutter, Thomas A.
> > > Subject: RE: Unable to run sshd under a domain sshd_server account
> > [SOLVED]
> > >
> > > On Mon, 12 May 2008, Schutter, Thomas A. wrote:
> > >
> > > > > -----Original Message-----
> > > > > From: Schutter, Thomas A.
> > > > > Sent: Monday, May 12, 2008 9:52 AM
> > > > > To: 'cygwin@XXXXXX.XXX'
> > >
> > > <http://cygwin.com/acronyms/#PCYMTNQREAIYR>.
> > >
> > > > > Subject: Unable to run sshd under a domain sshd_server account
> > > > >
> > > > > I am having problems setting up sshd to run under a domain
> > > sshd_server
> > > > > account instead of a local sshd_server account.
> > > > > [snip]
> > > > > But when I login via ssh:
> > > > > $ echo $USER
> > > > > tschutter
> > > > > $ echo $USERNAME
> > > > > sshd_server
> > >
> > > Yes -- Windows does not understand user impersonation and does not
> > > allow real user switching. So what sshd does is invoke processes with
> > > the appropriate token privileges for the user it's impersonating,
> > > while updating internal Cygwin data structures, but still running as
> > > sshd_server. So Cygwin sees the right user (in its internal state),
> > > but Windows processes, of course, don't.
> >
> > Interesting. I suspected this, but this is the first time that I have
> > seen this explicitly stated.
>
> Well, at least Windows processes don't understand the Cygwin notion of
> effective UID, which is why $USERNAME and $USER don't match (one is set by
> Windows, and the other by a Cygwin process -- bash).
>
> > > > > The application event log has this error message:
> > > > > The description for Event ID ( 0 ) in Source ( sshd ) cannot be
> > > > > found. The local computer may not have the necessary registry
> > > > > information or message DLL files to display messages from a remote
> > > > > computer. You may be able to use the /AUXSOURCE= flag to retrieve
> > > > > this description; see Help and Support for details. The following
> > > > > information is part of the event: sshd: PID 2068: service `sshd'
> > > > > failed: signal 11 raised.
> > >
> > > Oops -- a segfault. This is definitely a bug somewhere -- no matter
> > > what, sshd should not segfault.
> >
> > Agreed.
>
> Those problems are usually very hard to reproduce. If you're set up to
> build a debug version of sshd and run it under gdb to reproduce the fault,
> a stack backtrace would be helpful.
>
> > > > In the other thread, Larry Hall pointed me to the FAQ
> > > > http://cygwin.com/faq/faq-nochunks.html#faq.using.shares. One of the
> > > > suggestions was to "provide your password to a net use command". I
> > > > was unable to make that work, because "net use" never asks for my
> > > > password:
> > > > $ net use \\other\f$
> > > > System error 67 has occurred.
> > > >
> > > > The network name cannot be found.
> > >
> > > See "net help use":
> > > The syntax of this command is:
> > > NET USE
> > > [devicename | *] [\\computername\sharename[\volume] [password | *]]
> > > ...
> > > password Is the password needed to access the shared
> > > resource.
> > > * Produces a prompt for the password. The password is
> > > not displayed when you type it at the password
> > > prompt.
> > >
> > > So, you need to type "net use '\\other\f$' \*" (note the
> > escaped/quoted
> > > '*'), and it'll prompt you for the password.
> >
> > OK. So on a console cygwin shell:
> > $ net use '\\other\f$'
> > The command completed successfully.
> >
> > But when run in a ssh shell (using the sshd_server account):
> > $ net use '\\other\f$' \*
> > Type the password for \\zoom\f$: System error 1326 has occurred.
> >
> > Logon failure: unknown user name or bad password.
>
> Umm, yes. Sorry. I forgot that sshd runs in a pty, which is a pipe as
^^^^
the ssh remote session
> far as Windows is concerned. And 'net' cannot read the password from a
> pipe...
>
> > Same thing happens with:
> > $ net use '\\other\f$' '*'
> > $ net use '\\other\f$' "*"
>
> Actually supplying the password instead of '*' should work.
> Igor
--
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ZZZzz /,`.-'`' -. ;-;;,_ Igor Peshansky, Ph.D. (name changed!)
|,4- ) )-,_. ,\ ( `'-' old name: Igor Pechtchanski
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Torah; the rest is commentary. Go and study it." -- Rabbi Hillel
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