RE: Unable to run sshd under a domain sshd_server account [SOLVED]

["Schutter, Thomas A." <tschutter@proxix.com>]

> -----Original Message-----
> On May 12 18:29, Igor Peshansky wrote:
> > 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.
> 
> That's not correct.  This problem cropped up on the list a lot
already.
> When not using password authentication, Cygwin has to create a user
> token from scratch.  The resulting processes are running under a
normal
> user token with correctly set user and group ownership.

Except that is not what I am seeing.  When I run "id" from a console
cygwin shell:
  $ id
  uid=18718(tschutter) gid=10513(Domain Users)
groups=544(Administrators),545(Users),10513(Domain
Users),18169(FDSV-GG-PrxBLD),22611(FDSV-GG-PrxPCAdmins)

But when I run "id" from a ssh shell:
  $ id
  uid=18718(tschutter) gid=10513(Domain Users)
groups=545(Users),10513(Domain Users)

So when I am using pubkey authentication, the user token is not a member
of the "Administrators", "FDSV-GG-PrxBLD", or "FDSV-GG-PrxPCAdmins"
groups.

> What's missing
> is a logon session for this user because only a LSA authentication
> module can do that.  As a result, the processes of the new user are
> running in the logon session of the user running sshd.  And here's the
> problem.  For some reason, the appropriate Windows functions like
> LookupAcccountSid identify the user token's user SID incorrectly as
the
> user who's owning the logon session.  And that's all:  The connection
> SID <-> Username is broken.  The token itself is ok.  Usually that's
> not a big deal, except that some WIndows application stumble over
that,
> like some Visual Studio stuff.


> The way to fix this is to use a special LSA authentication module
which
> will be available with the next major release of Cygwin.
> 
> 
> Corinna

--
Tom Schutter
First American - Proxix Solutions
(512) 977-6822


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