NT login problems

Corinna Vinschen vinschen@cygnus.com
Mon Jul 31 04:56:00 GMT 2000


I have just uploaded a patched version of login to sources.redhat.com.

There was a bad mistake in NT password authentication.

Sigh. I shouldn't upload on weekend...

Jens Yllman wrote:
>  I also have trouble with login after upgrading to 1.1.3 of cygwin1.dll.
> It worked earlier. And the funny thing is that if I run login and don't
> enter any password it say it's ok. The same if I connect through telnet.
> But if I do ftp it will work with the password and not without.
> 
>  Jens Yllman
> 
> Edmund GRIMLEY EVANS wrote:
> >
> > Is there some trick for getting passwords to work with NT? If I run
> > telnetd under Cygwin, I can connect, but my password is not
> > recognised. Similary if I run login. If I run passwd, it only asks me
> > for the new password ... then says it's incorrect!

Thanks to your description I have found an error in the passwd tool
which usually only affects admin users. In that case, a local variable
remained uninitialized. This will show up in the 1.1.4 version of Cygwin
which should be uploaded this week.
I'm wondering why that wasn't found much earlier since that tool wasn't
changed for months.
However, it's correct that you are not asked for the old passwd as
admin user. Otherwise you wouldn't be able to change other user's
passwords as admin.

> > Alternatively, is there some way of just bypassing NT's authentication
> > (which is presumably the cause of the problem) other than rebuilding
> > login with a back door?

No. If started inetd as user LocalSystem, you must give your password
since it's required to change user context.

If you want to bypass login, you would have to wrote your own (shell
script doing nothing but execing a shell for example),
as well as starting inetd under your user account so that the user
context is correct on startup.

This doesn't help for ftpd. In that case, you would need to rewrite
ftpd so that it doesn't use NT security.

Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Developer                        mailto:cygwin@sources.redhat.com
Red Hat, Inc.
mailto:vinschen@cygnus.com

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