Cygwin/X server -query fails with recent versions of Gnome GDM

[Jon TURNEY]

On 30/09/2009 10:34, Richard Evans wrote:
> Cygwin 1.7beta, cygcheck output attached.
>
> I am trying to start a remote session using:
>
> XWin -query host
>
> where the host is running GDM from Gnome 2.28.  The connect fails.   A
> wireshark network snoop (attached) shows that GDM is sending

Thanks for the packet capture, that helps a lot understanding what's happening 
here.

> X_ChangeHosts requests with an address family of 5 (ServerInterpreted)
> and a address like
>
> 	localuser:root
>
> XWin responds with a BadValue error and the connection attempt fails.  I
> speculate that XWin was compiled without support for the
> ServerInterpreted address family.

I don't think this speculation is well-founded. :-)

So GDM is doing the equivalent of:

$ xhost +si:localuser:root
$ xhost +si:localuser:gdm

... which fails, I'm guessing for the not entirely unreasonable reason that 
these users don't exist.

> I cannot find a workround for this.

You might try adding users root and gdm in your cygwin installation (perhaps 
by adding them to /etc/passwd)

If that works around the problem, I think it's probably a bug in GDM that it 
fails if these users don't exist.

Even after reading the manpage formerly known as Xsecurity ('man 7 security') 
and the source, I'm really not clear about how this form of credentials are 
supposed to work, but it seems pretty clear that they can only work locally.

Note that a server built with NO_LOCAL_CLIENT_CRED (or old enough to pre-date 
these credentials) will reject all si:localuser and si:localgroup credentials, 
so it seems GDM should be prepared for it to fail...


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