Steven M. Bellovin wrote:
> I upgraded my laptop and a desktop to yesterday's -current.  I'm
> now having trouble running certain X applications over ssh.
> 
> The laptop uses XFree86 4.4.0; the desktop uses xorg.
> I did not upgrade X on either machine.  If I log in from my desktop
> to my laptop via ssh (with X forwarding -- it's all done by scripts
> that haven't changed), I can't fire up (for example) exmh, acroread5,
> or psi.  With the first two, the startup fails completely.  I get
> 
> X Error of failed request:  BadAtom (invalid Atom parameter)
>   Major opcode of failed request:  18 (X_ChangeProperty)
>   Atom id in failed request:  0x182
>   Serial number of failed request:  137
>   Current serial number in output stream:  138
> 
> with acroread5 (via Linux emulation, of course) and
> 
> X Error of failed request:  BadAtom (invalid Atom parameter)
>   Major opcode of failed request:  18 (X_ChangeProperty)
>   Atom id in failed request:  0x184
>   Serial number of failed request:  12
>   Current serial number in output stream:  15
> 
> for exmh (native).  
> 
> psi is rather weirder -- I get lots of mesages like this, every few
> seconds:
> 
> X Error: BadWindow (invalid Window parameter) 3
>   Major opcode:  2
>   Minor opcode:  0
>   Resource id:  0x40
> 
> but it fires up.  (The messages continue while psi is running.)  When
> I exit, I get 
> 
> X Error of failed request:  BadWindow (invalid Window parameter)
>   Major opcode of failed request:  2 (X_ChangeWindowAttributes)
>   Resource id in failed request:  0x40
>   Serial number of failed request:  20747
>   Current serial number in output stream:  20767
> 
> On the other hand, I can fire up some X applications, such as xterm
> and xwininfo.  I can run xmms successfully, but when it exits it says
> 
> Gdk-ERROR **: BadAccess (attempt to access private resource denied)
>   serial 2977 error_code 10 request_code 102 minor_code 0
> 
> I didn't see any such problems with exmh or psi when only the laptop
> was upgraded, which tends to implicate something on the desktop.
> But I haven't a clue what the problem might be.  (Local psi runs
> just fine on the desktop; both run just fine locally on the laptop.)

This is caused by a new feature in OpenSSH 3.8 and above that makes 
clients using the ssh tunnel 'untrusted' for the X Security extension. 
This denies them access to some resources in the X server.

Until clients are fixed to work correctly in untrusted mode, a 
workaround is to use the -Y ssh option instead of -X, or use 
'ForwardX11Trusted yes' in ssh_config.


-- 
					Matthieu