Bug in remote gui app execution via cygwin sshd

Harmon Nine hnine at isis.vanderbilt.edu
Thu Apr 28 01:44:43 EST 2011



Platform:   Windows XP

Package:   Cygwin openssh


There appears to be a bug in the ssh-daemon in version 5.8p1-1 of the

openssh package for cygwin.  The bug does not present itself on systems

sshd from the 5.1p1-10 version of cygwin openssh.


The bug is as follows:

A remote system R has Cygwin sshd running from version 5.8p1-1 of

openssh.  The daemon is running as a service, configured using

Further, the service is running under the "Local System account", and in

its properties as a service, "Allow service to interact with desktop"

has been checked.


A user on a local machine logs into R using ssh.  Then, in the resulting

shell, the user executes a gui app such as notepad.  On the remote

machine R, what appears on the display, rather than the gui for the

notepad app, is a rectangular area with what appears to be a title-bar

at the top, although what this bar contains is a long white or

multi-colored rectangle.   The "window" itself displays the contents of

what was behind it when it was spawned, and keeps displaying this when

moved.  Beyond the ability to move it, the rectangle is non-functional.


If R is running sshd from version 5.1p1-10 of cygwin openssh, with the

configuration, a functional notepad app is spawned.


This doesn't appear to be due to any windows updates, as we have updated

all of our machines recently.  Those with 5.8p1-1 have the bug, and

those with 5.1p1-10 do not.


Any help/information is appreciated.


-- Harmon


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