First, remove any definitions for the DISPLAY environment variable from any profile...
The correct value will be set by sshd when the login is successful.
IF there is no DISPLAY environment variable after login, then you are not running the X server on your workstation OR the machine you are logging in on has forwarding disabled (look in /etc/ssh/ssd_config to see if "X11Forwarding" has the value "no". If the line is commented out, then the value shown should be the compiled default, and you have to put a line "X11Forwarding yes" in, and restart the service).
The only time the :10 is valid is:
1. when the sshd_config file specifies an offset of 10(X11DisplayOffset) for the first connection - this is the default, but other values are possible.
2. this is the first connection.
After that the correct value can be 11, 12, 13... And those can occur for several reasons (usually network or client related). If the client system for instance gets rebooted the previous connection may still not have timed out and closed... thus the new connection would get 11.
Next, make sure the sshd_server has "X11UseLocalhost" enabled (otherwise you won't be allowing "localhost:nn" to be a valid display). This the usual value is "yes".
Last edited by jpollard; 12-23-2014 at 02:26 PM.