Fedora Core 14. I logged in as root from SSH and imported the WHOLE environment from logged-in user's gnome-terminal:
export $(cat /proc/`/sbin/pidof gnome-terminal`/environ | tr '\0' '\n' | egrep -v 'PS1|LESS|GDM_KEYBOARD_LAYOUT' | tr '\n' ' ')
XAUTHORITY is valid and readable. DISPLAY is correct.
# xset led81
No protocol specified
xset: unable to open display ":0.0"
What's more to be done to access local X server? SELinux enforcement is off.
Update: When I also su to user that gnome-terminal it starts working. How to connect from other user?