Hi, i have the same problem, i can't open gedit.
I connect to CentOS server with Putty with enabled X11 forwarding.
I tried to use Cygwin X or Xming, didn't help.
In Putty i do:
- export DISPLAY='IP of local station:0.0'
- xhost+
But after that - error: cannot open display.
I installed all X packages (xorg-x11-xauth, xorg-x11-fonts-*, xorg-x11-utilsxorg, etc).
X11Forwarding options is 'Yes' in /etc/ssh/sshd_config on CentOS server.
In /etc/hosts:
127.0.0.1 localhost localhost.localdomain localhost4 localhost4.localdomain4
IP-address-of-server hostname
What is wrong? Help pls.
I looked in the Internet all advices to solve the issue, but nothing helped.

Have you installed an X server on your Windows machine? Which one?
Disclamer: I've never understood how to connect a remote client to X on a server. (or why one would want to)

Consider: Rather than using gedit, install WinSCP and SciTE on the Windows PC. WinSCP can open remote files into SciTE, which is an excellent text editor for scripting/programming.

For remote management SSH and a text editor as VIM is all you ever need. Works reliably over thousands of miles, even if there is slow internet connection somewhere in the way.

gedit it is just example. i can't launch gui apps. Oracle DB doesn't launch too.

This is how it works. Your local box must accept incoming X connections, local X server must be listening on port 6000. The xhost command has to be run in local box, not remote. How it all works in Windows - I have no clue. I do not run Windows, never will.

On the local box I use multiple users and one X session. And this is my method of sorts.

$ startx -- :0 -dpi 100 -to 10 -nolisten tcp -retro -depth 24 -layout MultiHead

$ xhost local:

$ su - otheruser

$ export DISPLAY=":0"

$ xcalc

I would imagine that the X on the server has something like "-nolisten tcp" which disables remote X services. Various Xephyr and Xdmx ways to get things going. Assuming linux to linux. Otherwise vnc, x2go, and other methods might prove simpler. If I'm fiddling with Xdmx or other things I drop the "-nolisten tcp" option so that ssh -X and stuff works. Not that I've done any remote X stuff in recent history.

ssh -X works even if X server is not listening.