CentOS 7 Minimal Installation on Hyper-V: X11 forwarding using Xming and PuTTy error, xhost: unable to open display ":0.0"

Question

Before telling me that there are a lot of post relates to X11 forwarding error, let me put you in context of the things that I have done:

I have installed the following packages:

yum install -y xorg-x11-app*
yum install -y xorg-x11-server-utils
yum groupinstall -y 'X Window System'
yum install -y xorg-x11-xauth xorg-x11-fonts-* xorg-x11-utils xterm
yum -y groupinstall fonts

Also I uncommented the following setting in/etc/ssh/ssh_config

X11Forwarding yes

On my Windows 8 PC, I ran Xming. Then I checked "Enable X11 forwarding" on PuTTy, and set the X display location to ":0.0". Then I opened PuTTy again and connected to my virtual machine. Then I ran the following:

xhost +
export DISPLAY=:0.0
xclock

This is the resulting error:

Error: Can't open display: :0.0

Does somebody have an idea what I am doing wrong or what else do I need to fix that problem? Let me tell you that I have done this before but only for CentOS 7 Desktop Installation and it wasn't hosted on a Hyper-V VM.

Thanks in advance.

Solution

export DISPLAY=:0.0

Don't do that. If ssh is forwarding X, then it will set the DISPLAY variable to the correct value. You're overriding the correct value with ":0.0", which is not the correct value here.

The DISPLAY value ":0.0" means to connect to the default X display running on the same computer. So you're telling your X programs to connect to an X server running on the remote computer (and probably displaying on the remote computer's screen).

If you check, you'll probably find that DISPLAY is already set to "localhost:10" or something similar. That value tells your X applications to connected to the port which SSH has set up to receive forwarded X connections.

As for this:

xhost +

xhost sets access permissions for your X display. It's almost certainly unnecessary for you to run it here, and you're opening your display up for someone else on the network to connect to your display. Don't run this unless you know that it's necessary.

Comments

[Jakuje]

why do you do export DISPLAY=:0.0?

[Mario Echeverría]

I need to Install Oracle 11g, and I want to test in Putty If I am able to display the GUI wizards, and I found on many tutorials that they set DISPLAY to that values.