I got following error message when I try to run KVM Virtual Machine Manager: virt-manager on SSH.

Gtk-WARNING **: cannot open display:

There are several things need to be checked:

• Make sure “X11Forwarding” is set to “yes” in /etc/ssh/sshd_config on the machine you run virt-manager.

  cat /etc/ssh/sshd_config | grep "^X11"

• If you are using Windows to connecting SSH. The X11 need to be forwarded to an “X Window server” on top of Windows. I use xming.
• If you connect SSH by Putty on Windows. Please configure X11 forwarding.
  • Go to “Connection” -> “SSH” -> “X11“.
  • Check “Enable X11 forwarding“.
  • Assign xming.exe path in “X authority file for local display“.
• If you are using terminal on Mac OS. You need to install Xquartz. It configures terminal automatically.

Now you are ready to use “virt-manager“.