X11 forwarding request failed on channel 0


When trying to connect via ssh to a CentOS 6 server to invoke a GTK+ application, I received this message.
$ ssh root@ -X
root@'s password:
X11 forwarding request failed on channel 0
Last login: Thu Apr 12 08:15:43 2012 from

After double check on my client Arch linux the /etc/ssh/ssh_config file and corroborate that “ForwardX11 yes” was uncommented, began to search the web for a bug in CentOS’s openssh.

Firsts impressions and answers said that it was my openssh client’s fault… then I installed putty, enabled X11 Forwarding and tried again. Now it connected without saying nothing but when I tried to open the graphical application, it said this
# system-config-lvm
Unable to initialize graphical environment. Most likely cause of failure is that the tool was not run using a graphical environment. Please either start your graphical user interface or set your DISPLAY variable. Caught exception: could not open display

So it wasn’t openssh’s fault as someone said. Doing a bit more of research gave me the correct answer. Finally I found a bug on CentOS 5 bugzilla where is explained in detail.

My problem was that xorg-x11-xauth wasn’t installed on my system (I did a minimal instalation). By installing xorg-x11-xauth and rebooting the server (until I did, it did not work), it connects without problems by typing

$ ssh root@IP_ADDRESS -Y

I tried with the -X parameter instead -Y, but it gave me some problems. With -Y it works like a charm!


10 thoughts on “X11 forwarding request failed on channel 0

  1. malevolent

    Hi @TrinitronX,

    What OS are you using as client? Ubuntu perhaps?

    That “AddressFamily” workaround sound to me to a issue with ubuntu.
    Isn’t it the other potential solution you mentioned, to corroborate you have xauth installed in your system?


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