13

I'm having an annoying problem.

When I'm logged in to a specific host via SSH, the message

X11 connection rejected because of wrong authentication.

occurs three times seemingly random about once a minute. I have no idea where it comes from.

Actually, there is not even any slight problem with X11-forwarding, it works like a charm. But this message keeps appearing and it's driving me crazy.

Does anyone have an idea how to get rid of it?

I'm facing the problem no matter where I'm coming from, it happens from my Gnome-Desktop and also from a Windows-system using PuTTY, MobaXterm, Cygwin, whatever.


After twiddling some more I found the cause to be a monitoring-agent (check_mk). This checks some runtime-parameters of running tasks, the message appeared every time, when this agent was triggered from the monitoring-system, exactly when PostgreSQL-status is checked. It seems this process tries to open an X11-connection but fails. The message is then spit over into my terminal-session as it tried to use my forwarded X11-session.

Is there a way to disable this message at all?

18

Make sure you are not running out of disk space

Run df and make sure you have sufficient disk space, if you are low on disk space remove unnecessary files from your system:

$ df -h

If there are quotas imposed on the file systems, check that you did not exceed your quota:

$ quota -s

Make sure ~/.Xauthority owned by you

Run following command to find ownweship:

$ ls -l ~/.Xauthority

Run chown and chmod to fix permission problems [replace user:group with your actual username and groupname]:

$ chown user:group ~/.Xauthority
$ chmod 0600 ~/.Xauthority

Make sure X11 SSHD Forwarding Enabled

Make sure following line exists in sshd_config file:

$ grep X11Forwarding /etc/ssh/sshd_config

Sample output:

X11Forwarding yes

If X11 disabled add following line to sshd_cofing and restart ssh server:

X11Forwarding yes

Make sure X11 client forwarding enabled

Make sure your local ssh_config has following lines:

Host *
ForwardX11 yes

Finally, login to remote server and run X11 as follows from your Mac OS X or Linux desktop system:

ssh -X user@remote-host.com

Credit for information belongs here: http://www.cyberciti.biz/faq/x11-connection-rejected-because-of-wrong-authentication/

Hope that helps.

  • I read that, but as there is actually no problem starting X11-applications those steps were not appliable. However, in the meantime I found the cause of the problem and will update now. – Christian Oct 19 '14 at 13:49
  • As mentioned, this is not relevant in this case. The problem is not that my attempt to forward an X11-connection fails. The problem is that another user tries to use my X11-Forwarding and that the message is spit over to my active terminal session what I don't want. The question is "Is there a way to disable this message at all?". – Christian Oct 21 '14 at 11:28
  • I updated my answer for a user that asked for it then removed his comment after. For your question try disabling wall access to all but root(assuming that process isn't being run by user root):$ sudo chmod g-s /usr/bin/wall $ echo foo | wall – devnull Oct 21 '14 at 12:21
  • I issued "mesg n" what supresses wall-messages, but still kept getting those :( – Christian Oct 21 '14 at 12:50
  • If that process is executed by root then you would. Root can't be surpressed. If that is the case, create a 'monitor' or whatever user and move the monitoring and such to be executed by that user and then you won't see those messages anymore because it won't be from root. – devnull Oct 21 '14 at 13:23
4

It could be untrusted X11 forwarding timeout. Using the ForwardX11Timeout option with a large timeout may help, as suggested in https://bugzilla.mindrot.org/show_bug.cgi?id=1718 (I got this problem in the past, but IIRC, it disappeared after some upgrade).

  • Unfortunately not, also when I explicitly set ForwardX11Trusted yes in /etc/ssh_config. – Christian Oct 19 '14 at 13:34
2

If you have SELINUX enforcing, and your home directory is not under the /home directory, that is your problem. Targeted SELINUX settings assume all user home directories are under /home, so xauth doesn't work correctly because the SELINUX type on your home directory is not correct. I wish I could recommend a fix, but the one I found did not work. I set SELINUX to permissive to get around this problem.

0

Try to set this and it works for me:

X11UseLocalhost yes

reference: https://medium.com/@toja/using-x11-apps-in-mac-os-x-c74b304fd128

0

Install XQuartz on mac if required and login directly with the user. Example - While installing oracledb I was trying to login with root and then running the command from oracle user after sudo su - oracle.

Login directly with oracle ssh -X oracle@hostname

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