The day that time stood still

No, it’s not about that episode of “Supercar” from 1962. It’s about why running stock Xen-enabled Ubuntu 2.6.22 x86_64 kernel is generally a Bad Idea™: So, you log into your dom0 on your regular Ubuntu compute cluster just to find out that all your users’ passwords have expired and the kernel is greeting you with messages from the distant future (Mon Apr 29 03:21:20 EET 2301 in that particular case)::

X11 forwarding with "X11UseLocalhost no"

Just a quick tip. If you’ve ever tried to run sshd with the option X11UseLocalhost set to no (e.g. in a cluster environment where interactive jobs running not on the login node should be able to display something), you might have observed that X11 forwarding suddenly stops working. And although the $DISPLAY is set accordingly and xauth list shows that authentication tokens are present, X clients still can’t connect: hristo@cn001:~$ echo $DISPLAY cn001:10.