X11 forwarding comes in handy from time to time. For example, say you want to use virt-manager to work with KVM VMs on your lab machine but want to do it from your Mac (ahem).

Yeah, if you didn’t gather it already, by “you”, I mean “me”. 😉

The one main issue with this very specific above scenario is that virt-manager will more than likely require some sort of root-level privileges, and neither the ~/.Xauthority file, nor the DISPLAY or XAUTHORITY environment variables survive sudo escalation.

The manual fix is pretty easy though. Before escalation, run xauth list to get the session data.

The output looks like:

$ xauth list
localhost.localdomain/unix:99  MIT-MAGIC-COOKIE-1  aabbccddeeffgghh00112233445566

Take the second line (which is the session data). Then, after getting root (sudo su - works great), run xauth add with the session data:

xauth add localhost.localdomain/unix:99  MIT-MAGIC-COOKIE-1  aabbccddeeffgghh00112233445566

This will create the ~/.Xauthority file and aforementioned environment variables.

We are now able to run X11 apps as root!

Shout out to Backdrift for the source.