xauth(1) says: /if [the X server] does not support the SECURITY extension, the [generate] command fails./
The xauth command is used to generate the .Xauthority file, which is required for X11Forwarding. But the Security Extension is not enabled by default: - - xcsecurity : Build Security extension but I don't find anybody asking why X11 forwarding doesn't work under gentoo. What am I missing?