Graphical applications use the host X server as display through a tap interface created by marionnet-daemon, so the host X server must:
- accept tcp connections
- allow your client to connect
Most distributions disable both for security reasons, here is how to change them:
exec /usr/bin/X11/X -nolisten tcpto:
exec /usr/bin/X11/X #-nolisten tcp
$ sudo xhost +
WARNING: these changes allow everybody to connect to your X server, so we suggest not to use them as your default!!!