xauth au "su -" issue

[Dominique Deleris <dominique.deleris@bluewin.ch>]

Hello,

I am trying to allow access to my X server to anyone connected
locally on my machine. I know that I can "xhost +" to allow
unlimited connections, but I've read about the file /etc/X0.hosts
which may contain the list of allowed hosts to access display :0

So I've created a /etc/X0.hosts file, which contains the entry
"localhost". OK, fine.

But now, when I am in an xterm as my standard user, and type in
"su -", then "export DISPLAY=:0", I always get error messages :
Xlib: connection to ":0.0" refused by server
Xlib: No protocol specified
Error: Can't open display: :0.0

The only way to avoid that is to issue a "xhost +" before suing.

It works fine with simple "su", but I need to have a login shell.

Is it a bug? What do I miss?

I am running Sarge.

Thank you,

Dominique

PS : I already know about "ssh -X -l whoever localhost", my
question is about this xhost issue.