I have been having the following problem lately:
When I run an X app under su in a terminal, I get the following error:

Xlib: connection to ":0.0" refused by server
Xlib: Client is not authorized to connect to Server
kedit: cannot connect to X server :0.0

In this case, I tried to run kedit to edit a file without having to log out and back in again as root, but the problem occurs with any program which uses X. I have found in other places that the command xhost +localhost removes this problem temporarily, but I would like to know if it is possible to make it go away for good.

I am running debian, with XFree4 and KDE 3.1
Any help would be most appreciated
Guy

# Allow root to use X
xhost +local:
su -
export DISPLAY=:0.0

Unfortunately this does not work.
Again, it temporarily fixes the problem, but once I restart the X server, it no longer works.

If you want it to be automatic, put it in your .bashrc, .bash_profile or your .xinitrc or other X init file you might use. Then it activates on log-in.

You have to do root's command in root's .bashrc, IIRC. I think there is a posting about it in the hints thread in my sig.

I put roots command in .bashrc, and the other command in my init files, but still it doesn't work. Sorry to be a pain.

Perhaps debian sources another file rather than the .bashrc in the home directory.

Does it work if you command:

source ./.bashrc

If the DISPLAY variable is set to

yourhostname.yourdomain.COM:0.0

rather than just :0,

then you will need to issue the command

xhost + yourhostname.yourdomain.COM

before issuing the su - root command.

If the HOST variable is correctly set to your host name then you can just
do

xhost + $HOST

but note that if HOST is not set, then the above becomes

xhost +

which allows anybody on any machine anywhere who can connect to your machine access to your display.

The xhost + local: only enables non networked local connections from the localhost.

Automatically disabling the access control from the local machine is a BAD thing, since it enables any other user logged in on your machine to mess about with your DISPLAY and even run a program to see your screen and capture keystrokes (including the keys pressed for the root password when you su).

And if you say, "Oh this is on my home machine, and I am the only user" then remember that "Security begins at home" and habits, bad or good, formed there will be transferred to multi user machines in the business place.