SSH Xforwarding changing user accounts

Question

I am trying to make a script to install more or less automatically oracle database as well as some other application of my own. I haven't writen a line yet because I want to make all steps manually first.

So, my environment is the following. I have RHEL 5 with no graphic interface. I am connecting to the server from Windows laptop through SSH as root. I have enabled XForwarding, so when I login with root account I can run xdpyinfo so that I can check XServer configuration.

I need XForwarding because the Oracle DB installation procedure requires an XServer. However, Oracle requires the user oracle to perform the installation. I have already created the oracle user but when changing the user from root to oracle I can no longer run xdpyinfo command so the Oracle installation procedure fails. I get the following error:

Xlib: connection to "localhost:10.0" refused by server
Xlib: PuTTY X11 proxy: wrong authorisation protocol attempted
xdpyinfo:  unable to open display "localhost:10.0".

I have tried to use xhost to enable my laptop to access my server but I have failed as well to do that.

Answer 1

If you really feel the need to do this, then while you are root, get the current $DISPLAY value, particularly the first value after the colon, which is 10 in your case. Then find the current X authorisation token for your session:

xauth list | grep ":10 "

Which will give you something like:

hostname/unix:10  MIT-MAGIC-COOKIE-1  2b3e51af01827d448acd733bcbcaebd6

After you su to the oracle account, $DISPLAY is probably still set but if not then set it to match your underlying session. Then add the xauth token to your current session:

xauth add hostname/unix:10 MIT-MAGIC-COOKIE-1 2b3e51af01827d448acd733bcbcaebd6

When you've finished you can clean up with:

xauth remove hostname/unix:10

That's assuming PuTTY is configured to use MIT-Magic-Cookie-1 as the remote X11 authentication protocol, in the Connection->SSH->X11 section. If that is set to MDM-Authorization-1 then the value you get and set with xauth will have XDM-AUTHORIZATION-1 instead.

It might be simpler to disconnect from root and start a new ssh session as oracle to continue the installation, which would also make sure you don't accidentally do anything unexpected as root. Well, until you have to run root.sh, anyway.

If you do a silent install with a response file then you don't need a working X11 connection anyway; you just need $DISPLAY to be set, but nothing is ever actually opened on that display so it doesn't matter if xdpyinfo or any other X11 command would fail. I'm not sure how you're thinking of scripting the X11 session, but even if that is possible a silent install will be simpler and more repeatable.