Odd XDMCP problems

[Harold L Hunt II]

Mike,

Mike Campbell wrote:

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> Here is an odd one for you to try to help me figure out.
> 
> I have configured my RedHat Linux 9.0 system to allow XDCMP connections.
> When I reboot the server the console comes up with the default kdm login
> box.
> 
> ~From my win2k machine I have installed all of the cygwin Xfree tools. I
> used the startxdmcp.bat file (after editing it for the remote_address
> parameter) and it successfully connects to the linux box and I see the
> login dialog box. So far so good.
> 
> Initally when I would log in the cygwin screen would turn light blue and
> then after 5 seconds or so the login box would reappear and a message
> about my session lasting less than 10 seconds. I found on the linux
> machine where I was logging in the following in the .xsession-errors file:
> 
> set:  unable to open display ":0.0"
> xsetroot:  unable to open display ':0.0'
> xrdb: Connection refused
> xrdb: Can't open display ':0.0'
> startkde: Starting up...
> ksplash: cannot connect to X server :0.0
> _KDE_IceTransmkdir: Owner of /tmp/.ICE-unix should be set to root
> kded: cannot connect to X server :0.0
> kdeinit: Can't connect to the X Server.
> kdeinit: Might not terminate at end of session.
> kcminit: cannot connect to X server :0.0
> knotify: cannot connect to X server :0.0
> ksmserver: cannot connect to X server :0.0
> startkde: Shutting down...
> startkde: Running shutdown scripts...
> KLauncher: Exiting on signal 1
> startkde: Done.
> 

Looks like you might need the -from MY_IP_ADDRESS command-line parameter 
in startxdmcp.bat for XWin.exe.  Although, this doesn't make a lot of 
sense because you probably wouldn't even get the login screen if the 
from address wasn't being set correctly.

> I then edited the /etc/kde/kdm/Xstartup file on the linux machine and
> added a line that said 'xhost +' and restart the X server on the linux
> machine.
> 

The xhost + is not the answer.  Please remove that line or accept the 
security risks that it has, even though it is providing you with no benefit.

I think the real problem here is that XDM on your linux machine is not 
setting the DISPLAY variable correctly.  The output from the log file 
shows this:

 > xsetroot:  unable to open display ':0.0'

:0.0 means to connect to the local machine on display 0, screen 0.  That 
is typically the console.  This is obviously incorrect, since you need 
all X Clients to connect to the X Server running on your Windows machine.

> For some odd reason my DISPLAY from the xdmcp session seems incorrect.
> It should set DISPLAY to point back to the cygwin xfree server instead
> of the linux console. How do I fix this???

I have never, ever, heard of anyone reporting this problem before where 
the DISPLAY is not getting set correctly by the XDM server (again, 
unless you just need the -from parameter as mentioned above).  Can we 
assume that this RedHat 9.0 installation is 100% non-modified or have 
people had their hands on it, "customizing" it?  If the installation has 
been heavily customized, then I think that someone made a mistake in one 
of those customizations.  If the installation has not been heavily 
customized, then perhaps you could do some searching to find out if this 
a generic problem for RedHat 9.0.

Hey, I have an idea... why don't you try opening an XDMCP session to 
your RedHat 9.0 machine from another *nix machine.  That would help 
determine if Cygwin/XFree86 or the RedHat machine configuration is at fault.

Harold