topic Re: unable to display remote X traffic in Operating System - Linux

unable to display remote X traffic

Rick Garland — Thu, 03 Mar 2005 18:29:46 GMT

Hi all:

Fedora Core 3 on an intel system.

I was provided this system and it has all packages loaded (don't ask me why, I didn't do it)

I am unable to display remote X traffic on my linux system from HPUX systems. I am setting xhost +, exporting my DISPLAY on the HPUX, have my linux firewall turned off, SELinux is permissive.

I am stumped - any more ideas out there?

Many thanks!

Re: unable to display remote X traffic

Jan Sladky — Fri, 04 Mar 2005 08:06:27 GMT

Hi Rick,

seems like your display manager is blocking
x connection

on SUSE it's in

/etc/sysconfig/displaymanager

DISPLAYMANAGER_XSERVER_TCP_PORT_6000_OPEN="yes"

if you are using GDM, there is option to enable it in settings on welcome screen

rgds Jan

Re: unable to display remote X traffic

Bryan Eley — Fri, 04 Mar 2005 08:13:52 GMT

Rick,

Do you ssh to the HPUX machine to export the display via something like #> export DISPLAY=:0.0? Did you then do ssh -X user@host? If you haven't, give it a shot.

Re: unable to display remote X traffic

Dave Falloon — Fri, 04 Mar 2005 09:35:51 GMT

On my debian workstation I had to edit my xdm config, as it was starting X without tcp sockets. Look for the arguments -nolisten tcp being fed to your X server, the default is to only allow unix socket connections.

ps -efww |grep -i nolisten

I don't know if this is debian specific. A quick recursive grep through /etc/[xX]* for anything with tcp or network would probably help narrow down possibilities.

Hope that helps,

--Dave

Re: unable to display remote X traffic

Rick Garland — Fri, 04 Mar 2005 11:17:38 GMT

Update:

Login as my $LOGNAME, do the xhost +, on the Fedora system - my desktop.

Do the command 'ssh -X root@' and then fire up an X application works, no need to export the DISPLAY variable.

Do the command 'ssh -X $LOGNAME@' and then 'su -' to the root user, run the X application will not work. This is still the case after exporting the DISPLAY.

Is this an 'sshd' config issue or a 'xdm' config issue?

Re: unable to display remote X traffic

Bryan Eley — Fri, 04 Mar 2005 13:30:40 GMT

Hmmm...maybe could be either? If it is the ssh d, check to see if there's a line in /etc/ssh/sshd_config that reads 'X11Forwarding yes'

or, if it is XDM, check /etc/X11/xdm-config and see if there is a line which reads
DisplayManager.requestPort: 0

If so, try putting an an exclamation mark in front of this line.

I must confess to a bit of a rusty memory on this...

Re: unable to display remote X traffic

Rick Garland — Fri, 04 Mar 2005 13:52:10 GMT

No joy.

Tried the xdm-config modification and the sshd modification.

If I 'ssh -X root@' then I can run the X applications, i.e. sam.

Preference would be to 'ssh ' as my $LOGNAME, do the 'su -' to the root account, export DISPLAY and then run the X applications.

Re: unable to display remote X traffic

Rick Garland — Fri, 04 Mar 2005 14:44:44 GMT

Got it.

The port 6000 is not open by default. Issue the command 'nmap localhost' and the entry for 600 is not there.

In /etc/X11/gdm is a file called gdm.conf. Modify this file so that the line 'DisallowTCP=true' is changed to read 'DisallowTCP=false'.

Stop and restart X server. (This is usually done bu rebooting.)

Once system comes up you will see port 6000 is open via the 'nmap localhost' command.

Many thanks to all for the help!