Red Hat Bugzilla – Bug 197964
Fecdora Core 5 wont accept incoming X11 displays even when the firewall is turned off
Last modified: 2007-11-30 17:11:36 EST
Description of problem:
I can easily send X11 displays from Fedora Core 5 to Red Hat 9, Solaris 10 or
Windows XP. I cant get Fedora Core 5 to accept an incoming X11 display under any
circumstance. I have totally turned off the firewall, enabled xhost for all
hosts, but still no luck.
Version-Release number of selected component (if applicable):
Steps to Reproduce:
0. log in as root
1. Turn off firewall on both PC
2. Do "xhost +"
3. Type: setenv DISPLAY 192.168.0.101:0.0
4. Type: gedit &
5. Or type: mozilla &
cannot open display: (null)
new window to appear on second PC
If I redirect the display to the same PC, the windows will not open.
Please verify that your X server is not being run with the '-nolisten tcp'
argument, as it is by default in some /etc/X11/xdm/*rc files:
# ps -ef | grep nolisten
should print no output, and
# netstat -nautp | grep 6000
should show the X server listening on TCP port 6000 .
If neither of the above conditions holds, this is NOTABUG - you need to enable
the X server to listen on port 6000 by removing the '-nolisten tcp' argument
from your /etc/X11/xdm/*rc script.
You are correct that the -nolisten option is in effect. I modified the
/etc/X11/xdm/kdmrc file to comment out the entries for ServerArgsLocal and
ServerArgsRemote. After a reboot that didnt change the situation. I tried
setting them to "-listen tcp" with no luck. I cant find any man pages on the
topic. Could you tell me exactly how you turned on listening on your workstation?
I eventually found that gdmsetup is used to configure the X11 server. On the
Security Tab, you need to turn off the "Deny TCP connections" option. Then you
add port 6000 to the firewall, reboot and you can receive incoming X11 displays.