XDMCP connection failed.

Not able to connect to Xbrowser.


Enable XDMCP in Linux


Need to enable the xdmcp protocol in the Linux server for getting remote using XBrowser.


RedHat Enterprise Linux 5
S– USE Linux 10


Error :

XDMCP connection failed.

cat: 0.log: No such file or directory
[root@KWWBDCSRVOAM01 gdm]# cat :0.log

X Window System Version 7.1.1
Release Date: 12 May 2006
X Protocol Version 11, Revision 0, Release 7.1.1
Build Operating System: Linux 2.6.18-128.1.10.el5 x86_64 Red Hat, Inc.
Current Operating System: Linux KWWBDCSRVOAM01 2.6.18-155.el5 #1 SMP Fri Jun 19 17:06:31 EDT 2009 x86_64
Build Date: 03 June 2009
Build ID: xorg-x11-server 1.1.1-48.64.el5
Before reporting problems, check http://wiki.x.org
to make sure that you have the latest version.
Module Loader present
Markers: (–) probed, (**) from config file, (==) default setting,
(++) from command line, (!!) notice, (II) informational,
(WW) warning, (EE) error, (NI) not implemented, (??) unknown.
(==) Log file: “/var/log/Xorg.0.log”, Time: Tue Jan 24 14:06:34 2012
(==) Using config file: “/etc/X11/xorg.conf”
(WW) VMWARE(0): Failed to set up write-combining range (0xd4000000,0x400000)
The XKEYBOARD keymap compiler (xkbcomp) reports:
> Warning:          Multiple symbols for level 1/group 1 on key <I5F>
>                   Using XF86Sleep, ignoring XF86Standby
> Warning:          Symbol map for key <I5F> redefined
>                   Using last definition for conflicting fields
Errors from xkbcomp are not fatal to the X server


1)      Install the gdm package

# yum install gdm

2)      Enable the xdmcp protocol by adding the below entries in the custom.conf file.

# vi /etc/gdm/custom.conf






Note: Here “AllowRemoteRoot=true” used to allow root access.

3)      Restart the gdm service

# gdm-restart

4)      Check weather xdmcp port is opened or not, using netstat command

# netstat –an | grep 177

udp        0      0*

5)  Firewall was blocking the Xmanager connection.
6) SE Linux was on. Turning off the SE Linux resolved the issue.




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