mjhjmtu

I am trying to get xdmcp working on a Redhat 6 server.

I am mostly following the steps at:
http://www.yolinux.com/TUTORIALS/GDM_XDMCP.html#RHEL

In one of the steps it suggests:

Edit file:
Red Hat: /etc/X11/xdm/Xaccess

On my system, I do not see this file or the xdm folder. I only have /etc/X11:

$ ls -l /etc/X11
total 32
drwxr-xr-x. 2 root root 4096 Jun 29 2011 applnk
drwxr-xr-x. 2 root root 4096 Oct 2 2013 fontpath.d
-rwxr-xr-x 1 root root 1328 Aug 26 2014 prefdm
drwxr-xr-x 4 root root 4096 Oct 29 17:43 xinit
-rw-r--r-- 1 root root 547 Jun 6 2013 Xmodmap
-rw-r--r--. 1 root root 68 Oct 2 2013 xorg.conf
drwxr-xr-x 2 root root 4096 Nov 3 2016 xorg.conf.d
-rw-r--r-- 1 root root 493 Jun 6 2013 Xresources

So far, I am getting a blank screen if I try to open an xdmcp session via mobaXTerm.

I have already followed most of the steps in the tutorial I noted above including disabling my firewall.

I also have gdm running:

$ ps -eaf | grep gdm
root 1818 1 0 20:07 ? 00:00:00 /usr/sbin/gdm-binary -nodaemon
root 1848 1818 0 20:07 ? 00:00:00 /usr/libexec/gdm-simple-slave --display-id /org/gnome/DisplayManager/Display1
root 1851 1848 0 20:07 tty1 00:00:00 /usr/bin/Xorg :0 -br -verbose -audit 4 -auth /var/run/gdm/auth-for-gdm-h5txFF/database vt1
gdm 1937 1 0 20:07 ? 00:00:00 /usr/bin/dbus-launch --exit-with-session
gdm 1938 1 0 20:07 ? 00:00:00 /bin/dbus-daemon --fork --print-pid 5 --print-address 7 --session
gdm 1939 1848 0 20:07 ? 00:00:00 /usr/bin/gnome-session --autostart=/usr/share/gdm/autostart/LoginWindow/
gdm 1946 1 0 20:07 ? 00:00:00 /usr/libexec/gconfd-2
gdm 1964 1939 0 20:07 ? 00:00:00 /usr/libexec/at-spi-registryd
gdm 1965 1 0 20:07 ? 00:00:05 /usr/libexec/gnome-settings-daemon --gconf-prefix=/apps/gdm/simple-greeter/settings-manager-plugins
gdm 1967 1 0 20:07 ? 00:00:00 /usr/libexec/bonobo-activation-server --ac-activate --ior-output-fd=12
gdm 1974 1 0 20:07 ? 00:00:00 /usr/libexec/gvfsd
gdm 1975 1939 0 20:07 ? 00:00:00 metacity
gdm 1976 1939 0 20:07 ? 00:00:00 /usr/libexec/polkit-gnome-authentication-agent-1
gdm 1978 1939 0 20:07 ? 00:00:00 /usr/libexec/gdm-simple-greeter
gdm 1991 1 0 20:07 ? 00:00:00 /usr/bin/pulseaudio --start --log-target=syslog
root 1998 1848 0 20:07 ? 00:00:00 pam: gdm-password

At this point though, I do wish to be sure I have done the necessary xdm config. But how is it done with Redhat 6?

The only file you should really need to change on RHEL 6 would be the /etc/gdm/custom.conf. Did you set this to Enable=true and restarted GDM?