[Oracle DataBase Server 12.2 Installation on Oracle Linux 7.4]: Configuring Display Manager

Preparation and verification

192.168.1.5 - ip address of the computer from which the installation process is managed.
192.168.56.101 - ip address of the server

If installing from a Windows machine

Install XMing and additional fonts. :
http://sourceforge.net/projects/xming/
http://sourceforge.net/projects/xming/files/Xming-fonts/

Reboot. If you don’t reboot, during installation of version 10 RAC, problems occurred (buttons were not displayed on the last installation step).

Next, configure access rules.
In the simplest case, right-click on the xming shortcut. Go to properties and add -ac to the target (i.e., no access control)

If installing from a Linux machine

Preparing Oracle Linux 7.3 client with gnome environment

# yum install -y nmap nc xclock

# vi /etc/gdm/custom.conf

Add to the blocks:

[security]
DisallowTCP=false

[xdmcp]
Enable=true

# service gdm restart

$ xclock -display 192.168.1.5:0

If the clock appears, everything is fine and nothing else is needed.

Preparing Ubuntu client

$ sudo apt-get install -y nmap nc xclock

Option with lightdm.

If needed, you can switch later with commands:

# dpkg-reconfigure gdm
# dpkg-reconfigure lightdm

# vi /etc/lightdm/lightdm.conf

###########################

[SeatDefaults]
user-session=ubuntu
greeter-session=unity-greeter
xserver-allow-tcp=true

###########################

# sudo restart lightdm

$ xclock -display 192.168.1.5:0

If the clock appears, everything is fine and nothing else is needed.

If the clock does not appear:

$ ps ax | grep dm
$ ps lf -C Xorg

There should be no line “no-listen tcp” (Or something similar)

$ netstat -an | grep -F 6000

tcp        0      0 0.0.0.0:6000            0.0.0.0:*               LISTEN
tcp6       0      0 :::6000                 :::*                    LISTEN

# nmap -p 6000 192.168.1.5

Starting Nmap 6.40 ( http://nmap.org ) at 2017-11-23 09:02 MSK
Nmap scan report for 10.14.3.43
Host is up (0.000048s latency).
PORT     STATE SERVICE
6000/tcp open  X11

$ nc -vv 192.168.1.5 6000
Connection to 192.168.1.200 6000 port [tcp/x11] succeeded!=

Allow form output from server to client

Then on the client as root I do:

# xhost +

On the server:

Check if the client port is open and accessible

# yum install -y nmap

# nmap -p 6000 192.168.1.5

result

***
6000/tcp open  X11

Next, it’s best to do the following:

– if not installed earlier, install the xdpyinfo package. It is needed for displaying windows on the client machine.

# yum install -y xdpyinfo xclock
# su - oracle12

$ xclock -display 192.168.1.5:0

You can also try

$ export DISPLAY=192.168.1.5:0.0

$ xdpyinfo
name of display:    192.168.1.5:0.0
version number:    11.0
vendor string:    The X.Org Foundation
vendor release number:    11702000
X.Org version: 1.17.2
maximum request size:  16777212 bytes
motion buffer size:  256
bitmap unit, bit order, padding:    32, LSBFi
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