How to enable SSH X-11 forwarding and magic cookies

How to enable SSH X-11 forwarding and magic cookies 

Basically, whenever the any new database server provision by server admin team, X11 setup is not there, we are getting below error  :

X11 connection rejected because of wrong authentication.

Error: cannot open display: localhost:12.0

So, how easily you can setup this and enable GUI for server.

Once an SSH connection is established to server, the server will  generate a random authorization (xauth) cookie and store it in ~./Xauthority on the server, known as a MIT-MAGIC-COOKIE-1 entry.

Every time you login, a new cookie is generated, and because I’m switching to another user, its lost. In order to access the local display again, we need to add my cookie entry from the previous connection as below :

 Initially, we have to login server personal account ( If you have ) then sudo su - oracle or grid.

 

1)      Login to server with your personal account. ( ssh -Y sam.sam)

    ssh -Y sam.sam

    xauth list

2)      sudo su - oracle

3)      Check xauth rpm installed or not ?

[root@DB12345 ~]# yum install *xauth*
Loaded plugins: product-id, search-disabled-repos, subscription-manager
Package 1:xorg-x11-xauth-1.0.9-1.el7.x86_64 already installed and latest version
Nothing to do

4)       Check sshd configuration :

[root@DB12345 ~]# cat /etc/ssh/sshd_config | grep -i x11
X11Forwarding yes
X11DisplayOffset 10
X11UseLocalhost yes

5)      Now add the xauth entry to your oracle or grid xauth file :

[sam.sam@local.local@DB12345 ~]$ xauth list
DB12345/unix:10 MIT-MAGIC-COOKIE-1 c01db4311132e3774648671401c03adf

[oracle.oracle@local.local@DB12345 ~]$ xauth add  DB12345/unix:10 MIT-MAGIC-COOKIE-1 c01db4311132e3774648671401c03adf

[oracle.oracle@local.local@DB12345 ~]$ xauth list

DB12345/unix:10 MIT-MAGIC-COOKIE-1 c01db4311132e3774648671401c03adf

6)       Export Display

[sam.sam@local.local@DB12345 ~]$ export DISPLAY=localhost:10.0 

[sam.sam@local.local@DB12345 ~]$ echo $DISPLAY

7)    Now check with xclock or xterm , are you getting GUI or not ?

 [sam.sam@local.local@DB12345 ~]$ xclock

 [sam.sam@local.local@DB12345 ~]$ xterm

Using GUI you can install GI , Oracle Software and DBCA , NETCA all oracle utility