If you are on a remote terminal, and the local system has only one visual (which is typical), then use the following syntax to set your user account DISPLAY environment variable:
Remote Display
Bourne, Korn, and Bash shells
$ export DISPLAY=hostname:0
C shell
$ setenv DISPLAY hostname:0
For example, if you are using the Bash shell and if your host name is local_host, then enter the following command:
$ export DISPLAY=node1:0
X11 Forwarding
To ensure that X11 forwarding does not cause the installation to fail, use the following procedure to create a user-level SSH client configuration file for Oracle installation owner user accounts:
Using any text editor, edit or create the software installation owner's ~/.ssh/config file.
Ensure that the ForwardX11 attribute in the ~/.ssh/config file is set to no. For example:
Host *
ForwardX11 no
Ensure that the permissions on ~/.ssh are secured to the Oracle installation owner user account. For example:
$ ls -al .ssh total 28 drwx------ 2 grid oinstall 4096 Jun 21 2015 drwx------ 19 grid oinstall 4096 Jun 21 2015 -rw-r--r-- 1 grid oinstall 1202 Jun 21 2015 authorized_keys -rwx------ 1 grid oinstall 668 Jun 21 2015 id_dsa -rwx------ 1 grid oinstall 601 Jun 21 2015 id_dsa.pub -rwx------ 1 grid oinstall 1610 Jun 21 2015 known_hosts