How to enable SSH between nodes for RAC .

Login as oracle-user , And perform this on all nodes where you want the ssh to be enables. This is a mandatory process before you start the install. Install process (OUI) will not be able to perform remore operations on remote nodes.

su - oracle-user #Oracle-user is the oracle software owner with which you will install the oracle softwares.
mkdir ~/.ssh #~ is Home directory of oracle user.
chmod 700 ~/.ssh #Changing permissions on .ssh file
/usr/bin/ssh-keygen -t rsa (choose default) #Generate keys.

RSA public key is written to the ~/.ssh/id_rsa.pub file
private key to the ~/.ssh/id_rsa file.

cat id_rsa.pub >> authorized_keys

generate "authorized_keys" file on MACHINE1 and copy it to MACHINE2 using the following commands.
scp authorized_keys MACHINE2:/home/oracle-user/.ssh/

su - oracle-user
cd ~/.ssh
cat id_rsa.pub >> authorized_keys
scp authorized_keys MACHINE2:/home/oracle-user/.ssh/


log in as the "oracle-user" user on MACHINE2

su - oracle-user
cd ~/.ssh
cat id_rsa.pub >> authorized_keys
scp authorized_keys MACHINE1:/home/oracle-user/.ssh/The "authorized_keys"

Do this on all machines if more then 2 nodes.

To enable SSH user equivalency on the cluster member nodes issue the following commands on each node.

ssh MACHINE1 date
ssh MACHINE2 date
ssh MACHINE1.domain_name date
ssh MACHINE2.domain_name date
exec /usr/bin/ssh-agent $SHELL
/usr/bin/ssh-add

SSH between servers without entering passwords is now active.

Please make sure that you should be able to login to all machines without passwords:

From machine 1
ssh machine 2
from machine 2
ssh machine 1