Linux - How to Resolve INS-06006 Passwordless SSH connectivity not set up between the following node(s)

How to Resolve INS-06006 Passwordless SSH connectivity not set up between the following node(s)
-----------------------------------------------------------------------------------------------

You need to setup ssh public authentication between the nodes to allow oracle user to login to each node without promting for password.

Here's how to do it:
1. Login as oracle to node1
2. run:
/usr/bin/ssh-keygen -q -t rsa -f $HOME/.ssh/id_rsa -N ''
3. run
ssh-copy-id -i $HOME/.ssh/id_rsa oracle@node2

----
You may do this by hand:

1. Create ssh keys:
ssh-keygen -N '' -b 1024 -f identity
touch authorized_keys
chmod 600 authorized_keys
cat identity.pub >> authorized_keys
cat id_rsa.pub >> authorized_keys
HOSTIP=`/sbin/ip addr | grep "scope global eth0" | cut -d" " -f6 | cut -d"/" -f1`
ssh-keyscan -t rsa -H $HOSTNAME,$HOSTIP 2>&1 >> ~/.ssh/known_hosts
ssh-keyscan -t rsa -H $HOSTIP 2>&1 >> ~/.ssh/known_hosts
ssh-keyscan -t rsa -H $HOSTNAME 2>&1 >> ~/.ssh/known_hosts

HOSTNAMEALIAS=`hostname -s`
ssh-keyscan -t rsa -H $HOSTNAMEALIAS,$HOSTIP 2>&1 >> ~/.ssh/known_hosts
ssh-keyscan -t rsa -H $HOSTNAMEALIAS 2>&1 >> ~/.ssh/known_hosts

2. Do the same on each node.

3. Copy identity.pub from all nodes to one and:
echo identityA.pub >> authorized_keys.
echo identityB.pub >> authorized_keys.
...

4. Copy this authorized_keys to each node.

5. Generate known_hosts
ssh $USER@$NEWHOSTNAME 'ssh-keygen -R $HOSTNAME 2>&1'
ssh $USER@$NEWHOSTNAME 'ssh-keygen -R `hostname -s` 2>&1'
ssh $USER@$NEWHOSTNAME 'ssh-keygen -R $HOSTIP 2>&1'
ssh $USER@$NEWHOSTNAME 'ssh-keygen -R $HOSTNAME,$HOSTIP 2>&1'

eval "ssh $USER@$NEWHOSTNAME 'ssh-keyscan -t rsa -H $HOSTNAME,$HOSTIP 2>&1 >> ~/.ssh/known_hosts'"
eval "ssh $USER@$NEWHOSTNAME 'ssh-keyscan -t rsa -H $HOSTIP 2>&1 >> ~/.ssh/known_hosts'"
eval "ssh $USER@$NEWHOSTNAME 'ssh-keyscan -t rsa -H $HOSTNAME 2>&1 >> ~/.ssh/known_hosts'"
eval "ssh $USER@$NEWHOSTNAME 'ssh-keyscan -t rsa -H `hostname -s` 2>&1 >> ~/.ssh/known_hosts'"

---

You might think the SSH connectivity has been setup correctly by Oracle Universal Installer, but INS-06006 eventually appeared when you tried to test it or enter the next step.

The error usually from the network problems, please check the following questions:
Are /etc/hosts the same on both nodes? if yes, this could be the problem.
Are ~/.bash_profile of user grid or oracle the same on both nodes? if yes, this could be the problem.
Why? They couldn't be, can't be the same on both nodes. I think we probably copied the configurations from one node to another.
Are those host name resolutions wrongly registered on DNS?
Because OUI could take the wrong node as another to build a wrong connectivity.
Have you ever bound VIP or SCAN into any NIC?
Don't bind VIP or SCAN into any NIC. OUI will bind them into clusterware automatically during installation.

If the above resolutions failed, you can try to establish the connectivity manually. For your reference, the following post may provide some helps.
How to Build SSH Equivalency between Two Servers
It contains the steps to build and verify the connectivity, you can try it.

If you are still struggling in how to build a 12c RAC environment, please feel free to visit my posts for your reference:
How to Build 12c RAC (0/6) - An Overview