How to setup SSH Key passwordless login in Red Hat Enterprise Linux?

Issue

• How to setup SSH password less login?
• How do I setup SSH passwordless login?
• How to install SSH identity key onto a remote host on Red Hat Enterprise Linux?
• How to transfer files between servers via ssh without username/password?

• Getting below error on ssh client side even after appending rss public key to remote server:

  Trying below from primary server after configuring rsa key:
  [user@ssh-client.example.com ~]$ ssh someuser@10.0.0.1
  Connection closed by 10.0.0.1
  

• Getting below error on ssh server side in /var/log/secure:

  sshd[xxxx]: Authentication refused: bad ownership or modes for directory /home/XXX