SSH login to RHEL 7 server without password

In order to login to RHEL7 Linux server we first need to exchange public keys between server and client machine. To do that we can use ssh-copy-id command.

$ ssh-copy-id user@rhel-server
The authenticity of host 'rhel-server (rhel-server)' can't be established.
ECDSA key fingerprint is 21:4d:71:f6:ef:1f:c1:f7:a9:d9:81:4d:9d:34:4d:a9.
Are you sure you want to continue connecting (yes/no)? yes
/usr/bin/ssh-copy-id: INFO: attempting to log in with the new key(s), to filter out any that are already installed
/usr/bin/ssh-copy-id: INFO: 1 key(s) remain to be installed -- if you are prompted now it is to install the new keys
user@rhel-server's password: 

Number of key(s) added: 1

Now try logging into the machine, with:   "ssh 'user@rhel-server'"
and check to make sure that only the key(s) you wanted were added.

The above command will propt you for a password based upon which your access to the remote server will be authenticated and password exchanged. If you get an error message saying:

/usr/bin/ssh-copy-id: ERROR: No identities found

you first need to generate your ssh keys using below command:

$ ssh-keygen 
Generating public/private rsa key pair.
Enter file in which to save the key (/home/user/.ssh/id_rsa): 
Enter passphrase (empty for no passphrase): 
Enter same passphrase again: 
Your identification has been saved in /home/user/.ssh/id_rsa.
Your public key has been saved in /home/user/.ssh/
The key fingerprint is:
2a:2b:8b:c3:10:2c:0e:8a:7e:bf:0d:2c:fa:31:dc:99 user@localhost.localdomain
The key's randomart image is:
+--[ RSA 2048]----+
|                 |
|                 |
|.                |
|+.               |
|*.      S        |
|+.. o o.         |
|+  =.E.          |
|.+o.+oo          |
|.o++oo..         |

Once done attempt to the above ssh-copy-id command again.