How to install Ansible and enable passwordless SSH authentication with nodes on Linux -

Step1: Install Ansible:

# yum install ansible

Step2: Generate an SSH key pair on the control node:

# ssh-keygen

Go for default options for key name and location and leave 
passphrase blank.

Step3: Copy the public key to the remote nodes from control 
node.

# ssh-copy-id username@remote_host 		(Put username and hostname of remote machines)

Step4: Test SSH connection:

# ssh username@remote_host 	(You can login without entering a password)

Step5: Configure Ansible to use SSH keys:

Edit the ansible.cfg file on the control node to add the 
following lines:

    makefile
    [defaults]
    host_key_checking = False
    remote_user = username
    private_key_file = /path/to/private/key

Note: Replace "username" with the appropriate username and 
"path/to/private/key" with the path to the private key 
generated in step 2.

Step6: Test Ansible for all nodes added.

# ansible all -m ping

Ansible must connect to the remote nodes and ping them 
successfully without prompting for a password.