Step-by-Step Guide to Installing and Configuring Ansible on Linux

1. Install Ansible

Run the following command to install Ansible on a RHEL/CentOS system:

yum install ansible

2. Modify the configuration

Edit /etc/ansible/ansible.cfg and change the line

#host_key_checking = False

to

host_key_checking = False

This disables the SSH host‑key verification prompt on first connection.

3. Configure the hosts inventory

Add a group called [test] with the target servers and login credentials:

[test]
192.168.20.26 ansible_ssh_user=root ansible_ssh_pass='xxxxxx'
192.168.20.53 ansible_ssh_user=root ansible_ssh_pass='xxxxxx'

4. Test Ansible connectivity

Execute a simple module to check the remote host:

ansible test -m shell -a 'uptime'

5. Generate SSH key pair on the control node

Run:

ssh-keygen

Follow the prompts to create id_rsa and id_rsa.pub .

6. Distribute the public key with a playbook

Create key_pub.yml :

- hosts: test
  remote_user: root
  tasks:
    - name: copy ssh key
      authorized_key:
        user: root
        key: "{{ lookup('file', '/root/.ssh/id_rsa.pub') }}"
        state: present
        mode: 0600

7. Run the playbook

ansible-playbook key_pub.yml

This copies the public key to the remote hosts, enabling password‑less SSH.

8. Verify password‑less login

Test the SSH connection:

ssh 192.168.20.26

If the login succeeds without a password prompt, the setup is complete.

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