Install and Configure Ansible: Setting Up SSH Connections

In the previous article, we discussed how to install Ansible on different operating systems. Next, we’ll dive into configuring SSH connections between Ansible and remote hosts. Configuring SSH is one of the most critical steps in setting up Ansible—since Ansible relies entirely on SSH to execute commands and manage remote systems.

SSH Connection Fundamentals

Ansible uses SSH as its default communication protocol. To ensure smooth connectivity to target hosts, proper SSH configuration is essential. Here are the basic steps:

1. Ensure the SSH service is running: Verify that the SSH daemon is active on your target host.
2. Generate an SSH key pair: Passwordless authentication via SSH keys is the recommended approach.
3. Configure the hosts file: Specify the managed hosts in Ansible’s inventory configuration.

Generating an SSH Key Pair

Before configuring SSH, generate an SSH key pair on your Ansible control node—the machine where Ansible is installed and executed. Run the following command:

ssh-keygen -t rsa -b 2048

You’ll be prompted to specify a file location (default: ~/.ssh/id_rsa) and optionally set a passphrase (leave blank for passwordless login).

Upon successful generation, two files will appear:

• ~/.ssh/id_rsa: Your private key (keep this secure—never share it)
• ~/.ssh/id_rsa.pub: Your public key

Copying the Public Key to Remote Hosts

Next, copy the public key to your remote host so Ansible can authenticate without a password. Use this command:

ssh-copy-id user@remote_host

Replace user with the username on the remote host, and remote_host with its IP address or hostname. Upon success, you’ll see output similar to:

Number of key(s) added: 1

This confirms the public key has been appended to the remote host’s ~/.ssh/authorized_keys file.

Testing the SSH Connection

After installing the public key, test the connection manually:

ssh user@remote_host

If you log in successfully without being prompted for a password, your SSH setup is working correctly.

Configuring Ansible’s hosts File

Now configure Ansible’s inventory (hosts) file so it knows which machines to manage. By default, this file resides at /etc/ansible/hosts, but you may also define a custom hosts file in your project directory.

Edit the hosts file and add your target host—for example:

[my_servers]
remote_host ansible_user=user

Here:

• [my_servers] defines a group name of your choice,
• remote_host is the IP address or hostname of the target machine,
• ansible_user specifies the SSH username used for connection.

Testing Connectivity with Ansible’s ping Module

To verify Ansible can reach the remote host over SSH, use the built-in ping module:

ansible my_servers -m ping

With correct configuration, you should see output like:

remote_host | SUCCESS => {
    "changed": false,
    "ping": "pong"
}

This confirms Ansible has successfully established an SSH connection to the host.

Summary

In this section, we walked through the essential steps to configure SSH-based communication between Ansible and remote hosts: generating an SSH key pair, deploying the public key, and defining targets in Ansible’s inventory. These foundational configurations are vital—reliable SSH connectivity underpins all subsequent Ansible operations.

In the next article, we’ll explore how to create and customize Ansible’s main configuration file (ansible.cfg) to further optimize your workflow.

We hope this guide helps you set up Ansible’s SSH connectivity smoothly. If you have questions or run into issues, feel free to reach out!