Ansible Troubleshooting SSH Connection Issues
By Luca Berton · Published 2024-01-01 · Category: installation
Learn how to resolve SSH authentication errors in Ansible due to unestablished host authenticity for seamless playbook execution.
Error Overview
When running an Ansible playbook, you may encounter the following error message:
This error indicates a failure in SSH connection due to the inability to establish the authenticity of the host. Below, we provide a detailed explanation of the issue and steps to resolve it.
Error Explanation Warning: ansible-pylibssh not installed, falling back to paramiko • This warning means Ansible is using paramiko for SSH connections because pylibssh is not installed. While paramiko is functional, pylibssh is generally more efficient and secure. Fatal Error: The authenticity of host '10.96.192.10' can't be established. • This error occurs when the SSH client cannot verify the host's identity because the host key is not in the known hosts file.
Solutions
Install pylibssh
Installing pylibssh can improve SSH connection efficiency and security:
Automatically Accept Host Keys
You can configure Ansible to automatically accept host keys by setting the ansible_ssh_common_args variable in your playbook or inventory to disable host key checking. Note that this method can expose you to security risks, such as man-in-the-middle attacks.
Add the following configuration to your ansible.cfg file:
Alternatively, set the ANSIBLE_HOST_KEY_CHECKING environment variable to False:
Manually Add the Host Key
A more secure approach is to manually add the host key to the known hosts file. This can be done by SSHing into the host manually:
When prompted, accept the host key. This will add it to your ~/.ssh/known_hosts file.
Using Ansible's Known Hosts Module
Ansible provides a known_hosts module to manage known hosts. You can use this module to ensure the host key is added before making other connections. Here's an example playbook snippet:
Replace "ssh-ed25519 AAAA..." with the actual host key.
Example Playbook with Host Key Checking Disabled
Here's an example of how to disable host key checking in your playbook:
Conclusion
Choose the solution that best fits your security requirements. Disabling host key checking is quick and easy but less secure. Adding the host key manually or using the known_hosts module is more secure but requires additional setup. Balancing security and convenience is crucial when configuring SSH connections in Ansible.
Related Articles • Ansible Inventory Guide • Ansible Environment Variables Guide
Category: installation