Ansible Connection Timed Out During Banner Exchange When Using Jump Host: Causes, Troubleshooting & Prevention

When using Ansible with a jump host, users sometimes encounter the error “connection timed out during banner exchange.” This issue arises during the SSH connection setup phase, where the SSH client and server exchange identification strings. It’s particularly relevant for Ansible users managing remote servers through a bastion or jump host, as it can disrupt automation workflows and hinder efficient server management.

Understanding the Error

The error “Ansible connection timed out during banner exchange when using jump host” occurs when Ansible fails to establish an SSH connection through a jump host (bastion host). Here are the technical details:

1. Banner Exchange: This is the initial phase of an SSH connection where the client and server exchange version information and supported algorithms.
2. Jump Host: A server used as an intermediary to connect to another server in a private network.
3. Timeout: The connection attempt exceeds the allowed time, often due to network latency, incorrect SSH configurations, or firewall rules.

Common causes include:

• Incorrect ProxyCommand or ProxyJump settings in the SSH configuration.
• Network issues between the client, jump host, and target server.
• SSH key or authentication problems.
• Firewall rules blocking the connection.

Example configuration:

[nodes]
private-server-1.example.com ansible_ssh_common_args='-o ProxyCommand="ssh -W %h:%p -q [email protected]"'

This sets up an SSH proxy through the bastion host.

Common Causes

Here are the common causes of the “Ansible connection timed out during banner exchange when using jump host” error:

1. Network Issues:

   • Firewall Restrictions: Firewalls may block SSH traffic, preventing connections.
   • Network Latency: High latency can cause timeouts during the SSH handshake.
   • Unstable Network: Intermittent network connectivity can disrupt the connection.

2. SSH Configurations:

   • Incorrect ProxyCommand: Misconfigured ProxyCommand in SSH settings can lead to connection failures.
   • StrictHostKeyChecking: If StrictHostKeyChecking is enabled, new host keys might not be accepted automatically.
   • SSH Key Issues: Problems with SSH keys, such as incorrect permissions or missing keys, can cause timeouts.

3. Jump Host Settings:

   • Resource Limitations: The jump host might be overloaded or have insufficient resources to handle multiple connections.
   • SSH Daemon Configuration: Misconfigurations in the SSH daemon on the jump host can lead to connection issues.
   • Network Address Translation (NAT): NAT settings on the jump host might interfere with the SSH connection.

These are the primary factors to check when troubleshooting this error.

Troubleshooting Steps

Here’s a step-by-step guide to troubleshoot the “Ansible connection timed out during banner exchange when using jump host” issue:

1. Check Network Connectivity:

   • Ensure the Ansible control machine can reach the jump host.
   • Verify the jump host can reach the target hosts.
   • Use ping and traceroute to check connectivity.

2. Verify SSH Configurations:

   • Confirm SSH access to the jump host:

     ssh user@jumphost
     

   • Confirm SSH access from the jump host to the target hosts:

     ssh user@targethost
     

   • Check for any SSH key issues or host key verification problems.

3. Adjust Ansible Settings:

   • Update your inventory file to include the jump host configuration:

     [targets]
     targethost ansible_ssh_common_args='-o ProxyCommand="ssh -W %h:%p user@jumphost"'
     

   • Ensure ansible_ssh_common_args is correctly set to use the jump host.

4. Check SSH ProxyCommand:

   • Verify the ProxyCommand in your SSH config:

     Host targethost
       ProxyCommand ssh -W %h:%p user@jumphost
     

   • Ensure the ProxyCommand works manually:

     ssh -o ProxyCommand="ssh -W %h:%p user@jumphost" user@targethost
     

5. Review Ansible Configuration:

   • Check ansible.cfg for SSH connection settings:

     [ssh_connection]
     ssh_args = -o ControlMaster=auto -o ControlPersist=60s
     

   • Adjust ControlPersist and ControlPath if needed.

6. Debugging:

   • Increase verbosity to get more details:

     ansible-playbook -vvv playbook.yml
     

   • Look for specific error messages and trace the issue.

7. Firewall and Security Groups:

   • Ensure firewalls and security groups allow SSH traffic between the control machine, jump host, and target hosts.

8. Check for Interfering Scripts:

   • Ensure no scripts in .bashrc or .bash_profile on the remote hosts interfere with SSH connections.

Following these steps should help you identify and resolve the issue.

Preventive Measures

Here are some preventive measures to avoid the “Ansible connection timed out during banner exchange” error when using a jump host:

1. Optimize SSH Configurations:

   • Increase SSH Timeout: Add ConnectTimeout=60 to your SSH options.
   • Enable ControlMaster: Use ControlMaster=auto and ControlPersist=600s for persistent connections.
   • ProxyCommand: Configure ProxyCommand to handle the jump host, e.g., ProxyCommand="ssh -W %h:%p jump_host".

2. Ensure Stable Network Connections:

   • Check Network Stability: Ensure there are no intermittent network issues between your Ansible control node, jump host, and target nodes.
   • Firewall and Load Balancer: Verify that firewalls and load balancers are correctly configured and not dropping connections.

Implementing these measures should help mitigate the timeout issues.

To Resolve Ansible Connection Timed Out During Banner Exchange Error

When using a jump host with Ansible, you may encounter the ‘Ansible connection timed out during banner exchange’ error. To resolve this issue, follow these steps:

• Verify that the ProxyCommand is correctly set in your SSH config.
• Ensure the ProxyCommand works manually by running ssh -o ProxyCommand="ssh -W %h:%p user@jumphost" user@targethost.
• Review Ansible configuration for SSH connection settings, particularly ControlMaster and ControlPersist options.
• Adjust ControlPersist and ControlPath if necessary to optimize connections.
• Increase verbosity with -vvv to get more details about the issue.
• Look for specific error messages and trace the problem.

Preventive measures include:

• Optimizing SSH configurations by increasing timeout, enabling ControlMaster, and configuring ProxyCommand.
• Ensuring stable network connections between nodes.
• Verifying firewall and load balancer configurations.
• Checking for interfering scripts in remote hosts’ bash profiles.

Implementing these measures should help mitigate connection timeouts.