Remote execution fails with the error 'Failed to establish connection to remote host, exit code: 255'

Environment

• Red Hat Satellite 6

Issue

• While running a remote job/command from the Satellite webui, it fails with the following error.

  Error initializing command: RuntimeError - Failed to establish connection to remote host, exit code: 255
  2:
  Exit status: EXCEPTION
  

Resolution

• Verify if the SSH keys are properly copied to the host in question. To copy the SSH keys from the Satellite CLI, run:

  [root@sat]# ssh-copy-id -i ~foreman-proxy/.ssh/id_rsa_foreman_proxy.pub root@host.example.com
  

  Ensure the Satellite is able to run commands on the host without password.

  [root@sat]# ssh -i ~foreman-proxy/.ssh/id_rsa_foreman_proxy root@host.example.com 'uptime'
  

• Same error observed while running remote execution as non-root user on RHEL 8.7 and below versions. Try to run the job on RHEL 8.8 client.

• See if there is any SSH configuration file with wrong permission, /etc/ssh/ssh_config.d/02-rekey-limit.conf as an example. Permission should be 0644 for this file.

• This issue may also happen if a remote execution user account is not created on the client system. Verify the global params set for the particular client on Hosts -> All Hosts -> Concerned Host -> Edit -> Parameters tab .

For more KB articles/solutions related to Red Hat Satellite 6.x Remote Execution Issues, please refer to the Red Hat Satellite Consolidated Troubleshooting Article for Red Hat Satellite 6.x Remote Execution Issues

Root Cause

• SSH keys are not copied on the hosts.
• Wrong file permission on SSH config files.
• Actual Remote execution user was missing on the client.

Diagnostic Steps

• Following error logged when the wrong permissions set to /etc/ssh/ssh_config.d/02-rekey-limit.conf

  **2023-05-12T17:06:00  [D] Can't open user config file /etc/ssh/ssh_config.d/02-rekey-limit.conf: Permission denied**
  2023-05-12T17:06:00  [E] error while initializing command RuntimeError Failed to establish connection to remote host, exit code: 255:
  /usr/share/gems/gems/smart_proxy_remote_execution_ssh-0.7.3/lib/smart_proxy_remote_execution_ssh/runners/script_runner.rb:406:in `ensure_remote_command'
  /usr/share/gems/gems/smart_proxy_remote_execution_ssh-0.7.3/lib/smart_proxy_remote_execution_ssh/runners/script_runner.rb:179:in `establish_connection'
  /usr/share/gems/gems/smart_proxy_remote_execution_ssh-0.7.3/lib/smart_proxy_remote_execution_ssh/runners/script_runner.rb:146:in `start'
  /usr/share/gems/gems/smart_proxy_dynflow-0.8.2/lib/smart_proxy_dynflow/runner/dispatcher.rb:32:in `start_runner'
  /usr/share/gems/gems/dynflow-1.6.10/lib/dynflow/actor.rb:13:in `on_message'
  

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