Unable to SSH to vCSA - SSH Service gets disabled immediately.

Products

• VMware vCenter Server
• VMware vCenter Server 7.0
• VMware vCenter Server 8.0

Issue/Introduction

• Unable to SSH to vCenter Server Appliance.
• SSH service gets disabled automatically, even if enabled from either the DCUI or VAMI page.
• The following errors are observed in logs:
  
  

  systemd[1]: Started OpenSSH Daemon.
  sshd[8432]: /etc/ssh/sshd_config line 107: FipsMode should be set before Ciphers option
  systemd[1]: sshd.service: Main process exited, code=exited, status=255/n/a
  systemd[1]: sshd.service: Failed with result 'exit-code'.
  systemd[1]: sshd.service: Service RestartSec=100ms expired, scheduling restart.
  systemd[1]: sshd.service: Scheduled restart job, restart counter is at 4.
  systemd[1]: Stopped OpenSSH Daemon.

• The following error appears when verifying the status of the sshd service:
  

  # systemctl status sshd

Environment

vCenter Server Appliance 7.x

vCenter Server Appliance 8.x

Cause

The /etc/ssh/sshd_config file is corrupt or has wrong entries.

Resolution

To resolve this issue, modify or restore the sshd_config file from a working VCSA of the same version by following these steps:

Since SSH is down on the problematic VCSA, standard SCP clients like WinSCP may fail. 

1. Extract contents from the working VCSA:

   • Run the command cat /etc/ssh/sshd_config on the working VCSA.
   • Copy the output contents of the file and paste them into a local text editor.

2. Prepare the problematic VCSA:

   • Access the problematic VCSA via the console (VMRC or Web Console).
   • Navigate to the directory: cd /etc/ssh/
   • Rename the existing file to create a backup by running: 
     mv sshd_config sshd_config.bak

3. Create and populate the new configuration file:

   • Create a new file with the correct name using the vi editor: 
     vi sshd_config
     Note: Ensure the session is in the /etc/ssh/ folder when running this.
   • Press i to enter Insert mode and paste the text previously copied into the editor.

4. Save and exit:

   • Press Esc.
   • Save and force exit the editor by typing: 
     :wq!