vCenter Server SSH service fails to start with error unit sshd.service is masked

Products

• VMware vCenter Server 8.0

Issue/Introduction

• Manual start SSH on vCenter Server Appliance via systemctl --start sshd fails with output
  Failed to start sshd.service: Unit sshd.service is masked.

• KB-specific workarounds (e.g., Unmask vCenter Server Appliance services using shell script ) cannot be applied because remote access is blocked.

Environment

VMware vCenter Server 8.0.x

Cause

The sshd unit file has been linked to /dev/null (masked), preventing the service from being started manually or automatically. This is often the result of aggressive security hardening or manual administrative lockdown.

Resolution

1. Open the vSphere Client and locate the vCenter Server VM.

2. Launch the Web Console or Remote Console.

3. Press ALT+F1 (or the equivalent for your console) to switch to the login prompt.

4. Log in as root.

5. If you are in the Appliance Shell, type shell to enter the BASH interface.

6. Unmask the SSH service:

   systemctl unmask sshd
   

7. Enable and start the service:

   systemctl enable sshd
   systemctl start sshd
   

8. Verify the status:

   systemctl status sshd