Fixing “sshd: no hostkeys available -- exiting” in Ubuntu (VMware / Cloned VM)

If you’re trying to start SSH on Ubuntu and encounter this error:

sshd: no hostkeys available -- exiting.

Don’t worry — this is a common issue, especially when working with cloned virtual machines or golden images.

In this guide, we’ll break down:

• ✅ What this error means
• 🔍 Why it happens
• ⚙️ Step-by-step fix
• 🧠 Best practices for future

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🚨 What Does This Error Mean?

SSH (Secure Shell) requires host keys to identify the server securely.

These keys are stored in:

/etc/ssh/ssh_host_*

If these keys are missing, SSH cannot start — resulting in:

sshd: no hostkeys available -- exiting.

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🔍 Why This Happens

This issue typically occurs in these scenarios:

🧩 1. Cloned Virtual Machines

When you clone a VM, you may remove host keys intentionally to avoid duplication.

🧹 2. Golden Image Preparation

During template creation, admins often delete SSH keys for security reasons.

⚠️ 3. Manual Deletion or Misconfiguration

Accidental removal of /etc/ssh/ssh_host_* files.

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⚙️ Step-by-Step Fix

🔹 Step 1: Generate New Host Keys

Run the following command:

sudo ssh-keygen -A

This will generate all required SSH host keys automatically.

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🔹 Step 2: Restart SSH Service

sudo systemctl restart ssh

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🔹 Step 3: Verify SSH Status

sudo systemctl status ssh

You should now see:

active (running)

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🔹 Step 4: Confirm SSH is Listening

ss -tulnp | grep :22

If everything is working, SSH should be listening on port 22.

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🔐 Test SSH Connection

From your host machine:

ssh username@your-ip-address

Example:

ssh shashwat@192.168.59.18

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🧠 Best Practices (Important)

If you’re working with VMs, templates, or automation:

✅ Always regenerate SSH keys after cloning

sudo ssh-keygen -A

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✅ Use cloud-init (Advanced)

Automate:

• Hostname
• SSH keys
• Network config

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✅ Never reuse SSH host keys across machines

This can lead to:

• Security risks
• SSH warnings
• Connection issues

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🎯 Summary

Issue	Fix
SSH not starting	Generate host keys
Error: no hostkeys available	sudo ssh-keygen -A
Service failing	Restart SSH