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A simple oversight—leaving default passwords and password-based SSH authentication enabled—led to a compromised VM and a weekend crisis. Here’s how to prevent this with automation and hardened security practices.
You Should Know: Hardening SSH and Automating VM Security
1. Disable Password-Based SSH Authentication
Edit `/etc/ssh/sshd_config` to enforce key-based authentication:
sudo sed -i 's/PasswordAuthentication yes/PasswordAuthentication no/' /etc/ssh/sshd_config sudo systemctl restart sshd
2. Use Ansible for Automated SSH Hardening
Create an Ansible playbook (secure_ssh.yml) to enforce secure SSH settings:
<ul> <li>hosts: all become: yes tasks:</li> <li>name: Disable SSH password authentication lineinfile: path: /etc/ssh/sshd_config regexp: '^?PasswordAuthentication' line: 'PasswordAuthentication no' state: present notify: restart sshd</p></li> <li><p>name: Disable root login lineinfile: path: /etc/ssh/sshd_config regexp: '^?PermitRootLogin' line: 'PermitRootLogin no' state: present</p></li> <li><p>name: Restart SSH service service: name: sshd state: restarted when: ansible_service_mgr == 'systemd'
Run it with:
ansible-playbook -i inventory.ini secure_ssh.yml
3. Enforce Fail2Ban for SSH Bruteforce Protection
Install and configure Fail2Ban:
sudo apt install fail2ban -y sudo cp /etc/fail2ban/jail.conf /etc/fail2ban/jail.local
Edit `/etc/fail2ban/jail.local` to protect SSH:
[bash] enabled = true maxretry = 3 bantime = 1h
Restart Fail2Ban:
sudo systemctl restart fail2ban
4. Automate VM Deployment with Pre-Hardened Images
Use Packer to create secure VM templates:
{
"builders": [{
"type": "qemu",
"iso_url": "https://releases.ubuntu.com/22.04/ubuntu-22.04-live-server-amd64.iso",
"ssh_username": "ubuntu",
"ssh_password": "ubuntu",
"shutdown_command": "sudo shutdown -h now"
}],
"provisioners": [{
"type": "ansible",
"playbook_file": "secure_ssh.yml"
}]
}
5. Monitor Unusual Traffic with Linux Commands
Check active SSH sessions:
who -a
Monitor network traffic:
sudo netstat -tulnp | grep ssh
Block suspicious IPs manually:
sudo iptables -A INPUT -s MALICIOUS_IP -j DROP
What Undercode Say
Human errors happen, but automation and strict security policies prevent disasters. Key takeaways:
– Always disable password-based SSH.
– Use Ansible/Packer for repeatable, secure deployments.
– Monitor and restrict unauthorized access.
– Never deploy untested configurations on Fridays!
Expected Output:
A fully automated, secure VM deployment with SSH hardening, Fail2Ban protection, and real-time monitoring.
Relevant URLs:
References:
Reported By: Pierre Louis – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
