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System Hardening for OpenStack Private Cloud: A Step-by-Step Guide

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Managing an OpenStack Private Cloud brings the power and flexibility of cloud infrastructure under your control. However, with that control comes significant responsibility regarding security. Because OpenStack manages core resources like compute, network, and storage, system hardening is a crucial, non-negotiable step. It's the systematic process of reducing vulnerabilities and minimizing the attack surface, making your private cloud resilient against evolving cyber threats. 

This guide will walk you through the comprehensive steps to secure your OpenStack Private Cloud, from the underlying operating system layer to the specific OpenStack components themselves. 

Contents

  1. Step 1: Host Operating System (OS) Hardening 
    1. Minimalist Installation 
    2. Regular Patch and Update Management 
    3. User Account and Authentication Hardening 
    4. Secure SSH Configuration 
    5. Host Firewall Configuration (IPTables/Firewalld) 
    6. Logging and Auditing 
    7. Secure File System and Partitions 
  2. Step 2: OpenStack Components Hardening 
    1. Secure Communication Protocols (HTTPS/TLS) 
    2. Identity and Access Management (Keystone Hardening) 
    3. Database Service Hardening (MySQL/MariaDB/PostgreSQL) 
    4. Message Queue Hardening (RabbitMQ/Qpid/Kafka) 
    5. Compute Service Hardening (Nova) 
    6. Networking Service Hardening (Neutron) 
    7. Storage Service Hardening (Cinder/Swift/Glance) 
  3. Step 3: Network and General Environment Hardening 
    1. Physical/Virtual Network Segmentation 
    2. Zero Trust Architecture (ZTA) 
    3. Regular Security Audits and Vulnerability Scanning 
    4. Comprehensive Security Monitoring 
    5. Incident Response Plan 
  4. Step 4: Installation and Automation Process Hardening (Kolla-Ansible) 
    1. Secure Git Repositories 
    2. Secrets Management 
    3. Secure Kolla-Ansible Usage 

Step 1: Host Operating System (OS) Hardening 

Every node (controller, compute, network, storage) in an OpenStack cluster is a server running a Linux operating system. OS security is the foundation of your entire cloud's security. 

Minimalist Installation 

  • Goal: Reduce the attack surface by eliminating unnecessary components. 

  • Practice: 

  • During OS installation, choose a minimal option (e.g., "minimal install" or "server install" without a GUI). 

  • Remove or disable all software packages and services not directly relevant to your OpenStack node's function (e.g., unused web servers, games, desktop environments if not needed). 

Regular Patch and Update Management 

  • Goal: Protect against known (CVE) vulnerabilities that have been patched. 

  • Practice: 

  • Configure the OS to receive automatic security updates. For Debian/Ubuntu, use unattended-upgrades; for CentOS/RHEL, use yum-cron. 

  • Alternatively, schedule regular system updates (e.g., weekly or monthly) outside of peak operating hours to minimize disruption. 

  • Subscribe to security bulletins from your OS vendor. 

User Account and Authentication Hardening 

  • Goal: Prevent unauthorized access through weak or stolen credentials. 

  • Practice: 

  • Disable default or unused accounts, such as guest. 

  • Enforce strong, unique password policies for all accounts. Use a minimum of 12 characters, a combination of upper/lowercase letters, numbers, and symbols. Implement periodic password rotation. 

  • Enable Multi-Factor Authentication (MFA) for all administrative access (SSH, console). 

  • For SSH, use SSH Key-Based Authentication and disable password authentication (PasswordAuthentication no in sshd_config). 

  • Restrict direct root access. Use sudo for administrative activities instead of direct root logins. 

Secure SSH Configuration 

  • Goal: Reduce the risk of brute-force attacks and unauthorized server access. 

  • Practice: 

  • Change the default SSH port (22) to a non-standard port (e.g., 2222). 

  • Set PermitRootLogin to no. 

  • Set PasswordAuthentication to no. 

  • Allow only SSH protocol version 2 (Protocol 2). 

  • Disable X11 forwarding if not used. 

Host Firewall Configuration (IPTables/Firewalld) 

  • Goal: Control network traffic and prevent unauthorized access to services that should not be exposed. 

  • Practice: 

  • Implement strict firewall rules on each node. By default, block all incoming traffic. 

  • Only allow traffic on ports explicitly required by the relevant OpenStack components and management services (SSH). 

  • Ensure the loopback interface is allowed. 

Logging and Auditing 

  • Goal: Enable early detection of suspicious activity and aid in post-incident forensic investigations. 

  • Practice: 

  • Ensure system logging (e.g., syslog, auditd) is enabled and configured to record important security events. 

  • Send logs to a centralized log server or SIEM (Security Information and Event Management) for analysis and anomaly detection. Protect logs from tampering. 

Secure File System and Partitions 

  • Goal: Limit the impact of a compromise and prevent excessive disk space usage. 

  • Practice: 

  • Use separate partitions for sensitive directories like /var/log, /tmp, /home, /var/www. 

  • Set appropriate mount options, such as noexec on /tmp and /var/tmp to prevent code execution from these locations. 

  • Set strict file permissions (chmod, chown) to restrict access to critical files and directories. 

Step 2: OpenStack Components Hardening 

Once the base OS is secure, the focus shifts to securing the OpenStack services themselves. 

Secure Communication Protocols (HTTPS/TLS) 

  • Goal: Prevent eavesdropping and man-in-the-middle attacks. 

  • Practice: 

  • Configure all OpenStack API endpoints (Keystone, Nova, Glance, Neutron, Cinder, Swift, Horizon, etc.) to use HTTPS/TLS. 

  • Use valid and trusted SSL/TLS certificates. 

  • Secure communication between internal OpenStack services (e.g., Nova-API to Nova-Compute) with TLS or via isolated networks. 

Identity and Access Management (Keystone Hardening) 

  • Goal: Keystone is the heart of OpenStack authentication and authorization. A compromise of Keystone means a compromise of the entire cloud. 

  • Practice: 

  • Use strong, unique passwords for OpenStack service accounts in Keystone. 

  • Implement RBAC (Role-Based Access Control) with the principle of least privilege. Ensure each user, project, and service has only the minimum necessary permissions. 

  • Disable V2 token services if no longer used (migrate to V3). 

  • Configure short token validity periods and enable token revocation. 

Database Service Hardening (MySQL/MariaDB/PostgreSQL) 

  • Goal: The database stores all sensitive OpenStack configuration and operational data. 

  • Practice: 

  • Secure OpenStack database credentials with very strong and unique passwords. 

  • Restrict database access only from nodes that require it (typically controller nodes). 

  • Encrypt database communication using TLS. 

  • Disable password-less root@localhost access. 

Message Queue Hardening (RabbitMQ/Qpid/Kafka) 

  • Goal: Prevent unauthorized interception or injection of messages that could disrupt OpenStack operations. 

  • Practice: 

  • Secure credentials for message queue connections. 

  • Use TLS for communication between OpenStack components and the message queue. 

  • Disable guest or unnecessary default users. 

Compute Service Hardening (Nova) 

  • Goal: Nova manages VM instances, which are the core of user workloads. 

  • Practice: 

  • Secure communication between Nova-API and the hypervisor (e.g., using TLS for Libvirt). 

  • Configure resource limits (CPU, RAM, disk I/O) for instances to prevent intentional resource exhaustion. 

  • Ensure all VM images used are from trusted sources and have been hardened (e.g., no default passwords, latest patches). 

  • Consider using seccomp and AppArmor to restrict container or VM capabilities. 

Networking Service Hardening (Neutron) 

  • Goal: Neutron controls all aspects of cloud networking, making it a prime target for attacks. 

  • Practice: 

  • Implement strict security groups for VM instances. Only allow absolutely necessary traffic. This acts as a VM-level firewall. 

  • Consider using Firewall-as-a-Service (FWaaS) if more advanced firewall features are needed for VMs. 

  • Ensure Neutron agents run with the lowest possible privileges. 

  • Use strong network segmentation (VLANs, VXLANs) to isolate tenants. 

Storage Service Hardening (Cinder/Swift/Glance) 

  • Goal: Secure user data stored in the cloud. 

  • Practice: 

  • Encrypt Cinder volumes at rest (data stored) and in transit (data moving). 

  • Secure the backend storage used by Cinder and Swift with strong access controls. 

  • Ensure Glance images are stored securely and only verified images can be uploaded. Implement image integrity checks with checksums or signing. 

Step 3: Network and General Environment Hardening 

Security aspects beyond OpenStack components but crucial for a Private Cloud. 

Physical/Virtual Network Segmentation 

  • Goal: Reduce the impact of security breaches and limit access to critical components. 

  • Practice: 

  • Separate the OpenStack management network (for core service communication) from user data networks and public networks. 

  • Use VLANs, VXLANs, or micro-segmentation to isolate sensitive nodes and prevent lateral movement if one node is compromised. 

Zero Trust Architecture (ZTA) 

  • Goal: Implement a "never trust, always verify" approach. 

  • Practice: 

  • Authenticate and authorize every access request, regardless of its location (internal or external). 

  • Implement micro-segmentation to restrict communication between workloads even within the same network. 

Regular Security Audits and Vulnerability Scanning 

  • Goal: Identify weaknesses that might have been missed during the initial hardening process. 

  • Practice: 

  • Perform regular external and internal vulnerability scans on all OpenStack nodes and endpoints. 

  • Conduct periodic penetration testing by third parties to simulate real-world attacks. 

Comprehensive Security Monitoring 

  • Goal: Early detection is key to effective incident response. 

  • Practice: 

  • Implement a robust monitoring system for all OpenStack components, host OS, and network. 

  • Monitor performance metrics, security logs, and behavioral anomalies. 

  • Integrate with a SIEM for event correlation and effective alerting. 

Incident Response Plan 

  • Goal: Minimize the impact of an attack and accelerate recovery. 

  • Practice: 

  • Even with hardening, no system is 100% immune. Have a clear, documented, and tested incident response plan to handle security breaches. 

  • Conduct regular incident simulation exercises. 

Step 4: Installation and Automation Process Hardening (Kolla-Ansible) 

If you're using Kolla-Ansible (an excellent tool for deploying OpenStack in containers), it's important to secure this process as well. 

Secure Git Repositories 

  • Goal: Prevent unauthorized modification or access to your deployment configurations. 

  • Practice: 

  • Ensure Git repositories containing your Kolla-Ansible configurations and playbooks are securely hosted (e.g., on GitLab/GitHub with strong authentication, restricted access controls, and audit logging). 

Secrets Management 

  • Goal: Prevent hardcoding sensitive credentials. 

  • Practice: 

  • Never store credentials or private keys in Git repositories in plaintext. 

  • Use a secrets management solution like Ansible Vault, HashiCorp Vault, or a Kubernetes secrets management system to securely store all secrets. 

Secure Kolla-Ansible Usage 

  • Goal: Ensure the tool you use for deployment doesn't become a source of vulnerabilities. 

  • Practice: 

  • Ensure the Docker images used by Kolla-Ansible are from trusted sources (e.g., official images or images you've built and scanned yourself). 

  • Follow Kolla-Ansible's security best practices for configuration (global.yml, passwords.yml). 

Conclusion

System hardening for an OpenStack Private Cloud is an ongoing, layered effort. It's not a one-time task but a commitment to security that must adapt to new threats. By systematically implementing these steps, you not only build a functional cloud but also a resilient, secure cloud, ready to face future cybersecurity challenges. Neglecting hardening is akin to inviting trouble. 

Use System Hardening for OpenStack with Btech

contact@btech.id / +62-811-1123-242

 

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OpenStack Hardening System Hardening