The digital world feels increasingly precarious, doesn’t it? Concepts like “digital sovereignty” are no longer just conference buzzwords; they’re becoming critical considerations. For many, especially outside the US, relying entirely on proprietary, often US-based, security stacks raises uncomfortable questions about data control and geopolitical dependencies. We worry about our data in foreign clouds, but what about the very tools we use to protect it?
Can open source offer a viable alternative? Can we assemble a collection of powerful, community-driven tools into something more than just a disparate pile – something cohesive, effective, and manageable? Can we build a security platform that rivals commercial offerings without the eye-watering price tag?
This post is my attempt to outline such a possibility. It’s a blueprint, drawing inspiration from the open-source community, security best practices, and real-world experience. It’s an architecture designed primarily for the Small to Medium Business (SMB) world, often navigating hybrid cloud and on-premise environments. This is my take on leveraging the best of OSS to secure endpoints, defend networks, hunt vulnerabilities, and respond to incidents – all while keeping control firmly in your hands.
The Fortress: Layers and Pieces#
This isn’t just a random collection of tools; it’s a layered approach, designed to provide defense in depth. Think of it as a security onion – hopefully one that doesn’t make you cry too much when you’re configuring it.
Layer 1: Network Security (The Outer Perimeter)#
This is your first line of defense - controlling what gets in and out of your network:
- pfSense / OPNsense: Rock-solid, open-source firewall and router platforms. Your primary gateway and traffic control.
- Suricata IDS/IPS: Sniffing out and blocking network attacks before they reach your internal systems.
- Zeek (formerly Bro): For deep-dive network analysis and logging everything. Seriously, everything.
Layer 2: The Core (The Central Nervous System)#
This is where the data tsunami lands, gets processed, and turned into actionable intelligence:
- ELK Stack (Elasticsearch, Logstash, Kibana) / OpenSearch: The big data engine. Collects, parses, stores, and visualizes all those security logs and events.
- Wazuh Server: Centralizes all that security data. Think of it as the security hub.
- OpenVAS / GVM (Greenbone Vulnerability Management): Proactively scanning your network for vulnerabilities before the bad guys find them.
Layer 3: Identity & Access (The Guards)#
Managing who gets access to what:
- Keycloak / FreeIPA / OpenLDAP: Handling user identities and access control (IAM).
- Vaultwarden (or HashiCorp Vault): Securely storing your secrets (API keys, passwords, certificates) in a centralized vault.
- Ansible: Your automation enforcer. Ensuring security policies and configurations are consistently applied.
Layer 4: Endpoint Security (The Inner Guards)#
Protecting the actual systems where work happens:
- Wazuh Agents: Real-time monitoring, intrusion detection, and active response, right on the endpoint.
- ClamAV: The classic, open-source antivirus engine. Not perfect, but solid for scanning suspicious files.
- File Integrity Monitoring (FIM): Catching unauthorized file changes (built into Wazuh).
Layer 5: Incident Response (The Emergency Team)#
When something gets through, these tools help you respond:
- TheHive: A platform for tracking, managing, and investigating security incidents.
- MISP (Malware Information Sharing Platform): Sharing and consuming threat intel with the broader security community.
- Cortex: The analysis engine connecting TheHive to various analyzers (VirusTotal, sandboxes, etc.).
(Monitoring tools like Prometheus/Grafana could also fit here, providing visibility into the health and performance of the entire security stack).
Layer 6: Monitoring & Alerting (The Watchers)#
You need eyes on everything, and you need to know when something needs attention. This layer ties everything together with comprehensive monitoring and alerting:
Prometheus: The core metrics collection engine. Pulls metrics from:
- Node Exporter (system metrics)
- Wazuh API
- ELK/OpenSearch metrics
- pfSense/OPNsense metrics
- Custom exporters for your specific needs
AlertManager: Handles alert routing, deduplication, and grouping:
- Routes alerts to different teams/channels (Slack, Email, PagerDuty)
- Groups related alerts to reduce noise
- Implements on-call schedules and escalations
- Integrates with TheHive for automatic ticket creation
Grafana: Your primary visualization platform:
- Security Overview Dashboard: High-level security posture
- Network Security Dashboard: Firewall stats, IDS alerts, traffic patterns
- Endpoint Security Dashboard: Wazuh alerts, system health, compliance status
- Incident Response Dashboard: Active incidents, MISP alerts, response metrics
- Performance Dashboard: System health across your security stack
- Custom dashboards for specific needs
Loki: Log aggregation for metrics you can’t easily get into ELK:
- System logs
- Application logs
- Security tool logs
- Custom application logs
Vector/Fluentd: Log shipping and transformation:
- Routes logs to appropriate destinations (ELK, Loki)
- Transforms and enriches log data
- Handles backup destinations for reliability
Example Integrations:
- Wazuh alerts -> Prometheus -> AlertManager -> TheHive
- IDS alerts -> ELK -> Grafana alerts -> Slack/Email
- System metrics -> Prometheus -> Grafana -> Performance dashboards
- Log anomalies -> Loki -> Grafana -> AlertManager
This visibility layer gives your security team:
- Real-time awareness of security events
- Historical trend analysis
- Performance monitoring of security tools
- Automated alert handling and escalation
- Custom dashboards for different roles (SOC, Management, Engineering)
Remember: Good dashboards don’t just show data - they tell stories and guide actions.
Making It Work Together: A Practical Example#
Imagine a user clicks on a malicious link, downloading a dodgy file. Here’s how the integrated system might respond:
- Detection: The Wazuh agent on the laptop detects the suspicious file download or execution, perhaps confirming with a ClamAV scan.
- Alerting: The agent sends an alert to the Wazuh Server, which analyzes it and forwards the enriched data to Elasticsearch/OpenSearch.
- Correlation & Escalation: ELK/OpenSearch correlates this event with other logs (e.g., proxy logs showing the download source from Zeek, firewall logs from pfSense/OPNsense). An alert rule determines it’s a high-priority incident and automatically creates a case in TheHive.
- Automated Analysis: TheHive, via Cortex, automatically submits the file hash to MISP and other threat feeds, potentially sending the file itself to a sandbox for analysis. Cortex might also query ELK/OpenSearch for related activity.
- Containment: Based on the analysis results (e.g., confirmed malware), an Ansible playbook, triggered by TheHive/Cortex, isolates the infected laptop from the network using firewall rules pushed via pfSense/OPNsense or endpoint commands.
- Proactive Scanning: Another trigger initiates an OpenVAS/GVM scan to check if other systems are vulnerable to the same exploit.
- Remediation: If vulnerable systems are found, Ansible can be used to deploy patches or configuration changes.
- Visibility: Throughout the process, Kibana/OpenSearch Dashboards provide real-time visibility into the incident status, affected systems, and the overall security posture.
The Rewards vs. The Realities#
Building this open-source fortress isn’t trivial, so let’s be clear about the trade-offs.
Why Embrace This Approach? (The Upside)
- Significant Cost Savings: Dramatically reduce or eliminate expensive vendor license fees. Reinvest savings in hardware, talent, or training.
- True Digital Sovereignty: Maintain full control over your security data and infrastructure, crucial in today’s geopolitical climate.
- Transparency & Control: No black boxes. You can inspect the code and understand exactly how your security tools work.
- Unmatched Flexibility: Modular design allows you to swap components, customize workflows, and adapt quickly to new threats.
- Leverage the Community: Access vast knowledge bases, active forums, and rapid community-driven development.
- Escape Vendor Lock-In: Avoid proprietary ecosystems, forced upgrades, and unpredictable pricing.
What Challenges Await? (The Downside)
- Requires In-House Expertise: You need skilled personnel comfortable with Linux, networking, security concepts, and the specific tools involved. This isn’t plug-and-play.
- Integration Effort: Making disparate tools communicate effectively requires careful planning, configuration, and sometimes custom scripting (though choosing ELK/OpenSearch as the core simplifies this).
- Support is DIY: Forget vendor SLAs. You rely on community support, documentation, and your team’s troubleshooting skills.
- Documentation Can Be Scattered: Finding definitive answers might involve digging through wikis, forums, and code repositories.
- Upgrade Management: Updating one component requires careful testing to ensure compatibility with the rest of the stack.
Where Do You Go From Here?#
This blueprint provides a starting point, a vision for a cohesive, powerful, and sovereign open-source security platform. The real work lies in adapting it to your specific environment, diving deep into the configuration of each component, and fostering the skills needed to manage it effectively.
Mastering the central SIEM (ELK/OpenSearch in this blueprint) is paramount. Focus on:
- Securing the Core: Implement robust authentication, encryption (TLS), and access controls for your ELK/OpenSearch cluster.
- Optimizing Data Flow: Configure Logstash and Beats efficiently to parse and normalize logs from all your sources (Wazuh, Suricata, Zeek, firewalls, applications, etc.).
- Building Actionable Insights: Create dashboards and alerts in Kibana/OpenSearch that highlight critical security events and trends, not just noise.
- Integrating for Response: Connect ELK/OpenSearch tightly with TheHive, Cortex, and Ansible to enable automated analysis and response actions based on correlated data.
Building an open-source security fortress is a journey, not a destination. It requires commitment, skill, and a willingness to engage with the community. But the rewards – cost savings, control, flexibility, and true digital sovereignty – can be immense.
Now, I want to hear from you:
- What open-source security tools are indispensable in your setup?
- What crucial components or considerations did I miss?
- How vital is digital sovereignty for you or your organization?
- Would you add or remove anything from this blueprint?
- Is the effort truly worth the potential benefits for most SMBs?
Share your thoughts in the comments below! And hey, if you found this useful, let me know if you’d be interested in a deep dive into open-source monitoring solutions. I’m thinking about writing a follow-up post comparing tools like Zabbix, Prometheus, Nagios, and others – creating a comprehensive monitoring stack that complements this security blueprint. After all, you can’t secure what you can’t see, right?
Let’s build on this blueprint together. And who knows? Maybe we’ll explore how to keep an eye on everything we just built in the next post. 😉