Wazuh vs Security Onion: 2-Week SIEM/EDR Test

Choosing a SIEM (Security Information and Event Management) or EDR (Endpoint Detection and Response) platform is critical for any organization’s security posture. In an enterprise environment with thousands of endpoints, these decisions significantly impact threat detection capabilities and the security team’s operational efficiency. I recently had the opportunity to compare two popular open-source solutions, Wazuh and Security Onion, testing them for two weeks on a real-world log dataset from an infrastructure with over 2,000 workstations and 300+ VMware VMs. My goal was to evaluate not just their technical capabilities, but also resource consumption, ease of management, and effectiveness in detecting common threats in an operational context.

Tested on: Ubuntu 22.04 LTS · Wazuh 4.7.0 · Security Onion 2.4.50 · August 2026

Prerequisites / Test Environment

For this test, I set up two distinct environments with equivalent hardware specifications to ensure a fair comparison. Each environment consisted of a manager/master server and several agents distributed across a sample of Linux and Windows workstations and servers. Log collection included system events, FortiGate firewall logs, Active Directory events, and sampled network traffic data. The main challenge was managing the data volume and correlating events in real-time while maintaining an acceptable number of false positives.

Wazuh: Lightweight Agents, Endpoint Detection

Wazuh is an open-source security platform that integrates SIEM, EDR, HIDS (Host-based Intrusion Detection System), and compliance monitoring functionalities. Its architecture relies on lightweight agents installed on endpoints, which collect data and send it to a central manager for analysis. During the test, agent installation was relatively straightforward and scalable, using automation scripts for large-scale deployment.

# Install Wazuh agent on a Linux system (e.g., CentOS/RHEL)
sudo WAZUH_MANAGER='10.0.0.10' WAZUH_AGENT_GROUP='linux-servers' yum install wazuh-agent
sudo systemctl daemon-reload
sudo systemctl enable wazuh-agent
sudo systemctl start wazuh-agent

Wazuh Strengths:

HIDS/EDR Detection: Excellent for File Integrity Monitoring (FIM), rootkit detection, process monitoring, and system call monitoring. I configured custom rules to detect anomalous behaviors specific to our environment, such as PowerShell execution in unusual contexts. Read also: Fail2ban on Linux: Complete Setup and SSH Hardening
Compliance: Pre-built dashboards for standards like PCI DSS, NIST, and CIS Benchmark facilitate compliance verification. This is a critical aspect for many organizations.
Scalability: The underlying OpenSearch (formerly Elasticsearch) cluster handles high log volumes and scales horizontally. I configured a three-data-node cluster to manage 2,000 endpoints without significant slowdowns.
Cost: Being open-source, costs are primarily related to hardware and personnel. There are no direct software licenses, making it attractive for limited budgets.

Wazuh Weaknesses:

Network Visibility: Wazuh, by its nature, has limited visibility into network traffic. It relies on logs generated by endpoints or external firewalls. For in-depth network analysis, integration with dedicated tools is necessary.
Complex Correlation: Correlating events across different sources requires careful rule configuration and a good understanding of OpenSearch Query Language (OSQL).

Security Onion: Complete Network Analysis Suite

Security Onion is an Ubuntu-based Linux distribution that integrates a comprehensive suite of open-source tools for Network Security Monitoring (NSM), log analysis, and incident management. It includes Zeek (formerly Bro) for protocol analysis, Suricata for IDS/IPS, Elasticsearch/OpenSearch for log indexing, Kibana/Grafana for visualization, TheHive for incident response, and Playbook for automation. Installation is more complex than Wazuh, requiring detailed network interface configuration for traffic capture.

# Example command to start a Security Onion sensor setup
sosetup
# Interactive, requires selecting network interfaces for monitoring

Security Onion Strengths:

Network Visibility: The ability to deeply analyze network traffic is its biggest advantage. Zeek and Suricata provide granular details on sessions, protocols, and potential threats based on signatures or behavioral anomalies. This allowed us to detect scanning activities and exploit attempts that endpoint logs alone would not have shown.
Integrated Ecosystem: The pre-integrated suite of tools reduces setup and configuration time. Having TheHive and Playbook in the same environment significantly streamlines the incident response workflow.
Threat Hunting: Tools like Fleet and CyberChef, integrated into the distribution, are extremely useful for threat hunting teams who need to interactively analyze large amounts of data.

Security Onion Weaknesses:

Resource Consumption: Security Onion is notoriously resource-intensive, especially when full-packet capture and analysis of network traffic are enabled. To manage 2,000 endpoints, robust and well-sized hardware is essential. Read also: Elasticsearch OOM: Cluster RED from Unassigned Shard
Learning Curve: Managing all integrated tools requires a steeper learning curve compared to Wazuh, which has a more specific focus.
Agent Management: It does not have a distributed agent system like Wazuh; its strength lies primarily in network analysis and collecting logs from centralized sources.

Common Errors and Troubleshooting

During the test, one of the most common errors with Wazuh was agents failing to send logs due to connectivity issues or firewall misconfiguration. Always verify ports (default 1514/UDP for logs, 1515/TCP for enrollment) and certificates. For Security Onion, the main problem was incorrect hardware sizing, leading to dropped packets and slowdowns in log indexing. Closely monitoring system and network metrics is crucial for both solutions. Another frequent error is a lack of rule tuning, which leads to an excessive number of false positives, overwhelming the security team. Dedicating time to calibrate rules and create baselines for your specific environment is essential.

# Check Wazuh agent status
sudo systemctl status wazuh-agent
# Check Wazuh agent logs for errors
sudo tail -f /var/ossec/logs/ossec.log

FAQ — Frequently Asked Questions

Are Wazuh or Security Onion compliant with standards like NIS2?

Yes, both platforms, if properly configured and managed, can significantly contribute to achieving compliance with standards such as NIS2, ISO 27001, and GDPR. They offer essential features for continuous monitoring, incident management, threat detection, and audit logging, which are key requirements of these regulations. The choice depends on which aspect of compliance you want to strengthen most (endpoint vs. network).

Can I integrate Wazuh and Security Onion?

Absolutely. Many organizations choose to integrate the two solutions to combine their strengths. For example, you can use Wazuh for EDR visibility on endpoints and send its alerts to Security Onion’s TheHive for incident management. Alternatively, Security Onion logs can be sent to a Wazuh manager for centralized correlation. This hybrid architecture provides more robust security coverage.

What is the main difference in threat detection?

Wazuh excels at detecting anomalous activity at the host level, such as file system modifications, unauthorized access attempts, malicious software execution, and policy violations. Security Onion, on the other hand, is unsurpassed in identifying threats based on network traffic, such as port scans, known vulnerability exploits, C2 (Command and Control) communications, and network protocol anomalies.

How long does it take to implement either solution?

Initial implementation of Wazuh, especially with automation scripts for agents, can take from a few days to a couple of weeks for a medium-sized environment. Security Onion requires more time, from two weeks to a month or more, due to the complexity of network configuration, tool tuning, and rule calibration to reduce false positives. The tuning phase is the most critical for both.

Conclusions with Operational Takeaways

After two weeks of intensive testing, it’s clear that neither Wazuh nor Security Onion is a one-size-fits-all solution. The ideal choice depends on an organization’s specific needs. If your primary focus is endpoint protection, compliance, and you have limited hardware resources, Wazuh is an excellent choice for its agent-based approach and scalability. If, however, you need deep network traffic visibility, an integrated suite for threat hunting and incident response, and have the hardware and human resources to manage it, Security Onion offers unparalleled value. In many scenarios, combining the two platforms can provide the most comprehensive coverage, leveraging the best of both worlds.

My operational takeaway is this: before choosing, clearly define your security priorities, assess your budget for hardware and personnel, and consider the learning curve for your team. No open-source solution is truly “free” if you don’t account for the cost of time and expertise required to implement and maintain it. Measuring false positives and detection/response times, as outlined in the CISA Measures of Consumption and Detection, was fundamental in guiding our choice.

Sources

Updated: August 2026