From https://wazuh.com/:

Wazuh is a free, open source and enterprise-ready security monitoring solution for threat detection, integrity monitoring, incident response and compliance.

Security Onion Usage

Security Onion uses Wazuh as a Host Intrusion Detection System (HIDS). Wazuh is monitoring and defending Security Onion itself and you can add Wazuh agents to monitor other hosts on your network as well.


The main configuration file for Wazuh is /var/ossec/etc/ossec.conf.


If you want to configure Wazuh to send email, please see the Email section.


If you want to send Wazuh logs to an external syslog collector, please see the syslog-output section.

Active Response

Sometimes, Wazuh may recognize legitimate activity as potentially malicious, and engage in Active Response to block a connection. This may result in unintended consequences and/or blacklisting of trusted IPs. To prevent this from occurring, you can whitelist your IP address and change other settings in /var/ossec/etc/ossec.conf:


Tuning Rules

You can add new rules and modify existing rules in /var/ossec/rules/local_rules.xml.

Wazuh alerts of a level of 5 or greater will be populated in the Sguil database, and viewable via Sguil and/or Squert. If you would like to change the level for which alerts are sent to sguild, you can modify the value for OSSEC_AGENT_LEVEL in /etc/nsm/securityonion.conf and restart NSM services.

Adding Agents

The Wazuh agent is cross platform and you can download agents for Windows/Unix/Linux/FreeBSD from the Wazuh website:


It is important to ensure that you download the agent that matches the version of your Wazuh server. For example, if your Wazuh server is version 3.9.5, then you will want to deploy Wazuh agent version 3.9.5.

Once you’ve installed the Wazuh agent on the host(s) to be monitored, then perform the steps defined here:

You may need to run so-allow to allow traffic from the IP address of your Wazuh agent(s).

Maximum Number of Agents

Security Onion is configured to support a maximum number of 14000 Wazuh agents reporting to a single Wazuh manager.

Automated Deployment

If you would like to automate the deployment of Wazuh agents, the Wazuh server includes ossec-authd:
When using ossec-authd, be sure to add a firewall exception for agents to access port 1515/tcp on the Wazuh manager node:
sudo ufw allow proto tcp from agent_ip to any port 1515

More Information

For more information about Wazuh, please see https://documentation.wazuh.com/3.9/.