What is Zeek used for?

Zeek is an open source network analysis framework that passively monitors network traffic and generates detailed logs. It is a good fit for network forensics and compliance, and integration with SIEM systems for security analysis.

Yes. Zeek is open source under a custom licence. Its source code is on GitHub at zeek/zeek and is written mainly in C++.

Yes. Zeek is open source, so the software itself is free to use under the terms of its own licence.

Can I self-host Zeek?

Yes. Zeek can be self-hosted on your own server or infrastructure.

What is Zeek an alternative to?

Zeek is an open-source alternative to Palo Alto Networks, Check Point and Amazon GuardDuty. Other open-source alternatives to Palo Alto Networks include Suricata, OPNsense and Falco.

Is Zeek actively maintained?

Yes. The most recent commit to Zeek was on 13 October 2026, and the latest release is v9.0.0, published on 21 August 2026. The project has 8.1k stars on GitHub.

Zeek: open-source alternative to Palo Alto Networks

About Zeek

Zeek is an open source network monitor originally developed by Vern Paxson in the 1990s under the name Bro. It operates passively on a sensor, analyzing network traffic in real-time without interfering with operations.

The framework captures high-fidelity transaction logs, file contents, and customizable data outputs. It is designed for manual review or integration into SIEM systems for security analysts.

Key features

Passive monitoring that silently observes network traffic without interfering with operations
Rich logging that generates detailed, structured logs of all network activity
Highly extensible with custom scripts and packages to extend functionality
Deep inspection of application-layer protocols including HTTP, DNS, SSL/TLS, SSH, and more
Threat detection to identify suspicious patterns, known attack signatures, and anomalous behavior
Scriptable via the Zeek scripting language for customization

Good fit for

Network forensics and compliance
Integration with SIEM systems for security analysis

Built with: C++ tools
Tags: network monitor; network analysis; security; ids; open source; traffic analysis

Zeek: questions and answers

What is Zeek used for?: Zeek is an open source network analysis framework that passively monitors network traffic and generates detailed logs. It is a good fit for network forensics and compliance, and integration with SIEM systems for security analysis.
Is Zeek open source?: Yes. Zeek is open source under a custom licence. Its source code is on GitHub at zeek/zeek and is written mainly in C++.
Is Zeek free?: Yes. Zeek is open source, so the software itself is free to use under the terms of its own licence.
Can I self-host Zeek?: Yes. Zeek can be self-hosted on your own server or infrastructure.
What is Zeek an alternative to?: Zeek is an open-source alternative to Palo Alto Networks, Check Point and Amazon GuardDuty. Other open-source alternatives to Palo Alto Networks include Suricata, OPNsense and Falco.
Is Zeek actively maintained?: Yes. The most recent commit to Zeek was on 13 October 2026, and the latest release is v9.0.0, published on 21 August 2026. The project has 8.1k stars on GitHub.