OPNsense® is an open-source, user-friendly firewall and routing platform that combines the extensive features of commercial products, ranging from a stateful firewall to web application control and integrated inline intrusion detection and prevention. Based on FreeBSD for long-term support, OPNsense’s focus on security brings unique features such as an easy to use one time password authentication for various components. Through its modular design and - the in house developed - Model View Controller framework the product is extendible, and API functionality is readily available. The robust and reliable update mechanism gives OPNsense® the ability to provide important security updates in a timely fashion.