fluxion

Fluxion is a term with several distinct uses in mathematics, physics, and information security. In the history of calculus, fluxion was introduced by Isaac Newton as the name for the instantaneous rate of change of a flowing quantity, called a fluent. The fluxion of a fluent is the time derivative; conversely, a fluent is the quantity that changes over time. In this historical context, fluxions and fluents are the precursors to the modern concepts of derivatives and functions of time.

In contemporary mathematics and physics, the term fluxion is largely obsolete but appears in historical texts and some British sources. The concept corresponds to the derivative of a function with respect to time.

In information security, Fluxion is the name of an open-source cybersecurity tool used for wireless network security auditing. The project automates parts of the process of testing WPA/WPA2 networks by guiding the user through a social-engineering workflow to obtain credentials. It typically uses a rogue access point and a phishing page to capture the password, and depends on the user’s permission for legitimate testing. Because of its potential for misuse, deployment is restricted to authorized testing environments.