A new browser extension called Behave! will warn you if a web site is using scripts to perform scans or attacks on local and private IP addresses on your network. The extension was created by Stefano Di Paola, co-founder, CTO, and Chief Scientist of MindedSecurity. It was born as an experiment to warn users of web sites that abuse browser features to perform local attacks or scans on a visitor’s computer. It can also be configured to show browser notifications when concerning behavior is detected.
Source: https://www.bleepingcomputer.com/news/security/new-behave-extension-warns-of-website-port-scans-local-attacks/