Behave! is a free security extension for Firefox that focuses on protecting users from various web threats. It specifically monitors for potential DNS Rebinding attacks targeting private IPs, unauthorized access to private IP addresses, and browser-based port scans. This proactive approach ensures that users are alerted to suspicious activities that could compromise their security and privacy while browsing the internet.

The extension is categorized under Security & Privacy, specifically within the Anti-Spam & Anti-Spy subcategory. Its lightweight nature makes it easy to install and use without impacting browser performance. By providing real-time warnings, Behave! empowers users to take immediate action against potential threats, making it a valuable tool for anyone concerned about their online safety.