Masscan
Masscan is an open-source network port scanner designed for high-speed scanning of large networks, capable of scanning the entire IPv4 internet in under 6 minutes. It uses asynchronous transmission and custom TCP/IP stack to achieve speeds up to 10 million packets per second, making it significantly faster than traditional scanners like Nmap. It is commonly used for security assessments, network reconnaissance, and identifying open ports across vast IP ranges.
Developers and security professionals should learn Masscan when conducting large-scale network scans, such as for penetration testing, vulnerability assessments, or monitoring internet-wide threats, due to its unparalleled speed and efficiency. It is particularly useful for tasks like scanning entire subnets, performing internet-wide surveys, or quickly identifying exposed services in enterprise environments where time is critical. However, it should be used ethically and legally, as unauthorized scanning can violate laws or terms of service.