ZMap – Open Source Network Scanner
https://zmap.io/index.html

ZMap is an open-source network scanner that enables researchers to easily perform Internet-wide network studies. With a single machine and a well provisioned network uplink, ZMap is capable of performing a complete scan of the IPv4 address space in under 45 minutes, approaching the theoretical limit of gigabit Ethernet. ZMap can be used to study protocol adoption over time, monitor service availability, and help us better understand large systems distributed across the Internet. ZMap was developed by a team of computer scientists at the University of Michigan. While ZMap is a powerful tool for researchers, please keep in mind that by running ZMap, you are potentially scanning the ENTIRE IPv4 address space and some users may not appreciate your scanning. They encourage ZMap users to respect requests to stop scanning and to exclude these networks from ongoing scanning. They also suggest that users coordinate with local network administrators before performing any scans and they have developed a set of scanning best practices, which they encourage researchers to consider. It should go without saying that researchers should refrain from exploiting vulnerabilities or accessing protected resources, and should comply with any special legal requirements in their jurisdictions. This has been added to the tools section of Research Resources Subject Tracer™ Information Blog. This will be added to World Wide Web Reference Subject Tracer™ Information Blog.