MASSCAN - TCP port scanner, spews SYN packets asynchronously, scanning entire Internet in under 5 minutes

MASSCAN is Mass IP port scanner. This is the fastest Internet port scanner. It can scan the entire Internet in under 6 minutes, transmitting 10 million packets per second. It produces results similar to nmap, the most famous port scanner. Internally, it operates more like scanrand, unicornscan, and ZMap, using asynchronous transmission. The major difference is that it's faster than these other scanners. In addition, it's more flexible, allowing arbitrary address ranges and port ranges.