The masscan utility is the fastest Internet port scanner; in fact, it is capable of scanning the entire Internet in under 6 minutes. This obviously requires adequate hardware and network bandwidth. The masscan utility runs using asynchronous transmission, which is what allows it to scan so quickly. One thing to be aware of with masscan is that it utilizes its own custom TCP/IP stack, so some care needs to be taken to avoid conflicts with the local TCP/IP stack. This specific recipe demonstrates how we can use the masscan command to perform a TCP stealth scan.