Although the host group size customization we just learned about can help increase or decrease parallelism in full scans, it doesn't deal with the numbers of probes that are being sent out at a time. The actual parallelism flags, however, can help us deal with that!

As with many things, Nmap will attempt to automatically create the most efficient scanning groups, which is great for almost all instances. In my experience, changing the number of simultaneous probes being sent out without having a serious education in networking can result in disaster—but that's not always the case.

By increasing the value of --min-parallelism—say up to 10 or 12—you can force Nmap to scan at least that fast. Nmap will still make the scan run faster if it needs to, which reduces some of the risk.

On the other hand, it's possible to set the value of --max-parallelism as low as 1. This is very useful; in the sense that you can force Nmap to send out only one probe at a time,...