Similar to increasing the verbosity of a scan, it is invaluable to understand the network hops that occur between hosts—and to see the actual network traffic passing through. Although it's possible to use system tools such as traceroute and tcpdump to find out where on a network target servers land, it can be a painful (and time-consuming) process to do this to many hosts simultaneously.

Instead of using outside tools, Nmap allows packet tracing for each scan—which shows the exact information we need. Instead of looking at this as a security feature (although it certainly does have security-related uses), it's best to think of this as a tool for system administrators and network engineers.

This packet tracing example shows tcpdump-style output from Nmap to target machines. Although it doesn't provide excessive value in this simple one-port scan, the information can be great to understand network congestion, packet drop, offline hosts, and so on, on larger scans.