Introducing the Nmap network scanning tool
The Nmap tool is a commonly used tool for most penetration testers and ethical hackers. It is constantly updated by an active group of contributors to this open source project. Nmap is primarily a port scanner, showing which TCP and UDP ports are open on a target system.
However, Nmap is not just a port scanner. It also provides numerous other features, including ping sweeps, operating system fingerprinting, and tracerouting. It can even be expanded with the Nmap Scripting Engine (NSE) to become a general-purpose vulnerability scanner as well. We’ll look at each of these features.
When using Nmap, it can be helpful to have the tool itself display a summary of the packets that it sends. The command switch to invoke this is the –packet-trace switch. It displays various status messages on its output, including some of the calls it makes to the operating system such as connect() sent or received, the protocol used (TCP or...
