Nmap

Overview

Nmap (Network Mapper) is an open-source utility for network discovery and security auditing, developed and maintained by the Nmap Project, founded by Gordon Lyon (known online as “Fyodor”). It is one of the longest-running tools in the network scanning category and is widely referenced in networking and security documentation. Nmap is primarily a command-line application, though it ships with an official graphical front end, Zenmap, for users who prefer a visual interface. The tool is designed to help administrators identify hosts, services, and configurations on a network they manage or are authorized to examine.

Key capabilities

Nmap’s core function is host discovery: determining which devices on a given network segment are online and reachable. Beyond discovery, it performs port scanning to identify which TCP and UDP ports are open, closed, or filtered on a target host. Its service and version detection engine can identify the application and version running behind an open port, which is useful for inventory and patch-management purposes. Nmap also includes OS detection, which analyzes network responses to estimate the operating system of a target device.

A significant part of Nmap’s functionality comes from the Nmap Scripting Engine (NSE), which allows users to write and run scripts in the Lua programming language to automate a wide range of networking tasks, from advanced discovery to configuration checks. The broader Nmap suite includes several companion utilities: Ncat, a flexible tool for reading and writing data across network connections; Nping, a packet-generation and analysis tool; and Ndiff, which compares the results of different Nmap scans to highlight changes over time.

Typical use cases

Nmap is commonly used by network and system administrators for network inventory, mapping which hosts and services exist on a network they are responsible for. Security teams use it during authorized security assessments to identify open ports and potentially misconfigured services. It is also used for monitoring host or service uptime, verifying firewall and access-control configurations, and auditing network changes over time with the help of Ndiff. Scanning must only be performed on networks you own or have explicit authorization to assess; scanning third-party networks without permission may violate laws and acceptable-use policies.

Licensing and pricing

Nmap is open-source software distributed under the Nmap Public Source License (NPSL), a license specific to the Nmap Project that is based on elements of the GNU General Public License with additional terms. The software is free to download and use under the terms of this license. Organizations with licensing questions outside the scope of the standard terms, such as certain commercial redistribution scenarios, should consult the license text and the Nmap Project directly.

Platform support

Nmap is cross-platform and runs on Windows, macOS, and Linux and BSD-based systems. Official installers and packages are provided for each of these platforms, and Nmap is also frequently available through operating system package managers on Linux and BSD distributions.

Getting started

Nmap should be obtained only from its official website, nmap.org, or from trusted operating system package repositories. This catalog does not host installers or distribute the software directly; visit the official site to download the current release for your platform and to review current documentation. Zenmap, the graphical interface, is typically offered as part of the same distribution for users who prefer not to work from the command line. Before running any scan, confirm that you own the target network or have documented authorization to test it, as unauthorized scanning of systems you do not control can carry legal consequences.

Guides

• Nmap Cheat Sheet: Essential Commands

Where to download

Downloads are hosted by Nmap Project on their official website. The button below opens that site — we never host installers.