How to Install Nmap on Ubuntu Linux

Learn how to check whether Nmap is installed, refresh Ubuntu package information, install Nmap with APT, and verify the installation from a terminal.

Nmap is a command-line network discovery and security-scanning tool. This lesson explains how to install it on Ubuntu, a Linux distribution that uses APT for software package management.

Some Ubuntu installations may already include Nmap, so check for it before installing anything. The commands in this lesson use Ubuntu's configured package repositories rather than untrusted third-party downloads.

Prerequisites

Access to an Ubuntu system.
Ability to open a terminal and enter commands in a shell, the command-line environment used to interact with Linux.
An account authorized to use sudo for administrative operations.

How Ubuntu Package Management Works

A Linux distribution is a packaged operating system built around the Linux kernel. Distributions can use different software-management tools and package formats, so installation instructions are not identical across Linux systems.

This lesson focuses specifically on Ubuntu and its APT-based package management. APT finds, downloads, and installs software packages from configured package repositories. The apt-get command is a command-line interface for performing APT operations.

A package repository is a trusted software source that provides packages and package metadata. APT may also install dependencies, which are additional packages required for an application to function.

Check Whether Nmap Is Already Installed

Open a terminal from Ubuntu's application menu, or use your desktop environment's terminal shortcut. At the shell prompt, run:

nmap --version

The --version option asks the executable to display its version information without performing a scan.

Goal	Command	Expected Result
Check for Nmap	`nmap --version`	Version details if Nmap is installed, or an unavailable-command message if it is absent

Interpret the result

If the command displays Nmap version information, Nmap is already available from the command line. You can skip installation and begin using it.
If Ubuntu reports that Nmap is not installed or that the command cannot be found, continue with the installation steps.

Refresh Ubuntu Package Information

Before installing software, refresh the local package index. This index is local metadata that tells APT which package versions and dependencies are currently available from the configured repositories.

Run:

sudo apt-get update

sudo runs an administrative operation with elevated privileges. Refreshing package information does not upgrade installed software; it only downloads current package metadata. An upgrade is a separate operation that changes installed package versions.

APT may request your user password. While you type it, the terminal normally shows no characters or placeholder symbols. Enter the password and press Enter.

Install Nmap with APT

After the package index refresh completes, install the Ubuntu package named nmap:

sudo apt-get install nmap

APT examines the package and determines whether additional dependencies are needed. It may list Nmap, supporting libraries, or other packages that will be installed automatically.

Output Item	Meaning
Package lists	APT is reading available package metadata.
Dependency tree	APT is calculating package relationships and required supporting packages.
Additional packages	Other packages selected automatically because Nmap requires them.
Download size	The amount of data APT needs to obtain from the repositories.
Disk-space usage	The estimated storage required after installation.
Confirmation prompt	APT is waiting for approval before making the changes.

Review the package list, download amount, and disk-space estimate. If the changes are expected, type Y and press Enter when APT asks for confirmation. APT then downloads and installs Nmap and its required dependencies.

Verify the Installation

When installation finishes, run the version check again:

nmap --version

Version output confirms that Nmap is installed and available from the command line. The exact version depends on the Ubuntu release and the package version provided by its configured repositories.

Complete Installation Workflow

Open a terminal.
Run nmap --version.
If version information appears, Nmap is already installed.
If the command is unavailable, run sudo apt-get update.
Install Nmap with sudo apt-get install nmap.
Review the packages, dependencies, download size, and disk-space estimate.
Approve the confirmation prompt.
Run nmap --version again to verify the result.

Troubleshooting

Nmap is not installed or the command cannot be found

The executable is either not installed or is not available in the current command environment. Refresh package information, install the nmap package with APT, and repeat the version check.

APT asks for confirmation

This is normal. APT has calculated which packages will be installed, how much data must be downloaded, and how much disk space is needed. Review the changes and approve the prompt if they are expected.

Permission is denied

System-wide package installation requires administrator permission. Run the package command with sudo from an account authorized to use it. If the account is not permitted to use sudo, contact the Ubuntu system administrator.

APT has outdated package information

The local package index may not have been refreshed recently. Run:

sudo apt-get update

Then retry:

sudo apt-get install nmap

What to Do Next

Now that Nmap is installed, learn more about what Nmap is or continue to start Nmap. For a broader reference, see the Nmap guide. If you use Windows instead of Ubuntu, see how to install Nmap on Windows.