How To Install Nmap on Ubuntu 20.04 LTS

Install Nmap on Ubuntu 20.04

In this tutorial, we will show you how to install Nmap on Ubuntu 20.04 LTS. For those of you who didn’t know, Nmap is a utility for network exploration or security auditing. It is one of the essential tools used by network administrators to troubleshooting network connectivity issues and port scanning. Most Unix and Windows platforms are supported in both GUI and command line modes.

This article assumes you have at least basic knowledge of Linux, know how to use the shell, and most importantly, you host your site on your own VPS. The installation is quite simple and assumes you are running in the root account, if not you may need to add ‘sudo‘ to the commands to get root privileges. I will show you through the step by step installation of the Nmap security scanner on Ubuntu 20.04 (Focal Fossa). You can follow the same instructions for Ubuntu 18.04, 16.04, and any other Debian based distribution like Linux Mint.

Install Nmap on Ubuntu 20.04 LTS Focal Fossa

Step 1. First, make sure that all your system packages are up-to-date by running the following apt commands in the terminal.

sudo apt update
sudo apt upgrade

Step 2. Installing Nmap on Ubuntu 20.04.

Nmap is available from the default Ubuntu and Debian repositories. Just follow the step one by one:

sudo apt install nmap

After the installation is finished, verify the installed version of Nmap by entering:

nmap –version

Step 3. Using Nmap.

The article covers the basic options this tool has to offer. For a full list of options visit the Nmap official page or access the manual from your command line:

man nmap

Scan IP range or subnet:

To obtain general information of a remote system type:

sudo nmap target-IP-address or domain.com

Instead of scanning individual IPs, scan a whole IP range by defining it in your command line:

sudo nmap 192.168.77.2-222

The following command scans the entire specified subnet:

sudo nmap 192.158.77.0/24

Port Scanning with Nmap

Nmap is an efficient port scanner that recognizes six port states:

  • open – actively accepting TCP connections, UDP datagrams, or SCTP associations
  • closed – accessible; however, no application is listening on the port
  • filtered – Nmap cannot determine whether the port is open due to packet filtering
  • unfiltered – the port is accessible; however, Nmap is unable to determine if it is open or closed
  • open|filtered – Nmap cannot determine if a port is open or filtered
  • closed|filtered – Nmap cannot establish if a port is closed or filtered

Port Specification and Scan Order

By default, Nmap scans the thousand most common ports for each protocol. It also offers options for specifying which ports are to be scanned and whether the scan is random or ordered.

The -p option allows you to specify port ranges and sequences:

sudo nmap –p 80,443 192.168.77.222

This command scans ports 80 and 443 for the defined host.

TCP SYN scan

Initiate TCP SYN for a fast and unobtrusive scan. Since this type of scan never completes TCP connections, it is often referred to as half-open scanning. To run a TCP SYN scan, use the command:
sudo nmap -sS 192.168.77.222

Congratulations! You have successfully installed Nmap. Thanks for using this tutorial for installing the Nmap security scanner on your Ubuntu 20.04 LTS Focal Fossa system. For additional help or useful information, we recommend you to check the official Nmap website.

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