In this tutorial, we will show you how to install Nmap on CentOS 8. For those of you who didn’t know, Nmap, short for Network Mapper, is a powerful open-source tool used for network discovery and security auditing. Network administrators and security professionals rely on Nmap to identify devices on a network, discover open ports, and detect vulnerabilities. Installing Nmap on CentOS 8 is a straightforward process, but it requires a few essential steps to ensure a smooth setup.
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 the step-by-step installation of the Nmap security scanner on CentOS 8.
Prerequisites
- A server running one of the following operating systems: CentOS 8.
- Ensure your system has at least 512MB of RAM and 1GB of free disk space.
- It’s recommended that you use a fresh OS install to prevent any potential issues.
- You need root or sudo privileges to install software packages.
Install Nmap on CentOS 8
Step 1. Before installing Nmap, update your system to ensure all packages are current. Open a terminal and run the following commands:
sudo dnf clean all sudo dnf update
Step 2. Installing Nmap on CentOS 8.
Run the following command to install Nmap:
sudo dnf install nmap
To verify the installation and operation of Nmap, enter the following command to receive the version:
nmap -version
You should see an output similar to this, confirming the installation:
Nmap version 7.80 ( https://nmap.org ) Platform: x86_64-redhat-linux-gnu Compiled with: liblua-5.3.5 openssl-1.1.1c libpcre-8.42 libpcap-1.9.0 nmap-libdnet-1.12 ipv6
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 about a remote system type:
sudo nmap target-IP-address or your-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 CentOS 8 systems. For additional help or useful information, we recommend you check the official Nmap website.
