How to Scan a Network with Nmap on Linux (Ubuntu)

Installing and Using Nmap on Linux

• 💡 Nmap is a powerful network scanning tool for Linux, particularly useful on Ubuntu and Debian distributions.
• 🚀 To install Nmap, use the command sudo apt install nmap in the terminal.

Basic Network Scanning Techniques

• 📌 To find your IP address, use the command ip a.
• 🎯 Scanning a single host is done by typing nmap followed by the IP address (e.g., nmap 10.0.2.15).
• 🌐 Scanning an entire subnet is achieved using CIDR notation (e.g., nmap 10.0.2.0/24).
• ⚡ A ping scan (nmap -sn) can discover active hosts without port scanning.

Advanced Nmap Options

• 🔍 To scan specific ports, use the -p flag followed by the port number (e.g., nmap -p 80 10.0.2.15).
• 📊 The -sV flag is used to detect services and their versions running on open ports.
• 💻 OS detection can be performed with the sudo nmap -O command to identify the operating system.
• 💥 An aggressive scan (nmap -A) enables OS detection, version detection, script scanning, and traceroute for comprehensive information.
• 🛠️ Installing services like Apache2 (sudo apt install apache2) can help demonstrate scanning specific ports like HTTP (port 80).