What Is Nmap? A Beginner’s Guide to Network Scanning + Video

 NMAP (Network Mapper)

Nmap (short for Network Mapper) is a powerful, open-source tool used for network discovery and security auditing. It’s widely used by system administrators, network engineers, and cybersecurity professionals to map networks, identify devices, and detect vulnerabilities.

What Nmap Does

Nmap sends specially crafted packets to target hosts and analyzes the responses to determine:

• Which hosts are up
• What services (e.g., HTTP, FTP) they offer
• What operating systems they run
• What firewalls or filters are in place
• What ports are open, closed, or filtered

Key Features

1. Host Discovery

• Identifies live hosts on a network.
• Example: nmap -sn 192.168.1.0/24

2. Port Scanning

• Detects open ports and services.
• Example: nmap -p 1-1000 192.168.1.1

3. Service Version Detection

• Determines the version of services running.
• Example: nmap -sV 192.168.1.1

4. OS Detection

• Guesses the operating system of a host.
• Example: nmap -O 192.168.1.1

5. Scriptable Interaction (NSE)

• Uses the Nmap Scripting Engine to automate tasks like vulnerability detection, brute forcing, and malware discovery.
• Example: nmap --script vuln 192.168.1.1

6. Firewall Evasion Techniques

• Includes options for spoofing, fragmentation, and timing to bypass firewalls and IDS.

Common Use Cases

• Network inventory and management
• Penetration testing
• Vulnerability assessment
• Compliance auditing
• Troubleshooting connectivity issues

Platforms

Nmap runs on:

• Linux
• Windows
• macOS
• BSD variants

It also has a graphical front-end called Zenmap, which makes it easier for beginners to use.

Ethical Considerations

• Always get permission before scanning networks you don’t own.
• Unauthorized scanning can be considered illegal or malicious.