Nmap (Network Mapper) is an open-source tool for port and network service scanning.

What is Nmap?

Nmap is a security tool that allows discovering hosts and services on a network, as well as identifying vulnerabilities.

Main Features

Port Scanning

  • **TCP": TCP scanning
  • **UDP": UDP scanning
  • **SYN": SYN scanning
  • **ACK": ACK scanning

Service Detection

  • **Version detection": Version detection
  • **OS detection": Operating system detection
  • **Scripts": NSE scripts
  • **Vulnerabilities": Vulnerability detection

Network Scanning

  • **Host discovery": Host discovery
  • **Port scanning": Port scanning
  • **Service detection": Service detection
  • **OS fingerprinting": OS fingerprinting

Basic Commands

Simple Scanning

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# Basic scan
nmap 192.168.1.1

# Range scan
nmap 192.168.1.1-254

# Subnet scan
nmap 192.168.1.0/24

Advanced Scanning

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# TCP SYN scan
nmap -sS 192.168.1.1

# UDP scan
nmap -sU 192.168.1.1

# Version detection scan
nmap -sV 192.168.1.1

# OS detection scan
nmap -O 192.168.1.1

Port Scanning

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# Specific port scan
nmap -p 80,443,22,21 192.168.1.1

# Port range scan
nmap -p 1-1000 192.168.1.1

# Common ports scan
nmap --top-ports 1000 192.168.1.1

NSE Scripts

Security Scripts

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# Vulnerability scripts
nmap --script vuln 192.168.1.1

# Authentication scripts
nmap --script auth 192.168.1.1

# Discovery scripts
nmap --script discovery 192.168.1.1

Specific Scripts

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# HTTP script
nmap --script http-enum 192.168.1.1

# SSH script
nmap --script ssh-hostkey 192.168.1.1

# SMB script
nmap --script smb-enum-shares 192.168.1.1

Use Cases

Security Auditing

  • **Inventory": Asset inventory
  • **Vulnerabilities": Vulnerability identification
  • **Services": Service identification
  • **Ports": Open port identification

Network Monitoring

  • **Availability": Verify service availability
  • **Changes": Detect network changes
  • **Inventory": Maintain updated inventory
  • **Compliance": Verify compliance

Penetration Testing

  • **Reconnaissance": Reconnaissance phase
  • **Scanning": Target scanning
  • **Enumeration": Service enumeration
  • **Vulnerability assessment": Vulnerability assessment

Best Practices

Ethical Use

  • **Authorization": Obtain authorization
  • **Scope": Define scan scope
  • **Documentation": Document activities
  • **Responsibility": Take responsibility

Techniques

  • **Stealth": Use stealth techniques
  • **Timing": Adjust scan timing
  • **Fragmentation": Use fragmentation
  • **Decoy": Use decoys

Analysis

  • **Results": Analyze results
  • **False positives": Identify false positives
  • **Correlation": Correlate with other data
  • **Documentation": Document findings

References