📱 Mobile Security Tips
Mike Torres — Android Security Engineer
What is Nmap?
Nmap (Network Mapper) is an open-source tool designed for network discovery and security auditing. It is widely used by security professionals for tasks such as identifying hosts and services on a network, discovering open ports, and detecting vulnerabilities.
Installation
Nmap can be installed on various platforms. Below are the steps for major operating systems:
Linux: Use the package manager, for example:
sudo apt-get install nmap
Windows: Download the installer from the Nmap website and follow the setup instructions.
macOS: Use Homebrew:
brew install nmap
Basic Syntax
The basic syntax of Nmap is as follows:
nmap [options]
Where
Discovery
Ping Scan
To quickly determine which hosts are up in a network:
nmap -sn
Service Version Detection
Identify services running on open ports:
nmap -sV
Scanning
TCP Connect Scan
Perform a full TCP connection:
nmap -sT
Quick Scan
Quickly scan the most common 1,000 ports:
nmap -F
Exploitation
OS Detection
Identify the operating system running on a host:
nmap -O
Script Scan
Use Nmap scripts to check for vulnerabilities:
nmap -sC
Analysis
Output in XML
Save scan results in XML format for later analysis:
nmap -oX output.xml
Evasion
Fragment Packets
Evade firewalls using packet fragmentation:
nmap -f
Reporting
Save as Plain Text
Output results to plain text file:
nmap -oN output.txt
Quick Reference Table
| Flag | Description |
|---|---|
| -sT | TCP Connect Scan |
| -O | Enable OS Detection |
| -sV | Service Version Detection |
| -sn | Ping Scan |
| -f | Fragment packets |
Pro Tips
- Use
nmap -p-to scan all 65,535 ports. - Combine options for comprehensive scans, like
nmap -sS -Afor a stealth scan combined with OS and version detection. - Run background scans with
nmap -Pn.&
Real-World Examples
Example 1: Scanning a single target to identify services and OS:
nmap -sV -O
Example 2: Scanning an entire subnet with output saved:
nmap -oA subnet_scan -sS 192.168.1.0/24