📱 Mobile Security Tips
Sarah Chen — iOS Security Specialist
{
“title”: “Mastering Nmap: A Comprehensive Usage Cheatsheet”,
“content”: “
What is Nmap?
Nmap (Network Mapper) is a powerful open-source tool for network discovery and security auditing. It is widely used by security professionals to discover hosts and services on a computer network, thus creating a ‘map’ of the network. Nmap can also detect operating systems, versions, and vulnerabilities of devices on the network.
Installation
Nmap can be installed on various platforms:
- Linux: Use package managers
sudo apt install nmap(Debian/Ubuntu) orsudo yum install nmap(CentOS/Fedora) - Windows: Download the installer from the official Nmap website.
- macOS: Use Homebrew with
brew install nmap
Basic Syntax
The basic syntax to run Nmap is as follows:
nmap [options] [target]
Discovery
Ping Scan
Quickly determine the availability of hosts in a network.
nmap -sn 192.168.1.0/24
Service Version Detection
Identify the service versions running on discovered ports.
nmap -sV 192.168.1.10
Scanning
TCP Scan
Conduct a TCP connect scan on a target machine.
nmap -sT 192.168.1.10
Stealth Scan
A more discreet scanning method that avoids detection.
nmap -sS 192.168.1.10
Exploitation
Scriptable Scanning
Utilize Nmap’s scripting engine to automate tasks.
nmap --script=banner 192.168.1.10
Analysis
Output Options
Generate output in different formats for further analysis.
| Flag | Description |
|---|---|
| -oN | Normal output |
| -oX | XML output |
| -oG | Grepable output |
Evasion
Fragmentation
Split packets to avoid detection by firewalls.
nmap -f 192.168.1.10
Decoy Scan
Perform a scan that masks your real IP behind several decoy IPs.
nmap -D RND:5 192.168.1.10
Reporting
Combine Output Formats
Combine output formats for detailed reports.
nmap -oA report_name 192.168.1.10
Quick Reference Table
| Flag | Description |
|---|---|
| -sn | Ping scan |
| -sV | Service version detection |
| -sT | TCP connect scan |
| -sS | Stealth SYN scan |
| –script | Run Nmap scripts |
| -oN | Normal output report |
| -oX | XML output report |
| -oG | Grepable output report |
| -f | Fragment packets |
| -D | Decoy scan |
| -oA | Output in all formats |
Pro Tips
- Use Nmap with a range: Scan multiple hosts using CIDR or a simple range
nmap 192.168.1.1-50 - Run Nmap in background: Use
&to run processes in the background. - Use grep with Nmap: Combine Nmap with grep for quick filtering
nmap -sS 192.168.1.0/24 | grep open
Real-World Examples
Scanning a web server and service enumeration:
nmap -sS -sV -p 80,443 192.168.1.10
Combining output into different formats for reporting: