📱 Mobile Security Tips
Sarah Chen — iOS Security Specialist
What is Nmap?
Nmap (Network Mapper) is an open-source tool for network exploration and security auditing. It is widely used by security professionals to discover hosts and services on a computer network by sending packets and analyzing the responses.
Installation
To install Nmap, you can use the package manager for your operating system:
- Ubuntu/Debian:
sudo apt install nmap - CentOS/Fedora:
sudo yum install nmap - Windows: Download the installer from nmap.org.
Basic Syntax
The basic syntax of Nmap is:
nmap [options]
Discovery
Ping Scan
Identify live hosts in a network:
nmap -sn 192.168.1.0/24
This sends ICMP echo request packets to the specified subnet.
Service Version Detection
Determine service versions running on ports:
nmap -sV 192.168.1.1
Use this for detailed version information.
Scanning
TCP Connect Scan
Perform a standard TCP connect scan:
nmap -sT 192.168.1.1
Full Range of Ports
Scan all 65535 ports on a target:
nmap -p- 192.168.1.1
Exploitation
TCP ACK Scan
Discover if ports are filtered:
nmap -sA 192.168.1.1
Analysis
OS Detection
Identify the operating system of the target:
nmap -O 192.168.1.1
Evasion
Decoy Scan
Obfuscate the source of the scan to avoid detection:
nmap -D RND:10 192.168.1.1
Reporting
XML Output
Generate an XML output file:
nmap -oX output.xml 192.168.1.1
Quick Reference Table
| Flag | Description |
|---|---|
| -sS | SYN scan (stealth scan) |
| -p- | Scan all ports |
| -oN | Normal output |
Pro Tips
- Timing Options: Use
-T4for faster scanning during active hours. - Use Grepable Output: For quick reviews, consider
-oG output.gnmap.
Real-World Examples
Find Open HTTP Ports
nmap -p 80,443 -sV 192.168.1.1
Inventory Network Devices
nmap -sP 192.168.1.0/24
Scan with Specific Interface
nmap -e eth0 192.168.1.0/24