Visualizing Network Reconnaissance with Nmap and DrawNmap

Introduction

In the field of cybersecurity, network mapping and reconnaissance are foundational techniques for identifying potential attack surfaces and understanding infrastructure. One of the most trusted tools for this purpose is Nmap (Network Mapper) – a powerful open-source utility for network discovery and security auditing.

However, Nmap’s raw output, particularly in large or complex networks, can become difficult to interpret at a glance. That’s where DrawNmap, a Python-based visualization tool, becomes invaluable.

This article walks you through how to use Nmap for network scanning and how to leverage DrawNmap to convert scan results into intuitive, actionable visualizations.

Why Use Nmap?

Nmap is widely used in offensive and defensive security for:

• Port scanning (TCP/UDP)
• OS and service fingerprinting
• Identifying live hosts
• Network inventory and vulnerability assessments

Example use cases:

• Penetration testers looking to map out potential entry points
• Blue teams validating network configurations
• SOC analysts checking for unauthorized hosts or rogue services

The Problem with Raw Nmap Output

Nmap supports multiple output formats: normal (-oN), grepable (-oG), and XML (-oX). While XML is the most structured, parsing it manually or reviewing large results can be time-consuming and error-prone.

For instance, scanning a subnet of 256 IPs with service detection can result in thousands of lines of XML. This is not ideal for:

• Rapid visual inspection
• Executive reporting
• Spotting anomalies in complex topologies

What is DrawNmap?

DrawNmap is an open-source tool developed by jor6PS that transforms Nmap XML output into visually interpretable graphs. These graphs help visualize network structure, host relationships, and exposed services.

Key features:

• Parses nmap -oX XML output
• Generates .png or .svg network diagrams
• Uses NetworkX and Matplotlib for layout rendering
• Supports filtering, port grouping, and layout customization

Installation

git clone https://github.com/jor6PS/DrawNmap.git
cd DrawNmap
pip install -r requirements.txt

Ensure you have Python 3 and the following dependencies:

• networkx
• matplotlib
• lxml

How to Use DrawNmap with Nmap

Step 1: Perform an Nmap scan with XML output

nmap -sS -sV -O -T4 -oX scan.xml 192.168.1.0/24

• -sS: SYN scan
• -sV: Detect service versions
• -O: Attempt OS detection
• -T4: Faster execution
• -oX scan.xml: Save output in XML format

Step 2: Visualize with DrawNmap

python3 DrawNmap.py -f scan.xml -o network_map.png

Optional parameters:

• --layout circular|shell|spring|kamada_kawai
• --output-format svg|png

Example:

python3 DrawNmap.py -f scan.xml -o topology.svg --layout spring

Use Cases in Cybersecurity

1. Network Reconnaissance (Red Team)

Visual maps make it easier to:

• Identify critical assets
• Spot exposed management ports (e.g., SSH, RDP)
• Plan lateral movement paths

2. Network Auditing (Blue Team)

• Verify that only authorized services are running
• Detect inconsistencies (e.g., workstations running FTP servers)
• Report on network structure to non-technical stakeholders

3. Documentation & Reporting

• Integrate graphs into pentest reports
• Use in executive summaries to communicate risk visually

4. Continuous Security Monitoring

• Automate periodic scans and visual exports
• Integrate into CI/CD pipelines for DevSecOps

Benefits of Visualization

• 🔍 Quick Pattern Recognition: See which hosts are hubs or have too many open ports
• 🚩 Anomaly Detection: Spot unusual services or rogue devices visually
• 📊 Better Communication: Replace raw data with intuitive maps

Limitations

• Only supports XML output from Nmap
• Very large scans (>1000 hosts) may generate cluttered graphs
• Does not analyze vulnerabilities – visualizes structure only
• May require fine-tuning layout for clarity

Pro Tip: Automate the Workflow

You can script the entire flow for regular scans:

#!/bin/bash
nmap -sS -sV -O -T4 -oX /tmp/scan.xml 192.168.1.0/24
python3 /opt/DrawNmap/DrawNmap.py -f /tmp/scan.xml -o /var/www/html/nmap_report.svg

Then access the SVG report in a browser or send via email.

Conclusion

Combining Nmap’s powerful scanning capabilities with DrawNmap’s intuitive visualizations enables security professionals to:

• Accelerate network reconnaissance
• Simplify reporting
• Identify weak points faster

Whether you’re conducting a red team engagement or auditing your internal infrastructure, DrawNmap offers a fresh and effective way to understand your network visually.

Resources

• 🔗 Nmap official site
• 🔗 DrawNmap GitHub repository
• 📖 Nmap Reference Guide