You can’t defend what you can’t see.
That was the lesson I learned the hard way when troubleshooting a mysterious network slowdown. Logs didn’t help. Firewalls looked fine. But when I ran an Nmap scan, the results painted a different picture—an unauthorized device quietly communicating outside our network.
If you want to visualize network topology and spot vulnerabilities before attackers do, Nmap is your best tool. It doesn’t just scan for open ports; it reveals hidden pathways, exposes weak spots, and helps you map your entire infrastructure in a way that raw data alone can’t.
In this guide, we’ll break down how to transform Nmap scan results into a clear, visual representation of your network—so you can proactively secure your systems before threats emerge.
Ready to see your network like never before? Let’s dive in.
Exporting Nmap Scan Results
To visualize your network, you first need to export the scan results from Nmap. Use the following command in Termux to perform a network scan and save the results in a grepable format:
nmap -sn 192.168.1.0/24 -oG network_scan.txtExpected Output:
After running the command, your network_scan.txt file will contain data like this:
Nmap 7.80 scan initiated Fri Sep 19 10:10:00 2024 as: nmap -sn 192.168.1.0/24 -oG network_scan.txt
Host: 192.168.1.1 (router) Status: Up
Host: 192.168.1.1 (router) Ports: 80/open/tcp//http///; MAC Address: AA:BB:CC:DD:EE:FF (Router Manufacturer)
Host: 192.168.1.10 (device1) Status: Up
Host: 192.168.1.10 (device1) Ports: 22/open/tcp//ssh///; MAC Address: 11:22:33:44:55:66 (Device Manufacturer)
Host: 192.168.1.20 (device2) Status: Up
Host: 192.168.1.20 (device2) Ports: 80/open/tcp//http///; MAC Address: 77:88:99:AA:BB:CC (Device Manufacturer)
# Nmap done at Fri Sep 19 10:10:10 2024 -- 256 IP addresses (3 hosts up) scanned in 3.45 seconds· · ─ ·𖥸· ─ · ·
Recommended Visualization Tools
Once you have your scan results exported, you can use various visualization tools to create a graphical representation of your network. Here are some recommended tools:
Graphviz
Description: An open-source graph visualization software that can create visual graphs from DOT format.
How to Use: Convert your Nmap output to DOT format and visualize it.
Gephi
Description: A powerful open-source network visualization tool for exploring and visualizing complex networks.
How to Use: Convert the Nmap output to CSV and import it into Gephi.
Cytoscape
Description: A platform for complex network analysis and visualization, primarily used in bioinformatics but applicable to general network analysis.
How to Use: Import your data after converting it to a suitable format.
Nmap’s Zenmap
Description: The official GUI for Nmap, which can also visualize scan results.
How to Use: Load the Nmap output directly into Zenmap.
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Sample Code and Outputs
To visualize your Nmap scan results using Graphviz, you need to convert the network_scan.txt file into DOT format. Here’s a simple Python script to do that:
import re
# Read Nmap output
with open('network_scan.txt', 'r') as file:
lines = file.readlines()
# Prepare DOT format
dot_output = "digraph G {\n"
# Extract host data
for line in lines:
if "Host:" in line:
parts = re.split(r'\s+', line.strip())
ip = parts[1]
name = parts[2] if len(parts) > 2 else ""
dot_output += f' "{ip}" [label="{name}"];\n'
# Connect hosts based on open ports (example logic)
for line in lines:
if "Ports:" in line:
parts = re.split(r'\s+', line.strip())
ip = parts[1]
# Simple logic to connect to the router
if "router" in line:
dot_output += f' "{ip}" -> "192.168.1.1";\n'
dot_output += "}\n"
# Write to a .dot file
with open('network.dot', 'w') as dot_file:
dot_file.write(dot_output)
Example Output in DOT Format:
The generated network.dot file will look something like this:
digraph G {
"192.168.1.1" [label="(router)"];
"192.168.1.10" [label="(device1)"];
"192.168.1.20" [label="(device2)"];
"192.168.1.10" -> "192.168.1.1";
"192.168.1.20" -> "192.168.1.1";
}To visualize the graph, run the following command with Graphviz:
dot -Tpng network.dot -o network_topology.pngExpected Output:
The output will be a PNG image file (network_topology.png) representing the network topology based on your Nmap scan results.
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Visualize Network Weaknesses Before They Become Threats
Every open port, every connected device, and every overlooked configuration—your network tells a story. The difference between secure and compromised often comes down to visibility. When you visualize network topology with Nmap, you’re not just running a scan—you’re creating a blueprint of security risks before attackers do.
By transforming raw Nmap scan results into clear, actionable network maps, you gain the power to defend, optimize, and future-proof your infrastructure. Whether you’re securing a home lab or managing enterprise systems, seeing is securing.
Don’t let blind spots become breach points—start mapping your network today.
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