Create an Advanced Port Scanner using Python

Introduction

Have you ever wondered how those “white hat” hackers (the good guys!) identify weaknesses in a network? It all starts with a technique called port scanning! For network administrators, safeguarding your systems is a constant battle. Port scanning is a vital tool in this fight. It helps them to find open ports and potential security risks.

In this article, we’ll create an advanced port scanner using Python and the powerful Nmap tool. Whether you’re a seasoned security professional or just starting your journey, this tutorial will help you with the knowledge to build a powerful port scanner and gain valuable insights into network security.

Safety First!

This port scanner is designed to help you learn, not hack. Remember, scanning a device without permission is a big no-no. It can be illegal and seriously disrupt the network. Always ask before you scan!

What is a Port and Port Scanning?

A port is a communication endpoint that allows networked devices to exchange data. Each port is associated with a specific service or application. For example, web servers typically use port 80 for HTTP and port 443 for HTTPS.

Port scanning is the process of probing a server or host for open ports. This technique helps in identifying which services are available on a target machine. By scanning ports, you can discover potential vulnerabilities and ensure that only authorized services are accessible.

Why and Where is Port Scanning Required?

Port scanning is an essential tool in various scenarios:

1. Network Security: Identify and close open ports that shouldn’t be accessible to the outside world to prevent unauthorized access.
2. System Administration: Discover available services on a machine for maintenance and monitoring purposes.
3. Penetration Testing: Assess the security of a network by identifying potential entry points for attackers.
4. Troubleshooting: Diagnose network issues by ensuring that required services are running on the correct ports.

Requirements and Installation

To create our advanced port scanner, first, we need to install the Nmap tool and then the python-nmap library.

Installing Nmap

Nmap is a versatile and powerful network scanning tool. Here’s how you can install it on different operating systems:

Windows

1. Download the installer from the Nmap download page.
2. Run the installer and follow the on-screen instructions.

Linux

sudo apt-get install nmap  # For Debian-based systems
sudo yum install nmap      # For Red Hat-based systems

macOS

brew install nmap  # Using Homebrew package manager

Installing python-nmap

The python-nmap library provides a Python interface to Nmap. You can install it using the following command:

pip install python-nmap

The Program

Create a Python program file named “port_scanner.py” and copy the code below.

import nmap
import sys

# Function to perform the scan
def advanced_port_scanner(target, port_range):
    # Initialize the Nmap PortScanner
    nm = nmap.PortScanner()

    # Perform the scan
    try:
        nm.scan(target, port_range)
    except Exception as e:
        print(f"Error: {e}")
        sys.exit()

    # Print the results
    for host in nm.all_hosts():
        print(f"\nHost: {host} ({nm[host].hostname()})")
        print(f"State: {nm[host].state()}")

        for proto in nm[host].all_protocols():
            print(f"\nProtocol: {proto}")

            lport = nm[host][proto].keys()
            sorted(lport)
            for port in lport:
                print(f"Port: {port}\tState: {nm[host][proto][port]['state']}\tService: {nm[host][proto][port]['name']}")

if __name__ == "__main__":
    # Replace with your target hostname or IP address
    target = "example.com"

    # Define the range of ports to scan (e.g., "1-1024" for ports 1 to 1024)
    port_range = "1-1024"

    advanced_port_scanner(target, port_range)

The above script initializes the Nmap scanner using nmap.PortScanner(). Then the nm.scan(target, port_range) function performs the scan on the specified target and port range.

Output

Host: 127.0.0.1 (localhost)
State: up

Protocol: tcp
Port: 631 State: open Service: ipp

Recommended: Create a Python Network Scanner: Find IPs & MACs

Summary

In this article, we learned the concept of port scanning and its role in keeping your network secure. We built a cool Port Scanner using Python (with a little help from the Nmap tool) that lets you identify open ports on any device with an IP address.

By finding open ports, you can uncover potential vulnerabilities and take steps to patch them up before anyone else does. Remember, with this power comes responsibility! Use this scanner ethically to keep your own network strong and never target someone else’s system without permission.

Got questions? Feel free to reach out at contact@pyseek.com. Happy (and safe) scanning!