Scan Open Ports on IP Address Using Python

Port scanning helps identify open ports on a network device. It is useful for security checks and troubleshooting. Python makes it easy to create a port scanner.

What Is Port Scanning?

Port scanning checks which ports are open on a target IP. Open ports indicate running services. This helps in network analysis and security assessments.

Common ports include 80 (HTTP), 443 (HTTPS), and 22 (SSH). Scanning them reveals potential vulnerabilities.

Python Socket Programming Basics

Python's socket module allows network communication. It helps create connections to IP addresses and ports. This is key for building a port scanner.

Before scanning, ensure you have Python installed. Check out how to install IPython for a better coding environment.

Simple Port Scanner in Python

Here's a basic script to scan ports on an IP address. It uses socket to check connection status.

import socket

def scan_port(ip, port):
    try:
        sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        sock.settimeout(1)
        result = sock.connect_ex((ip, port))
        sock.close()
        return result == 0
    except:
        return False

target_ip = "127.0.0.1"  # Replace with target IP
ports_to_scan = [80, 443, 22, 21]  # Common ports

for port in ports_to_scan:
    if scan_port(target_ip, port):
        print(f"Port {port} is open")
    else:
        print(f"Port {port} is closed")

Port 80 is open
Port 443 is open
Port 22 is closed
Port 21 is closed

How the Code Works

The scan_port function checks if a port is open. It creates a socket and tries to connect. A timeout of 1 second prevents long waits.

Important: Always respect network policies. Unauthorized scanning may be illegal.

Enhancing the Port Scanner

You can improve the scanner by adding more features. For example, scan a range of ports or use threading for speed.

Learn about getting all IP addresses on a local network to expand your scanner's capabilities.

import socket
from concurrent.futures import ThreadPoolExecutor

def scan_port(ip, port):
    try:
        sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        sock.settimeout(1)
        result = sock.connect_ex((ip, port))
        sock.close()
        return port if result == 0 else None
    except:
        return None

def scan_ports(ip, start_port, end_port):
    open_ports = []
    with ThreadPoolExecutor(max_workers=100) as executor:
        futures = [executor.submit(scan_port, ip, port) for port in range(start_port, end_port + 1)]
        for future in futures:
            result = future.result()
            if result:
                open_ports.append(result)
    return open_ports

target_ip = "127.0.0.1"
open_ports = scan_ports(target_ip, 1, 1024)
print(f"Open ports: {open_ports}")

Security Considerations

Port scanning can be seen as a hostile act. Always get permission before scanning networks. Use this knowledge ethically.

For secure coding, validate IP addresses first. Read our guide on validating IPv4 and IPv6 addresses.

Conclusion

Python makes port scanning simple with the socket module. This guide showed basic and advanced scanning techniques. Always use these tools responsibly.

Remember to handle errors properly. For common Python errors, check our guides on TypeError solutions.