Challenge for newb python coders

Take this simple port scanner, and make it better.

#!/usr/bin/env python3

import socket
import sys

host = sys.argv[1] if len(sys.argv) > 1 else input("Host: ")

print(f"Scanning {host}...\n")

for port in range(1, 1025):
    s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    s.settimeout(0.2)

    if s.connect_ex((host, port)) == 0:
        try:
            service = socket.getservbyport(port)
        except:
            service = "unknown"
        print(f"{port:5d}/tcp  OPEN  ({service})")

    s.close()

print("\nDone.")

Note: If you build a longer version, paste your code into a pastebin or similar code-sharing page and leave the link in your reply. That keeps the thread readable while still letting everyone review the code.

#Python #Programming #Coding #challenge

On Jun 26, 2026 11:31 PM, yodabytz wrote:

I’d probably start by making it multithreaded since scanning each port one by one is gonna be pretty slow. I’d also add argparse for things like custom port ranges, timeout, and number of threads, plus some better error handling. Something like this:

#!/usr/bin/env python3

import argparse
import socket
from concurrent.futures import ThreadPoolExecutor, as_completed


def scan_port(host, port, timeout):
    try:
        with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
            s.settimeout(timeout)

            if s.connect_ex((host, port)) == 0:
                try:
                    service = socket.getservbyport(port, "tcp")
                except OSError:
                    service = "unknown"

                return port, service

    except OSError:
        pass

    return None


def main():
    parser = argparse.ArgumentParser()
    parser.add_argument("host")
    parser.add_argument("-p", "--ports", default="1-1024")
    parser.add_argument("-t", "--timeout", type=float, default=0.2)
    parser.add_argument("-w", "--workers", type=int, default=50)

    args = parser.parse_args()

    try:
        if "-" in args.ports:
            start, end = map(int, args.ports.split("-", 1))
            ports = range(start, end + 1)
        else:
            ports = [int(p) for p in args.ports.split(",")]

        ip = socket.gethostbyname(args.host)

    except (ValueError, socket.gaierror) as e:
        print(f"Error: {e}")
        return

    print(f"Scanning {args.host} ({ip})...\n")

    with ThreadPoolExecutor(max_workers=args.workers) as executor:
        futures = [
            executor.submit(scan_port, ip, port, args.timeout)
            for port in ports
        ]

        for future in as_completed(futures):
            result = future.result()

            if result:
                port, service = result
                print(f"{port:5}/tcp  OPEN  ({service})")


if __name__ == "__main__":
    main()

Then you could add stuff like banner grabbing, UDP scanning, IPv6 support, and maybe CIDR ranges later. But I’d probably keep it simple for now, otherwise it starts turning into a whole different project lol.