Code for How to Make a Port Scanner in Python

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simple_port_scanner.py

import socket # for connecting
from colorama import init, Fore

# some colors
init()
GREEN = Fore.GREEN
RESET = Fore.RESET
GRAY = Fore.LIGHTBLACK_EX

def is_port_open(host, port):
    """
    determine whether `host` has the `port` open
    """
    # creates a new socket
    s = socket.socket()
    try:
        # tries to connect to host using that port
        s.connect((host, port))
        # make timeout if you want it a little faster ( less accuracy )
        s.settimeout(0.2)
    except:
        # cannot connect, port is closed
        # return false
        return False
    else:
        # the connection was established, port is open!
        return True

# get the host from the user
host = input("Enter the host:")
# iterate over ports, from 1 to 1024
for port in range(1, 1025):
    if is_port_open(host, port):
        print(f"{GREEN}[+] {host}:{port} is open      {RESET}")
    else:
        print(f"{GRAY}[!] {host}:{port} is closed    {RESET}", end="\r")

fast_port_scanner.py

import argparse
import socket # for connecting
from colorama import init, Fore

from threading import Thread, Lock
from queue import Queue

# some colors
init()
GREEN = Fore.GREEN
RESET = Fore.RESET
GRAY = Fore.LIGHTBLACK_EX

# number of threads, feel free to tune this parameter as you wish
N_THREADS = 200
# thread queue
q = Queue()
print_lock = Lock()

def port_scan(port):
    """
    Scan a port on the global variable `host`
    """
    try:
        s = socket.socket()
        s.connect((host, port))
    except:
        with print_lock:
            print(f"{GRAY}{host:15}:{port:5} is closed  {RESET}", end='\r')
    else:
        with print_lock:
            print(f"{GREEN}{host:15}:{port:5} is open    {RESET}")
    finally:
        s.close()


def scan_thread():
    global q
    while True:
        # get the port number from the queue
        worker = q.get()
        # scan that port number
        port_scan(worker)
        # tells the queue that the scanning for that port 
        # is done
        q.task_done()


def main(host, ports):
    global q
    for t in range(N_THREADS):
        # for each thread, start it
        t = Thread(target=scan_thread)
        # when we set daemon to true, that thread will end when the main thread ends
        t.daemon = True
        # start the daemon thread
        t.start()

    for worker in ports:
        # for each port, put that port into the queue
        # to start scanning
        q.put(worker)
    
    # wait the threads ( port scanners ) to finish
    q.join()


if __name__ == "__main__":
    # parse some parameters passed
    parser = argparse.ArgumentParser(description="Simple port scanner")
    parser.add_argument("host", help="Host to scan.")
    parser.add_argument("--ports", "-p", dest="port_range", default="1-65535", help="Port range to scan, default is 1-65535 (all ports)")
    args = parser.parse_args()
    host, port_range = args.host, args.port_range

    start_port, end_port = port_range.split("-")
    start_port, end_port = int(start_port), int(end_port)

    ports = [ p for p in range(start_port, end_port)]

    main(host, ports)