Making a Fast Port Scanner

Question

So I'm making a port scanner in python...

import socket
ip = "External IP"
s = socket.socket(2, 1) #socket.AF_INET, socket.SOCK_STREAM

def porttry(ip, port):
    try:
        s.connect((ip, port))
        return True
    except:
        return None

for port in range(0, 10000):
    value = porttry(ip, port)
    if value == None:
        print("Port not opened on %d" % port)
    else:
        print("Port opened on %d" % port)
        break
raw_input()

But this is too slow, I want to somehow be able to some how close or break code after a period of time of not returning anything.

Answer 1

In addition to setting socket timeout, you can also apply multi-threading technique to turbo boost the process. It will be, at best, N times faster when you have N ports to scan.

# This script runs on Python 3
import socket, threading


def TCP_connect(ip, port_number, delay, output):
    TCPsock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    TCPsock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
    TCPsock.settimeout(delay)
    try:
        TCPsock.connect((ip, port_number))
        output[port_number] = 'Listening'
    except:
        output[port_number] = ''



def scan_ports(host_ip, delay):

    threads = []        # To run TCP_connect concurrently
    output = {}         # For printing purposes

    # Spawning threads to scan ports
    for i in range(10000):
        t = threading.Thread(target=TCP_connect, args=(host_ip, i, delay, output))
        threads.append(t)

    # Starting threads
    for i in range(10000):
        threads[i].start()

    # Locking the main thread until all threads complete
    for i in range(10000):
        threads[i].join()

    # Printing listening ports from small to large
    for i in range(10000):
        if output[i] == 'Listening':
            print(str(i) + ': ' + output[i])



def main():
    host_ip = input("Enter host IP: ")
    delay = int(input("How many seconds the socket is going to wait until timeout: "))   
    scan_ports(host_ip, delay)

if __name__ == "__main__":
    main()