Today, we are going to implement a simple port scanner implemented in python 3. The code is quite simple, and I think that it doesn’t need any explanation.

#!/usr/bin/env python3
# -*- coding: utf-8 -*-
 
from functools import partial
from multiprocessing import Pool
import socket
import optparse
 
DEFAULT_CORE_NUMBER = 2
 
 
def ping(host, port):
    try:
        socket.socket().connect((host, port))
        return port
    except socket.error as err:
        return False
 
 
def scanPorts(host, ports, cores):
    p = Pool(cores)
    ping_host = partial(ping, host)
 
    return filter(bool, p.map(ping_host, ports))
 
 
def main():
    parser = optparse.OptionParser('%prog -t <target host> -p <target port(s)> -n <number of cores>')
    parser.add_option('-t', dest='host', type='string', help='Specify the target host')
    parser.add_option('-p', dest='ports', type='string', help='Specify the target port(s); Separate them by commas.')
    parser.add_option('-n', dest='cores', type='int', help='Specify the number of CPU cores do you want to use.')
 
    (options, args) = parser.parse_args()
 
    if (options.host == None):
        print(parser.usage)
        exit(0)
    else:
        host = str(options.host)
 
    if (options.ports == None):
        ports = range(1, 65536)
    else:
        ports = list(map(int, str(options.ports).split(',')))
 
    if (options.cores == None):
        cores = DEFAULT_CORE_NUMBER
    else:
        cores = options.cores
 
    print('\nScanning ports on ' + host + ' ...')
 
    portsScanned = list(scanPorts(host, ports, cores))
 
    print(str(len(portsScanned)) + ' ports available.')
    print(portsScanned)
 
    print('\nDone.')
 
 
if __name__ == "__main__":
    main()

The script has three different options:

• -t: Specify the target host. It is a mandatory option.
• -p: Specify target ports.
• -n: Specify the number of cores that are going to be used.

We can see some invocation examples:

scanner.py
scanner.py -t 127.0.0.1
scanner.py -t 127.0.0.1 -p 21,80 -n 2

See you.