Port scanner

port_scan.py

import socket
import optparse


def createParser():
    # Create command line parser
    parser = optparse.OptionParser('usage prog -H <target host> -p ' + \
                                   '<target port>')

    parser.add_option('-H', dest='tgtHost', type='string',\
                      help='Specify target host')

    parser.add_option('-P', dest='tgtPorts', type='string', \
                      help='Specify target ports')
    return parser


def connScan(tgtHost, tgtPort):
    sock = socket.socket()

    try:
        sock.connect((tgtHost, tgtPort))
        print("[+] Open")

    except:
        print("[-] Closed")

    finally:
        sock.send("Hello".encode())
        response = sock.recv(128)
        print("[+] " + str(response))
        sock.close()


def portScan(hostname, ports):

    try:
        tgtHost = socket.gethostbyname(hostname)
    except:
        print("[-] Couldn't find host ", hostname)
        exit(0)

    print("[+] ", end="")
    print(hostname, tgtHost)
    for tgtPort in ports:
        print("[+] Trying port", tgtPort)
        connScan(tgtHost, int(tgtPort))


def main():
    parser = createParser()

    (options, args) = parser.parse_args()

    tgtHost = options.tgtHost
    tgtPorts = str(options.tgtPorts).split(', ')

    if tgtHost == None or tgtPorts == None:
        parser.print_help()
        exit(0)

    portScan(tgtHost, tgtPorts)

if __name__ == '__main__':
    main()