a simple port scanner done up in python

port_scanner.py

#!/usr/bin/python
# -*- coding: latin-1 -*-
# a python stealth port scanner

from logging import getLogger, ERROR
getLogger("scapy.runtime").setLevel(ERROR)
from scapy.all import *
from datetime import datetime
from time import stdftime

# In stealth scanning, one sends a SYN flag
# to the server. The server either responds
# with a packet with SYN/ACK or RST/ACK flags set,
# If it is RST/ACK, then the port is closed.
# If one gets SYN/ACK the poer is open.
# We then respond with a RST flag to terminate
# the connection before it is fully established.

random_port = RandShort

def check_host( ip ):
    try:
        ping = sr1(IP(dst = ip) / ICMP())
        return True
    except:
        print( "Target not resolvable." )
        return False

# stealth scanning techniques
def stealth_scan( src_ip, dst_ip ):
    if not check_host( dest_ip ):
        return None
    src_port = random_port()
    dst_port = 80
    ack = IP(src="127.0.0.1", dst=dst_ip) /\
          TCP(sport=666, dport=random_port(),
              flag='S')
    # initier TCP Handshake
    resp = sr1(ack, timeout = 10)
    if TCP in resp:
        if resp[TCP].flags == 0x12:
            # mais, finis la connexion avant d'etablir.
            rst = IP(dst = dst_ip) /\
                  TCP(sport=src_port, dport=dst_port, flag='R')
            send(rst)
        elif resp[TCP].flags == 0x14:
            # dommage..
            print( "Port is closed. " )
            return -1
    print(" Port 80 is open. ")
    return 0



if __name__ == '__main__':
    dst_ip = '127.0.0.1'