Python RawSocket Syn

#!/bin/env python  
# -*- coding: UTF-8 -*-   
 
# 必須以root許可權運行  
 
import socket  
import sys  
import time
import random
 
from struct import *  
 
# 計算校驗和  
def checksum(msg):  
    s = 0 
    # 每次取2個位元組  
    for i in range(0,len(msg),2):  
        w = (ord(msg[i]) << 8) + (ord(msg[i+1]))  
        s = s+w  
 
    s = (s>>16) + (s & 0xffff)  
    s = ~s & 0xffff 
 
    return s  
 
def CreateSocket(source_ip,dest_ip):  
    try:  
        s = socket.socket(socket.AF_INET, socket.SOCK_RAW, socket.IPPROTO_TCP)  
        s.setsockopt(socket.IPPROTO_IP, socket.IP_HDRINCL, 1)
    except socket.error, msg:  
        print 'Socket create error: ',str(msg[0]),'message: ',msg[1]  
        sys.exit()  
 
    # 設置手工提供IP頭部  
#     s.setsockopt(socket.IPPROTO_TCP, socket.IP_HDRINCL, 1)  
    return s  
 
# 創建IP頭部  
def CreateIpHeader(source_ip, dest_ip):  
    packet = '' 
 
    # ip 頭部選項  
    headerlen = 5 
    version = 4 
    tos = 0 
    tot_len = 20 + 20 
    id = random.randrange(18000,65535,1)  
    frag_off = 0 
    ttl = 255 
    protocol = socket.IPPROTO_TCP  
    check = 10 
    saddr = socket.inet_aton ( source_ip )  
    daddr = socket.inet_aton ( dest_ip )  
    hl_version = (version << 4) + headerlen  
    ip_header = pack('!BBHHHBBH4s4s', hl_version, tos, tot_len, id, frag_off, ttl, protocol, check, saddr, daddr)  
 
    return ip_header  
 
# 創建TCP頭部  
def create_tcp_syn_header(source_ip, dest_ip, dest_port):  
    # tcp 頭部選項  
    source = random.randrange(32000,62000,1)    # 隨機化一個源埠  
    seq = 0 
    ack_seq = 0 
    doff = 5 
    # tcp flags  
    fin = 0 
    syn = 1 
    rst = 0 
    psh = 0 
    ack = 0 
    urg = 0 
    window = socket.htons (8192)    # 最大視窗大小  
    check = 0 
    urg_ptr = 0 
    offset_res = (doff << 4) + 0 
    tcp_flags = fin + (syn<<1) + (rst<<2) + (psh<<3) + (ack<<4) + (urg<<5)  
    tcp_header = pack('!HHLLBBHHH', source, dest_port, seq, ack_seq, offset_res, tcp_flags, window, check, urg_ptr)  
    # 偽頭部選項  
    source_address = socket.inet_aton( source_ip )  
    dest_address = socket.inet_aton( dest_ip )  
    placeholder = 0 
    protocol = socket.IPPROTO_TCP  
    tcp_length = len(tcp_header)  
    psh = pack('!4s4sBBH', source_address, dest_address, placeholder, protocol, tcp_length);  
    psh = psh + tcp_header;  
    tcp_checksum = checksum(psh)  
 
    # 重新打包TCP頭部，並填充正確地校驗和  
    tcp_header = pack('!HHLLBBHHH', source, dest_port, seq, ack_seq, offset_res, tcp_flags, window, tcp_checksum, urg_ptr)  
    return tcp_header  
 
 
def range_scan(source_ip, dest_ip, start_port, end_port) :  
    syn_ack_received = []   # 開放埠存儲列表  
 
    for j in range (start_port, end_port) :  
        s = CreateSocket(source_ip, dest_ip)  
        ip_header = CreateIpHeader(source_ip, dest_ip)  
        tcp_header = create_tcp_syn_header(source_ip, dest_ip,j)  
        packet = ip_header + tcp_header  
 
        s.sendto(packet, (dest_ip, 0))  
        print 's.sendto',dest_ip,start_port,end_port
 
        data = s.recvfrom(1024) [0][0:]  
 
        ip_header_len = (ord(data[0]) & 0x0f) * 4 
        ip_header_ret = data[0: ip_header_len - 1]  
        tcp_header_len = (ord(data[32]) & 0xf0)>>2 
        tcp_header_ret = data[ip_header_len:ip_header_len+tcp_header_len - 1]  
 
        if ord(tcp_header_ret[13]) == 0x12: # SYN/ACK flags   
            syn_ack_received.append(j)  
    return syn_ack_received  
 
 
# 程式從這裡開始:  
open_port_list = []  
ipsource = '192.168.18.17' 
ipdest = '192.168.19.43' 
start = 20 
stop = 100
step = (stop-start)/10 
scan_ports = range(start, stop, step)  
if scan_ports[len(scan_ports)-1] < stop:  
    scan_ports.append(stop)
    print 'scan_ports.append',stop
    
for i in range(len(scan_ports)-1):  
    opl = range_scan(ipsource, ipdest, scan_ports[i], scan_ports[i+1])  
    open_port_list.append(opl)  
for i in range(len(open_port_list)):  
    print 'Process #: ',i,' Open ports: ',open_port_list[i]  
print 'A list of all open ports found: ' 
for i in range(len(open_port_list)):  
    for j in range(len(open_port_list[i])):  
        print open_port_list[i][j],', '