python构造IP报文的方法-创新互联

这篇文章主要讲解了python构造IP报文的方法，内容清晰明了，对此有兴趣的小伙伴可以学习一下，相信大家阅读完之后会有帮助。

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我就废话不多说了，大家还是直接看代码吧！

import socket
import sys
import time
import struct
 
HOST, PORT = "10.60.66.66", 10086
 
def make_forward_iphdr(source_ip = '1.0.0.1', dest_ip = '2.0.0.2', proto = socket.IPPROTO_UDP) :
  # ip header fields
  ip_ihl = 5
  ip_ver = 4
  ip_tos = 0
  ip_tot_len = 0 # kernel will fill the correct total length
  ip_id = 54321  #Id of this packet
  ip_frag_off = 0
  ip_ttl = 255
  ip_proto = proto
  ip_check = 0  # kernel will fill the correct checksum
  ip_saddr = socket.inet_aton ( source_ip )  #Spoof the source ip address if you want to
  ip_daddr = socket.inet_aton ( dest_ip )
 
  ip_ihl_ver = (ip_ver << 4) + ip_ihl
 
  # the ! in the pack format string means network order
  ip_header = struct.pack('!BBHHHBBH4s4s', ip_ihl_ver, ip_tos, ip_tot_len, ip_id, ip_frag_off, ip_ttl, ip_proto, ip_check, ip_saddr, ip_daddr)
  return ip_header
 
def make_forward_udphdr(src_port = 1024, dst_port = 10086) :
  udp_header = struct.pack('!HHHH', src_port, dst_port, 0, 0)
  return udp_header
  
# checksum functions needed for calculation checksum
def checksum(msg):
  s = 0
 
  # loop taking 2 characters at a time
  for i in range(0, len(msg), 2):
    w = ord(msg[i]) + (ord(msg[i+1]) << 8 )
    s = s + w
 
  s = (s>>16) + (s & 0xffff);
  s = s + (s >> 16);
 
  #complement and mask to 4 byte short
  s = ~s & 0xffff
 
  return s
  
def make_tcp_data(ip_header, src_port = 1024, dst_port = 10086, source_ip='1.0.0.1', dest_ip='2.0.0.2', user_data = 'test') :
  tcp_source = src_port  # source port
  tcp_dest = dst_port  # destination port
  tcp_seq = 454
  tcp_ack_seq = 0
  tcp_doff = 5  #4 bit field, size of tcp header, 5 * 4 = 20 bytes
  #tcp flags
  tcp_fin = 0
  tcp_syn = 1
  tcp_rst = 0
  tcp_psh = 0
  tcp_ack = 0
  tcp_urg = 0
  tcp_window = socket.htons (5840)  #  maximum allowed window size
  tcp_check = 0
  tcp_urg_ptr = 0
 
  tcp_offset_res = (tcp_doff << 4) + 0
  tcp_flags = tcp_fin + (tcp_syn << 1) + (tcp_rst << 2) + (tcp_psh <<3) + (tcp_ack << 4) + (tcp_urg << 5)
 
  # the ! in the pack format string means network order
  tcp_header = struct.pack('!HHLLBBHHH' , tcp_source, tcp_dest, tcp_seq, tcp_ack_seq, tcp_offset_res, tcp_flags, tcp_window, tcp_check, tcp_urg_ptr)
  
  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) + len(user_data)
 
  psh = struct.pack('!4s4sBBH' , source_address , dest_address , placeholder , protocol , tcp_length);
  psh = psh + tcp_header + user_data;
 
  tcp_check = checksum(psh)
  #print tcp_checksum
 
  # make the tcp header again and fill the correct checksum - remember checksum is NOT in network byte order
  tcp_header = struct.pack('!HHLLBBH' , tcp_source, tcp_dest, tcp_seq, tcp_ack_seq, tcp_offset_res, tcp_flags, tcp_window) + struct.pack('H' , tcp_check) + struct.pack('!H' ,tcp_urg_ptr)
 
  # final full packet - syn packets dont have any data
  packet = ip_header + tcp_header + user_data
  return packet

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