Python 实现 TCP 包注入与抓包实战

#! /usr/bin/env python
import socket
import struct
 
def checksum(data):
 s = 0
 n = len(data) % 2
 for i in range(0, len(data)-n, 2):
  s+= ord(data[i]) + (ord(data[i+1]) << 8)
 if n:
  s+= ord(data[i+1])
 while (s >> 16):
  s = (s & 0xFFFF) + (s >> 16)
 s = ~s & 0xffff
 return s
 
class ip():
 
 def __init__(self, source, destination):
  self.version = 4
  self.ihl = 5 # Internet Header Length
  self.tos = 0 # Type of Service
  self.tl = 0 # total length will be filled by kernel
  self.id = 54321
  self.flags = 0 # More fragments
  self.offset = 0
  self.ttl = 255
  self.protocol = socket.IPPROTO_TCP
  self.checksum = 0 # will be filled by kernel
  self.source = socket.inet_aton(source)
  self.destination = socket.inet_aton(destination)
 
 def pack(self):
  ver_ihl = (self.version << 4) + self.ihl
  flags_offset = (self.flags << 13) + self.offset
  ip_header = struct.pack("!BBHHHBBH4s4s",
     ver_ihl,
     self.tos,
     self.tl,
     self.id,
     flags_offset,
     self.ttl,
     self.protocol,
     self.checksum,
     self.source,
     self.destination)
  return ip_header
 
class tcp():
 
 def __init__(self, srcp, dstp):
  self.srcp = srcp
  self.dstp = dstp
  self.seqn = 0
  self.ackn = 0
  self.offset = 5 # Data offset: 5x4 = 20 bytes
  self.reserved = 0
  self.urg = 0
  self.ack = 0
  self.psh = 1
  self.rst = 0
  self.syn = 0
  self.fin = 0
  self.window = socket.htons(5840)
  self.checksum = 0
  self.urgp = 0
  self.payload = ""
 
 def pack(self, source, destination):
  data_offset = (self.offset << 4) + 0
  flags = self.fin + (self.syn << 1) + (self.rst << 2) + (self.psh << 3) + (self.ack << 4) + (self.urg << 5)
  tcp_header = struct.pack("!HHLLBBHHH",
      self.srcp,
      self.dstp,
      self.seqn,
      self.ackn,
      data_offset,
      flags, 
      self.window,
      self.checksum,
      self.urgp)
  #pseudo header fields
  source_ip = source
  destination_ip = destination
  reserved = 0
  protocol = socket.IPPROTO_TCP
  total_length = len(tcp_header) + len(self.payload)
  # Pseudo header
  psh = struct.pack("!4s4sBBH",
    source_ip,
    destination_ip,
    reserved,
    protocol,
    total_length)
  psh = psh + tcp_header + self.payload
  tcp_checksum = checksum(psh)
  tcp_header = struct.pack("!HHLLBBH",
     self.srcp,
     self.dstp,
     self.seqn,
     self.ackn,
     data_offset,
     flags,
     self.window)
  tcp_header+= struct.pack("H", tcp_checksum) + struct.pack("!H", self.urgp)
  return tcp_header
 
def test(source,site,data):
	s = socket.socket(socket.AF_INET,
     socket.SOCK_RAW,
     socket.IPPROTO_RAW)
	src_host=source
	dest_host=socket.gethostbyname(site)
	# IP Header
	ipobj=ip(src_host,dest_host)
	iph=ipobj.pack()
	# TCP Header
	tcpobj=tcp(1234,80)
	tcpobj.data_length=len(data)
	tcph=tcpobj.pack(ipobj.source,ipobj.destination)
	# Injection
	packet=iph+tcph+data
	s.sendto(packet,(dest_host,80))
	s.close()
 
if __name__ == '__main__':
	test("10.0.0.1","www.baidu.com","ITS TEST")

import socket
s=socket.socket(socket.AF_INET,socket.SOCK_RAW,socket.IPPROTO_TCP)
while True:
print(s.recvfrom(65565))