Python中利用原始套接字进行网络编程的示例

在实验中需要自己构造单独的HTTP数据报文，而使用SOCK_STREAM进行发送数据包，需要进行完整的TCP交互。

因此想使用原始套接字进行编程，直接构造数据包，并在IP层进行发送，即采用SOCK_RAW进行数据发送。

使用SOCK_RAW的优势是，可以对数据包进行完整的修改，可以处理IP层上的所有数据包，对各字段进行修改，而不受UDP和TCP的限制。

下面开始构造HTTP数据包，

IP层和TCP层使用python的Impacket库，http内容自行填写。

#!/usr/bin/env python

#-------------------------------------------------------------------------------
# Name:   raw_http.py
# Purpose:    construct a raw http get packet
#
# Author:  Yangjun
#
# Created:    08/02/2014
# Copyright:  (c) Yangjun 2014
# Licence:    <your licence>
#-------------------------------------------------------------------------------

import sys
import socket
from impacket import ImpactDecoder, ImpactPacket

def main():

  if len(sys.argv) < 3:
    print "Use: %s <src ip> <dst ip>" % sys.argv[0]
    print "Use: %s <src ip> <dst ip> <cnt>" % sys.argv[0]
    sys.exit(1)
  elif len(sys.argv) == 3:
    src = sys.argv[1]
    dst = sys.argv[2]
    cnt = 1
  elif len(sys.argv) ==4:
    src = sys.argv[1]
    dst = sys.argv[2]
    cnt = sys.argv[3]
  else:
    print "Input error!"
    sys.exit(1)
#print src, dst
  ip = ImpactPacket.IP()
  ip.set_ip_src(src)
  ip.set_ip_dst(dst)

  # Create a new ICMP packet of type ECHO.
  icmp = ImpactPacket.ICMP()
  tcp = ImpactPacket.TCP()
  tcp.set_th_sport(55968)
  tcp.set_th_dport(80)
  tcp.set_th_seq(1)
  tcp.set_th_ack(1)
  tcp.set_th_flags(0x18)
  tcp.set_th_win(64)

  tcp.contains( ImpactPacket.Data("GET /att/DIYLife/41264/528 HTTP/1.1\r\nHost: 192.168.111.1\r\nAccept-Encoding: identity\r\n\r\n"))

  ip.contains(tcp)

  # Open a raw socket. Special permissions are usually required.
  s = socket.socket(socket.AF_INET, socket.SOCK_RAW, socket.IPPROTO_TCP)
  s.setsockopt(socket.IPPROTO_IP, socket.IP_HDRINCL, 1)
  seq_id = 0
  while cnt >= 1:
    # Calculate its checksum.
    seq_id = seq_id + 1
    tcp.set_th_seq(seq_id)
    tcp.calculate_checksum()

    # Send it to the target host.
    s.sendto(ip.get_packet(), (dst,80))
    cnt= cnt -1

if __name__ == '__main__':
  main()