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()