在树莓派上被动嗅探 TCP/HTTP GET 请求

在网络设备上，我们需要被动嗅探 TCP/HTTP GET 请求。嗅探数据包来追踪网络设备的流量。

2.解决方案

嗅探所有的数据包，将TCP数据包提取出来，过滤出包含HTTP请求的数据包。

import socket, sys
import sys
from threading import RLock
from struct import *

# Convert a string of 6 characters of ethernet address into a dash separated hex string
def eth_addr (a) :http://www.jshk.com.cn/mb/reg.asp?kefu=xiaoding；//爬虫IP免费获取；
  b = "%.2x:%.2x:%.2x:%.2x:%.2x:%.2x" % (ord(a[0]) , ord(a[1]) , ord(a[2]), ord(a[3]), ord(a[4]) , ord(a[5]))
  return b

# create a AF_PACKET type raw socket (thats basically packet level)
# define ETH_P_ALL    0x0003          /* Every packet (be careful!!!) */
try:
    s = socket.socket( socket.AF_PACKET , socket.SOCK_RAW , socket.ntohs(0x0003))
except socket.error , msg:
    print 'Socket could not be created. Error Code : ' + str(msg[0]) + ' Message ' + msg[1]
    sys.exit()

# receive a packet
while True:
    packet = s.recvfrom(65565)

    # packet string from tuple
    packet = packet[0]

    # parse ethernet header
    eth_length = 14

    eth_header = packet[:eth_length]
    eth = unpack('!6s6sH' , eth_header)
    eth_protocol = socket.ntohs(eth[2])
    source_mac = eth_addr(packet[6:12])
    print 'Destination MAC : ' + eth_addr(packet[0:6]) + ' Source MAC : ' + source_mac + ' Protocol : ' + str(eth_protocol)

    # Parse IP packets, IP Protocol number = 8
    if eth_protocol == 8 :
        # Parse IP header
        # take first 20 characters for the ip header
        ip_header = packet[eth_length:20+eth_length]

        # now unpack them :)
        iph = unpack('!BBHHHBBH4s4s' , ip_header)

        version_ihl = iph[0]
        version = version_ihl >> 4
        ihl = version_ihl & 0xF

        iph_length = ihl * 4

        ttl = iph[5]
        protocol = iph[6]
        s_addr = socket.inet_ntoa(iph[8]);
        d_addr = socket.inet_ntoa(iph[9]);

        # print 'Version : ' + str(version) + ' IP Header Length : ' + str(ihl) + ' TTL : ' + str(ttl) + ' Protocol : ' + str(protocol) + ' Source Address : ' + str(s_addr) + ' Destination Address : ' + str(d_addr)

        # TCP protocol
        if protocol == 6 :
            t = iph_length + eth_length
            tcp_header = packet[t:t+20]

            # now unpack them :)
            tcph = unpack('!HHLLBBHHH' , tcp_header)

            source_port = tcph[0]
            dest_port = tcph[1]
            sequence = tcph[2]
            acknowledgement = tcph[3]
            doff_reserved = tcph[4]
            tcph_length = doff_reserved >> 4

            # print 'Source Port : ' + str(source_port) + ' Dest Port : ' + str(dest_port) + ' Sequence Number : ' + str(sequence) + ' Acknowledgement : ' + str(acknowledgement) + ' TCP header length : ' + str(tcph_length)

            h_size = eth_length + iph_length + tcph_length * 4
            data_size = len(packet) - h_size

            # get data from the packet
            data = packet[h_size:]
            print 'Data:'
            print data

上面给出的代码可以嗅探到所有的数据包，并将TCP数据包提取出来。之后，我们就可以过滤出包含HTTP请求的数据包，然后解码GET请求。