sniffer_3.py

import socket
import os
import struct
from ctypes import *
import threading
import time
from netaddr import IPNetwork, IPAddress

host = "192.168.148.135"
subnet = "192.168.1.0/24"

magic_message = "PythonRules"



def udp_sender(subnet, magic_message):
    time.sleep(5)
    sender = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    
    for ip in IPNetwork(subnet):
        #print "Sending to " + str(ip)
        try:
            sender.sendto(magic_message, ("%s"%ip, 65212))
        except Exception, e:
            print str(ip), e


class IP(Structure):
    _fields_ = [
        ("ihl",          c_ubyte, 4),
        ("version",      c_ubyte, 4),
        ("tos",          c_ubyte),
        ("len",          c_ushort),
        ("id",           c_ushort),
        ("offset",       c_short),
        ("ttl",          c_ubyte),
        ("protocol_num", c_ubyte),
        ("sum",          c_ushort),
        ("src",          c_uint32),
        ("dst",          c_uint32)
    ]
    
    
    def __new__(self, socket_buffer=None):
        return self.from_buffer_copy(socket_buffer)
    
    def __init__(self, socket_buffer=None):
        #map protocol constants
        self.protocol_map = {1:"ICMP", 6:"TCP", 17:"UDP"}
        
        #human readable IP adresses
        k = struct.pack("q", self.src)
        self.src_address = socket.inet_ntoa(struct.pack("@I",self.src))
        self.dst_address = socket.inet_ntoa(struct.pack("@I",self.dst))
        
        #human readable protocol
        try:
            self.protocol = self.protocol_map[self.protocol_num]
        except:
            self.protocol = str(self.protocol_num)


class ICMP(Structure):
    _fields_ = [
        ("type",        c_ubyte),
        ("code",        c_ubyte),
        ("checksum",    c_ushort),
        ("unused",      c_ushort),
        ("next_hop_mtu",c_ushort)
    ]
    
    def __new__(self, socket_buffer=None):
        return self.from_buffer_copy(socket_buffer)
    
    def __init__(self, socket_buffer=None):
        pass   
    
if os.name == "nt":
    socket_protocol = socket.IP
else:
    socket_protocol = socket.IPPROTO_ICMP

sniffer = socket.socket(socket.AF_INET, socket.SOCK_RAW, socket_protocol)
sniffer.bind((host, 0))

#include ip header in capture
sniffer.setsockopt(socket.IPPROTO_IP, socket.IP_HDRINCL, 1)        

if os.name == "nt":
    sniffer.ioctl(socket.SIO_RCVALL, socket.RCVALL_ON)
    
t = threading.Thread(target=udp_sender, args=(subnet, magic_message))
t.start()
    
try:
    while True:
        #read in a packet
        raw_buffer = sniffer.recvfrom(65535)[0]
        
        #create an IP header from first 20 bytes of buffer
        ip_header = IP(raw_buffer)
        
        #print protocol and address
        #print "Protocol: %s %s -> %s" %(ip_header.protocol,ip_header.src_address,
                                        #ip_header.dst_address)
        if ip_header.protocol == "ICMP":
            
            # calculate where our ICMP packet starts
            offset = ip_header.ihl * 4
            buf = raw_buffer[offset:offset + sizeof(ICMP)]
            
            #create our ICMP Structure
            icmp_header = ICMP(buf)
            
            #print "ICMP -> Type: %d code: %d"%(icmp_header.type, icmp_header.code)
            
            if icmp_header.code == 3 and icmp_header.type == 3:
                if IPAddress(ip_header.src_address) in IPNetwork(subnet):
                    #make sure it has our magic message
                    if raw_buffer[len(raw_buffer)-len(magic_message):] == magic_message:
                        print "Host up: %s"%ip_header.src_address
                
            
   
except KeyboardInterrupt:
    #if windows set up IOCTL to turn off promiscous mode
    if os.name == "nt":
        sniffer.ioctl(socket.SIO_RCVALL, socket.RCVALL_OFF)