Write a program to Implement a packet sniffing tool in C++/Java/Python.

Problem Statement:
Write a program to Implement a packet sniffing tool in C++/Java/Python. 

PROGRAM

#Packet sniffer in python for Linux

#Sniffs only incoming TCP packet

import socket, sys

from struct import *

#create an INET, STREAMing socket

try:

    s = socket.socket(socket.AF_INET, socket.SOCK_RAW, socket.IPPROTO_TCP)

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]

  

    #take first 20 characters for the ip header

    ip_header = packet[0:20]

  

    #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_header = packet[iph_length:iph_length+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 = iph_length + tcph_length * 4

    data_size = len(packet) - h_size

  

    #get data from the packet

    data = packet[h_size:]

  

    print 'Data : ' + data