#Packet sniffer in python
#For Linux - Sniffs all incoming and outgoing packets :)
#Silver Moon ([email protected])
#credits: http://www.binarytides.com/python-packet-sniffer-code-linux/

import socket, sys
from struct import *

#Convert a string of 6 characters of ethernet address into a dash separated hex string
def eth_addr (a) :
  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 as 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])
    print('Destination MAC : ' + eth_addr(packet[0:6]) + ' Source MAC : ' + eth_addr(packet[6:12]) + ' 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
            #hostname = socket.gethostbyaddr(d_addr)

            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 : ' + data)

        #ICMP Packets
        elif protocol == 1 :
            u = iph_length + eth_length
            icmph_length = 4
            icmp_header = packet[u:u+4]

            #now unpack them :)
            icmph = unpack('!BBH' , icmp_header)

            icmp_type = icmph[0]
            code = icmph[1]
            checksum = icmph[2]

            print('Type : ' + str(icmp_type) + ' Code : ' + str(code) + ' Checksum : ' + str(checksum))

            h_size = eth_length + iph_length + icmph_length
            data_size = len(packet) - h_size

            #get data from the packet
            data = packet[h_size:]

            print('Data : ' + data)

        #UDP packets
        elif protocol == 17 :
            u = iph_length + eth_length
            udph_length = 8
            udp_header = packet[u:u+8]

            #now unpack them :)
            udph = unpack('!HHHH' , udp_header)

            source_port = udph[0]
            dest_port = udph[1]
            length = udph[2]
            checksum = udph[3]

            print('Source Port : ' + str(source_port) + ' Dest Port : ' + str(dest_port) + ' Length : ' + str(length) + ' Checksum : ' + str(checksum))

            h_size = eth_length + iph_length + udph_length
            data_size = len(packet) - h_size

            #get data from the packet
            data = packet[h_size:]

            print('Data : ' + data)

        #some other IP packet like IGMP
        else :
            print('Protocol other than TCP/UDP/ICMP')

        print()