81 lines
2.1 KiB
Python
81 lines
2.1 KiB
Python
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#!/usr/bin/python
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import socket
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import struct
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import threading
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import time
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import sys
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import random
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import re
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import logging
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from optparse import OptionParser
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from scapy.all import *
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def calculate_tcp_length(pkt):
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iphdr_len = pkt[IP].ihl * 4
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total_len = pkt[IP].len
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tcp_hdrlen = pkt[TCP].dataofs * 4
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tcp_payload_len = total_len - iphdr_len - tcp_hdrlen
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return tcp_payload_len
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def recalculate_tcp_md5_signature(pkt,password):
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destination_ip = pkt[IP].dst
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source_ip = pkt[IP].src
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reserved = 0
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protocol = socket.IPPROTO_TCP
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tcp_hdrlen = pkt[TCP].dataofs *4
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tcp_payload_len =calculate_tcp_length(pkt)
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total_length = tcp_hdrlen + tcp_payload_len
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#pseudo header
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psh = struct.pack("!4s4sBBH",
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source_ip,
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destination_ip,
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reserved,
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protocol,
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total_length
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)
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iphdr_len = pkt[IP].ihl * 4
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tcp_header = pkt[iphdr_len:iphdr_len+20]
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tcp_payload = pkt[iphdr_len+20:]
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tcp_sport = pkt[TCP].sport
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tcp_dport = pkt[TCP].dport
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tcp_seq = pkt[TCP].seq
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tcp_ack = pkt[TCP].ack
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tcp_dataofs = pkt[TCP].dataofs
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tcp_reserved = pkt[TCP].reserved
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tcp_flags = pkt[TCP].flags
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tcp_window = pkt[TCP].window
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tcp_chksum = pkt[TCP].chksum
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tcp_urgptr = pkt[TCP].urgptr
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reassemble_pkt[TCP].seq = seq
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reassemble_pkt[TCP].ack = ack
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reassemble_pkt[TCP].sport = sport
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reassemble_pkt[TCP].dport = dport
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if tsecr!=None and tsval!=None:
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if reassemble_pkt[TCP].options != None:
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#logging.info("tcp options:",reassemble_pkt[TCP].options)
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listopt = []
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for opt in reassemble_pkt[TCP].options:
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if opt[0] != 'Timestamp':
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listopt.append(opt)
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else:
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timestamp = ('Timestamp',(tsval,tsecr))
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listopt.append(timestamp)
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reassemble_pkt[TCP].options = listopt
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#logging.info("11111tcp options:",reassemble_pkt[TCP].options)
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del reassemble_pkt[TCP].chksum
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del reassemble_pkt[IP].chksum
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