class PacketManipulation:
def __init__(self, packet_headers, net_info, data, connection,
from_server):
self.Checksum = Checksums()
self.packet_headers = packet_headers
self.dst_mac, self.wan_subnet = net_info
self.data = data
self.connection = connection
self.from_server = from_server
self.tcp_header_length = 0
self.dst_ip = None
self.nat_port = None
self.payload = b''
if (from_server):
self.src_mac = connection['LAN']['MAC']
self.src_ip = connection['Server']['IP']
self.dst_ip = connection['Client']['IP']
self.client_port = connection['Client']['Port']
self.client_port = struct.pack('!H', connection['Client']['Port'])
else:
self.src_mac = connection['NAT']['MAC']
self.src_ip = connection['NAT']['IP']
self.nat_port = connection['NAT']['Port']
self.nat_port = struct.pack('!H', self.nat_port)
self.dst_ip = self.packet_headers.dst
self.dst_port = self.data[36:38]
def Start(self):
self.CheckDestination()
self.TCP()
self.PsuedoHeader()
self.RebuildHeaders()
def CheckDestination(self):
if (self.dst_ip in self.wan_subnet):
Int = Interface()
dst_mac = Int.IPtoMAC(self.dst_ip)
if (not dst_mac):
run(f'ping {self.dst_ip} -c 1', shell=True)
self.dst_mac = Int.IPtoMAC(self.dst_ip)
else:
self.dst_mac = dst_mac
''' Parsing TCP information like sequence and acknowledgement number amd calculated tcp header
length to be used by other classes for offset/proper indexing of packet contents.
Returning all relevant information back to HeaderParse Start method to be redistributed to other classes
based on need '''
def TCP(self):
bit_values = [32, 16, 8, 4]
tcp = self.data[34:94]
tmp_length = bin(tcp[12])[2:6]
for i, bit in enumerate(tmp_length):
if (bit == '1'):
self.tcp_header_length += bit_values[i]
self.tcp_header = self.data[34:34 + self.tcp_header_length]
self.tcp_length = len(self.data) - 34
if (len(self.data) > 34 + self.tcp_header_length):
self.payload = self.data[34 + self.tcp_header_length:]
def PsuedoHeader(self):
psuedo_header = b''
psuedo_header += inet_aton(self.src_ip)
psuedo_header += inet_aton(self.dst_ip)
psuedo_header += struct.pack('!2BH', 0, 6, self.tcp_length)
if (self.from_server):
psuedo_header += self.tcp_header[
0:2] + self.client_port + self.tcp_header[
4:16] + b'\x00\x00' + self.tcp_header[18:]
else:
psuedo_header += self.nat_port + self.tcp_header[
2:16] + b'\x00\x00' + self.tcp_header[18:]
psuedo_packet = psuedo_header + self.payload
tcp_checksum = self.Checksum.TCP(psuedo_packet)
self.tcp_checksum = struct.pack('<H', tcp_checksum)
def RebuildHeaders(self):
ethernet_header = self.RebuildEthernet()
ip_header = self.RebuildIP()
tcp_header = self.RebuildTCP()
self.send_data = ethernet_header + ip_header + tcp_header + self.payload
def RebuildEthernet(self):
eth_header = struct.pack(
'!6s6s', binascii.unhexlify(self.dst_mac.replace(':', '')),
binascii.unhexlify(self.src_mac.replace(':', '')))
eth_header += self.packet_headers.eth_proto
return eth_header
def RebuildIP(self):
ipv4_header = b''
ipv4_header += self.packet_headers.ipv4H[:10]
ipv4_header += b'\x00\x00'
ipv4_header += inet_aton(self.src_ip)
ipv4_header += inet_aton(self.dst_ip)
if (len(self.packet_headers.ipv4H) > 20):
ipv4_header += self.packet_headers.ipv4H[20:]
ipv4_checksum = self.Checksum.IPv4(ipv4_header)
ipv4_checksum = struct.pack('<H', ipv4_checksum)
ipv4_header = ipv4_header[:10] + ipv4_checksum + ipv4_header[12:]
return ipv4_header
def RebuildTCP(self):
if (self.from_server):
tcp_header = self.tcp_header[:2] + self.client_port + self.tcp_header[
4:16] + self.tcp_checksum + b'\x00\x00'
else:
tcp_header = self.nat_port + self.tcp_header[
2:16] + self.tcp_checksum + b'\x00\x00'
if (self.tcp_header_length > 20):
tcp_header += self.tcp_header[20:self.tcp_header_length]
return tcp_header
class TCPPacket:
def __init__(self, wan_int, packet):
self.packet = packet
self.wan_int = wan_int
self.Checksum = Checksums()
def Create(self):
self.AssignValues()
self.CreateIPv4()
self.CreateTCP()
self.AssembleIPv4()
self.AssembleTCP()
self.ipv4_checksum = self.Checksum.IPv4(self.ipv4_header)
self.tcp_checksum = self.PseudoHeader()
def AssignValues(self):
self.l2pro = 0x0800
Int = Interface()
self.smac = Int.MAC(self.wan_int)
self.dmac = self.packet.src_mac
self.src_ip = Int.IP(self.wan_int)
self.dst_ip = self.packet.src_ip
self.src_port = self.packet.dst_port
self.dst_port = self.packet.src_port
self.sport = struct.pack('!H', self.src_port)
# print(self.packet.seq_number)
self.ack_number = self.packet.seq_number + 1
## -- L2 - Ethernet Section ---- ##
def AssembleEthernet(self):
self.ethernet_header = struct.pack(
'!6s6sH', binascii.unhexlify(self.dmac.replace(':', '')),
binascii.unhexlify(self.smac.replace(':', '')), self.l2pro)
## -- L3 - IP Section ---- ##
def CreateIPv4(self):
ip_ver = 4
ip_vhl = 5
self.ip_ver = (ip_ver << 4) + ip_vhl
ip_dsc = 0
ip_ecn = 0
self.ip_dfc = (ip_dsc << 2) + ip_ecn
self.ip_tol = 20 + 20 # ---- [ Total Length]
self.ip_idf = 1 # ---- [ Identification ]
ip_rsv = 0 # ---- [ Flags ]
ip_dtf = 0
ip_mrf = 0
ip_frag_offset = 0
self.ip_flg = (ip_rsv << 7) + (ip_dtf << 6) + (ip_mrf << 5) + (
ip_frag_offset)
self.ip_ttl = 255 # ---- [ Total Length ]
self.ip_proto = TCP # ---- [ Protocol ]
self.ipv4_checksum = 0 # ---- [ Check Sum ]
self.ip_saddr = inet_aton(self.src_ip) # ---- [ Source Address ]
self.ip_daddr = inet_aton(self.dst_ip) # ---- [ Destination Address ]
def AssembleIPv4(self):
self.ipv4_header = struct.pack(
'!2B3H2B',
self.ip_ver, # IP Version
self.ip_dfc, # Differentiate Service Field
self.ip_tol, # Total Length
self.ip_idf, # Identification
self.ip_flg, # Flags
self.ip_ttl, # Time to leave
self.ip_proto # protocol
)
self.ipv4_header += struct.pack(
'<H',
self.ipv4_checksum # Checksum
)
self.ipv4_header += struct.pack(
'!4s4s',
self.ip_saddr, # Source IP
self.ip_daddr # Destination IP
)
## -- L4 - UDP Section ---- ##
def CreateTCP(self):
self.tcp_seq = 0
self.tcp_ack_seq = self.ack_number
self.tcp_hdr_len = 80
tcp_urg = 0
tcp_ack = 1
tcp_psh = 0
tcp_rst = 1
tcp_syn = 0
tcp_fin = 0
tcp_doff = 5
self.tcp_offset_res = (tcp_doff << 4) + 0
self.tcp_flags = tcp_fin + (tcp_syn << 1) + (tcp_rst << 2) + (
tcp_psh << 3) + (tcp_ack << 4) + (tcp_urg << 5)
self.tcp_wdw = htons(0)
self.tcp_checksum = 0
self.tcp_urg_ptr = 0
self.padding = b'\x00' * 12
def AssembleTCP(self):
self.tcp_header = struct.pack('!2H2L2B3H', self.src_port,
self.dst_port, self.tcp_seq,
self.tcp_ack_seq, self.tcp_offset_res,
self.tcp_flags, self.tcp_wdw,
self.tcp_checksum, self.tcp_urg_ptr)
def PseudoHeader(self):
pseudo_header = b''
pseudo_header += inet_aton(self.src_ip)
pseudo_header += inet_aton(self.dst_ip)
pseudo_header += struct.pack('!2BH', 0, 6, 54)
pseudo_header += self.sport + self.tcp_header[
2:16] + b'\x00\x00' + self.tcp_header[18:]
tcp_checksum = self.Checksum.TCP(pseudo_header)
return tcp_checksum
class CreatePacket:
def __init__(self, connection, to_server=False):
self.connection = connection
self.to_server = to_server
self.Checksum = Checksums()
def Create(self):
self.AssignValues()
self.CreateIPv4()
self.CreateTCP()
self.AssembleIPv4()
self.AssembleTCP()
self.ipv4_checksum = self.Checksum.IPv4(self.ipv4_header)
self.tcp_checksum = self.PseudoHeader()
def AssignValues(self):
self.l2pro = 0x0800
self.nat_port = struct.pack('!H', self.connection['NAT']['Port'])
self.client_port = struct.pack('!H', self.connection['Client']['Port'])
if (self.to_server):
self.smac = self.connection['NAT']['MAC']
self.src_ip = self.connection['NAT']['IP']
self.sport = self.connection['NAT']['Port']
self.dmac = self.connection['DFG']['MAC']
self.dst_ip = self.connection['Server']['IP']
self.dport = self.connection['Server']['Port']
else:
self.smac = self.connection['LAN']['MAC']
self.src_ip = self.connection['Server']['IP']
self.sport = self.connection['Server']['Port']
self.dmac = self.connection['Client']['MAC']
self.dst_ip = self.connection['Client']['IP']
self.dport = self.connection['Client']['Port']
## -- L2 - Ethernet Section ---- ##
def AssembleEthernet(self):
self.ethernet_header = struct.pack('!6s6sH' ,
binascii.unhexlify(self.dmac.replace(":","")),
binascii.unhexlify(self.smac.replace(":","")),
self.l2pro)
## -- L3 - IP Section ---- ##
def CreateIPv4(self):
ip_ver = 4
ip_vhl = 5
self.ip_ver = (ip_ver << 4 ) + ip_vhl
ip_dsc = 0
ip_ecn = 0
self.ip_dfc = (ip_dsc << 2 ) + ip_ecn
self.ip_tol = 20 + 20 # ---- [ Total Length]
self.ip_idf = 1 # ---- [ Identification ]
ip_rsv = 0 # ---- [ Flags ]
ip_dtf = 0
ip_mrf = 0
ip_frag_offset = 0
self.ip_flg = (ip_rsv << 7) + (ip_dtf << 6) + (ip_mrf << 5) + (ip_frag_offset)
self.ip_ttl = 255 # ---- [ Total Length ]
self.ip_proto = IPPROTO_TCP # ---- [ Protocol ]
self.ipv4_checksum = 0 # ---- [ Check Sum ]
self.ip_saddr = inet_aton(self.src_ip) # ---- [ Source Address ]
self.ip_daddr = inet_aton(self.dst_ip) # ---- [ Destination Address ]
def AssembleIPv4(self):
self.ipv4_header = struct.pack('!2B3H2B' ,
self.ip_ver, # IP Version
self.ip_dfc, # Differentiate Service Field
self.ip_tol, # Total Length
self.ip_idf, # Identification
self.ip_flg, # Flags
self.ip_ttl, # Time to leave
self.ip_proto # protocol
)
self.ipv4_header += struct.pack('<H' ,
self.ipv4_checksum # Checksum
)
self.ipv4_header += struct.pack('!4s4s' ,
self.ip_saddr, # Source IP
self.ip_daddr # Destination IP
)
## -- L4 - UDP Section ---- ##
def CreateTCP(self):
self.tcp_seq = 696969
self.tcp_ack_seq = 0
self.tcp_hdr_len = 80
tcp_urg = 0
tcp_ack = 0
tcp_psh = 0
tcp_rst = 1
tcp_syn = 0
tcp_fin = 0
tcp_doff = 5
self.tcp_offset_res = (tcp_doff << 4) + 0
self.tcp_flags = tcp_fin + (tcp_syn << 1) + (tcp_rst << 2) + (tcp_psh << 3) + (tcp_ack << 4) + (tcp_urg << 5)
self.tcp_wdw = htons(5840)
self.tcp_checksum = 0
self.tcp_urg_ptr = 0
self.padding = b'\x00'*12
def AssembleTCP(self):
self.tcp_header = struct.pack('!2H2L2B3H',
self.sport,
self.dport,
self.tcp_seq,
self.tcp_ack_seq,
self.tcp_offset_res,
self.tcp_flags,
self.tcp_wdw,
self.tcp_checksum,
self.tcp_urg_ptr
)
def PseudoHeader(self):
pseudo_header = b''
pseudo_header += inet_aton(self.src_ip)
pseudo_header += inet_aton(self.dst_ip)
pseudo_header += struct.pack('!2BH', 0, 6, 54)
if (self.to_server):
pseudo_header += self.nat_port + self.tcp_header[2:16] + b'\x00\x00' + self.tcp_header[18:]
else:
pseudo_header += self.tcp_header[0:2] + self.client_port + self.tcp_header[4:16] + b'\x00\x00' + self.tcp_header[18:]
pseudo_packet = pseudo_header
tcp_checksum = self.Checksum.TCP(pseudo_packet)
return tcp_checksum