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Python sending three-way handshake raw socket

I'm trying to code a python script through which I want to send packets from one host (desktop ubuntu) to a server (Ubuntu server) using multiple source addresses. I decided that would be best to use raw sockets and define my own TCP and IP header. I succeed to send the SYN packet and also get a response with the SYN-ACK packet but then my host doesn't respond with the ACK packet but with the RST packet. This is the first problem with I met in my solution. After the beginning of a three-way handshake I would like to send an HTTP GET keep-alive request. Does anyone know how to do it? Or does anyone know a better solution or library to use?
def send_raw_socket():
s = socket.socket(socket.AF_INET, socket.SOCK_RAW, socket.IPPROTO_TCP)
s.setsockopt(socket.IPPROTO_IP, socket.IP_HDRINCL, 1)
version_ihl_type_of_service = b'\x45\x00'
total_length = b'\x00\x3c'
Indentification = b'\xab\xcd'
flags_fragment_offset = b'\x00\x00'
TTL_protocol = b'\x40\x06'
Dest_add = b'\x0a\x0a'
Dest_add2 = b'\x1e\x03'
Src_add = b'\x0a\x0a'
src_add2 =b'\x0a\x0a'
Header_Checksum = my_ip_header_checksum(version_ihl_type_of_service, total_length, Indentification, flags_fragment_offset, TTL_protocol, Src_add,src_add2, Dest_add, Dest_add2)
IP_protocol = b'\x00\x06'
TCP_header_lenght = b'\x00\x14'
src_port = (int(src_port.hex(), 16)+49607).to_bytes(2, byteorder='big')
dest_port = b'\x1f\x95' # Source Port | Destination Port
seq_n1 = b'\x00\x00'
seq_n2 = b'\x00\x00' # Sequence Number
ack_n1 = b'\x00\x00'
ack_n2 = b'\x00\x00' # Acknowledgement Number
do_res = b'\x50\x02'
flags_win_s = b'\x71\x10' # Data Offset, Reserved, Flags | Window Size
checksum= tcp_header_checksum(IP_protocol, Src_add, src_add2, Dest_add, Dest_add2, TCP_header_lenght, src_port, dest_port, seq_n1, seq_n2, ack_n1, ack_n2, do_res, flags_win_s)
u_pinter= b'\x00\x00' # Checksum | Urgent Pointer
packet = version_ihl_type_of_service+total_length+Indentification+flags_fragment_offset+TTL_protocol+Header_Checksum+Src_add+src_add2+Dest_add+Dest_add2+src_port+dest_port+seq_n1+seq_n2+ack_n1+ack_n2+do_res+flags_win_s+checksum+u_pinter
s.sendto(packet, ('10.10.30.3',8085))
Wireshark three-way handshake

How can I separate two sockets that receive two multicasts on the same port?

I created a program, that receives multicast stream and analyzes its bitrate.
The problem started, when I wanted to use multithreading approach here, in order to analyze many multicasts at the same time. Every multicast has it's unique addres, however they have the same port. First stream: 239.0.1.104 has constant bitrate of 10.69 Mbps, second: 239.0.1.105 has also CBR of 6.082 Mbps. The problem is, my program sums up results, and at the end i have:
16.328928
16.328928
16.802688
16.802688
16.750048
16.750048
16.813216
16.813216
16.771104
16.771104
Whereas I expect:
10.69
6.082
10.69
6.082
etc
Important:
I use socket option SO_REUSEADDR which in case of multicast is equal to using both SO_REUSEADDR and SO_REUSEPORT.(Mentioned few lines below)
I read article:
https://lwn.net/Articles/542629/
And also(very compact information providing):
How do SO_REUSEADDR and SO_REUSEPORT differ?
Where i read:
The meaning of SO_REUSEADDR changes for multicast addresses as it allows multiple sockets to be bound to exactly the same combination of source multicast address and port. In other words, for multicast addresses SO_REUSEADDR behaves exactly as SO_REUSEPORT for unicast addresses. Actually, the code treats SO_REUSEADDR and SO_REUSEPORT identically for multicast addresses, that means you could say that SO_REUSEADDR implies SO_REUSEPORT for all multicast addresses and the other way round.
I tried providing socket_name as parameter in order to distinguish both sockets, I tried also to add bitrateList_name and totalSize name as parameters, but always there is the same problem.
import socket
import struct
import time
import threading
from collections import Counter
MCAST_GRP = ['239.0.1.104','239.0.1.105']
MCAST_PORT1 = 12345
MCAST_PORT2 = 12345
def mcanalysis(multicast_group, MCAST_PORT):
IS_ALL_GROUPS = True
#scan time in seconds
SCAN_TIME = 5
#sampling time in seconds
SAMPLING_TIME = 1
bufferUDP = 2048
totalSize = 0
bitrateList = []
sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM, socket.IPPROTO_UDP)
sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
if IS_ALL_GROUPS:
# on this port, receives ALL multicast groups
sock.bind(('', MCAST_PORT))
else:
# on this port, listen ONLY to MCAST_GRP
sock.bind((multicast_group, MCAST_PORT))
#Creating socket that gets UDP multicast packets
for group in MCAST_GRP:
mreq = struct.pack("4sl", socket.inet_aton(group), socket.INADDR_ANY)
sock.setsockopt(socket.IPPROTO_IP, socket.IP_ADD_MEMBERSHIP, mreq)
print("_____.:| Starting analysis of multicasts! |:._____\n")
print("͞◌͞◌͞◌͞◌͞.:| IP: {} PORT: {} |:.͞◌͞◌͞◌͞͞◌͞◌".format(multicast_group,MCAST_PORT))
SCAN_TIME = int(SCAN_TIME *(SAMPLING_TIME**(-1)))
for x in range(SCAN_TIME):
stop = time.time() + SAMPLING_TIME
while (time.time()<stop):
data, address = sock.recvfrom(bufferUDP)
totalSize += len(data)
bitrateList.append(totalSize)
print(bitrateList[x]*8/(1000000*SAMPLING_TIME))
totalSize = 0
bitrateList.pop(0)
txtfile = open("Bitrate_history_ip_{}.txt".format(multicast_group),"w+")
for x in range(SCAN_TIME-1):
bitrateList[x] = bitrateList[x]*8/(1000000*SAMPLING_TIME)
txtfile.write("{}.Bitrate was equal to: {} Mbps\n".format(x+1,bitrateList[x]))
txtfile.write("Maximum bitrate value was: {} Mbps\n".format(max(bitrateList)))
txtfile.write("Minimum bitrate value was: {} Mbps\n".format(min(bitrateList)))
t1 = threading.Thread(target=mcanalysis, args=(MCAST_GRP[0],MCAST_PORT1))
t2 = threading.Thread(target=mcanalysis, args=(MCAST_GRP[1],MCAST_PORT2))
t1.start()
t2.start()
t1.join()
t2.join()
print('End of test')
time.sleep(5)
I would to thank in advance for any information that can bring me closer to resolving this problem

socket programming Reliable Data Protocol

For part 1 of the project, you will implement a simple go-back-N protocol similar to TCP. This protocol is called the 352RDPv1.
(unfortunately my python knowledge is not that strong, I am being forced to code it in python)
I must implement: init(udp_port1, udpport2)
socket()
connect(address)
I am given the following pseudo code:
import binascii
import socket as syssock
import struct
import sys
# this init function is global to the class and
# defines the UDP ports all messages are sent
# and received from.
def init(UDPportTx,UDPportRx): # initialize your UDP socket here
# create a UDP/datagram socket
# bind the port to the Rx (receive) port number
pass
class socket:
def __init__(self): # fill in your code here
# create any lists/arrays/hashes you need
return
def connect(self,address): # fill in your code here
global UDPportTx # example using a variable global to the Python module
# create a new sequence number
# create a new packet header with the SYN bit set in the flags (use the Struct.pack method)
# also set the other fields (e.g sequence #)
# add the packet to the outbound queue
# set the timeout
# wait for the return SYN
# if there was a timeout, retransmit the SYN packet
# set the outbound and inbound sequence numbers
return
I have given a shot so far at a few methods but I know I have errors and my program does not work.
import binascii
import socket as syssock
import struct
from collections import namedtuple
import sys
import select
version = 0x1
header_len = 7
payload_len = 0
flags = 0
SOCK352_SYN = 0x01
SOCK352_FIN = 0x02
SOCK352_ACK = 0x04
SOCK352_RESET = 0x08
SOCK352_HAS_OPT = 0xA0
sequence_no = 0
ack_no = 0
timeout = 0.2
#given these values to set them to
def init(UDPportTx,UDPportRx):
global sock
global useRx
global useTx
useTx = int(UDPportTx)
useRx = int(UDPportRx)
sock = syssock.syssock(syssock.AF_INET, syssock.SOCK_DGRAM)
sock.bind(('', useRx))
print "Listening on port :", useRx
pass
class socket:
def __init__(self):
global pkt
pkt = namedtuple("pkt",["version", "flags", "sequence_no", "ack_no", "payload_len"])
return
def connect(self, address):
global header_raw
udpPkt = struct.Struct('!BLBBB')
header_raw = udpPkt.pack(version, SOCK352_SYN, sequence_no, ack_no, payload_len)
sock.sendto(header_raw, ('', useTx))
return
I believe I am having errors in these first few methods and before I move onto the others I need to figure in I want to see if anyone is able to help me understand how to handle these few to begin.

Read TTL from an ICMP message received via Python raw sockets

I'm building a traceroute-ish tool to determine the number of hops required for a UDP packet to reach an address using only one probe. To do this, I want to extract the TTL from the ICMP message I receive after sending the probe. I'm doing the following and successfully receiving the ICMP message:
data, source = in_socket.recvfrom(d_bufsize)
But I have no idea how to turn data into something that I can read the TTL from. in_socket is declared like this:
in_socket = socket.socket(socket.AF_INET, socket.SOCK_RAW, icmp_proto)
Here, icmp_proto is just the protocol number for ICMP (obtained by doing icmp_proto = socket.getprotobyname("icmp")).
Any help would be much appreciated!

But I have no idea how to turn data into something that I can read
the TTL from.
pyping does it this way:
def header2dict(self, names, struct_format, data):
""" unpack the raw received IP and ICMP header informations to a dict """
unpacked_data = struct.unpack(struct_format, data)
return dict(zip(names, unpacked_data))
…
packet_data, address = current_socket.recvfrom(ICMP_MAX_RECV)
icmp_header = self.header2dict(
names=[
"type", "code", "checksum",
"packet_id", "seq_number"
],
struct_format="!BBHHH",
data=packet_data[20:28]
)
if icmp_header["packet_id"] == self.own_id: # Our packet
ip_header = self.header2dict(
names=[
"version", "type", "length",
"id", "flags", "ttl", "protocol",
"checksum", "src_ip", "dest_ip"
],
struct_format="!BBHHHBBHII",
data=packet_data[:20]
)
packet_size = len(packet_data) - 28
ip = socket.inet_ntoa(struct.pack("!I", ip_header["src_ip"]))
The TTL can then be read from ip_header["ttl"].

Receive UDP packet from specific source

I am trying to measure the responses back from DNS servers. Making a sniffer for a typical DNS response that is less than 512 bytes is no big deal. My issue is receiving large 3000+ byte responses - in some cases 5000+ bytes. I haven't been able to get a socket working that can receive that data reliably. Is there a way with Python sockets to receive from a specific source address?
Here is what I have so far:
import socket
import struct
def craft_dns(Qdns):
iden = struct.pack('!H', randint(0, 65535))
QR_thru_RD = chr(int('00000001', 2)) # '\x01'
RA_thru_RCode = chr(int('00100000', 2)) # '\x00'
Qcount = '\x00\x01' # question count is 1
ANcount = '\x00\x00'
NScount = '\x00\x00'
ARcount = '\x00\x01' # additional resource count is 1
pad = '\x00' #
Rtype_ANY = '\x00\xff' # Request ANY record
PROtype = '\x00\x01' # Protocol IN || '\x00\xff' # Protocol ANY
DNSsec_do = chr(int('10000000', 2)) # flips DNSsec bit to enable
edns0 = '\x00\x00\x29\x10\x00\x00\x00\x00\x00\x00\x00' # DNSsec disabled
domain = Qdns.split('.')
quest = ''
for x in domain:
quest += struct.pack('!B', len(x)) + x
packet = (iden+QR_thru_RD+RA_thru_RCode+Qcount+ANcount+NScount+ARcount+
quest+pad+Rtype_ANY+PROtype+edns0) # remove pad if asking <root>
return packet
def craft_ip(target, resolv):
ip_ver_len = int('01000101', 2) # IPvers: 4, 0100 | IP_hdr len: 5, 0101 = 69
ipvers = 4
ip_tos = 0
ip_len = 0 # socket will put in the right length
iden = randint(0, 65535)
ip_frag = 0 # off
ttl = 255
ip_proto = socket.IPPROTO_UDP # dns, brah
chksm = 0 # socket will do the checksum
s_addr = socket.inet_aton(target)
d_addr = socket.inet_aton(resolv)
ip_hdr = struct.pack('!BBHHHBBH4s4s', ip_ver_len, ip_tos, ip_len, iden,
ip_frag, ttl, ip_proto, chksm, s_addr, d_addr)
return ip_hdr
def craft_udp(sport, dest_port, packet):
#sport = randint(0, 65535) # not recommended to do a random port generation
udp_len = 8 + len(packet) # calculate length of UDP frame in bytes.
chksm = 0 # socket fills in
udp_hdr = struct.pack('!HHHH', sport, dest_port, udp_len, chksm)
return udp_hdr
def get_len(resolv, domain):
target = "10.0.0.3"
d_port = 53
s_port = 5353
ip_hdr = craft_ip(target, resolv)
dns_payload = craft_dns(domain) # '\x00' for root
udp_hdr = craft_udp(s_port, d_port, dns_payload)
packet = ip_hdr + udp_hdr + dns_payload
buf = bytearray("-" * 60000)
recvSock = socket.socket(socket.PF_PACKET, socket.SOCK_RAW, socket.ntohs(0x0800))
recvSock.settimeout(1)
sendSock = socket.socket(socket.AF_INET, socket.SOCK_RAW, socket.IPPROTO_RAW)
sendSock.settimeout(1)
sendSock.connect((resolv, d_port))
sendSock.send(packet)
msglen = 0
while True:
try:
pkt = recvSock.recvfrom(65535)
msglen += len(pkt[0])
print repr(pkt[0])
except socket.timeout as e:
break
sendSock.close()
recvSock.close()
return msglen
result = get_len('75.75.75.75', 'isc.org')
print result
For some reason doing
pkt = sendSock.recvfrom(65535)
Recieves nothing at all. Since I'm using SOCK_RAW the above code is less than ideal, but it works - sort of. If the socket is extremely noisy (like on a WLAN), I could end up receiving well beyond the DNS packets, because I have no way to know when to stop receiving packets when receiving a multipacket DNS answer. For a quiet network, like a lab VM, it works.
Is there a better way to use a receiving socket in this case?
Obviously from the code, I'm not that strong with Python sockets.
I have to send with SOCK_RAW because I am constructing the packet in a raw format. If I use SOCK_DGRAM the custom packet will be malformed when sending to a DNS resolver.
The only way I could see is to use the raw sockets receiver (recvSock.recv or recvfrom) and unpack each packet, look if the source and dest address match within what is supplied in get_len(), then look to see if the fragment bit is flipped. Then record the byte length of each packet with len(). I'd rather not do that. It just seems there is a better way.

Ok I was stupid and didn't look at the protocol for the receiving socket. Socket gets kind of flaky when you try to receive packets on a IPPROTO_RAW protocol, so we do need two sockets. By changing to IPPROTO_UDP and then binding it, the socket was able to follow the complete DNS response over multiple requests. I got rid of the try/catch and the while loop, as it was no longer necessary and I'm able to pull the response length with this block:
recvSock = socket.socket(socket.AF_INET, socket.SOCK_RAW, socket.IPPROTO_UDP)
recvSock.settimeout(.3)
recvSock.bind((target, s_port))
sendSock = socket.socket(socket.AF_INET, socket.SOCK_RAW, socket.IPPROTO_RAW)
#sendSock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
sendSock.settimeout(.3)
sendSock.bind((target, s_port))
sendSock.connect((resolv, d_port))
sendSock.send(packet)
pkt = recvSock.recvfrom(65535)
msglen = len(pkt[0])
Now the method will return the exact bytes received from a DNS query. I'll leave this up in case anyone else needs to do something similar :)