handshake.py

# Research:
# https://stackoverflow.com/questions/26480854/3-way-handshake-in-scapy
# https://wiki.python.org/moin/TcpCommunication
# https://null-byte.wonderhowto.com/how-to/build-stealth-port-scanner-with-scapy-and-python-0164779/
# https://www.hackingarticles.in/nmap-scans-using-hex-value-flags/
# https://www.keycdn.com/support/tcp-flags

import sys
from scapy.layers.inet import *
from scapy.sendrecv import send
import argparse
from datetime import datetime

parser = argparse.ArgumentParser(description="Send a three-way TCP handshake.")
parser.add_argument(
    "host",
    nargs="?",
    help="Target host ip address."
)
parser.add_argument(
    "-p",
    "--port",
    default=80,
    help="Port of host. probably 80."
)

arguments = parser.parse_args()

NULL = 0x00
FIN = 0x01
SYN = 0x02
RST = 0x04
PSH = 0x08
ACK = 0x10
SYNACK = 0x12
RSTACK = 0x14
URG = 0x20
ECE = 0x40
CWR = 0x80
NS = 0x100

if len(sys.argv) <= 1:
    parser.print_help()
    sys.exit()

startClock = datetime.now()
sourcePort = 80  # source port is static 80
host = arguments.host
hostPort = int(arguments.port)
conf.verb = 0  # Scapy verbosity level [1-3]

SYNACK_packet = sr1(IP(dst=host) / TCP(sport=sourcePort, dport=hostPort, flags="S"))  # Send SYN packet
packetFlag = SYNACK_packet.getlayer(TCP).flags

if packetFlag == SYNACK:
    print("Server responed with SYN, ACK")
    ACK_packet = IP(dst=host) / TCP(sport=sourcePort, dport=hostPort, flags="A")  # send ACK packet
    response = send(ACK_packet)

    # print(response.getlayer(TCP).flags)
elif packetFlag == RSTACK:
    print("Server responed with RST, ACK")
elif packetFlag == RST:
    print("Server responed with RST")
else:
    print("connection timed out".format(hostPort))

print("Time elapsed {}".format(datetime.now() - startClock))