tcp_handshake.py

#!/usr/local/bin/python
# Example of TCP's threeway handshake using python and scapy
# source: https://www.fir3net.com/Programming/Python/how-to-build-a-tcp-connection-in-scapy.html

# Requires:
# iptables -A OUTPUT -p tcp --tcp-flags RST RST -j DROP
# Otherwise the kernel will send a TCP RESET as the kernel is not aware of TCP connection going on.

from scapy.all import *

# VARIABLES
src = "172.17.0.2"
dst = "rpii01"
sport = random.randint(1024,65535)
dport = 80
    
print "sport: " + str(sport)

# SYN
ip=IP(src=src,dst=dst)
SYN=TCP(sport=sport,dport=dport,flags='S',seq=1000)
SYNACK=sr1(ip/SYN)

# ACK
ACK=TCP(sport=sport, dport=dport, flags='A', seq=SYNACK.ack, ack=SYNACK.seq + 1)
send(ip/ACK)