Packet Payload Modification for Network Traffic

modify_network.py

#!/usr/bin/env python3
from netfilterqueue import NetfilterQueue
import scapy.all as scapy

# Configuration variables
original_keyword = b"search"
modified_keyword = b"replace"

def modify_packet(packet):
    scapy_packet = scapy.IP(packet.get_payload())
    if scapy_packet.haslayer(scapy.Raw):
        packet_payload = scapy_packet[scapy.Raw].load
        new_payload = packet_payload.replace(original_keyword, modified_keyword)
        scapy_packet[scapy.Raw].load = new_payload
        packet.set_payload(bytes(scapy_packet))

        print("Original payload:", packet_payload)
        print("Modified payload:", new_payload)
        
    packet.accept()

nfqueue = NetfilterQueue()
nfqueue.bind(0, modify_packet)
try:
    nfqueue.run()
except KeyboardInterrupt:
    print("Flushing iptables rules...")
    nfqueue.unbind()

iptables -I INPUT -p tcp --dport 80 -j NFQUEUE --queue-num 0