replaceProxy.py

import socket
import threading

# Configuration
LISTEN_HOST = '0.0.0.0'   # Listen on all interfaces
LISTEN_PORT = 12345       # Port to listen on
TARGET_HOST = 'example.com'  # Destination host
TARGET_PORT = 80          # Destination port
SEARCH_BYTES = b'hello'   # Byte sequence to search for
REPLACE_BYTES = b'world'  # Replacement byte sequence

def handle_client(client_socket):
    """Handles client connection and forwards data to the target server."""
    server_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    server_socket.connect((TARGET_HOST, TARGET_PORT))

    def forward(source, destination):
        """Forwards data between sockets, replacing specific byte sequences."""
        try:
            while True:
                data = source.recv(4096)
                if not data:
                    break
                modified_data = data.replace(SEARCH_BYTES, REPLACE_BYTES)
                destination.sendall(modified_data)
        except Exception as e:
            print(f"Connection error: {e}")
        finally:
            source.close()
            destination.close()

    # Start bidirectional forwarding
    threading.Thread(target=forward, args=(client_socket, server_socket)).start()
    threading.Thread(target=forward, args=(server_socket, client_socket)).start()

def start_proxy():
    """Starts the TCP proxy."""
    proxy_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    proxy_socket.bind((LISTEN_HOST, LISTEN_PORT))
    proxy_socket.listen(5)
    print(f"Listening on {LISTEN_HOST}:{LISTEN_PORT} and forwarding to {TARGET_HOST}:{TARGET_PORT}")

    while True:
        client_socket, addr = proxy_socket.accept()
        print(f"Accepted connection from {addr}")
        threading.Thread(target=handle_client, args=(client_socket,)).start()

if __name__ == "__main__":
    start_proxy()