simple_tcp_sinkhole.py

# sudo iptables -t nat -p tcp -I PREROUTING -m multiport --dports 23:65535 -j DNAT --to-destination :5555
# sudo python3 fake_tcp_server.py
# sudo tcpdump -i eth0 port not 22 -C 100000 -w dump

### fake_tcp_server.py

import asyncio


class TcpSinkhole(asyncio.Protocol):
    peername = None
    def connection_made(self, transport):
        peername = transport.get_extra_info('peername')
        print(f'Connection from {peername}')
        self.transport = transport

    def data_received(self, data):
        message = data.decode()
        print(f'Data received {self.peername}: {message}')
        self.transport.close()


async def main():
    loop = asyncio.get_running_loop()

    server = await loop.create_server(
        lambda: TcpSinkhole(),
        '0.0.0.0', 5555)

    async with server:
        await server.serve_forever()

asyncio.run(main())