From https://stackoverflow.com/questions/17453212/multi-threaded-tcp-server-in-python
```python
#!/usr/bin/env python

import socket, threading

class ClientThread(threading.Thread):

    def __init__(self,ip,port,sock):
        threading.Thread.__init__(self)
        self.ip = ip
        self.port = port
        self.socket = sock
        print("[+] New thread started for "+ip+":"+str(port))


    def run(self):    
        print("Connection from : "+ip+":"+str(port))

        self.socket.send("\nWelcome to the server\n\n".encode())

        data = "dummydata"

        while len(data := self.socket.recv(2048)) > 0:
            print("Client sent : "+data.decode())
            self.socket.send("You sent me : ".encode()+data)

        print("Client disconnected...")

host = "0.0.0.0"
port = 9999

tcpsock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
tcpsock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)

tcpsock.bind((host,port))

threads = []

while True:
    tcpsock.listen(4)
    print("\nListening for incoming connections...")
    (clientsock, (ip, port)) = tcpsock.accept()
    newthread = ClientThread(ip, port, clientsock)
    newthread.start()
    threads.append(newthread)

for t in threads:
    t.join()
```