下面是一个简单的例子，演示如何在Python中启动TCP服务并监听连接，以及如何从客户端发送消息：

TCP服务端代码：

import socket

HOST = '192.168.6.211'
PORT = 8888

server_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
server_socket.bind((HOST, PORT))
server_socket.listen()

print(f'Server is listening at {HOST}:{PORT}')

while True:
    client_socket, client_address = server_socket.accept()
    print(f'Client connected from {client_address}')

    message = client_socket.recv(1024).decode('utf-8')
    print(f'Received message from client: {message}')

    response = 'Hello from server!'
    client_socket.send(response.encode('utf-8'))

    client_socket.close()

TCP客户端代码：

import socket

HOST = '192.168.6.211'
PORT = 8888

client_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
client_socket.connect((HOST, PORT))

message = 'Hello from client!'
client_socket.send(message.encode('utf-8'))

response = client_socket.recv(1024).decode('utf-8')
print(f'Received response from server: {response}')

client_socket.close()

这个例子中，服务端首先创建一个socket对象并绑定地址和端口，然后开始监听连接。当客户端连接到服务器时，服务端接受客户端的连接请求并打印客户端地址，然后接收从客户端发送过来的消息，并回复一条消息。客户端首先创建一个socket对象并连接到服务器，然后发送一条消息，并等待接收回复消息。