How to create a TCP Server and Client on Python 3

Sep 28, 2018 1 min read
How to create a TCP Server and Client on Python 3


The Transmission Control Protocol (TCP) is one of the main protocols of the Internet protocol suite. It establishes a two-way connection between a server and a single client. Also, it provides reliable byte stream transmission of data with error checking and correction, and message acknowledgement.

Get the code:

This is a simple example of how to connect a Client and a Server


import socketserver

class MyTCPHandler(socketserver.BaseRequestHandler):
    The request handler class for our server.

    It is instantiated once per connection to the server, and must
    override the handle() method to implement communication to the

    def handle(self):
        # self.request is the TCP socket connected to the client = self.request.recv(1024).strip()
        print("{} wrote:".format(self.client_address[0]))
        # just send back the same data, but upper-cased

if __name__ == "__main__":
    HOST, PORT = "localhost", 9999

    # Create the server, binding to localhost on port 9999
    with socketserver.TCPServer((HOST, PORT), MyTCPHandler) as server:
        # Activate the server; this will keep running until you
        # interrupt the program with Ctrl-C


import socket
import sys

class socketserver.TCPServer(server_address, RequestHandlerClass, bind_and_activate=True)
This uses the Internet TCP protocol, which provides for continuous streams of data between the client and server. If bind_and_activate is true, the constructor automatically attempts to invoke server_bind() and server_activate(). The other parameters are passed to the BaseServer base class.

HOST, PORT = "localhost", 9999
data = " ".join(sys.argv[1:])

# Create a socket (SOCK_STREAM means a TCP socket)
with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as sock:
    # Connect to server and send data
    sock.connect((HOST, PORT))
    sock.sendall(bytes(data + "\n", "utf-8"))

    # Receive data from the server and shut down
    received = str(sock.recv(1024), "utf-8")

print("\n\nSent from Client:     {}".format(data))
print("Received from Server: {}".format(received))

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