Python, create a TCP server

By Flavio Copes

Learn how to create a TCP server in Python using the socketserver package with TCPServer and a request handler, then test it with the Netcat nc command.

The Python standard library provides the socketserver package. We can use that to create a TCP server.

from socketserver import BaseRequestHandler, TCPServer

class handler(BaseRequestHandler):
    def handle(self):
        while True:
            msg = self.request.recv(1024)
            if msg == b'quit\n':
                break
            self.request.send(b'Message received: ' + msg)

with TCPServer(('', 8000), handler) as server:
    server.serve_forever()

Connect to this using Netcat, a handy utility that is very useful to test-drive TCP and UDP servers. It’s installed by default on Linux and macOS, available under the nc command:

nc localhost 8000

Once it’s connected to the server, you can send any message by typing it. The server will reply with a confirmation of the message received.

Until you say quit. Then the connection will close (but the server will still run, you can connect again)

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