CODEWITHSUNDEEP
pythonsockets
DBtake3
DBtake3

Reputation: 126

Is there a way in python sockets (on the server) to know the hostname that a client connected to?

I'm relatively new to Python, so apologies for what me a simple question, I just cannot find the solution. First off, I am not looking for the client's hostname. My situation is that I have a simple socket server (basically this https://docs.python.org/3/library/socketserver.html#socketserver-tcpserver-example) which clients connect to. The exact server code is;

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
    client.
    """

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

if __name__ == "__main__":
    HOST, PORT = "0.0.0.0", 8080

    # 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
        server.serve_forever()

The clients connect successfully and are sending data which the server is receiving. My issue is that need to know the hostname that the client used to connect. The architecture will be like;

The DNS entry for client1.mydomain.net, client2.mydomain.net and client3.mydomain.net will all map to 123.123.123.123 so behind the scenes there is only one server.

The 3 clients will connect to their respective server and send their data. I have no control over the payload and I cannot augment it with a string or parm like "client=1".

So my question is, is there a way in python sockets (on the server) to know the hostname that a client connected to, so for example I know when I'm process data from client1.

Thanks!

Upvotes: 0

Views: 931

Answers (1)

Steffen Ullrich
Steffen Ullrich

Reputation: 123674

Nothing at the TCP level reveals which hostname the client is connected to. This means there is no way for a generic TCP server to get this information.

Various protocols on top of TCP contains such information though. For example HTTP has a Host header so that different domains with different contents can be server on the same IP and port. TLS has the server_name extension in the TLS handshake so that the expected certificate can be given matching the hostname used by the client.

Thus, if you need this information you need to define your application protocol so that the client will include this information.

Upvotes: 1

Related Questions