Simple telnet chat server in Python

Question

I was reading about sockets and found a nice exercise to try: a simple chat server that echoes input. This appears to be a common exercise and I have found several examples such as chatserver5.py and some SO questions. The problem is I can only connect when using telnet localhost 51234 and not telnet 192.168.1.3 51234 (where 192.168.1.3 is the network IP of my "server"). Needless to say, I can't connect from another machine on my network. I get the following output:

Trying 192.168.1.3...
telnet: connect to address 192.168.1.3: Connection refused
telnet: Unable to connect to remote host

Here is my code:

import socket, threading

HOST = '127.0.0.1'
PORT = 51234 

s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.bind((HOST, PORT))
s.listen(4)
clients = [] #list of clients connected
lock = threading.Lock()


class chatServer(threading.Thread):
    def __init__(self, (socket,address)):
        threading.Thread.__init__(self)
        self.socket = socket
        self.address= address

    def run(self):
        lock.acquire()
        clients.append(self)
        lock.release()
        print '%s:%s connected.' % self.address
        while True:
            data = self.socket.recv(1024)
            if not data:
                break
            for c in clients:
                c.socket.send(data)
        self.socket.close()
        print '%s:%s disconnected.' % self.address
        lock.acquire()
        clients.remove(self)
        lock.release()

while True: # wait for socket to connect
    # send socket to chatserver and start monitoring
    chatServer(s.accept()).start()

I have no experience with telnet or sockets. Why I can't connect remotely and how can I fix it so I can?

score 8 · Accepted Answer · edited Jan 25 '16 at 18:38

8

If you set HOST = '', then you'll be able to connect from anywhere. Right now, you're binding it to 127.0.0.1, which is the same as localhost.

edited Jan 25 '16 at 18:38

randomdude999

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answered Jun 27 '11 at 01:13

Ravi

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Wow that was easy. Telnet should be the same on any OS, correct? So no need for a client program; anyone can just telnet and type? – styfle Jun 27 '11 at 01:27
Yes, you can telnet from any OS to test this server. – Ravi Jun 27 '11 at 01:33
I think Telnet is used for remote login, so is there a security risk running this on my machine? – styfle Jun 27 '11 at 01:39
1

Your server isn't a telnet server, so you're ok. – Ravi Jun 27 '11 at 01:48

score 1 · Answer 2 · edited Nov 29 '16 at 15:45

1

Replace HOST = '127.0.0.1' with HOST = '192.168.1.3' or HOST = ''. This will bind you to your OUTGOING IP and not your internal localhost

edited Nov 29 '16 at 15:45

Rdster

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answered Aug 22 '13 at 10:53

Vogon Jeltz

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Simple telnet chat server in Python

2 Answers2