Basic UDP & TCP Program

Question

I am trying to write a simple server that will listen for one set of messages on UDP and another set of messages on TCP. I have written the following code:

from threading import Thread
import time
import socket 

#define UDP listening function
def UDPListen():
    Listening_UDP_Port = 300
    Listening_IP = "127.0.0.1"
    BUFFER_SIZE = 64

    sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM) # IPv4, UDP
    sock.bind((Listening_IP, Listening_UDP_Port))

    while True:
        data, address = sock.recvfrom(BUFFER_SIZE)
        print "UDP Messsage from address: ", address
        print "Message: ", data

# END UPDListen() FUCNTION


#define a TCP listening function
def TCPListen():
    Listening_TCP_Port = 300
    Listening_IP = "127.0.0.1"
    BUFFER_SIZE = 64

    sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM) # IPv4, TCP
    sock.bind((Listening_IP, Listening_TCP_Port))

    while True:
        sock.listen(1)
        conn, address = sock.accept()
        print "TCP connection from", address
        data = conn.recv(BUFFER_SIZE)
        print "Mesage: ", data
        conn.close()

# END TCPListen() FUCNTION


# main function
def main():
    ThreadUDP = Thread(target=UDPListen)
    ThreadTCP = Thread(target=TCPListen)

    print "Starting Server..."
    ThreadUDP.start()
    ThreadTCP.start()
    print "Server Started!"

#END main() FUNCTION


if __name__ == "__main__":
    main()

However when I run it in Python 2.7 it throws a wobbly, any ideas where I am going wrong?

Ports below 1024 are reserved for programs that are running as root. So either change your port numbers to something above 1024, or run the program as root (preferably the former). FWIW I changed the port number to 3000 and then your program ran fine — Jeremy Friesner, Mar 12 '15 at 23:50
@JoranBeasley There's no conflict. One's on the TCP port, the other one's on the UDP port. — , Mar 15 '15 at 01:00

score 2 · Accepted Answer · edited May 23 '17 at 12:06

2

For me on Windows it launches fine as it is.

For linux you'll have to run it as root or use sudo

e.g.

sudo python ./yourserver.py

Or else change your port number to 1024 or above.

It's ok that they have the same port number. If it were 2 tcp service though it wouldn't be ok. See here.

Edit:

Given the OP's clarification of the real issue the solution is to use.

sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)

After creating the sockets. Where sock is your socket name.

edited May 23 '17 at 12:06

Community

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1

answered Mar 13 '15 at 00:16

Paul Rooney

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Thanks for your advice, I realised this morning that it was because the server doesn't close the ports when the process is killed it. So I had to restart the machine. Will need to find a nice way to close it down when its finished. Thanks again. – Thomas Morgan Mar 13 '15 at 10:52

Basic UDP & TCP Program

1 Answers1