[Tutor] python sockets

[Marc Tompkins]

On Tue, Jun 10, 2014 at 4:08 PM, Jon Engle <jon.engle at gmail.com> wrote:
> Ok, so when I run the code it immediately terminates and never 'listens' to
> the ports in the loop. I have verified by running netstat -an | grep 65530
> and the startingPort is not binding.

The problem is that all threads started by a program terminate when
the program terminates - and you haven't told your program to stick
around when it's done setting up.    So it's setting up and then
immediately exiting - and by the time you run netstat a few seconds
later you find nothing.  (Also, by leaving HOST = '', you're listening
at address 0.0.0.0, so good luck catching any traffic...)
Try something like this:


#!/usr/bin/python         # This is server.py file
from socket import *      #import the socket library
import thread  #import the thread library

def setup(PORT):
    HOST = '127.0.0.1'    #we are the host
    ADDR = (HOST,PORT)    #we need a tuple for the address
    BUFSIZE = 4096    #reasonably sized buffer for data

    serv = socket( AF_INET,SOCK_STREAM)

    serv.bind((ADDR))    #the double parens are to create a tuple with
one element
    serv.listen(5)    #5 is the maximum number of queued connections we'll allow
    print '\nlistening on port %i...' % PORT
    conn,addr = serv.accept() #accept the connection
    print '\n...port %i connected!'  % PORT
    conn.send('TEST')
    conn.close()

def main():
    startingPort=int(raw_input("\nPlease enter starting port: "))
    for port in range (startingPort, 65535):
        thread.start_new_thread(setup, (port,))
    quitNow = ''
    while quitNow not in ('Q', 'q'):
        quitNow = raw_input('Enter Q to quit.')

if __name__ == '__main__':
    main()


This will stick around until you enter 'Q', and if you run netstat in
another window you'll see that it's LISTENING on all the ports you
asked for.  (All of those print statements will show up in a
surprising order!)

I'm not running the other side of this experiment, so I haven't tested
a successful connection... good luck.