Can't get UDP example to work

[Paul Barry]

I'm trying to get one of the examples from Foundation of Python
Network Programming to work.  Specifically this is the UDP example
from Ch 3.  First there is the server:

#!/usr/bin/env python
# UDP Echo Server - Chapter 3 - udpechoserver.py
import socket, traceback, time

host = '127.0.0.1'                               # Bind to all
interfaces
port = 51423

s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
s.bind((host, port))

while 1:
    try:
        message, address = s.recvfrom(8192)
        print "Got message '%s' from %s" % (message, address)

        # Echo it back
        s.sendto(message, address)
        print "Sent response to '%s'" % (address,)

    except (KeyboardInterrupt, SystemExit):
        raise
    except:
        traceback.print_exc()

Next I have a client written in Ruby, which works.  I am posting thing
not to start a Ruby/Python flame war, but to simply prove that the
server works and there are no weird networking issues that would
prevent the Python client from working.  The Ruby code is:

#!/usr/bin/env ruby
require 'socket'

socket = UDPSocket.new
socket.connect ARGV[0], ARGV[1]

puts "Enter data to transmit: "
data = STDIN.gets.chomp

socket.send data, 0
puts "Looking for replies; press Ctrl-C or Ctrl-Break to stop."

loop do
  buf = socket.recvfrom(2048)
  puts buf.first
end

When I start the server and run that, the output looks like this:

$ ch02/udp.rb 127.0.0.1 51423
Enter data to transmit:
foobar
Looking for replies; press Ctrl-C or Ctrl-Break to stop.
foobar

Now, when I try the python example:

#!/usr/bin/env python
# UDP Example - Chapter 2 - udp.py

import socket, sys

host = sys.argv[1]
textport = sys.argv[2]

s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
try:
    port = int(textport)
except ValueError:
    # That didn't work.  Look it up instead.
    port = socket.getservbyname(textport, 'udp')

s.connect((host, port))
print "Enter data to transmit: "
data = sys.stdin.readline().strip()
s.sendall(data)

print "Looking for replies; press Ctrl-C or Ctrl-Break to stop."
while 1:
    buf = s.recvfrom(2048)
    sys.stdout.write(buf[0])

I don't ever get a response:

$ ch02/udp.py 127.0.0.1 51423
Enter data to transmit:
foobar
Looking for replies; press Ctrl-C or Ctrl-Break to stop.

The server sees the message and says it has sent a reply:

Got message 'foobar' from ('127.0.0.1', 49623)
Sent response to '('127.0.0.1', 49623)'

Any ideas as to why this doesn't work?