Code Snippet: Ping local IP addresses

Here is a code snippet that I have created for the purpose of finding a Raspberry Pi when it is connected to a network without a screen. For my setup, I have both an ethernet connection and a WiFi connection. Normally the ethernet connection is connected directly to the raspberry pi, and the WiFi connection goes directly to the router. My code was written and tested on Windows 8.1, with Python 2.7.10. 

from __future__ import print_function

import socket

import os

import time

import subprocess

from threading import Thread

def ping(hostname, timeout=100):

    timeout=str(timeout)

    #perform ping command. -n sets the number (1 here) and -w sets the timeout.

    #creationflag=8 hides the window.

    response = subprocess.Popen(["ping", hostname, "-n", '1', "-w", timeout],

                                stdout=subprocess.PIPE, creationflags=8).stdout.read()

    ping_reply=0

    if "time=" in response.lower() or "time<" in response.lower():

        ping_reply=1

    return ping_reply

def ping_and_print(hostname):

    #perform ping command

    ping_reply=ping(hostname)

    #print whether ip address responded to ping or not.

    #I added the "\n" character to the print command because

    #when multiple threads try to print, it was causing

    #overlapping for some reason. It seems there is a bit of a delay

    #between the string being printed and the end of line

    #character being printed.

    if (ping_reply==1):

        print(hostname + " - UP!\n", end="")

    else:

        if verbose==1:

            print(hostname + " - Down!\n", end="")

    return

verbose=0 #also print out ips that aren't responding to pings.

#this gets the local ip range, the range with the ethernet adapter

local_ip=socket.gethostbyname(socket.gethostname())

#this pings the gmail server and gets the IP address used to connect, so

#should always be the ip address used for internet connections

s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)

s.connect(("gmail.com",80))

web_facing_ip=s.getsockname()[0]

s.close()

print("Local IP     : " + str(local_ip))

print("Web facing IP: " + str(web_facing_ip))

#check we can actually ping the internet

hostname="8.8.8.8"

ping_reply=ping(hostname,5000)

print("Internet ping: " + str(ping_reply))

#create the network stem for the local ip range

network_stem=".".join(local_ip.split(".")[0:3])

#ping primary ip range

for ip in range(1,255):

    this_ip_address=network_stem + "." + str(ip)

    t = Thread(target=ping_and_print, args=(this_ip_address,))

    t.start()

#create the network stem for the internet connecting ip range

network_stem=".".join(web_facing_ip.split(".")[0:3])

#check we are running on a second network range and not just repeating the

#previous tests.

if local_ip<>web_facing_ip:

    #ping secondary ip range

    for ip in range(1,255):

        this_ip_address=network_stem + "." + str(ip)

        t = Thread(target=ping_and_print, args=(this_ip_address,))

        t.start()

#sleep at the end for a bit to wait for remaining responses.

for i in range(1,100):

    time.sleep(0.01)

print("Done.")