Skeleton Python Code for the ICMP Pinger
from socket import * 
import os
import sys 
import struct 
import time 
import select 
import binascii
ICMP_ECHO_REQUEST = 8

def checksum(string): 
	csum = 0
	countTo = (len(string) // 2) * 2 
	count = 0
	while count < countTo:
		thisVal = ord(string[count+1]) * 256 + ord(string[count]) 
		csum = csum + thisVal
		csum = csum & 0xffffffff 
		count = count + 2

	if countTo < len(string):
		csum = csum + ord(string[len(string) - 1]) 
		csum = csum & 0xffffffff

	csum = (csum >> 16) + (csum & 0xffff) 
	csum = csum + (csum >> 16)
	answer = ~csum
	answer = answer & 0xffffanswer = answer >> 8 | (answer << 8 & 0xff00) 
	return answer

def receiveOnePing(mySocket, ID, timeout, destAddr): 
	timeLeft = timeout
	while 1:
	   startedSelect = time.time()
	   whatReady = select.select([mySocket], [], [], timeLeft) 
	   howLongInSelect = (time.time() - startedSelect)
	   if whatReady[0] == []: # Timeout 
		return "Request timed out."
	   timeReceived = time.time()
	   recPacket, addr = mySocket.recvfrom(1024)
	   #Fill in start
	   #Fetch the ICMP header from the IP packet
	   #Fill in end
	   timeLeft = timeLeft - howLongInSelect 
           if timeLeft <= 0:
	       return "Request timed out.”

def sendOnePing(mySocket, destAddr, ID):
	# Header is type (8), code (8), checksum (16), id (16), sequence (16)
	myChecksum = 0
	# Make a dummy header with a 0 checksum# struct -- Interpret strings as packed binary data
	header = struct.pack("bbHHh", ICMP_ECHO_REQUEST, 0, myChecksum, ID, 1) 
	data = struct.pack("d", time.time())
	# Calculate the checksum on the data and the dummy header. 
	myChecksum = checksum(str(header + data))

	# Get the right checksum, and put in the header 
	if sys.platform == 'darwin':
		# Convert 16-bit integers from host to network byte order 
		myChecksum = htons(myChecksum) & 0xffff
	else:
		myChecksum = htons(myChecksum)
	header = struct.pack("bbHHh", ICMP_ECHO_REQUEST, 0, myChecksum, ID, 1) 
	packet = header + data

	mySocket.sendto(packet, (destAddr, 1)) # AF_INET address must be tuple, not str
	# Both LISTS and TUPLES consist of a number of objects
	# which can be referenced by their position number within the object.

def doOnePing(destAddr, timeout): 
	icmp = getprotobyname("icmp")
	# SOCK_RAW is a powerful socket type. For more details: http://sock-raw.org/papers/sock_raw
	mySocket = socket(AF_INET, SOCK_RAW, icmp)
	myID = os.getpid() & 0xFFFF	# Return the current process i 
        sendOnePing(mySocket, destAddr, myID)
	delay = receiveOnePing(mySocket, myID, timeout, destAddr)
	mySocket.close() 
	return delay

def ping(host, timeout=1):
	# timeout=1 means: If one second goes by without a reply from the server,
	# the client assumes that either the client's ping or the server's pong is lost 
	dest = gethostbyname(host)
	print("Pinging " + dest + " using Python:") 
        print("")
	# Send ping requests to a server separated by approximately one second 
	while 1 :
		delay = doOnePing(dest, timeout) 
		print(delay)
		time.sleep(1)# one second 
	return delay