dynip.py

import urllib
import smtplib

# Emails new ip address when it changes via gmail
# This is designed to be used with an OS scheduler
# The url is not to be used more often than ever 300 seconds
def get_ip():
    # Queries url to receive external ip address
    ipurl = 'http://automation.whatismyip.com/n09230945.asp'
    return urllib.urlopen(ipurl).readlines()[0]

def send_new_ip(ip):
    msg = "New ip address is " + ip
    # From and to email addresses
    fromaddr = '[email protected]'
    toaddr = '[email protected]'

    #gmail credentials
    username = 'username'
    password = 'password'

    #send email
    server = smtplib.SMTP('smtp.gmail.com:587')
    server.starttls()
    server.login(username,password)
    server.sendmail(fromaddr, toaddr, msg)
    server.quit()
    print "Email sent to " + toaddr

#writes ip to <filename>
def write_ip(ip, filename):
    FILE = open(filename,'w')
    FILE.write(ip + '\n')
    FILE.close()

ip = get_ip()
filename = 'ipaddress.txt'

try:
    FILE = open(filename,'r')
    old_ip = FILE.read().strip()
    FILE.close()

    # if new ip, sends email and replaces <filename>
    if ip != old_ip:
        send_new_ip(ip)
        write_ip(ip, filename)
    else:
        exit

# if <filename> does not exist, creates it and sends email
except:
    write_ip(ip, filename)
    send_new_ip(ip)