Python script for detecting IP change and send email to admin.

ip-check.py

import os.path
import time
import urllib
import re
from email.MIMEMultipart import MIMEMultipart
from email.MIMEText import MIMEText
import smtplib


fileName = "mylastip.txt"

fileExist = os.path.isfile(fileName)

if fileExist :
    fp = open (fileName, "r")
    last_ip = fp.read()
    fp.close()
else :
    last_ip = "0.0.0.0"

url = "http://checkip.dyndns.org "

while (True):
    request = urllib.urlopen(url).read()
    theIP = re.findall(r"\d{1,3}\.\d{1,3}\.\d{1,3}.\d{1,3}", request)
    theIP2 = theIP[0]
    
    if ( theIP2 != last_ip ):
        fp = open (fileName, "w")
        fp.write(theIP2)
        fp.close()

        fromaddr = "<myname>@gmail.com"
        toaddr = "<myname>@gmail.com"
        msg = MIMEMultipart()
        msg['From'] = fromaddr
        msg['To'] = toaddr
        msg['Subject'] = "my server ip address changed"
        
        body = theIP2
        msg.attach(MIMEText(body, 'plain'))

        server = smtplib.SMTP('smtp.gmail.com', 587)
        server.ehlo()
        server.starttls()
        server.ehlo()
        server.login("<myname>", "<mypassword>")
        text = msg.as_string()
        server.sendmail(fromaddr, toaddr, text)
        server.quit()
        last_ip = theIP2
        
    
    time.sleep(120)