A script for Sky customers to email out their external IP address when it changes

currentIP.py

#! /usr/bin/env python
from urllib.request import urlopen, Request
import urllib
import base64
from bs4 import BeautifulSoup
import os.path
import time
import smtplib

def main():
    addr = getIPAddress()
    emailIfChanged(addr)

def getIPAddress():
    req = Request('http://192.168.0.1/sky_router_status.html')
    up_b = base64.b64encode(b'username:password')
    up_s = up_b.decode('ascii')
    req.add_header('Authorization', 'Basic {up_s}'.format(**{'up_s':up_s}))
    try:
        resp = urlopen(req).read()
    except urllib.error.HTTPError:
        # sometimes 401 errors happen on the first attempt
        print('401 error, trying again in 10 seconds')
        time.sleep(10)
        resp = urlopen(req).read()
    soup = BeautifulSoup(resp, 'html.parser')
    script = soup.find_all('script')[8].contents[0]
    lines = script.split('\n')
    longvar = lines[12]
    parts = longvar.split(' = ')[1].split('_')
    return parts[5]

def emailIfChanged(IP):
    last_ip = ''
    if os.path.isfile('last_ip.txt'):
        with open('last_ip.txt', 'r') as ipfile:
            last_ip = ipfile.read()

    if last_ip == IP:
        print('IP not changed ({IP})'.format(**{'IP':IP}))
    else:
        sendEmail(IP)
        with open('last_ip.txt', 'w') as ipfile:
            ipfile.write(IP)

def sendEmail(IP):
    days = ['Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat', 'Sun']
    mons = ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec']
    recipient = ['my email address']
    sender = 'email address I want this to come from'
    subject = 'New IP Address at Home'
    dt = time.gmtime()
    date_str = '{day}, {date:02} {mon} {year} {hour:02}:{minute:02}:{second:02} +0000'.format(**{'day':days[dt.tm_wday], 'date': dt.tm_mday, 'mon': mons[dt.tm_mon-1], 'year':dt.tm_year, 'hour':dt.tm_hour, 'minute':dt.tm_min, 'second':dt.tm_sec})
    message = 'From: IPALERT <{sender}>\nTo: My Name <{recipient}>\nSubject: {subject}\nDate: {date}\n\n The IP address has changed to {IP}'.format(**{'sender': sender, 'recipient':recipient[0], 'subject':subject, 'date':date_str, 'IP':IP})

    try:
        print ('sending email message')
        smtp = smtplib.SMTP_SSL('SMTP server address')
        smtp.login('username', 'password')
        smtp.sendmail(sender, recipient, message)
        print('sent message')
    except smtplib.SMTPException as ex:
        print('failed to send message')
        print(ex)
            
if __name__ == '__main__':
    main()

This uses python 3 and requires beautiful soup to be installed