import requests
from bs4 import BeautifulSoup

username = 'user'
password = 'pass'
scrape_url = 'http://www.ivolatility.com/options.j?ticker=SPX&lhid=141519256'

login_url = 'https://www.ivolatility.com/login.j'
login_info = {'email': username,'password': password}

#Start session.
session = requests.session()

#Login using your authentication information.
session.post(url=login_url, data=login_info)

#Request page you want to scrape.
url = session.get(url=scrape_url)

soup = BeautifulSoup(url.content, 'html.parser')