RestClient::Resource.new("http://someurl.com/page.html")

require 'rubygems'
require 'mechanize'

agent = Mechanize.new
agent.get("http://someurl.com/page.html")
form = agent.page.forms.first
form.login_username = 'user'
form.login_password = 'password'
form.submit
tds = agent.page.search(".//td")
ip = tds[37].text.to_f