scraper.rb

#!/usr/bin/env ruby
#
#  http://gmarik.info/blog/2010/10/16/scraping-asp-net-site-with-mechanize
 
require 'rubygems'
require 'mechanize'
require 'logger'

user = 'user'
pass = 'pass' 
login_url = 'https://asp.net.site'

class Mechanize::Page::Link
   def asp_click(action_arg = nil)
    etarget,earg = asp_link_args.values_at(0, 1)

    f = self.page.form_with(:name => 'aspnetForm')
    f.action = asp_link_args.values_at(action_arg) if action_arg
    f['__EVENTTARGET'] = etarget
    f['__EVENTARGUMENT'] = earg
    f.submit
  end

  def asp_link_args
    href = self.attributes['href']
    href =~ /\(([^()]+)\)/ && $1.split(/\W?\s*,\s*\W?/).map(&:strip).map {|i| i.gsub(/^['"]|['"]$/,'')}
  end
end

agent = Mechanize.new do |a| 
  a.log = Logger.new($stdout); 
  a.log.level = 1 
  a.user_agent_alias = 'Mac Safari'
end

page = agent.get(login_url)

f = page.form_with(:name => 'LgForm')
f['lgLg$User'] = user
f['lgLg$Pass'] = pass
page = agent.submit(f, f.buttons.first)

# Follow links
file = page.link_with(:text => 'Journall').asp_click.
  link_with(:text => 'All Downloads').asp_click(4).
  link_with(:text => 'Download').asp_click

file.save_as(file.filename)

puts 'Done!'
puts "\nFile: #{file.filename}"