local_settings.yml

ip_address_whitelist:
   - 127.0.0.1
   - 1.2.3.4
   - 5.6.7.8
whitelisted_pages:
   - /assets/.*
   - /
   - /login

rack-attack.rb

module YourProject
  class Application < Rails::Application
    whitelist = YAML.load_file(File.expand_path('../local_settings.yml', __FILE__))

    Rack::Attack.whitelist 'requests' do |req|
      whitelist['whitelisted_pages'].find do |str|
        regexp = Regexp.new(str)
        req.path =~ regexp
      end.any?
    end

    Rack::Attack.whitelist 'ips' do |req|
      whitelist['ip_address_whitelist'].include? req.ip
    end

  end
end