お問い合わせ攻撃対応
google http://tango-ruby.hatenablog.com/entry/2016/01/21/191706
古いやつ https://github.com/plataformatec/mail_form https://github.com/pludoni/simple-captcha
dos対応
https://github.com/kickstarter/rack-attack
https://www.upguard.com/articles/top-7-ways-to-hack-rails-how-to-fix
http://guides.rubyonrails.org/security.html
https://github.com/rauchy/rack-attack-recaptcha
rack attack テスト
http://blog.hayleyanderson.us/2015/06/05/using-and-testing-rack-attack-to-improve-the-security-of-your-rails-app/
https://hakiri.io/blog/ruby-security-tools-and-resources
https://github.com/ankane/secure_rails