Chinese Captcha module, provided validation way by input a Chinese characters, this module is mainly developed for Chinese user , aim to prevent spam attack from robot,
Drupal has inbuilt IP blocking. Drupal also has an inbuilt Flood Control API to detect bulk activity. But.. IPBlocking is not automated. And Flood Control has no UI.
Via AJAX to determine if the user currently accessing the site still has an active session and reload the page if they don not. Effectively logging the user out of the site.