Exibir código-fonte para Plugin contra spam em WordPress

* https://wordpress.org/plugins/spam-destroyer/
* https://wordpress.org/plugins/antispam-bee/
* https://wordpress.org/plugins/wangguard/
* https://wordpress.org/plugins/goodbye-captcha/
* https://wordpress.org/plugins/stop-spam-comments/
* https://wordpress.org/plugins/cleantalk-spam-protect/
* https://wordpress.org/plugins/stop-spammer-registrations-plugin/
* https://wordpress.org/plugins/zero-spam/
* https://wordpress.org/plugins/growmap-anti-spambot-plugin/
* https://wordpress.org/plugins/wp-spamshield/
* https://br.wordpress.org/plugins/anti-spam/
* https://jetpack.com/install/personal/en/
* http://ayudawordpress.com/como-combatir-el-spam/
* http://ayudawordpress.com/evita-comentarios-spam-desde-htaccess/
* https://wordpress.org/plugins/simple-trackback-validation-with-topsy-blocker/
* https://wordpress.org/plugins/cookies-for-comments/
* https://wordpress.org/plugins/bad-behavior/

regra no nginx
* https://serverfault.com/questions/177304/different-nginx-rules-based-on-referrer
* https://stackoverflow.com/questions/24105799/nginx-block-from-referrer
* https://fadeit.dk/blog/2015/04/22/nginx-referer-spam-blacklist/
* https://gist.github.com/juanpasolano/2d18fd452c3a2f57a7a1