Re-captcha your comments

Comment spam sucks, its as simple as here at Venture Skills blog we get hundreds of spam a day most are caught by Akismet but not all are. If your hosting your own blog or site then no doubt you have tried many combinations. One simple method of reducing spam is a CAPTCHA “Completely Automated Public Turing test to tell Computers and Humans Apart” These provide puzzles which are easy for a human to solve but are much more difficult for a machine.

Commonly CAPTCHA is a visual image where the user is asked to type the word they see (or hear) however some provide a logic puzzle such as “if I have 2 cats and 3 kettles how many animals do I have” or even show multiple images and ask the user to click on the picture of the cat.

Given that most comment spam is automated the use of a CAPTCHA should reduce spam and help make your blog or site a little happier, but they are annoying for users so should be used sparingly.

Re-Captcha Service

Is a service run by the Carnegie Mellon University who also own the CAPTCHA trademark, it provides webmasters with a CAPTCHA service as well as to help digitise old books.

It works by asking the user for two words instead of the normal one, one word is known to the system and is the actual CAPTCHA the second is an unknown word, if the user gets the CAPTCHA then the users “guess” for the unknown word is recorded, over time a word is given a probability score and when high enough becomes a known word.

This system kills several birds with one stone

• It makes setting up a CAPTCHA easy
• No bandwidth problems for your site
• Audio accessibility built in (so is legal in the EU many CAPTCHA are not)
• Helps save old books by digitising them

Setting up re-captcha with Drupal

Register with captcha http://recaptcha.net/whyrecaptcha.html
Then register your sites at which point you are given a private and public key.

Download

• http://drupal.org/project/captcha - CAPTCHA Module
• http://drupal.org/project/recaptcha - RECAPTCHA Module
• http://code.google.com/p/recaptcha/downloads/list?q=label:phplib-Latest - re-CAPTCHA library

Upload the CAPTCHA and RECAPTCHA modules to your server as normal unzip and add the recaptchalib.php to the RECAPTCHA module in the subfolder called recaptcha.

Add the modules via admin/modules/ and select CAPTCHA and RECAPTCHA under spam protection section.

You can admin CAPTCHA from /admin/user/captcha select RECAPTCHA from the drop down list for every form you wish to protect and click ok, the tab at the top includes a link to the RECAPTCHA page, simply add the keys and hit ok. (If your site or pages use SSL choose the secure socket version under server settings)

You can fine tune which visitors see CAPTCHA via the permissions page.

DEMO - Yes I knew you would ask, www.timnash.me.uk is running re-captcha feel free to leave a comment, but say delete me in the comment if you don’t want it to stay.

Re-CAPTCHA WordPress

A WordPress plugin is available and easy to install from http://recaptcha.net/plugins/wordpress/wordpress but doesn’t have the granularity of the Drupal method and has no means to hook into the permission system.

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