Captcha is a security mechanism aimed to prevent robots to submit forms.

Captchas are available on the following forms:

  • Login form: where user enters login and password to authenticate
  • Password reset by mail form: where user enters mail to recover a lost password
  • Register form: where user enters information to create a new account


We use the Perl module GD::SecurityImage to generate images, you need to install it if you enable Captcha feature.


Go in General parameters > Portal > Captcha:

  • Activation in login form: set to 1 to display captcha in login form
  • Activation in password reset by mail form: set to 1 to display captcha in password reset by mail form
  • Activation in register form: set to 1 to display captcha in register form
  • Size: length of captcha
  • Captcha module: allows you to use a custom Captcha module, see below. Leave it blank to use the default Captcha implementation
  • Captcha module options: options for the custom Captcha module

Custom Captcha modules

New in version 2.0.15.

If the default Captcha does not meet your requirements, you can replace it with a different implementation. See the Lemonldap::NG::Portal::Captcha manual page for details on how to implement a Captcha module.