Captcha is a security mechanism to prevent forms from being submited by robots.

Captchas are available on following forms:

  • Login form: where user inputs login and password for authenticating

  • Password reset by mail form: where user inputs mail to recover a forgotten password

  • Register form: where user inputs information to create a new account


We use the GD::SecurityImage Perl module to generate images. This module is required if you enable Captcha feature. With Debian-based distributions, you may have to install ‘gsfonts’ package.


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: define captcha length

  • 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.