Quote from Asgaros on January 3, 2017, 11:10 am

For protection against spam and bots it can be necessary to use a captcha in the forums – especially when the guest posting functionality is enabled. There are already a lot of existing captcha plugins available for WordPress. Thats why I dont want to ship another one with the forum at the moment. Two of the available hooks and filters for the Asgaros Forum plugin allows you to integrate them into your forum:

• asgarosforum_editor_custom_content_bottom hook: Allows you to add custom functions to the bottom area of the editor
• asgarosforum_filter_insert_custom_validation filter: Can be used for custom checks to decide if a user is allowed to post new content

In this example we want to integrate the WordPress extension Really Simple CAPTCHA into our forum. To do this you just have to add this code to your themes functions.php file:

function editor_custom_content_bottom() {
  global $asgarosforum;
  if (!is_user_logged_in() && $asgarosforum->options['allow_guest_postings']) {
    $captcha_instance = new ReallySimpleCaptcha();
    $captcha_word = $captcha_instance->generate_random_word();
    $captcha_prefix = mt_rand();
    $captcha_file = $captcha_instance->generate_image($captcha_prefix, $captcha_word);
    $captcha_url = plugins_url().'/really-simple-captcha/tmp/'.$captcha_file;
    echo '<div class="editor-row editor-row-captcha">';
    echo '<span class="row-title">'.__('Captcha:', 'asgaros-forum').'</span>';
    echo '<img src="'.$captcha_url.'" /><br />';
    echo '<input type="text" name="captcha_value">';
    echo '<input type="hidden" name="captcha_prefix" value="'.$captcha_prefix.'">';
    echo '</div>';
  }
}
add_action('asgarosforum_editor_custom_content_bottom', 'editor_custom_content_bottom');
function insert_custom_validation($status) {
  global $asgarosforum;
  if (!is_user_logged_in() && $asgarosforum->options['allow_guest_postings']) {
    $captcha_instance = new ReallySimpleCaptcha();
    $captcha_value = $_POST['captcha_value'];
    $captcha_prefix = $_POST['captcha_prefix'];
    $captcha_correct = $captcha_instance->check($captcha_prefix, $captcha_value);
    $captcha_instance->remove($captcha_prefix);
    if (!$captcha_correct) {
      $asgarosforum->info = __('You must enter the correct captcha.', 'asgaros-forum');
      return false;
    }
  }
  return $status;
}
add_filter('asgarosforum_filter_insert_custom_validation', 'insert_custom_validation');

 

Alternative Google reCAPTCHA implementation

https://wordpress.org/plugins/recaptcha-for-asgaros-forum/