Prevent Multiple user registrations from single IP I'm using Drupal 6.19.I need two things to be done.First thing, I want to disable multiple user registrations from the same IP.The Second thing is ,I want to allow only 3 user to register at a time.
Anyone know this how to do in Drupal6.19?

Please help me to do this.
You may find the problem there is that Drupal doesn't store the IP address of the user during normal core registration process.

Assuming you can hook in and store that IP address for later lookup, you could then validate that ip address count for the user with something like:

/**
 * Implements hook_form_FORM_ID_alter
 */
function mymodule_form_user_register_alter(&amp;$form, &amp;$form_state) {
  $form['#validate'][] = 'mymodule_user_register_validate';
}

/**
 * hook_form_user_register_alter validation callback
 */
function mymodule_user_register_validate($form, &amp;$form_state) {
  $account = (object) $form_state['values'];
  $ip_address = ip_address(); // api call
  // do something to look up ip_address on registered user..
  // for example: 
  $count = db_query("SELECT count(uid) FROM {user_ip} WHERE ip = :ip", array(':ip' =&gt; $ip_address))-&gt;fetchField();
  if($count &gt; 3){
    $error = t('Sorry, too many registrations.');
    form_set_error('name', $error);
  }
}