Drupal behind a proxy

drupal-proxy.php

/**
 * @file
 * This snippet shows how you can run drupal from a different host behind a proxy.
 * Include this code at the bottom of your settings.php file.
 */

// Set the hosts that are allowed to be proxied to this drupal installation.
$conf['reverse_proxy_addresses'] = array('example.com', 'example2.com');
// If the request was proxied from a different domain we change the internal URL.
if (isset($_SERVER['HTTP_X_FORWARDED_HOST']) && in_array($_SERVER['HTTP_X_FORWARDED_HOST'], $conf['reverse_proxy_addresses'])) {
  $base_url = 'http://' . $_SERVER['HTTP_X_FORWARDED_HOST'];
  $conf['reverse_proxy'] = TRUE;
}