How to put magento in maintenance

Question

Is it possible to put a magento site under an maintenance flag so that visitors will get a message that the site is under construction? I can\'t find this setting in the admin a

Answer 1

Thats what I add to the index in order to be able to continue working from different IPs:

//EGS to show a maintenance page but be able to work
$ip = $_SERVER['REMOTE_ADDR'];

// these are the IP's that are  allowed to view the site:
$allowed = array('111.111.111.111', '222.222.222.222');

if (file_exists($maintenanceFile) && !in_array($ip, $allowed)) { 
    include_once dirname(__FILE__) . '/errors/503.php';
    exit;
}