Yes, it's possible to set Maintenance Flag and then have your index.php
check for a set of addresses that are let through while serving everyone else a 503 page. Only those systems will be allowed admin and public access while maintenance.flag is set. Find the section in index.php
and make some modifications. I use the following on Magento 1.4.2.0, check to make sure 1.7 uses the same mechanism in index.php
:
$maintenanceFile = 'maintenance.flag';
$ip = $_SERVER['REMOTE_ADDR'];
/***************
* IP's allowed in maintenance.
* Use publicly visible IP addresses on LIVE, local if on DEV
***************/
$allowed = array('10.0.0.100','10.0.0.101','10.0.0.20');
if (file_exists($maintenanceFile) && !in_array($ip, $allowed)) {
$basePath = dirname($_SERVER['PHP_SELF']);
include_once dirname(__FILE__) . '/errors/503.php';
exit;
}