if ( ( !isset( $_SERVER['PHP_AUTH_USER'] )) || (!isset
($_SERVER['PHP_AUTH_PW'])) 
     || ( $_SERVER['PHP_AUTH_USER'] != 'userName' ) || (
$_SERVER['PHP_AUTH_PW'] != 'password' ) ) {

    header( 'WWW-Authenticate: Basic
realm="Private"' );
    //header( 'HTTP/1.0 401 Unauthorized' );
    header('Status: 401 Unauthorized');
 
    echo 'Authorization Required.';
    exit;