Configuration/settings/restrict admin domain
Set this to a domain name in order to restrict access to the administrative page to only be available on that particular domain.
$c->restrict_admin_domain = 'admin.davical.mycompany.com';
The default is that any DAViCal instance will have the administrative pages active. When this setting is enabled, any requests for administrative URLs such as index.php, admin.php, setup.php and so forth, will be redirected to 'caldav.php'.
Available from DAViCal version: 0.9.7.4 and later