How does the Identification of admin user happen in Magento?
I have an admin module, how do I make sure that the url route is not accessible from outside the admin area?
Usually you don't need to worry about this, magento will take care of the authentication for you. But you can create an ACL for this module, in there you can define which roles has access to your module.
Check here for more info: http://alanstorm.com/magento_acl_authentication