You will find there's web application on the domain. Now another domain uses this application using a 301 redirection to former domain. What exactly are methods to safeguard the application. To ensure that no-one can can get on directly. Referrer check is an excellent method, although not reliable.
You can need a key along with a hash to become passed along for your webapp within the redirect. The redirecting application creates the important thing, hashes it having a shared secret, after which passes the important thing and also the hashed value for your webapp. Your webapp hashes the important thing using the shared secret and when it's comparable to the hashed value which was provided, access is permitted.