title: how do you prevent verification code attack to server
body: <p>building a server for an app and one of the steps of the registration in the app is to enter a phone number verification code. The verification code will be sent to the phone through sms and the verification code needs to be entered to continue the registration</p>
  
  <p>The app will send a request to the server and is it possible for someone to find out the url and keep sending fake phone verification code requests to the server? How do you prevent the attack?</p>