title: FB LOG IN RESTRICTIONS, allow only specific users to log in on your site using fb login
body: <p>I am trying to make a website where only specific users can log in, and I was hoping to use FB LOG IN for this purpose, </p>
  
  <p>is there a way to make only allowed users to log in using FB LOGIN SDK,</p>
  
  <p>I already tried by using userID, but seems the userID I am getting is different from what I can get from their profile,
  using their name isn't also reliable as anyone can create a dummy account with the same name, 
  I cannot get their username showing on facebook.com/"username"</p>
  
  <p>are there ways to get that or any other way to restrict the log in button</p>