How to prohibit jumping to a file through the index line?

Question

PHP

There are 2 files: admin.php and login.php
1 - admin panel, 2 - entrance to it. If the login is successful, you are redirected to admin.php
How can I make it so that I can't go through the address bar to the admin.php file?

Answer 1

Check in admin.php for user authorization, and if it is absent, redirect it to login.php