How to set up a redirect so that the site opens only when you go to it from Yandex search?

Question

URL Handling

Found a site in the top for a specific request. I studied it to the best of my knowledge.
In fact, I see that the site has a 301 redirect, which works when you go to it from the yandex.ru search.
If the site is simply opened in a browser (by simply writing the domain in the address bar), a 500 internal Server Error pops up.
How to implement it?
Thank you.

Answer 1

Check http referer