How to properly set permissions on public_html?

Question

linux

I'm sure this is a lamer question (excuse me), but I've been googling and can't find it. How to properly set up permissions on public_html so that the user cannot get into the core?
We have a structure:
/var/www/toster.ru/public_html
We set
sudo chmod -R 755 /var/www
and now we can all easily climb into
/var/www/toster.ru/public_html/core
what is not good.
How to be?

Answer 1

Change permission to core :-) And then they won't climb :-)