Nginx Prevent direct ip access

why would you even want to do that ?

if you do there's a few solutions at nginx - how to disable direct access to a web site by ip address - Stack Overflow

probably best is just setup an additional server context in separate or same nginx vhost as your domain

try 302 temp redirect first before setting 301 which is permanently cached in browser

Code:

server {
        listen 80;
        server_name IP_ADRESS;
        return 301 http://YOUR.DOMAIN;
}

or specifying hostname to allow return 403 or 302/301 redirect etc

Code:

    if ($http_host != "YOUR.DOMAIN") {
        return 403;
    }