How to close access to the proxied site?

Question

Nginx

If you make a site proxy from one server to port 80 in another server. Do I need to close access to the proxy on port 80? How to do it? Is it possible to deny access not from the IP of the main host using NGINX?
Will this work correctly?

deny all;
     
    allow $realip_remote_addr; 
    set_real_ip_from XXX.XXX.XXX.XXX;
    real_ip_recursive on;

Answer 1

a firewall is more reliable
, well, it would be nice to clarify the question
host A 10.0.0.1:80 host
B 10.0.0.2:80