I will give an example of setting up access by IP in nginx.
Suppose you use the standard nginx configuration file, open it in a text editor:
sudo nano /etc/nginx/sites-enabled/default
Find the string:
server {
And after it we will add networks from which it is necessary to allow access:
allow 10.0.0.0/24;
allow 172.0.0.0/11;
After the list of networks, add a line that denies access to all other unspecified networks:
deny all;
To apply the configuration changes, restart nginx:
service nginx restart
See also my article:
Install and configure Nginx