Nginx: Allow selected IP addresses only

  server {
    listen 80;
    server_name www.foo.bar;

    location / {

      allow   my.public.ip.here;
      deny    all;
    }
  } 

You can have multiple "allow" lines.

http://stackoverflow.com/questions/8438867/how-can-i-allow-access-to-a-single-ip-address-via-nginx-conf