You may find that .htaccess allows and denies for IPs work under Apache but not under Nginx with Reverse Proxy (ea-nginx).
This may be due to mod_remoteip not being set up for Apache, causing all proxied connections to appear to be coming from the server's own IP.
Apache will need mod_remoteip installed and configured to properly translate the visitor IP from the Nginx proxy header. The article below covers how to enable mod_remoteip. Note that Nginx uses the X-Forwarded-For header.