Server receiving hit from this IP Address "::ffff:". Why is that and how to resolve this?

I have a MEAN Stack application deployed on a server and I am using Nginx as proxy server to handle the request and redirect to application’s particular port.

I wrote a short script in node.js which fetches IP and location of the users visiting my website. I can see the searched queries and usage of my API from external users and are same as those I can see via Google Analytics.

But I am also getting a strange hit to my server (and API links) from the IP address “::ffff:”. Why is that? Is that because of Nginx? How can I resolve this? Is this even an actual user or what?

Someone suggested that it might because of the Monitoring tool installed on your server. Can this be the reason as well or its something else?

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I solved it with:

set $remote_addr_ipv4 $remote_addr;
if ($remote_addr ~ ^\:\:ffff\:(.+)$) {
    set $remote_addr_ipv4 $1;

set $proxy_add_x_forwarded_for_ipv4 $proxy_add_x_forwarded_for;
if ($proxy_add_x_forwarded_for ~ ^\:\:ffff\:(.+)$) {
    set $proxy_add_x_forwarded_for_ipv4 $1;

proxy_set_header    X-Forwarded-For    $proxy_add_x_forwarded_for_ipv4;
proxy_set_header    X-Real-IP          $remote_addr_ipv4;



::ffff: is the IPv6 version of an IPv4 IP address, just to clarify.

What does your current NGINX server block look like? (the one that has the proxy configuration)