Google Analytics Proxy using Nginx to bypass Adblock and other blockers

1.google-analytics-proxy-nginx.conf

server {
    listen 80;
    server_name your.domain.com;

    location = /analytics.js {
        # you have to compile nginx with http://nginx.org/en/docs/http/ngx_http_sub_module.html (this is not default)
        # and http://nginx.org/en/docs/http/ngx_http_proxy_module.html (it's a default module)
        
        proxy_set_header Accept-Encoding "";
        sub_filter 'www.google-analytics.com'  'your.domain.com';
        sub_filter_types *;
        sub_filter_once off;

        proxy_pass https://www.google-analytics.com/analytics.js;
        break;
    }

    location / {
        proxy_pass http://www.google-analytics.com/;
    }
}

2.browser-javascript-file.js

(function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){
  (i[r].q=i[r].q||[]).push(arguments)},i[r].l=1*new Date();a=s.createElement(o),
  m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m)
})(window,document,'script','//your.domain.com/analytics.js','ga');

# after this run your regular ga code
ga('create', 'UA-XXXXXXX-Y', 'auto');

ga('set', 'userId', 'your logged user id');

ga('send', 'pageview');

Nevermind, I found the answer.

For some reason, IPv6 is not working correctly on my box.
Nginx timed out when it used the IPv6 address of www.google-analytics.com.

The solution was to add the following line to the server block:

resolver 8.8.8.8 ipv6=off;

And wait a long time (I would say 10m) until the cache expires.

I found a mistake in the NGINX configuration shown at the top.
It should not be:

proxy_pass http://www.google-analytics.com/;

but it should be:

proxy_pass http://www.google-analytics.com;

It's crucial to remove the trailing slash; otherwise, NGINX drops all the query parameters.

Some adblockers are strict and even block urls like '/r/collect/'
Sot he trick is to replace sub_filter 'r/collect' 'rrr/upstreamer';
then add a block of code

location /rrr/upstreamer/{
        proxy_set_header Accept-Encoding "";
        sub_filter 'www.google-analytics.com'  'subcode.example.com';
        sub_filter_types *;
        sub_filter_once off;
        proxy_pass https://www.google-analytics.com/r/collect;
        break;
    }

Please keep in mind if people are going out of their way to block GA, they probably really do not want their data being collected by Google