Caveats!! a human brain must be used !!!
First, get ALL your access IPs from your HTTP server
cut -d' ' -f1 /var/log/nginx/access.log | sort | uniq > /tmp/all_ips
Now we can use a docker image to have the IPtoASN API https://iptoasn.com/ running locally
docker run -itd --name my-iptoasn -p 80:53661 ilyaglow/iptoasn-webservice