Quote:
Originally Posted by e1-531g
Some companies like Google use servers outsourced for them by other companies (it means other AS number) to handle traffic to regional domains. For example google.com is blocked by your script, but google.pl is not always blocked. To seal this leak use information stored in public DNS servers via dig(1) tool and then concatenate CIDRs with CIDRs retrieved by whois(1).
I don't know how this approach plays with websites behind Cloudflare reverse proxy.
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Proxies and CDNs pose a particularly sticky problem with this approach. It shouldn't be relied upon as a silver bullet, but it may find a place within a bigger scheme to block traffic.