I made this to scratch my own itch. When I get DDoS'd I can relieve the pressure very easily by blocking Cloudflare, ChinaNet, DigitalOcean, Linode, Hetzner and OVH. The problem is, it's difficult to get the up-to-date subnets associated with those hosts in bulk.<p>I stumbled upon a free source of AS data a while ago, and integrated it into my custom OpenResty/Lua firewall.<p>But I wanted a quick way to block an ASN earlier in the process (iptables), mostly to keep my HTTP logs cleaner during a DDoS. And thus, ASN Tool was born.<p>I am running it on a cheap DO box with OpenResty/Lua as the backend. It seems to handle about 500 requests/second, which I hope is good enough for the time being.<p>After this <a href="https://krebsonsecurity.com/2022/12/six-charged-in-mass-takedown-of-ddos-for-hire-sites/" rel="nofollow">https://krebsonsecurity.com/2022/12/six-charged-in-mass-take...</a> I haven't been hit by any DDoS attacks, so this might be all for naught. But I'm putting it out there anyway.<p>Under the "Info" section, you can download the data file to run ASN lookups yourself. I suspect bandwidth may be an issue in the future. If anyone wants to sponsor hosting the file, email me at rumpelstiltskin at asntool.