A New Future for Icanhazip

This story is kind of sad. I wonder why the operator didn't blacklist certain netblocks/ASNs who were abusing the service.

Why punish a group for one bad actor?

> There were many times where I saw a big traffic jump and I realized the traffic was coming from the same ASN, and likely from the same company. I tried reaching out to these companies when I saw it but they rarely ever replied. Some even became extremely hostile to my emails.

A hostile reply from a netblock operator seems like a perfectly valid reason to block their traffic.

The problem is that you don't know what the source of the traffic is. It could be an incompetent network operator/sysadmin, but it could just as well be something like an IP camera that people bought in good faith. If you block the CGNAT system of an operator that has a hundred million subscribers because it all seems to come from a single IP range you know nothing about, you could be hurting innocent users with the block.

That being said, a service like this doesn't come with any guarantees and if it'd disappear from the net tomorrow, I wouldn't blame the author. Blocking is a perfectly valid solution to this problem, but assuming malice isn't always the right answer.

Were I in this situation, I'd rate limit networks per /24 (maybe even /16?) as much as I could, and work together with antivirus companies to help identify infections of malware known to use the service to discourage criminals from abusing the system. I wouldn't even bother hosting the site on IPv6 since those addresses are supposed to be public anyway. The author clearly has more patience than I do.

Looking at the icanhazip.com site, I wonder how much any kind of rate-limiting per address/block would even help.

At the HTTP level it's probably cheaper to just return the HTTP 200 response. I suppose if you're doing TLS handshakes then a packet-level rate-limit would help significantly, but at the same time I'd be wary of triggering any kind of retry-behavior.

Worst-case scenario for a service like this would be having an error response/timeout trigger some kind of unlimited retry flood.