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Simpler than what you suggest is to read RFC 2644, then turn off directed broadcasts in routers being deployed, and making the default be DISABLED on new routers.

I agree. But, for some reason, that isn't working as well as it should. BTW, one feature that has been enabled for years is a default ingress filter that blocks inbound packets that have a source addr from inside the net-block (obviously wrong or an attack). Because bcast addrs values are configuration dependent, it is not possible to use such a generic filter. However, it should be possible to build dynamic bcast scanning into a router such that it scans the internal net for bcast addrs and subsequently ingress filters all packets to those source addrs that do not originate on the local netblock. This will not solve the immediate problem with existing routers. But, that same method can be used to scan the /24 and auto-generate the required filter statements for the firewall. The upstream can run it the other way, for the client, except that they would be egress filtering. This method requires no in-addr.arpa edits.

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I'd rather see sites spend their time on that rather than adding INADDR entries to their domains. Remember that delegations to other organizations (i.e. clients of ISPs) are able to subdivide networks further, and that won't be apparent to the ISP.

Agreed, that's why I also wrote about dynamic bcast discovery methods.

In case anyone missed my point, using BGP blackholing becomes anti-social behavior when more surgical techniques are available. Moreso when such techniques aren't even explored before implementing the blackhole method.

MAPS has only gained a modicum of acceptability because more socially acceptable methods were tried and subsequently failed. Moreover, they have been shown to not even be feasible. This is NOT the case with the smurf-amp problem. I, for one, am NOT convinced that sufficient thought has been directed at more socially acceptable alternative solutions.