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  • HAN WANG thinks this is interesting:

Directed broadcasts were found to be such a big problem from a security point of view that they are effectively disabled on the Internet today. [RFC0919] describes the various types of broadcasts for IPv4, and [RFC1812] suggests that support for forwarding directed broadcasts by routers should not only be available but enabled by default. This policy was reversed by [RFC2644] so that by default routers must now disable the forwarding of directed broadcasts and are even free to omit support for the capability altogether.

From

Cover of TCP/IP Illustrated, Volume 1: The Protocols

Note

Directed Broadcast is disabled by default.