Re: ICMP responses to broadcasts

Jeff Mogul (
14 Apr 1986 1132-PST (Monday)

    Let me second John Romkey's assertion that no good ICMP implementation
    should send redirects in response to a broadcast packet. Might I also
    ask at this time why our core gateway does just that? We receive
    several redirects a second in response to the rwho/ruptime packets
    our Unix hosts send (no ruptime flames, please.)

Maybe it's because your Unix host is sending broadcasts to the wrong
IP address? (That is, Net.0.0.0 instead of Net.255.255.255)
Of course, it would be nice if gateways looked at the
data-link header to see if something arrived as a broadcast, but
this is one of those little things that is impossible in some systems
(e.g., 4.3), which is why these systems really are unsuited for
use as gateways.

One would hope that the core gateways are capable of handling this, but
I would not be surprised if they are not.

I would also be unsurprised if the core gateways still know nothing
at all about broadcasts. Perhaps someone can fill us in.

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