Some help with broadcasts through a Linux system

Dan Kaminsky effugas at
Wed Feb 3 13:36:54 GMT 1999

>Correct. You don't forward broadcasts. Imagine what ping
>do if you did

A little more information, since I've been pulling the Dan "Broken Record"
Kaminsky routine in my last couple of emails.

The following comes from RFC922:



      - Broadcast to all hosts on a remote hardware network: It is
        occasionally useful to send a broadcast to all hosts on a
        non-local network; for example, to find the latest version of a
        hostname database, to bootload a host on a subnet without a
        bootserver, or to monitor the timeservers on the subnet.  This
        case is the same as local-network broadcasts; the datagram is
        routed by normal mechanisms until it reaches a gateway attached
        to the destination hardware network, at which point it is
        broadcast.  This class of broadcasting is also known as
        "directed broadcasting", or quaintly as sending a "letter bomb"


   For reasons of performance or security, a gateway may choose not to
   forward broadcasts; especially, it may be a good idea to ban
   broadcasts into or out of an autonomous group of networks.


My point is, while one *usually* doesn't want to forward and/or bridge
broadcasts, the authors of the broadcasts standards foresaw that it could be
at least useful.  For issues of what Richard is trying to do with Directed
Broadcasts, there's really no other way to do it.

Hurm.  I think I need more sleep, but then don't we all?  :-)

Yours Truly,

        Dan Kaminsky
        DoxPara Research

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