Some help with broadcasts through a Linux system

[Jeremy Allison]

Richard Sharpe wrote:
> 
> Hi again,
> 
> OK, what I did not make clear was that I was trying to use directed
> broadcasts, not the local broadcasts address (255.255.255.255).
> 
> That is, in the context of the following diagram:
> 
>      172.30.0.0/24               16.153.112.0/24
>    --------------------[Linux]---------------------
> 
> If from 172.30.0.120 I ping 16.153.112.255, I would expect to see the
> broadcast on the other interface.
> 
> Linux seems to be stoping it, and I cannot find a switch to prevent it from
> stopping it.

I think that's an anti-SMURF security measure
(little blue horrors, I *hate* em, and don't get
me started on Father Abraham.... :-).

It's done to stop directed broadcasts of ICMP
packets - the dreaded SMURF attack.

Jeremy.

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