Re: Filter out broadcast messages

[Antony Stone <Antony@Soft-Solutions.co.uk>]

On Wednesday 07 January 2004 9:44 pm, Gabby James wrote:

> Hi,
>
> I would like to filter out all broadcast messages.  The packets could come
> from 255.255.255.255 or multiple other addresses of the form 10.*.*.255.
> What kind of syntax do I use to DROP these packets?  The line below will
> filter out packets from 255.255.255.255 but I'm not sure what syntax to use
> to DROP the other adresses.

Second idea:

If you mean what you say, and the other broadcasts fit the pattern 10.*.*.255, 
you could always use the little-known but perfectly valid netmaslk 
255.0.0.255 in a rule such as:

iptables -I INPUT -s 10.0.0.255/255.0.0.255 -j DROP

This will do exactly what you asked - match packets where the source IP's 
first byte=10 and the last byte=255, with the middle two bytes being 
anything, and drop them.

Antony.

-- 
Perfection in design is achieved not when there is nothing left to add, but 
rather when there is nothing left to take away.

 - Antoine de Saint-Exupery

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