From mboxrd@z Thu Jan 1 00:00:00 1970 From: Antony Stone Subject: Re: Filter out broadcast messages Date: Wed, 7 Jan 2004 22:05:29 +0000 Sender: netfilter-admin@lists.netfilter.org Message-ID: <200401072205.29859.Antony@Soft-Solutions.co.uk> References: Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: Errors-To: netfilter-admin@lists.netfilter.org List-Help: List-Post: List-Subscribe: , List-Id: List-Unsubscribe: , List-Archive: Content-Type: text/plain; charset="us-ascii" To: netfilter@lists.netfilter.org 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 Please reply to the list; please don't CC me.