From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jim Nelson Subject: Re: tcpdump: How do I filter 'bootp' packets? Date: Wed, 08 Dec 2004 17:10:45 -0500 Message-ID: <41B77BE5.6000001@verizon.net> References: <5.1.0.14.1.20041207220544.01f98370@celine> <41B6FDFC.3070309@gelm.net> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <41B6FDFC.3070309@gelm.net> Sender: linux-newbie-owner@vger.kernel.org List-Id: Content-Type: text/plain; charset="us-ascii"; format="flowed" To: chuck@gelm.net Cc: linux-newbie@vger.kernel.org chuck gelm wrote: > Howdy: > > I have cable modem access to the internet now and the download speed is > double my original DSL speed. :-) However, I am concerned about > security. > > Can other cable modem subscribers see my packets? > IIRC, most modern cable modems filter anything not addressed to them - you'd have to hack your modem to get it to go into promiscuous mode. It's not easy to do, and it relies on brain-dead network admins to leave some back doors in. OTOH, you could probably find hardware to do just this - if you were in law enforcement. > To test this, I am trying to use tcpdump to monitor packets that my > cable modem is sending to my 'router'. > > I am using these arguments: > tcpdump -i eth1 -c 9 -nt not arp and not host W.X.Y.Z > \ > http://gelm.net/tcpdump.txt > > > ( == My assigned IP address) > > I am still seeing many 'bootp' packets. > > How do filter out 'bootp' packets with tcpdump? > > Regards, Chuck > > - > To unsubscribe from this list: send the line "unsubscribe linux-newbie" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.linux-learn.org/faqs > - To unsubscribe from this list: send the line "unsubscribe linux-newbie" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.linux-learn.org/faqs