From: Jim Nelson <james4765@verizon.net>
To: chuck@gelm.net
Cc: linux-newbie@vger.kernel.org
Subject: Re: tcpdump: How do I filter 'bootp' packets?
Date: Wed, 08 Dec 2004 17:10:45 -0500 [thread overview]
Message-ID: <41B77BE5.6000001@verizon.net> (raw)
In-Reply-To: <41B6FDFC.3070309@gelm.net>
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
>
>
> (<W.X.Y.Z> == My assigned IP address)
>
> I am still seeing many 'bootp' packets.
>
> How do filter out 'bootp' packets with tcpdump?
>
> Regards, Chuck
>
> -
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next prev parent reply other threads:[~2004-12-08 22:10 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-12-08 2:26 right form for sources.list entries James Miller
2004-12-08 2:41 ` J.
2004-12-08 3:59 ` James Miller
2004-12-08 6:27 ` Ray Olszewski
2004-12-08 13:13 ` tcpdump: How do I filter 'bootp' packets? chuck gelm
2004-12-08 15:50 ` Ray Olszewski
2004-12-08 22:10 ` Jim Nelson [this message]
2004-12-08 22:56 ` chuck gelm
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