Re: Packet capturing, iptables and eth0 vs. dummy0

[DervishD <lkml@dervishd.net>]

    Hi Harald :)

 * Harald Welte <laforge@gnumonks.org> dixit:
> On Wed, Nov 17, 2004 at 09:30:33PM +0100, DervishD wrote:
> please send netfilter/iptables related questions to the respective
> lists:
> 	netfilter@lists.netfilter.org (for user questions)
> 	netfilter-devel@lists.netfilter.org (for development issues)

    This time the iptables issue was just... collateral, so to say.
The problem was with tcpdump since I knew that packets were being
filtered.
 
> >     I've noticed that, no matter what filtering is iptables doing,
> > tcpdump gets all packets from interface eth0 as seen in the bus, 
> This is correct.  iptables is a IPv4 packet filter.  It is part of the
> IPv4 stack.  tcpdump uses PF_PACKET which attaches right above the
> NIC driver, therefore you capture packets way before they enter the IPv4
> stack.

    OK, I didn't see the problem from that perspective. Anyway, using
'lo' instead of 'dummy' solved the problem :)

    Thanks for the help :)

    Raúl Núñez de Arenas Coronado

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