Re: firewall + tcpdump

[Peggy Kam <ppkam@n-dsi.com>]

As you have said that all traffic hitting the interface is seen whether 
netfilter allows it or not, my question was how do I know whether the 
packets being sent get blocked?

>Not sure quite what you by "in front or behind", however I can tell you that 
>tcpdump works "closer to the wire" than netfilter, so it will see all traffic 
>hitting the interface, whether netfilter allows it or not.
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>>If it dumps traffic in front of a firewall, would anyone kindly suggest
>>a way to test the firewall?
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>Um, test it by sending packets which should be allowed, and making sure they 
>are, then sending ones which should be blocked, and making sure they are?
>
>Or have I misunderstood the question?   How would you propose to use tcpdump 
>to test the firewall anyway?
>
>Regards,
>
>Antony.
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