Re: firewall + tcpdump

[Peggy Kam <ppkam@xxxxxxxxx>]

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.
>
>  
>
> > If it dumps traffic in front of a firewall, would anyone kindly suggest
> > a way to test the firewall?
> >    
>
> 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.
>
>
>