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Network Security Firewalls
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Re: OSI Packet Filter

Subject: Re: OSI Packet Filter
Date: Sat, 27 Nov 2004 11:39:27 +0100
Le vendredi 26 novembre 2004 à 00:09 -0200, Anderson|RootSec-Labs| a
écrit :
I wanna known, what layer of OSI Model packet filtering Works ?

My 0,02€.
Afaik, they work at :

        . network, typically IP
        . transport, typically TCP, UDP, ICMP
        . session, when dealing with stuff like FTP, H323, etc.

Encapsulations are dealt reinjection encapsulated data in the correct
layer. So can filter regarding some layer 2 (link) informations such as
source MAC address (see Netfilter). Some have layer 2 filtering (MAC src
and dst, layer 3 proto, etc.), especially when operating in bridged
mode, but that's frame filtering, more than packet filtering.

Some firewalls are providing "application filtering", but it is still
correct to call this "packet filtering" ? I don't think so.


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