To, Netfilter Giants and Professionals,
I am a netfilter newbie, trying to analyse the system architecturally.
Sorry for answering the questions myself, Let me know if I am wrong !!!!!
QUES: What code is present architecturally in net/ipv4/netfilter
directory and what code is present architecturally in net/netfilter
directory ?
Kernel 2.6.34 --> ubuntu Linux 10.04
net/ipv4/netfilter --> This code contains connection
trackers, NAT helpers and
kernel part for rule targets.
net/netfilter --> This code contains conntrack helpers and
main conntrack system and
conntrack subsystem.
QUES: Why do we use terms layer 5 connection trackers and layer 3
connection trackers whereas connection is maintained only
at layer 4 ?
Finally after studying the code I got what I wanted.
Layer 3 connection trackers are just for ipaddress tuple
entries and are practically
useless if there is no layer 4 connection tracker with it.
i.e we can say layer3 conection trackers are entry point
into the conntrack system as
they are not dependent on incoming and outgoing interfaces.
Layer 5 connection trackers are nothing but merely helpers
like FTP data port
connection and which tells whether a particular connection
is related to the
main connection or not.
Layer 4 connection trackers functioning shows us the actual
entries in the conntrack
table/tuple doubly linked list or in proc/net/nf_conntrack entries.
Finally the connection is registered at the exit from POST
ROUTING HOOK.
Thanks,
A newbie into the world of firewall security mechanism.
On Mon, Jun 21, 2010 at 1:13 PM, Ninad Adi <adi.ninad@xxxxxxxxx> wrote:
> QUES: What code is present architecturally in net/ipv4/netfilter
> directory and what code is present architecturally in net/netfilter
> directory ?
>
> QUES: Why do we use terms layer 5 connection trackers and layer 3
> connection trackers whereas connection is maintained only
> at layer 4 ?
>
>
>
> Ninad.
>
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