help with conntrack

help with conntrack

[Miguel Alejandro González]

Hello

I'm making a netfilter module and I need to have interaction with
conntrack, as I understand conntrack is a hash table of all connections
IPv4 and IPv6. I basically need to know how to do lookups, insertions an
deletions, can you tell me how do this? If you can give me some
documentation or code to see how conntrack works and how to achieve what I
need to do, that would be great

Regards,
thanks in advance!

Re: help with conntrack

[Andrew Beverley]

On Tue, 2012-09-11 at 23:08 -0500, Miguel Alejandro González wrote:
> Hello
> 
> I'm making a netfilter module and I need to have interaction with
> conntrack, as I understand conntrack is a hash table of all connections
> IPv4 and IPv6. I basically need to know how to do lookups, insertions an
> deletions, can you tell me how do this? If you can give me some
> documentation or code to see how conntrack works and how to achieve what I
> need to do, that would be great

The "Writing Netfilter Modules" should help you (see part II):
http://inai.de/documents/Netfilter_Modules.pdf

Of course, there's also libnetfilter_conntrack which includes some good
examples, although it's a userspace library.

Andy


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Re: help with conntrack

[Pablo Neira Ayuso]

On Wed, Sep 12, 2012 at 08:27:30PM +0100, Andrew Beverley wrote:
> On Tue, 2012-09-11 at 23:08 -0500, Miguel Alejandro González wrote:
> > Hello
> > 
> > I'm making a netfilter module and I need to have interaction with
> > conntrack, as I understand conntrack is a hash table of all connections
> > IPv4 and IPv6. I basically need to know how to do lookups, insertions an
> > deletions, can you tell me how do this? If you can give me some
> > documentation or code to see how conntrack works and how to achieve what I
> > need to do, that would be great
>
> The "Writing Netfilter Modules" should help you (see part II):
> http://inai.de/documents/Netfilter_Modules.pdf
> 
> Of course, there's also libnetfilter_conntrack which includes some good
> examples, although it's a userspace library.

This should also help to get an overall idea on how is implemented:

http://1984.lsi.us.es/~pablo/docs/login06.pdf

But you'll have to get ready to read Linux kernel code.

Start with net/netfilter/nf_conntrack_core.c

Good luck!
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