how to use sk_buff in netfilter

how to use sk_buff in netfilter

[jywang]

Hi,all

    i want to make some change on ip packet in NF_IP_PRE_ROUTING
hook. but i don't know what is the exactly means of each piece in
struct sk_buff.

    i know how to generate a packet, but how to generate a correct
sk_buff of the packet is a difficult for me, and how to put the
sk_buff to the system is a problem too.

    How? or where to get more details of that? is there a example
program to learn?

    so great appreciation to you all.


-----------------------------------------------------
 Name:       jinyi wang
 Phone:      (86-10) 5881-2325
 Division:   R&D,Computer Network Information Center,
             Chinese Academy of Sciences
 Address:    4,4th South Street, Zhongguancun, 
             Haidian District, Beijing, China
 Zip code:   100080
 Email:      jywang@cnic.cn

Re: how to use sk_buff in netfilter

[KOVACS Krisztian]

  Hi,

On Thursday 27 October 2005 09.22, jywang wrote:
>     i want to make some change on ip packet in NF_IP_PRE_ROUTING
> hook. but i don't know what is the exactly means of each piece in
> struct sk_buff.

  http://vger.kernel.org/~davem/skb.html is a pretty good description of 
the skbs.

-- 
 Regards,
  Krisztian Kovacs

Re: how to use sk_buff in netfilter

[jywang]

 this so good a tutorial of sk_buff.

and, what is about the struct sock and other core structures?

is there something like the skb.html?

----- Original Message ----- 
From: "KOVACS Krisztian" <hidden@balabit.hu>
To: <netfilter@lists.netfilter.org>
Sent: Thursday, October 27, 2005 4:55 PM
Subject: Re: how to use sk_buff in netfilter


> 
>   Hi,
> 
> On Thursday 27 October 2005 09.22, jywang wrote:
> >     i want to make some change on ip packet in NF_IP_PRE_ROUTING
> > hook. but i don't know what is the exactly means of each piece in
> > struct sk_buff.
> 
>   http://vger.kernel.org/~davem/skb.html is a pretty good description of 
> the skbs.
> 
> -- 
>  Regards,
>   Krisztian Kovacs
> 
> 

Re: how to use sk_buff in netfilter

[Henrik Nordstrom]

On Mon, 31 Oct 2005, jywang wrote:

> this so good a tutorial of sk_buff.
>
> and, what is about the struct sock and other core structures?

most are not allowed to be used from netfilter hooks...

but many are documented in the kernel docbook documentation received with 
the kernel sources ("make doc" in the kernel tree to build them..)

Regards
Henrik

Re: how to use sk_buff in netfilter

[jywang]

when i perform the command 'make htmldocs', a error  occur as below:

Error(fs/dcache.c:687): cannot understand prototype: 'DENTRY_UNUSED_THRESHOLD 30000 '

how to fix it.





----- Original Message ----- 
From: "Henrik Nordstrom" <hno@marasystems.com>
To: "jywang" <jywang@cnic.cn>
Cc: "KOVACS Krisztian" <hidden@balabit.hu>; <netfilter@lists.netfilter.org>
Sent: Monday, October 31, 2005 3:00 PM
Subject: Re: how to use sk_buff in netfilter


> On Mon, 31 Oct 2005, jywang wrote:
> 
> > this so good a tutorial of sk_buff.
> >
> > and, what is about the struct sock and other core structures?
> 
> most are not allowed to be used from netfilter hooks...
> 
> but many are documented in the kernel docbook documentation received with 
> the kernel sources ("make doc" in the kernel tree to build them..)
> 
> Regards
> Henrik
>