Looking for small Confirmation about skb_pull & NF_ACCEPT !!!

[SaNtosh kuLkarni]

are u doin some sort of tunneling ?

On Fri, Apr 6, 2012 at 6:03 AM, Sri Ram Vemulpali
<sri.ram.gmu06 at gmail.com>wrote:

> Whenever you manipulate the packet before PRE_ROUTING point in the
> stack, the kernel will decide whether to route the packet to LOCAL or
> FORWARD. If you have pointer pointing to right IP header kernel will
> use it to route. You really do not have to write routing code.
>
> Also, when you say inner and outer header what do you mean by it. I
> did not encounter this.
>
> Thanks,
> Sri.
>
> On Thu, Apr 5, 2012 at 5:00 AM, SaNtosh kuLkarni
> <santosh.yesoptus at gmail.com> wrote:
> > i had a similar problem where in i was using SKB_PUSH to add extra
> > header,,,, i used this... structure called flowi.... which can be used to
> > define a sort of traffic class...based on some combination of fields
> >
> >
> > iph->daddr =htonl(xxxxxx);
> > {
> > struct rtable *rt;
> > struct flowi fl;
> > memset(&fl, 0x0, sizeof(struct flowi));
> > fl.fl4_dst  = htonl(xxxxxxx);
> > fl.proto = IPPROTO_TCP;
> > if (!ip_route_output_key(&init_net, &rt, &fl))
> > {
> > iph->saddr= htonl(ntohl(rt->rt_src));
> >
> > skb_dst_set(skb2, &rt->u.dst);
> >
> > }
> >
> > }
> >
> >
> > On Mon, Apr 2, 2012 at 2:12 PM, Kesava Srinivas <vunnavafuture at gmail.com
> >
> > wrote:
> >>
> >> HI Friends,
> >> Looking for a Confirmation on my analysis.
> >>
> >> Once after Capturing the Socket Buffer in PRE_ROUTING Hook; Manipulated
> >> the Socket Buffer by using the "skb_pull" Kernel Function. Using
> skb_pull;
> >> stripped 28 bytes (IP+UDP) which are the Part of outer UDP/IP Header.
> Now;
> >> My intention was to route the skb based on the Inner IP Header which is
> >> sitting after stripping 28 bytes. At the END; returned NF_ACCEPT.
> >>
> >> Even though; skb_pull worked Fine., Kernel's Stack is still looking in
> to
> >> Outer Header only for Routing the Packet.I expected ;Kernel will look
> the
> >> Inner Header (As data Pointer was incremented by 28 bytes via skb_pull)
> and
> >> Take decision based on the Inner one. But; that didn't  happened. It
> looks
> >> to me like; we need to always use NF_STOLEN & should write our own code
> to
> >> route based on the INNER HEADER. Was my conclusion correct ??
> >>
> >> -Thanks in Advance,
> >> VKS
> >>
> >>
> >>
> >> _______________________________________________
> >> Kernelnewbies mailing list
> >> Kernelnewbies at kernelnewbies.org
> >> http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
> >>
> >
> >
> > _______________________________________________
> > Kernelnewbies mailing list
> > Kernelnewbies at kernelnewbies.org
> > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
> >
>
>
>
> --
> Regards,
> Sri.
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.kernelnewbies.org/pipermail/kernelnewbies/attachments/20120406/0b40cac7/attachment.html