bpf packet capture and SOCK_STREAM socket redirects...

Alireza Torabi alireza.torabi at gmail.com
Thu Mar 20 04:27:54 PDT 2008

Imagine this:

           | (1)
           |                     | (4)
        [nic1]             [nic2]
         bpf             SOCK_STREAM
          |  (2)                |
              [FreeBSD] (3)

1) all user traffic are being monitored
2) bpf on [nic] is capturing these packets
3) after processing we know a connection is about to be established from A to B

4) I want to deliver this packet to the socket on [nic2]
and as this is a tcp socket it'll take care of it from there
(my code here for this sockets sends and arbitary data to A making it
think it came from B)

hope this helps.

On 3/20/08, Vadim Goncharov <vadim_nuclight at mail.ru> wrote:
> Hi Alireza Torabi!
> On Thu, 20 Mar 2008 10:57:39 +0000; Alireza Torabi wrote about 'Re: bpf packet capture and SOCK_STREAM socket redirects...':
> > That's sort of the problem. I've got a data link capture of the packet
> > (bpf) and let say I redirect this packet to a  SOCK_STREAM on another
> > machine and the whole thing will work fine (OK after rewritting some
> > mac and ip and checksums...).
> > I just need to do this on the SOCK_STREAM of the same machine. If I
> > try to put it in another way:
> > Is it possible to do a bpf write of a packet that can be seen by the
> > interface the bpf is bound to?
> AFAIK, no.
> > This means that the interface does it's normal work and the packet
> > will be deliverd to SOCK_STREAM bound to it.
> What exactly is your task? May be it is worth consider some other ways if
> additional details are known.
> --
> WBR, Vadim Goncharov. ICQ#166852181       mailto:vadim_nuclight at mail.ru
> [Moderator of RU.ANTI-ECOLOGY][FreeBSD][http://antigreen.org][LJ:/nuclight]
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