Question about Netgraph (I'm in a mess :)

[Juan Rodriguez Hervella]

On Wednesday 26 November 2003 13:24, Gerasimos Dimitriadis wrote:
> Hi,
>
> I believe that the best approach would be to divert all the traffic from/to
> the interface you are interested. Connect
> the 'upper' and 'lower' hooks of the corresponding ng_ether node to a node
> that implements the functionality you want. By checking the 'type' value in
> the ethernet header you can find when you are dealing with IP packets,
> while letting all the others simply pass through.

Ok, but there's something I still don't understand about the ng_ether node.
If I wan't to get the packets sent by the host to the outside world, I should
connect my node to "upper", right ? then I would modify the IP header, and
I would send the packet to the "lower" hook, is this ok ?

Now I'm thinking about the ethernet hearders...if I get the packet from the 
"upper" hook and I modify the destination IP address, it will be wrong to
write the ethernet frame on the "lower" hook because the ethernet destination
addr. would be likely to be different... is this right ?

Thanks for you help.


>
> Gerasimos
>
> ----- Original Message -----
> From: "Juan Rodriguez Hervella" <jrh at it.uc3m.es>
> To: <freebsd-net at freebsd.org>
> Sent: Wednesday, November 26, 2003 1:53 PM
> Subject: Question about Netgraph (I'm in a mess :)
>
> > Hello,
> >
> > I'd like to make some modifications to the IPv6 hearder of some packets
> > before sending them out the interface. I'm thinking where's the best
> > way of doing this. So, I've found out the Netgraph tool (I didn't know it
> > before :) but now I'm wondering how to use it properly.
> >
> > As far as I understand, I could have a "ng_iface" node which would
> > have a "ipv6" hook to my new node, which would change the IPv6
> > packet.... I would grab the packets installing a new route towards the
> > "ng_iface" node, right ? Then, if I want to insert the modified packet
> > to send it out the interface, I should connect my new node to the
> > "ng_ether" node ? or again sending out the packet through the same
> > "ng_iface" node ?
> >
> > I'm a bit mix up with all this stuff, any help will be very appreciated.
> >
> > --
> > ******
> > JFRH
> > ******
> >
> > With every passing hour our solar system comes forty-three thousand
> > miles closer to globular cluster M13 in the constellation Hercules, and
> > still there are some misfits who continue to insist that there is no
> > such thing as progress.
> > -- Ransom K. Ferm
> >
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-- 
******
JFRH
******

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