addition to ipfw..

[Max Laier]

On Monday 11 December 2006 23:58, Julian Elischer wrote:
> Andre Oppermann wrote:
> > Julian Elischer wrote:
> >> in ipfw layer 2 processing, the packet is passed to the firewall
> >> as if it was a layer 3 IP packet but the ether header is also made
> >> available.
> >>
> >> I would like  to add something similar in the case where a vlan tag
> >> is also on the packet..
> >>
> >> basically I have a change where:
> >>
> >> If we are processing layer 2 packets (in ether or bridge code)
> >> AND a sysctl says to do it,
> >> and it is a vlan packet,
> >>
> >> Then the vlan header is also held back so that the packet can be
> >> processed and examined as an IP packet. It is
> >> (in the same way the ether header is) reattached when the packet is
> >> accepted.
> >>
> >> This allows me to filter packets that are traversing my bridge,
> >> even though they are encapsulated in a vlan.
> >>
> >> I have patches to allow this. I need this function. does anyone
> >> else?
> >
> > Please have the ipfw code examine the vlan tag in the mbuf instead of
> > fiddling with the mbuf contents.
>
> The ipfw will be ignoring the vlan contents.. the patch is to move the
> 'start of ip header' pointer past the vlan header.. (if asked) so that
> it can identifu the IP packet.
>
> part of the patch is to make sure all the code uses this pointer
> instead of the case now where some code uses it and some uses mtod().
>
> This could be used in conjunction with vlan keyword that would look at
> the vlan header, but that is a different feature..

I understand you do have a patch?  Let's see it, so we are clear what we 
are talking about.  I think that w/o a ipfw feature to identify the vlan 
number, it is pretty useless.  Of course, it would enable you to do some 
basic sanity checks, but real filtering needs to know the vlan it is 
concerned with.  BTW, what speaks against plugging the bridge into the 
vlan on either side and bridge the vlan interfaces together?

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