Max Laier wrote:
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?
The ability to look inside a vlan is separate from the ability
to select ON the vlan. This is for a device that wants to
appear as a bump on the wire. It just wants to filter out
packets that have some characteristics..
If you can select on a vlan with another command (e.g. a skipto)
then the two are orthogonal.
I don't know ahead of time what vlans are in use across the trunk I'm
filtering and there may be many.. So making a separate vlan interface
for each vlan that I find (what all 4096 of them?) and filtering
that separatly is not feasible.
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