On Sat, Oct 27, 2001 at 12:23:02AM -0400, Michael Richardson wrote:
> 1) We wish to set something in netfilter and/or advanced routing and examine
> it in dev xmit. (for entering the tunnel)
> 2) We wish to set something in dev recv, and examine it in netfilter.
> (for checking that the packet that exited the tunnel complied to policy)
netfilter is not a layer in this definition, so ->cb is not free for your
use. It would be e.g. if you're a device driver and manage the skb in queue
or if you're TCP/IP and also manage it in your queues.
> Andi> I would recommend to use nfmark. as far as I can see you'll need
> Andi> destination cache support anyways, and it gets you that for free.
> Thanks. We'll use nfmark.
> What will you guys use? We'll need between 16 and 32 bits of nfmark :-)
For the current kernel nfmark is just an opaque value with no policy.
ipchains/tables currently expose 32bit to the administrators for firewall
purposes; if you don't want to wrestle with the admins about these bits
it may be needed to expand it to 64bit and reserve the upper 32bits for