GRE and BPF

[Michael Sierchio]

On Wed, May 22, 2013 at 8:39 AM, Brian Hechinger <wonko at 4amlunch.net> wrote:

> Hello all,
>
> I've been having some trouble with a GRE tunnel. Specifically with
> non-IP traffic (DECnet, in this case) and BPF.
>
> I can see the GRE packets containing the DECnet packets coming over the
> physical interface but when I do a tcpdump of bge0 I never see them.
>
> This is an issue because the program I want to use will be using pcap to
> pull packets off of the bge0 interface.
>
> I can get IP packets off of the bge0 interface with tcpdump, however.
>
> Is this just never going to work or am I missing something here?
>
>
What does ifconfig report for the MTU of the gre interface?  Does it match
the Cisco?  Is grekey set?

Do you have a route to the network that is encapsulated on the other side?

is net.inet.ip.forwarding set to 1?

- M