gif(4) and bpf(4)

[Jeremie Le Hen]

> In a previous existence, I was able to tcpdump on a gif(4) interface;
> the tunnel was being used so that I could IPSEC-encapsulate multicast
> traffic which was necessary to get past some ISP filters (IPIP was
> being dropped at the border).
> 
> This was in 5.2.1-RELEASE on a sparc64.
> 
> Hope this helps,

Well this is a start.  But I would really like to make it work on
RELENG_4.  In fact, if bpf.h was not included in if_gif.c, I would not
mind.  But although I'm not (yet ;p) a kernel hacker, I read quickly
bpf(9) manpage and I really think the code should work.  I dread that
this is due to some back magic I can't even imagine.  That's why I
made a call here for testimonies or explanations.

Thanks.
Regards,
-- 
Jeremie Le Hen
jeremie at le-hen.org