>Some comments on an exercise this afternoon to do this:
>1. Adding pfil struct reference to protosw.  It seems best to do this
>   without it being conditional on PFIL_HOOKS so that user programs pick
>   don't need to screw with this option.  A side effect of this is that
>   adding a "#include <net/pfil.h>" to the top of <sys/protosw.h> was the
>   quick way to avoid touching many files where <sys/protosw.h> is used
>   already.
>2. New struct created in pfil.h which contains two tailq heads and an
>   init variable - pfil_init_done has been removed: an init must be done
>   per pfil struct for each protosw.  Considering this, I'd like to be
>   able to do some sort of pfil_init() in ip_init() when inetsw and
>   ip_protox[] are initialized.

	I'm still not sure what will be the relationship with "additional
	per-protocol data" and filtering engine/filter command parser.
	Could you please let me know more?

>3. ip_protox[] was moved from ip_input.c to in_proto.c and an extern for it
>   added to <sys/protosw.h> and removed from where it was present in .c
>   files.
>4. An extern for inetsw was added to <sys/protosw.h> and removed from where
>   it was present in .c files.

	please notice that sys/netinet6 uses sys/netinet6/ip6protosw.h.

itojun