[CFT] ng_nptv6 (IPv6-to-IPv6 Network Prefix Translation)

Hi, all

I have created a netgraph node which performs a IPv6-to-IPv6 Network  
Prefix Translation(RFC6296).
It works with ipfw(ng_ipfw). a sample configuration is follows.

1 setup netgraph
    ngctl mkpeer ipfw: nptv6 1000 inbound
    ngctl name ipfw:1000 nptv6
    ngctl connect ipfw: nptv6: 2000 outbound
    ngctl  msg nptv6: setconfig { inner=fd00:1234:1234::/48  
outer=2001:db8::/32 }
   or use rcng script(ng_nptv6.sh) which is included in archive.
2 setup ipfw
   # inbound
   ipfw 1000 allow ip6 from any to 2001:db8::/64 in
   ipfw 1010 netgraph 1000 ip6 from any to 2001:db8::/32 in
   ipfw 1090 allow ip6 from any to any in
   # outbound
   ipfw 2000 allow ip6 from 2001:db8::/64 to any out
   ipfw 2010 netgraph 2000 ip6 from 2001:db8::/32 to any out
   ipfw 2090 allow ip6 from any to any in

You can download from
http://hp.vector.co.jp/authors/VA052357/ng_nptv6-0.0.tar.xz

Comments and tests results are welcome!
-- 
HIROSHI OOTA