IPFW questions (log fragments, ipfw show)

[Beat Siegenthaler]

Hi,

i cannot find info about following two points, maybe somebody can shed a
light on that:

ipfw show:
63000     56    28136 Wed May  2 22:51:43 2018 allow udp from any to me6
53,123 recv gif0 keep-state :default

what says ":default" at the end? Only on rules with keep-alive. I do not
remember to see this some months ago.

ipfw logging:

May  2 22:48:36 myhost kernel: ipfw: 65100 Deny UDP [2001:470:1a::1]
[2001:xxxx:xxxx:xxxx::x] in via gif0 (frag ab0a815c:966 at 9856)
May  2 22:48:36 myhost kernel: ipfw: 65100 Deny UDP [2001:470:1a::1]
[2001:xxxx:xxxx:xxxx::x] in via gif0 (frag d52823ef:978 at 9856)
May  2 22:48:37 myhost kernel: ipfw: 65100 Deny UDP [2001:500:48::1]
[2001:xxxx:xxxx:xxxx::x] in via gif0 (frag dad5be95:361 at 9856)
May  2 22:48:38 myhost kernel: ipfw: 65100 Deny UDP [2001:5a0:10::1]
[2001:xxxx:xxxx:xxxx::x] in via gif0 (frag e9d303a0:659 at 9856)
May  2 22:48:38 myhost kernel: ipfw: 65100 Deny UDP [2001:5a0:10::1]
[2001:xxxx:xxxx:xxxx::x] in via gif0 (frag d35fff84:647 at 9856)

what encodes frag info? (frag d35fff84:647 at 9856)

thanks