Received IPv6 packets return with 0 hlen

[csmall@enc.com.au (Craig Small)]

Hello,
  I've got a strange setup which is giving stranger results.

I can ping all interfaces on my firewallm however if i try to ping
thorugh a tunnel, I an unusual result

16:03:18.805776 3ffe:8001:6:10::17 > 3ffe:8001:c:ffff::2e: icmp6: echo request (len 64, hlim 64)
16:03:18.805820 150.101.196.28 > 138.25.6.14: 3ffe:8001:6:10::17 > 3ffe:8001:c:ffff::2e: icmp6: echo request (len 64, hlim 63) (DF) (ttl 64, id 0, len 124)
16:03:18.925955 138.25.6.14 > 150.101.196.28: 3ffe:8001:c:ffff::2e > 3ffe:8001:6:10::17: icmp6: echo reply (len 64, hlim 255) (DF) (ttl 239, id 0, len 124)
16:03:18.926041 bad-hlen 0

Lines 1-3 look normal:
  IPv6 ping from inside
  IPv6inIPv4 packet containing the ping
  IPv6inIPv4 packet coming back with ping reply

The line 4. bad-hlen 0

What's that? A 0 length packet?

  - Craig
-- 
Craig Small      GnuPG:1C1B D893 1418 2AF4 45EE  95CB C76C E5AC 12CA DFA5
Eye-Net Consulting http://www.enc.com.au/   MIEE         Debian developer
csmall at : enc.com.au                      ieee.org           debian.org