Re: Received IPv6 packets return with 0 hlen

[Jochen Friedrich <jochen@scram.de>]

Hi Craig,

> 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

Just some wild guesses:

- you use tcpdump to display the packages
- your firewall rejects the tunnel packets with ICMP protocol unreachable

1. echo request on sit0 interface
2. outgoing packet on eth0
3. incoming packet on eth0
4. outgoing ICMP on eth0

As the ICMP packet contains part of the tunneled packet, apparently
tcpdump tries to decode this part and fails miserably...

Could you run tethereal -V and repeat the test? That should give much more
information on the 4 packets in question.

--jochen