Fwd: Re: [ipv6hackers] funny FreeBSD bug

[Bjoern A. Zeeb]

On Thu, 26 Jul 2012, Doug Barton wrote:

> FYI, this conversation is happening in the list below. I have no opinion
> regarding whether it is a bug or not, but I thought folks here might be
> interested.
>

You can point the people at both the RFC and the SA we have issues a
couple of years ago and why it's always 4 or 8 bytes below the minimal
MTU.  It's all good.


>
>
> -------- Original Message --------
> Subject: Re: [ipv6hackers] funny FreeBSD bug
> Date: Thu, 26 Jul 2012 19:26:08 +0200
> From: Marc Heuse <mh at mh-sec.de>
> Reply-To: IPv6 Hackers Mailing List <ipv6hackers at lists.si6networks.com>
> To: IPv6 Hackers Mailing List <ipv6hackers at lists.si6networks.com>,
> Simon Perreault <simon.perreault at viagenie.ca>
>
> Hi Simon,
>
> Am 26.07.2012 17:47, schrieb Simon Perreault:
>> Le 2012-07-26 08:35, Marc Heuse a écrit :
>>> I found a funny bug in freebsd (9.0 with all updates):
>>> if you send an ICMP toobig message to it with a too low MTU size,
>>> FreeBSD will prepend any packet data with an one-shot fragment (or
>>> atomic fragment as Fernando calls it).
>>
>> Why do you think it's a bug?
>
> first it servs no use to add the fragmentation header if the packet is
> not fragmented. second I have not seen this behaviour in other OS,
> however I havent looked for it though.
>
>> Seems like normal IPv6 behaviour to me. It's in the RFC...
> I cant remember having seen this in any rfc - do you have a pointer?
>
> Greets,
> Marc
>
> --
> Marc Heuse
> www.mh-sec.de
>
> PGP: FEDD 5B50 C087 F8DF 5CB9  876F 7FDD E533 BF4F 891A
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-- 
Bjoern A. Zeeb                                 You have to have visions!
          Stop bit received. Insert coin for new address family.