[ipv6hackers] funny FreeBSD bug

Marc Heuse mh at mh-sec.de
Thu Jul 26 19:26:08 CEST 2012

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?


Marc Heuse

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