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NIST and SP800-119




On Tue, 15 Feb 2011, Steven Bellovin wrote:

>
> On Feb 15, 2011, at 10:36 54AM, William Herrin wrote:
>
>> On Tue, Feb 15, 2011 at 10:09 AM, Joe Abley <jabley at hopcount.ca> wrote:
>>> On 2011-02-14, at 21:41, William Herrin wrote:
>>>> On Mon, Feb 14, 2011 at 7:24 PM, TR Shaw <tshaw at oitc.com> wrote:
>>>>> Just wondering what this community thinks of NIST in
>>>>> general and their SP800-119 (
>>>>> http://csrc.nist.gov/publications/nistpubs/800-119/sp800-119.pdf )
>>>>> writeup about IPv6 in particular.
>>>>
>>>> Well, according to this document IPv4 path MTU discovery is,
>>>> "optional, not widely used."
>>>
>>> Optional seems right. Have there been any recent studies on how widely pMTUd is actually used in v4?
>>
>> Hi Joe,
>>
>> Are you aware of a TCP implementation in an OS that shipped within the
>> last decade but doesn't enable IPv4 pMTUd by default? Each version of
>> Windows and all the major unixes use it on every TCP connection unless
>> you explicitly turn it off.
>>
> All modern TCPs support it; many firewalls are configured to block the necessary ICMPs.

Then probably blackholing themselves the firewall operators....
Best Regards,
 		Janos Mohacsi