Re: [TLS] Ignoring unrecognized extensions

[Matt McCutchen <[e-mail]>]

On Tue, 2010-06-22 at 21:09 +0200, Martin Rex wrote:
> Matt McCutchen wrote:
> > 
> > I think it is the intent of RFC 5246 that a TLS server, in addition to
> > tolerating an "extensions" field in the ClientHello that is nonempty as
> > a whole, MUST ignore individual extensions that it does not recognize.
> > However, I cannot find this stated anywhere in RFC 5246.  Am I missing
> > something?  Would this be worthy of an erratum?
> 
> My copy of rfc-5746, section 3.6 says this in the second last paragraph:
> 
> http://tools.ietf.org/html/rfc5746#section-3.6
> 
>    TLS servers implementing this specification MUST ignore any unknown
>    extensions offered by the client and they MUST accept version numbers
>    higher than their highest version number and negotiate the highest
>    common version.  These two requirements reiterate preexisting
>    requirements in RFC 5246 and are merely stated here in the interest
>    of forward compatibility.

I saw that.  My point is that I can't find the preexisting requirements
in RFC 5246 that are being reiterated.

-- 
Matt