Re: [tcpm] tcpsecure: how strong to recommend?

Joe Touch <touch@ISI.EDU> Tue, 25 September 2007 21:50 UTC

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Date: Tue, 25 Sep 2007 14:47:51 -0700
From: Joe Touch <touch@ISI.EDU>
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To: "Anantha Ramaiah (ananth)" <ananth@cisco.com>
Subject: Re: [tcpm] tcpsecure: how strong to recommend?
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Anantha Ramaiah (ananth) wrote:
>>
>> Hat off ... 
>>
>> This is a lot of hang wringing mumbo-jumbo, I think.  It 
>> seems to me ...
>>
>>   + If a standards track document says "a TCP SHOULD do X" then as a
>>     particular TCP evolves it really ought to do X unless the
>>     implementers have a very good reason not to do X.
> 
> Since, all these discussions about started due to TCP secure, let me use
> the same as an example. There is nothing wrong in making all mitigations
> SHOULD since the "very good reason" can be one of :-

... I'll number these for references:

#1
> - I don't care about security/robustness of TCP connections and hence my
> products don't need to implement these.
#2
> - well I do care about security but I always use additional protection
> like MD5 or IPsec and hence implementing this is optional. I'll think
> about it.
#3
> - I like the mitigations in the draft and I see them lightweight and
> I'll go ahead and implement them, but since these are tagged SHOULD I
> may have a knob to control this behaviour.
#4
> - I definetely would want to implement these. Even though it is a
> SHOULD, to me it is like a MUST.
> 
> So what I am tryng to say is: it is upto the implementers to interpret
> and implement it if they wish to do so. Saying SHOULD is not an issue
> since it gives enough leeway for all of the above scenarios.

I don't think SHOULD covers #1 very well above, and it arguably doesn't
voer case 2 either. SHOULD really intends to mean "MUST unless you know
you know a specific reason that would be undesirable".

That's why I think some of us (myself included) prefer MAY for all (with
the caveat that there can be MAY for the whole set, and the additional
relative requirements, i.e., If you do A, you MUST do B.)

Joe

> 
> But I am open to the idea of adding a generic applicability statement
> like : "these mitigations are useful in blah blah... Conditions etc., "
> Already if I remember correctly we do have some text to that effect in
> the draft, but we can polish it further or formalize it.
> 
> -Anantha
> 
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