Re: [IPsec] AD review of draft-ietf-ipsecme-ikev2-multiple-ke-06

2022-10-12 Thread Valery Smyslov
Hi Tero,

> Roman Danyliw writes:
> > ** Section 3.2.4.
> >
> > The responder MUST handle this
> >situation gracefully and delete the associated state if it does not
> >receive the next expected IKE_FOLLOWUP_KE request after some
> >reasonable period of time.
> >
> > Is there a guidance on the timeout value?
> >
> > IKEv2 traditionally does not mandate exact timeouts. For example, the
> same
> > situation happens if the initiator completes IKE_SA_INIT and never starts
> > IKE_AUTH. The responder should eventually delete the incomplete IKE SA,
> but
> > RFC 7296 does not specify how long the waiting time is.
> >
> > FWIW, our implementations waits 5 seconds by default (which is
> adjustable
> > value).
> >
> > Do you think we should recommend (but not mandate) to wait for 5-10
> seconds?
> >
> > [Roman] A recommended value would help if you are comfortable giving
> it, or
> > explaining why it’s hard to give one.  This is a common question that
> comes
> > from transport review during IETC LC or IESG review.
> 
> Suitable values can be between few seconds up to few minutes. For
> example timeout between IKE_SA_INIT and IKE_AUTH might require user
> interaction, thus it might be up to minutes if PIN code to unlock user
> auth device is required etc.
> 
> Because the timeouts are so different depending on the environment and
> usage scenario we do not give them in the IKEv2 document.

With the IKE_FOLLOWUP_KE exchange user interaction is not a problem (it should 
not take place).
However, since we are talking about PQ algorithms and some of them
may be quite costly in terms of generating a key pair, the initiator may just
be unable to provide data for the next IKE_FOLLOWUP_KE exchange quickly.

So, while I think that several minutes is too long in this case,
I agree that timeout values could be very different depending on the 
initiator's resources and on the algorithm employed. For this reason
we didn't specify it. We can give a vague recommendation
that waiting for 5-20 seconds can be appropriate in most situations,
but definitely we don't want making these values normative.

Regards,
Valery.

> --
> kivi...@iki.fi
> 
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Re: [IPsec] AD review of draft-ietf-ipsecme-ikev2-multiple-ke-06

2022-10-12 Thread Tero Kivinen
Roman Danyliw writes:
> ** Section 3.2.4. 
>
> The responder MUST handle this
>situation gracefully and delete the associated state if it does not
>receive the next expected IKE_FOLLOWUP_KE request after some
>reasonable period of time.
>
> Is there a guidance on the timeout value?
> 
> IKEv2 traditionally does not mandate exact timeouts. For example, the same
> situation happens if the initiator completes IKE_SA_INIT and never starts
> IKE_AUTH. The responder should eventually delete the incomplete IKE SA, but
> RFC 7296 does not specify how long the waiting time is.
> 
> FWIW, our implementations waits 5 seconds by default (which is adjustable
> value).
> 
> Do you think we should recommend (but not mandate) to wait for 5-10 seconds?
> 
> [Roman] A recommended value would help if you are comfortable giving it, or
> explaining why it’s hard to give one.  This is a common question that comes
> from transport review during IETC LC or IESG review.

Suitable values can be between few seconds up to few minutes. For
example timeout between IKE_SA_INIT and IKE_AUTH might require user
interaction, thus it might be up to minutes if PIN code to unlock user
auth device is required etc.

Because the timeouts are so different depending on the environment and
usage scenario we do not give them in the IKEv2 document. 
-- 
kivi...@iki.fi

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