Subject: RE: Allocating a bit in the RFC2374 Interface Identifier

From: "Mohan Parthasarathy" <[email-masked]>
Date: Thu, 21 Mar 2002 13:06:00 -0800

> 
> 
> Mohan Parthasarathy wrote:
> 
> > t very clear as to why you have to reserve a bit in the address to 
> > express different security mechanisms being used. Why can't this be 
> > built into the protocol itself ? Is it because that the future 
> > security mechanisms will not use the same set of message 
> exchanges as 
> > RR and hence you want a protocol independent way of indicating the 
> > method ? I would assume that any mechanism to establish the binding 
> > between home address and care of address  would have a few message 
> > exchanges. Can you
> 
> Because the MitM attacker can change everything related to 
> these messages, it doesn't help to put anything to the 
> messages for the bidding down protection.
> 
> Note that the MitM can also change the IP address, but if he 
> does so, he is *not* attacking the original host, as the 
> address is changed.
> 
Ok. This is not very obvious (at least to me). It would be useful
to put this in some document.

Is it possible that the MN can use both the RR and secure (that is
to be defined in the future) mechanism under different occasions ?
This means MN should be able to recognise both the addresses. 
If MN sets the bit (means do something more secure than RR) and
attacker clears the bit, the response will still come back and
the assumption is MN will be able to detect this. Similarly, when
the bit is cleared but set by the attacker. I did not see a good
analysis on this (though I saw some references in Pekka's and your
other document). Perhaps missed it..

Sorry if this discussion should be happening in mobile-ip working
group. But I guess we are evaluating the motivation for reserving
the bits. So, I guess it is okay.

thanks
mohan

> Jari

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From: Jari Arkko <[email-masked]>
Date: Fri, 22 Mar 2002 00:07:29 +0200

> other document). Perhaps missed it..

If a node wants to allow both RR and another more secure
method, it can do so simply by allowing it on its RR address.

Jari

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From: Jari Arkko <[email-masked]>
Date: Fri, 22 Mar 2002 00:07:29 +0200

Jari