Subject: Re: [MOBILE-IP] Challenge/Response

From: Kory Keith <[email-masked]>
Date: Mon, 18 Dec 2000 08:28:55 -0800

I understand section 3.2 to say that the FA needs to
store (CHALLENGE_WINDOW + 1) challenges to protect
against unknown challenges, but it does not define how
many to store to protect against STALE_CHALLENGE (sec.
3.2 previous paragraph).

Kory Keith

> Section 3.2
> "The Foreign Agent MUST NOT accept any Challenge in
> the Registration
>    Request unless it was offered in last successful
> Registration Reply
>    issued to the Mobile Node, or else advertised as
> one of the last
>    CHALLENGE_WINDOW (see section 9) Challenge values
> inserted into the
>    immediately preceding Agent advertisements."

> 2) Say that a foreign agent allow for a Challenge
> window of 3, i.e. it will
> allow registrations to pass which contain one of the
> last three challenges
> that were sent out from the foreign agent. That
> means that the foreign agent
> need to save the last three challenges it sent on
> that interface. It also
> need to store the challenge it receives in
> registration request in order to
> prevent a mobile to use the same challenge twice.
> This means at least
> one/mobile that tries to register. If the foreign
> agent also chose to send a
> Challenge in the registration reply to a mobile, it
> has to store one extra
> Challenge / mobile it sends a reg reply to. Is it
> reasonable that a foreign
> agent should store and process that many challenges?
>
> /Fredrik
>
----------------------------------------------------------------------------
> -------
> Fredrik Johansson                    W: +46 (0)8 725
> 5916
> Interactive People Unplugged     M: +46 (0)709 684
> 376
> mailto:[email-masked]
> http://www.ipunplugged.com

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