Subject: [AAA-WG]: [ISSUE] key lifetime

From: Sivasundar Ramamurthy <[email-masked]>
Date: Wed, 10 Apr 2002 14:59:30 -0700 (PDT)

Submitter Name:                 Siva Ramamurthy
Submitter email address:        [email-masked]
Date first submitter:           3/27/2002
Document:                       Mobile IP
Comment Type:                   T
Priority:                       1
Section:                        1.6, 5.1, 6.13

Rationale/Explanation of Issue:

Please bear with me for bringing this up again, for I dont want to
regret later that I did not!

As I understand the draft, session Termination at the mobility agents
can be caused by two events:

1. MN not re-authorizing before the auth lifetime expires

2. Keys to the MN expiring

Consider the scenario where the a MN is given keys for infite time (or
a value many time bigger that the authentication time) and an
authentication time of 300 secs. And during the course of roaming
around, the MN at some point is not able to re-authenticate itself (no
FA/co-located COA). This leads to termination of the session at the HA
and any sessions maintained for this MN by FA(s). Sometime later, the
MN does find that its way back to a previously visited FA and is able
to register without the need for requesting keys (which are still
alive). Since the MN does not include the MN-AAA auth ext, AAA cannot
be used and thus no new session can be created for the MN. So the FA
and HA provide services to the MN even while no session exists.

I find nothing in the current standards that say that this is wrong or
not permissible, which probably means that there is nothing special to
handling this scenario and/or the standards provide the answers on
what to do. Can the WG please verify this? Thanks for the
consideration.

regards,

Siva

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From: Joe Lau <[email-masked]>
Date: Wed, 10 Apr 2002 15:34:39 -0700 (PDT)

Another point that I would like to bring to the table...

The situation described here has deep implications on accounting which
relies on having a live AAA session associated with the MN.

Joe Lau

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From: "Fredrik Johansson" <[email-masked]>
Date: Fri, 12 Apr 2002 06:50:06 +0200

Siva,

this is just poor configuration, if an administrator gives someone infinite
lifetime on the session keys, it's bad configuration, and nothing that the
protocol itself can do to prevent.

/Fredrik
>-----Original Message-----
>From: [email-masked] [mailto:[email-masked]]On Behalf Of
>Sivasundar Ramamurthy
>Sent: den 11 april 2002 00:00
>To: AAA Working Group
>Subject: [AAA-WG]: [ISSUE] key lifetime
>
>
>
>

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From: Sivasundar Ramamurthy <[email-masked]>
Date: Fri, 12 Apr 2002 10:05:44 -0700 (PDT)

Fredrick,

> protocol itself can do to prevent.

the example I gave you was mainly to convey this:

We can run into scenarios when the MN can use AAA distributed keys (to
the FA and the HA) and register even while the FA and HA cannot create
seesions and account for this usage (as Joe pointed out). When the 
keys do expire, a new session can be created and usage can be
accounted for. But the services provided prior to that cannot be
accounted for. Dont we need to avoid this? 

thanks,

Siva

> >what to do. Can the WG please verify this? Thanks for the

Thanks,

Siva

====================================
Sivasundar Ramamurthy		
(She-va-su-ndar Ra-ma-moor-thee)

Engineer, Mobile IP Project
Hewlett Packard
(408) 447 7255
====================================

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From: Tony Johansson <[email-masked]>
Date: Fri, 12 Apr 2002 10:23:40 -0700

Siva,

IMHO, this is more of deployment issues. We cannot really specify every possible
bad configuration that can be made in the spec. I definitely agree with Fredrik
below.

/Tony