Subject: Re: [Seamoby] Security Requirments for CAR Discovery

From: "Hemant Chaskar" <[email-masked]>
Date: Wed, 13 Mar 2002 22:09:36

Hi James:

Please see coments below marked as [HC]

--------------------------snip---------------------------------------
> > >on
> > >     the security of routing information distribution.
> >
> > I do not agree with this part. What is the relation between routing
>and CAR
> > requirements? The first part of your requirement covers all the IETF
> > security policies and protocols, and that should be enough in my
>opinion.
> >
>
>CAR discovery involves sending information about the reachability and
>capabilities of one router to another, possibly via a host.

[HC] CAR discovery is not about spreading reachability information of one 
router to another. That is the job of routing protocols. It is about 
capability exchange between GAARs.

Routing
>information distribution involves sending information about the
>reachability and capabilities of one router to another, usually not via
>a host. The only thing the two don't have in common is that one could
>possibly use a host while the other doesn't.

[HC] I think there is little commanality between routing protocols and CAR 
discovery. Let me explain. There are two main parts of CAR discovery: GAAR 
discovery and capability exchange. I will come to GAAR discovery later. As 
far as the capability exchange between the GAARs is considered, once the two 
GAARs have decided to exchange capabilities they can do so by opening simply 
a peer-to-peer connection such as TCP between them or use open loop 
messaging like UDP and ICMP. I see no involvment of routing protocols here 
(beyond the point that they will help route the packets containing these 
messages). To give an analogy, if two routers need to do FTP between them 
they simply do it using TCP. FTP is however not deemed to be related to 
routing. If capabilities are exchanged via MN instead, the same logic still 
applies. Only, there is extra node between them.

Now coming to GAAR discovery part, I struggle to see how a routing protocol 
are related to GAAR discovery. The problem statement clearly points hout how 
GAAR discovery (Geospace) is different from logical neighborhood discovery 
(Cyberspace) on which routing protocols are built.

In either case, the routing
>fabric has to be able to trust the information it gets.

[HC] Why CAR discovery needs to inject any information in routing fabric? As 
I have explained above, it is about peer to peer information exchange 
between GAARs.

Thus, the
>security on the information distribution needs to be the same. Note that
>this is *not* to say that, a priori, CAR discovery and routing
>information distribution should be solved by the same protocol, just
>that they involve the same kind of security problem.
>
>For an example of the problems it might cause if security on CAR
>discovery were any less than that on routing information distribution,
>consider security on MIP binding updates. The newly decided upon
>protocol, return routability, depends critically upon the security of
>the routing fabric. If the security on CAR discovery causes the security
>of the routing fabric to be compromised, then MIP RR security on BU
>updates is compromised.
>
>             jak
>

[HC] I am not denying that the security problem may exist. But then, we need 
to point it out more directly and precisely rather than saying that the 
security problem is something like the one involved in routing. I think the 
problem is that "why will the two GAARs involve in capability exchange in 
the first place, unless they are assured about the validity of each other". 
Now we do have to come up with a solution to that. But, it is difficult to 
see how this problem alone can draw relation between CAR discovery and 
routing protocols.

Regards,
Hemant

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---

From: "James Kempf" <[email-masked]>
Date: Wed, 13 Mar 2002 16:43:07 -0800

Hemant,

> capability exchange between GAARs.

I think we have a fundamental disconnect here. Please go back
and review draft-ietf-seamoby-cardiscovery-issues-02.txt.

One of the primary drivers behind the CAR discovery work is spreading
reachabilty information for fast handover purposes. The access routers
need to know what other routers a mobile node can get to in order
to be able to perform fast handover. This is, fundamentally, spreading
routing
reachability information.

BTW, I am not aruging this from a purely theoretical perspective.
We are in the process of implementing fast handover, and
we have implemented one of the CAR discovery algorithms
for exactly this purpose.

> (Cyberspace) on which routing protocols are built.

Both OSPF and BGP have the ability to send capability information, in
the form
of attributes. While I am not advocating that CAR discovery use OSPF or
BGP, I am trying to point out that the problem is not all that
different.

> I have explained above, it is about peer to peer information exchange

Because the routing fabric is going to use information about reachable
GAARs in order to make decisions about what GAARs to offer the MN.
The GAARs are part of the routing fabric.

> see how this problem alone can draw relation between CAR discovery and

What I have tried to say (perhaps unsuccessfully) is that a GAAR that
receives
CAR information has to have the same level of trust in that information
as
it has in path information received via OSPF. Whether or not the same
protocol is used is solution space, and therefore not part of the
current discussion.

            jak

---

From: "James Kempf" <[email-masked]>
Date: Wed, 13 Mar 2002 16:43:07 -0800

Hemant,

            jak