Subject: [mobile-ip] Cthon issue #279: NS source from HA during de-registration

From: Jari Arkko <[email-masked]>
Date: Sun, 16 Mar 2003 06:54:44 +0200

so we can track them better. Lets all use an issue specific subject
line from now on.

Secondly: I am writing this offline (~20 hrs), so there may have been
e-mails that I have missed...

Then: To the issue at hand.

 > For clarity, I'd think, HA should include PI with NS if it uses
 > link-local address as its source address (since RFC2461 is liberal
 > about scope of source address of NS), so MN can verify that it's indeed
 > coming from the HA.

This would seem possible. But I think the MN would know the home
agent's link-local address. Every RA MUST use a link-local address,
and presumably we must have seen an RA to even know that this particular
home agent is on the link? This still leaves the possibility that
if the home agent has multiple link-local addresses, the NS could
come from a different one than the RA. Hmm... perhaps this is an
issue.

 > On the other hand if we say that NA from MN's hoa always over-rides
 > the proxy NA from HA, I am afraid, that might create some security
 > hole. What if a malicous node starts sending NA by using a MN's home
 > address while the HA is defending the actual MN's address. Is it a
 > valid concern ?

This is possible in any case, until SEND comes around. So lets
not try to solve that here. ;-)

So, we appear to have the following possibilities:

1. Vijay: Just allow the MN to respond to NS starting from the sending
    of the BU, not from the reception of the BA.
2. Samita: Use a PI option in the NS to distinguish the HA from
    other senders.
3. Jari: Rely on NS and RA to come from the same link-local address.
    Or require this.

I think we should do #2 or #1. It is not very clear to me which one
should be preferred.

Jari

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From: Vijay Devarapalli <[email-masked]>
Date: Sun, 16 Mar 2003 17:13:14 -0800

>    of the BU, not from the reception of the BA.

lets go with #1. I feel we are wasting our time discussing such a minor
issue. the window of this happening would be in terms of milliseconds.
and there is no harm done, because the NA from the mobile node overrides
the proxy NA from the home agent.

Vijay

---

From: Vijay Devarapalli <[email-masked]>
Date: Sun, 16 Mar 2003 17:16:51 -0800

I guess I was not very clear in my earlier mail. my proposal is
to let the MN respond to any NS.

Vijay

Vijay Devarapalli wrote:

---

From: "Ed Remmell" <[email-masked]>
Date: Mon, 17 Mar 2003 12:03:06 -0800

> to let the MN respond to any NS.

Yes, please, I'm strongly in favor of this, it is much simpler for the MN.

Thanks.
- Ed