Subject: [Fwd: I-D ACTION:draft-nikander-multi6-hip-00.txt]

From: Brian E Carpenter <[email-masked]>
Date: Sun, 25 Jan 2004 16:59:37 +0100

-------- Original Message --------
Subject: I-D ACTION:draft-nikander-multi6-hip-00.txt
Date: Fri, 23 Jan 2004 15:59:31 -0500
From: [email-masked]
Reply-To: [email-masked]
To: IETF-Announce: ;

A New Internet-Draft is available from the on-line Internet-Drafts directories.

	Title		: draft-nikander-multi6-hip-00
	Author(s)	: P. Nikander
	Filename	: draft-nikander-multi6-hip-00.txt
	Pages		: 28
	Date		: 2004-1-23
	
The Host Identity Protocol implements the identifier locator
   separation by introduing a new name space and a new layer to the IP
   stack.  The new structure insulates the transport layer protocols
   from the internetworking layer, thereby allowing transport sessions
   to remain unaffected even if the underlying IP addresses change.
   That, in turn, seems to make it easier to solve the so called site
   multi-homing problem than without introducing such an indirection
   layer.

   This document discusses how the proposed HIP mobility and
   multi-homing solution, described separately, would fit to the IETF
   multi6 working group requirements.

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From: "marcelo bagnulo" <[email-masked]>
Date: Wed, 28 Jan 2004 16:10:46 +0100

Hi Pekka,

A question about section 3.2: what do you mean by "update the state" when
the Recipient wants to open a connection in the reverse direction.

I think i understand the attack that you are trying to prevent here,
however, i am not sure that i really understand what do you mean by update
the state.

The attack, as i understand it could be the following

An attacker A wants to steal the identity of a Server S in a certain victim
B. Since the identity for the transport layer is the HIT, A wants to pretend
to be HITS in the eyes of B.
So, A initiates a communication with B, and A uses HITS as HIT and IPA as
address.
Since they are using LHIP, no validation about HITS is performed by A.
This is not really a problem I think because it is A who started the
communication, so it is hard to perform an attack.

The problem is when B wants to contact S, since if B accept the binding
between HITS and IPA, then it will be initiating a communication with A
thinking that it is communicating with S.(this is why you mention in your
draft that when the recipient wants to initiate a communication in the
reverse sense it has to be careful, right?)

Now, you state that the recipient in this case B has to update the state,
what does this means?
- Does it means that it has to obtains the IP addresses of the HIT again,
for instance from the DNS? and then it can use LHIP
- Does this means that it can initiate the reverse communication but it has
to perform the 4 way handshake validating the HIT? This would mean that LHIP
cannot be used in reverse communications, right?
- something else?

BTW i couldn't find draft-yitalo-multi6-hc, i guess it is not submitted yet.

A question about mobility: does the rendez vous server described in section
5.2.1.2.1 forwards packets to mobile hosts, like the Home Agent of mobileip,
or it just informs about the current address of the mobile node?

question about 5.2.2.3: hosts MUST verify reachability of an address before
start using it? i understood from recent mail exchanges at the HIP ml that
this was optional.

about 5.3.1.4- policy
How would the adoption of hip impact current default address selection
mechanism?
IMHO, hip would apply rfc 3484 to select addresses, right?
then you could use the policy table defined in rfc 3484 to express policy, i
think

about 5.3.1.8 - ingress filtering
I am not sure that what is stated in the draft in completely accurate...
Other multiaddress solutions propose concrete approaches to deal with
ingress filtering, for instance SIM uses source address rewriting by exit
routers. To support this they require a rewrite OK bit in the header, in
order to inform the exit router if this packet can be rewritten.
AFAIK, hip does not define something like this, and i am not sure if HIP
would work if all the source address of all packets is rewritten. In
particular, interaction with IPsec comes to my mind, and interaction with
legacy hosts.
Perhaps with some modifications hip could support this, but i don't really
know that.

There are other approaches to deal with ingress filtering that probably
could be directly supported by HIP, such as the ones presented in
draft-huitema-multi6-hosts.

regards, marcelo

> -----Mensaje original-----
> De: [email-masked] [mailto:[email-masked]]En
> nombre de Brian E Carpenter
> Enviado el: domingo, 25 de enero de 2004 17:00
> Para: Multi6
> Asunto: [Fwd: I-D ACTION:draft-nikander-multi6-hip-00.txt]
>
>
>
>