Subject: RE: [mobile-ip] How to handle RoutingHeader Type zero

From: [email-masked]
Date: Fri, 30 Aug 2002 10:36:33 -0500

From:
http://www.piuha.net/~jarkko/publications/mipv6/security-considerations-new.txt
"
15.7      Type 2 Routing Header

The definition of the Type 2 Routing Header is described in Section
6.4. This definition and the associated processing rules have been
chosen so that the header can not be used for what is traditionally
viewed as source routing. In particular, the IPv6 the Home Address in
the routing header will always have to be assigned to the home address
of the receiving node. Otherwise the packet will be dropped.

Generally, source routing has a number of security concerns. These
include the automatic reversal of unauthenticated source routes (which
is an issue for IPv4, but not for IPv6). Another concern is the
ability to use source routing to "jump" between nodes inside, as well
as outside a firewall. These security concerns are not issues in
Mobile IPv6, due to the rules mentioned above.

In essence the semantics of the type 2 routing header is the same as a
special form of IP-in-IP tunneling where the inner and outer source
addresses are the same.  This implies that a device which implements
filtering of packets should be able to distinguish between a Type 2
Routing header and other Routing headers, as required in section
8.3. This is necessary in order to allow Mobile IPv6 traffic while
still having the option to filter out other uses of Routing headers.
"

So are you suggesting that the spec make a recommendation that MNs 
MUST NOT process packets with RH type 0?

> 
> Draft 18 sections 4.1, 9.6, 11.2.3 and 14.7 explain why type 2 routing
> headers are a good idea and how they should be validated. But the spec
> does not say what the MN must do if a RH type 0 is received where a RH
> type 2 is expected. As I read things (strictly) a type zero with a
> LastSeg=HoA could go all the way through with less validation than a
> type 2. 
> 
>

---

From: Jari Arkko <[email-masked]>
Date: Sat, 31 Aug 2002 01:23:02 +0300

Hi Greg!

The intent has been to use RH2, and only RH2, for MIPv6 (perhaps
we need to remove the text about "assuming ... if no other use...").

There's an open question, however. What does this mean for RH0.
Possible interpretations:

   (a) Orthogonal. For some other purpose, RH0 may also be used. If
       so, we may need some rules on how RH0 and RH2 work if they
       are applied together, and perhaps also some rules on
       home addresses appeaering in RH0.

   (b) Not at the same time. Forbid RH0 if RH2 appears in the packet.
       If for some obscure reason someone wants to use RH0, then
       the use of RO is not possible at the same time.

   (c) Not by MIPv6 MNs and CNs. Devices supporting MIPv6 CN or MN
       functionality may no longer support RH0 at all.

   (d) Deprecate. Thou shall not use RH0 at all.

Personally, I think the last one is the really right action but
I realize this isn't going to be agreed upon now ;-) Perhaps
the second option would be the way to go. Other opinions?

Jari

---

From: Francis Dupont <[email-masked]>
Date: Sat, 31 Aug 2002 15:29:08 +0200

There's an open question, however.

=> no, RFC 2460 stands (RHs are processed in order).

   What does this mean for RH0.
   Possible interpretations:

   

=> I strongly disagree because we can need RH0 one day. So the proper
action is (a) and Mobile IPv6 has nothing to specify.

=> I can't see a problem with multiple RHs even this case has no
usage today. So let just apply RFC 2460 which gives (a).

Regards

[email-masked]