Subject: comments on send-ipsec-00

From: Alper Yegin <[email-masked]>
Date: Wed, 12 Mar 2003 19:56:31 -0800

Hello,

I just finished reading the draft. Here are some questions/comments:

- This is a simple, and possibly a dumb question: In what type of networks
are we concerned about unauthorized nodes sending bogus router
advertisements? Possibly in public access networks, right? Couldn't we
simply prevent client hosts from sending RAs by installing filters on the
enforcement points (like APs in WLAN hotspots)? Any RA sent on the radio
network can be dropped. Sure it is none of the business of the L2 bridge to
do that from an architectural point of view, but from a practical point of
view......

- "If (DAD) clashes are detected
   after three tries, the node is probably under attack, so it should
   shut down and report the situation to an administrator."

Isn't DAD mechanism protected by CGAs as well? How can the attacker produce
the right cryptographic information to claim 3 different IP addresses in a
row?

- Can the routers still send unsolicited advertisements that can be verified
by hosts with different Trusted Roots? Or, do they have to unicast a
different advertisement to each host?

- "One effect of this is that secure hosts can not communicate with
   insecure hosts using link-local addresses, and vice versa." Can an
insecure host and SEND-secured host still detect DAD collision on their
link-local addresses? If not, then we end up duplicate link-local addresses
on the same link, and this is a no good.

- "An attacker may still be able to
   prevent valid responses or requests from reaching the intended
   recipient.  As a result both participants are forced to believe that
   no address collision exists, when there in fact is."
How can the attacker do that? Is it a MitM physically separating victims?

Thanks in advance.

alper 

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From: Alper Yegin <[email-masked]>
Date: Tue, 25 Mar 2003 11:51:02 -0800

Hello,

I had sent the message below prior to IETF, but haven't seen any response on
the ML. Does any one of the SEND authors care to respond?

Thanks.

alper

> - This is a simple, and possibly a dumb question: In what type of networks are
> we concerned about unauthorized nodes sending bogus router advertisements?
> Possibly in public access networks, right? Couldn't we simply prevent client
> hosts from sending RAs by installing filters on the enforcement points (like
> APs in WLAN hotspots)? Any RA sent on the radio network can be dropped. Sure
> it is none of the business of the L2 bridge to do that from an architectural
> point of view, but from a practical point of view......
> 
> by hosts with different Trusted Roots? Or, do they have to unicast a different
> advertisement to each host?
> 
>  insecure hosts using link-local addresses, and vice versa." Can an insecure
> host and SEND-secured host still detect DAD collision on their link-local
> addresses? If not, then we end up duplicate link-local addresses on the same
> link, and this is a no good.
>