Re: Questions about OSPF v3 security draft

[Mike Fox <[e-mail]>]

Vishwas,

I shared your response with our security expert and here is his response:

What we need to know is whether the paragraph is referring to unicast. " 
What it means is we will use the same crypto-algorithm and keys for all 
traffic to a neighbor over an interface." If this comment is referring to 
unicast, the point remains is that there will be multiple SAs. We will not 
be able to adhere to the figure 3 requirements for unicast, and there will 
be full meshing of SAs required between all communicating OSPFs. Not so 
bad if using IKE. Really bad if using manual SAs. 

Here is the thread of notes being referred to (since it's been a couple of 
weeks):



Vishwas Manral <[e-mail]>
Sent by: Mailing List <[e-mail]>
02/15/2005 12:01 AM
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        Subject:        Re: Questions about OSPF v3 security draft


Hi Mike,
 
I think both the authors are on leave, so they will probably reply later.
 
However regarding the first point, I agree the wording should be clearer. 
However what it means is we will use the same crypto-algorithm and keys 
for all traffic to a neighbor over an interface.
 
Regarding the second point, I think I too have brought the issue on this 
list and the reply I think was that the draft does not prohibit the use of 
IKE for unicast flows.
   
Thanks,
Vishwas

From: Mailing List [mailto:[e-mail]] On Behalf Of Mike 
Fox
Sent: Friday, February 11, 2005 8:04 PM
To: [e-mail]
Subject: Questions about OSPF v3 security draft
 

Regarding 
http://www.ietf.org/internet-drafts/draft-ietf-ospf-ospfv3-auth-07.txt, 
and the previous drafts, a couple of questions have come up in our shop. 

1) Section 7, 2nd paragraph says "the implementations MUST use manually 
configured keys with same SA for inbound and outbound traffic (as shown in 
figure 3).  I assume the "same SA" MUST rule applies to multicast traffic 
only and not unicast traffic. This is because an SA is defined as an SPI, 
security protocol (AH or ESP), and destination IP address. For unicast 
addresses, by definition there will be as many SAs as there are unicast 
destination addresses. Therefore, I don't think it is possible to apply 
this MUST rule given the current IPSec definition (RFC 2401 section 4.1) 
of an SA for unicast. Assuming the intention of the draft was to apply 
only to multicast and given the number of potential SAs carrying unicast 
traffic, it would seem that using IKE to setup the SAs dynamically would 
be a reasonable alternative to manual keying.     
  
2)Section 9, 2nd paragraph discusses setting up a "secure IPSec channel 
dynamically once it acquires the required information".  Since this 
traffic is unicast only, IKE could easily set up the required SAs without 
knowing the specific IP addresses in advance. Creating SAs dynamically do 
not fit easily within scope of manual SA functional capabilities. Why not 
use IKE for this traffic? Is this an acceptable option?   

Mike