Subject: [karp] Security Extension for OSPFv2 when using Manual Key Management

From: shraddha <[email-masked]>
Date: Mon, 24 Jan 2011 11:51:22 +0530

Hi Sam,

In section 2, while explaining the challenge response solution
For a new router coming up on the LAN is described, a router changes it's 
Nonce when it detects a new node on the LAN.

1. This feature can be used to launch DOS attacks and cause a router to
change the nonce continuously. However I cannot think of a completely secure
solution to avoid DOS but introducing a minimum time (Similar to
MinLSArrival) to change the nonce might be helpful to reduce the effect. 

2. When a node detects change in the nonce in a hello message, it might have
to send hello immediately to ensure it's adjacency as it's some of the
previous hellos might be dropped by the router which changed the nonce.
This can be mentioned explicitly in the Receive packet handling section.

3. As I understand, the nonce is not checked for messages other than hello
so it can be removed from the trailer for other messages?

Rgds
Shraddha

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From: Sam Hartman <[email-masked]>
Date: Mon, 24 Jan 2011 08:33:25 -0500

>>>>> "shraddha" == shraddha  <[email-masked]> writes:

    shraddha> Hi Sam, In section 2, while explaining the challenge
    shraddha> response solution For a new router coming up on the LAN is
    shraddha> described, a router changes it's Nonce when it detects a
    shraddha> new node on the LAN.

    shraddha> 1. This feature can be used to launch DOS attacks and
    shraddha> cause a router to change the nonce continuously. However I
    shraddha> cannot think of a completely secure solution to avoid DOS
    shraddha> but introducing a minimum time (Similar to MinLSArrival)
    shraddha> to change the nonce might be helpful to reduce the effect.

It's not actually changing the nonce that is problematic; it is sending
hello packets with the new nonce.
Yes, you can introduce a minimum time between hello packets to fix this.

    shraddha> 2. When a node detects change in the nonce in a hello
    shraddha> message, it might have to send hello immediately to ensure
    shraddha> it's adjacency as it's some of the previous hellos might
    shraddha> be dropped by the router which changed the nonce.  This
    shraddha> can be mentioned explicitly in the Receive packet handling
I    shraddha> section.

I'm not sure you need to check nonces  for hellos for things in 2-way or
greater.
So I don't think this is a concern.

    shraddha> 3. As I understand, the nonce is not checked for messages
    shraddha> other than hello so it can be removed from the trailer for
    shraddha> other messages?
Yep.

    shraddha> Rgds Shraddha

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    shraddha> *********** This e-mail and attachments contain
    shraddha> confidential information from HUAWEI, which is intended
    shraddha> only for the person or entity whose address is listed
    shraddha> above. Any use of the information contained herein in any
    shraddha> way (including, but not limited to, total or partial
    shraddha> disclosure, reproduction, or dissemination) by persons
    shraddha> other than the intended recipient's) is prohibited. If you
    shraddha> receive this e-mail in error, please notify the sender by
    shraddha> phone or email immediately and delete it!