Re: [icnrg] Review of draft-irtf-icnrg-icntraceroute

Spyros – thank you!

Chris – could you please check if the following would address your concerns?

Thanks,
Colin

On 1 Jul 2022, at 12:22, Spyridon Mastorakis wrote:

> Hi Chris,
>
> Thank you very much for your feedback! Please see my response to each of your comments inline. If you agree with my responses, I can go ahead and update the draft.
>
> Please let me know.
>
> Thank you again!
> Spyros
>
>> On Jun 15, 2022, at 9:48 AM, Christopher Wood <caw@heapingbits.net> wrote:
>>
>> Non-NU Email
>>
>> Like the ping document, I found this to be very well structured and written. The use case for the protocol is clear, the protocol itself -- including the forwarder behavior -- is simple, and the security and privacy considerations are thorough.
>>
>> Section 1.
>>
>>   To this end, the problem of
>>   ascertaining the characteristics (i.e., transit forwarders and
>>   delays) of at least one of the available routes to a name prefix is a
>>   fundamendal requirement for instumentation and network management.
>>
>> nit: s/instumentation/instrumentation
>
> Thanks for pointing out this typo!
>
>>
>> Section 6.
>>
>>   The TrReply Code TLV value of the reply is set to indicate the
>>   specific condition that was met.  If none of those conditions was
>>   met, the TrReply Code is set to 4 to indicate that the hop limit
>>   value reached 0.
>>
>> Perhaps I overlooked it, but why does the TrReply Code need to be 4? Is it because there are three prior conditions for the final reply in the session?
>
> This value is based on the protocol specification. We have mentioned it at the end of Section 4.2.
>
>>
>> Section 8.
>>
>>   This approach does not protect against on-path attacks, where a
>>   compromised forwarder that receives a traceroute reply replaces the
>>   forwarder's name and the signature in the message with its own name
>>   and signature to make the client believe that the reply was generated
>>   by the compromised forwarder.  To foil such attack scenarios, a
>>   forwarder can sign the reply message itself.  In such cases, the
>>   forwarder does not have to sign its own name in reply message, since
>>   the message signature protects the message as a whole and will be
>>   invalidated in the case of an on-path attack.
>>
>> Could a compromised forwarder swap out the name of a traceroute request with the name of its choosing? If so, perhaps this should also be listed in the paragraph above? To be honest, I forget the semantics for how content object response signatures are verified, so this might not be an issue.
>>
>
> My understanding is both in CCNx and NDN, changing the name of a request would invalidate the state in PIT, therefore, a response will not reach the client. To this end, it is unclear to me how much damage swapping out the name of a request could cause in our case. Indeed, unless requests are signed and the signature is verified, a forwarder could swap out the names of requests, but the corresponding response will not reach the client. I suppose a malicious forwarder could still see the response before the response is dropped. I am happy to mention that in Section 8.
>
>> Hope this helps.
>>
>> Best,
>> Chris
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