[Nfd-dev] LINK spec discussion

Alex Afanasyev alexander.afanasyev at ucla.edu
Sun Sep 14 15:57:35 PDT 2014


On Sep 14, 2014, at 3:37 PM, Burke, Jeff <jburke at remap.ucla.edu> wrote:

> Hi,
> 
> Maybe I am coming into the middle of another discussion, but I still have
> yet to understand the status (and the choice of name) for NDNS.
> 
> Is this new component now a "given" in the architecture?  Or, is it an
> example of where LINKs may come from?
> 
> Junxiao uses the phrase "perform a NDNS lookup for /ndnsim" - is this
> different than just issuing an Interest for "/ndnsim"?

For this particular discussion, we can assume that there is some kind of resolution mechanism.  It doesn't need to be NDNS, but it would provide such a service (I hope very soon).   

The question here is what we want such lookup service to return and what actions should happen after link is received.  We can also discuss questions of who issues queries, but this is different type of discussion and I would prefer if we get to understanding on the basic elements.

Answering the specific question about the lookup.  In terms of NDNS, the lookup process is more complex than simply sending an interest (= sending a set of interests according to the protocol spec).  For example, if not all NDNS authoritative servers can be directly accessed (/net/ndnsim's authoritative NDNS server in this example), one would need to discover first LINK for that server, after which it can send another query to discover link for the actual data item.  In any case, I would like to defer this specific conversation until we have initial specification for updated the NDNS protocol (should be available some time this week).

---
Alex

> Jeff
> 
> On 9/12/14, 4:40 PM, "Alex Afanasyev" <alexander.afanasyev at ucla.edu> wrote:
> 
>> Hi!
>> 
>> I want continue our discussion about LINK specification
>> (named-data.net/downloads/memos/link.pdf).
>> 
>> Currently we preliminary defined three elements:
>> 
>> a) link for redirection:
>> 
>>   signA("nameA", content: "nameB")
>> 
>> b) link for delegation
>> 
>>   signA("nameA", content: signB("nameB", content: "prefixOfNameA"))
>> 
>> c) "link" for encapsulation
>> 
>>   sha256("nameB" | "nameA", content: ("delegation or redirection link",
>> data("nameA"))
>> 
>> 
>> The option (b) is the latest addition and I have some reservations about
>> it.  In particular, what exactly this delegation achieves?  What security
>> problem we are solving with it.
>> 
>> Let me give some example of (b).  I own a "non-routable" namespace
>> /ndnsim and my site is connected to /att and /ucla networks.  So, the (b)
>> option would require:
>> 
>> - I will have to obtain a "redirection" links from /att and /ucla to
>> /ndnsim (option (a)) = get a permission from /att and /ucla to host
>> /ndnsim site
>> 
>> - Then I will create a delegation packet(s) that I can put in NDNS to
>> tell others that my site is currently available through /att and /ucla.
>> 
>> The process looks ok, but the question I have is what significance is in
>> the first permission.  What is the point of me of requesting permission
>> from my provider to host a website?  What I would gain and what provider
>> itself would gain?
>> 
>> I personally, do not yet see a clear benefit from this process, only that
>> it would complicate the delegation process.  Only me is able to tell
>> others that my site is available at different places, so there is no
>> question about others claiming that my site is available somewhere else.
>> If I mistakenly put a wrong link, then I myself will be at loss: i
>> wouldn't be able to serve my content and somebody else would receive my
>> interests and could reply to them with some junk.
>> 
>> If I "maliciously" put somebody else's network as a link, then interests
>> for my data would go there.  But what is the harm?  If nobody replies to
>> them, then routers can start ignoring/pushing back such interests.  If
>> somebody replying, then somebody serves data and from the network point
>> of view nothing bad is happening.
>> 
>> 
>> In short, I want us have a deep discussion on what exactly we are
>> protecting and from whom.  For me, even with only one signature (option
>> a), only the owner of the original namespace (/ndnsim) is able to create
>> a legitimate link to somewhere else.   Additional signature could protect
>> "provider" (destination of the link), but is it really a problem?
>> Anybody could send any number of interests to that provider even without
>> any link (erroneous or malicious).
>> 
>> 
>> ---
>> Alex
>> 
>> 
>> 
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> 





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