[Nfd-dev] LINK spec discussion

[Wentao Shang]

I was involved in the previous discussion and I have a quick question: the
document says the LINK type will be a "sub-type of NDN DATA packet". Is the
"sub-type" referring to implementation mechanism (i.e., Link class is
inherited from Data class) or do we actually have some way to encode the
"sub-type" relationship in the TLV format?

I remember the type field is using flat number so not sure whether the
latter is possible. If it is the former case, I don't think specifying
implementation detail in the document is a good idea (what if the
programming language doesn't support inheritance?).

Wentao

On Fri, Sep 12, 2014 at 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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>



-- 
PhD @ IRL, CSD, UCLA
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