Re: Review of draft-ietf-geopriv-http-location-delivery-07

Hi Ekr,

Eric Rescorla wrote:
> $Id: draft-ietf-geopriv-http-location-delivery-07-rev.txt,v 1.1 2008/05/24 15:03:19 ekr Exp $
>
> TECHNICAL
>
>
> S 4.2.
>    which a Location Recipient (LR) can use to retrieve LI.  A location
>    URI provided by a LIS can be assumed to be globally-addressable; that
>    is, anyone in possession of the URI can access the LIS.  However,
>    this does not in any way suggest that the LIS is bound to reveal the
>    location associated with the location URI.  This issue is deemed out
>
> I don't understand this point. anyone in possession of the URI can
> access the URI but the LIS isn't required to reveal it? Those
> seem kind of contradictory.
>
>   
Compare this with a HTTP URL where you might know it but still there are 
access policies that control access.
Possession does not necessarily mean that you can always get the location.

> S 4.3.1.
>    Devices that establish VPN connections for use by other devices
>    inside a LAN or other closed network could serve as a LIS, that
>    implements the HELD protocol, for those other Devices.  Devices
>    within the closed network are not necessarily able to detect the
>    presence of the VPN and rely on the VPN device.  To this end, a VPN
>    device should provide the address of the LIS server it provides, in
>    response to discovery queries, rather than passing such queries
>    through the VPN tunnel.
>
> How do you envision this happening? Isn't this going to require 
> changing every VPN protocol? I think some more text would be 
> appropriate here...
>
>   
It requires location information to be obtained before the tunnel is setup.

> S 5.1.
>    o  The HELD protocol must provide authentication, confidentiality and
>       protection against modification per Section 10.3.
>
> Are you talking about HELD, which doesn't seem to have these
> features, or about the transport protocol? Also, authentication
> for who? Based on what model?
>
>
>   
The solution for HELD is to provide these capabilities as part of TLS.

For the client to LIS interaction we are talking about server-side 
authentication and not client-side authentication.

It would be important to spell this out.

> S 6.5.
> I'm having trouble keeping straight two kinds of URIs:
>
> - URIs that a Device uses to get its own LI.
> - LbyR references that the LIS hands out.
>
> This text seems to imply that an LIS can hand out a helds:
> URI. Is that *also* the URI that a Device derferences?
>   

The reference points to the device. What the Target uses this reference 
either for itself (if it wants to learn it's own location) or (more 
likely) it forwards that URI to someone else, for example to a PSAP.

>
> S 6.5.1.
>
>    A "locationURI" SHOULD NOT contain any information that could be used
>    to identify the Device or Target.  Thus, it is RECOMMENDED that the
>    "locationURI" element contain a public address for the LIS and an
>    anonymous identifier, such as a local identifier or unlinked
>    pseudonym.
>
> 1. This seems like it should be clearer about what is desired.
>    In particular it's not just "identify" but also "link".
>    Also this needs to be clarified to indicate the implications
>    of idetntifiction by position.
>
> 2. Shouldn't this be MUST strength?
>
>
>   
This is a MUST when possession of the reference also means access to the 
resource without any additional authorization policy being used by the 
LIS when access to location is being requested.

This is a SHOULD when such policies are applied.

It might make sense to differentiate these two cases in the document.

> S 8.
> Does this say somewhere what "helds" actually means? I see the
> definitition of the URI, but it doesn't say what the 
> underlying transport is, as far as I can tell. Given
> a "helds:" URI, what am I supposed to do with it?
>
>
> S 9.
> OK and here's how I get confusied about the two types of URI,
> since this is an HTTP binding, but there's no corresponding
> URI.
>
>
>    The implementation of HTTP as a transport mechanism MUST implement
>    TLS as described in [RFC2818].
>
> Is this MUST implement or MUST use? Don't the next two sentences
> imply MUST use?
>
>
>    TLS provides message integrity and
>    privacy
>
> "privacy" -> "confidentiality"
>
>    between Device and LIS.  The LIS MUST use the server
>    authentication method described in [RFC2818]; the Device MUST fail a
>    request if server authentication fails, except in the event of an
>    emergency.
>
> This is incomplete, because 2818 assumes the presence of a URI to
> compare against. Where does that come from? 
>
> How is client authentication supposed to work here?
>
>
>   
The client learns the URI using a discovery method, see
http://tools.ietf.org/wg/geopriv/draft-ietf-geopriv-lis-discovery/

This URI is then used for comparison.

> S 10.3.
>    o  The network SHOULD have mechanisms that protect against IP address
>       spoofing, such as those defined in [RFC3704].
>
> Is this WG really in a position to levy a SHOULD level requirement
> for network ingress filtering? Recall that this is really a global level
> technology. Or do you mean something else?
>   

Being able to deal with IP address spoofing is a useful in certain 
environments.
Hence, saying that in a document is very useful.

>
>    o  The LIS and network SHOULD be configured so that the LIS is made
>       aware of Device movement within the network and addressing
>       changes.  If the LIS detects a change in the network that results
>       in it no longer being able to determine the location of the
>       Device, then all location URIs for that Device SHOULD be
>       invalidated.
>
> This probably needs some more detail about how it's going to work.
>
>   
This depends on the type of network.

Very hard to describe this in general.

I doubt it is useful to go into a lot of descriptions.

>    When there are further mechanisms available to authenticate ownership
>    of the IP address, the LIS SHOULD use them to authenticate that the
>    client is the owner of the target IP address.  For example, in a TLS
>    transaction, the client could present a certificate with a public key
>    bound to an IPv6 Cryptographically Generated Address, and the LIS
>    could verify this binding.
>
> Not that I think that any situation in which the client has an IP
> level cert is particularly likely, but this one seems particularly
> unlikely.
>
>
>   
This paragraph is certainly forward looking. I wouldn't feel sad to 
remove it.

>
>     
>
> EDITORIAL
> Abstract:
>    independent of session-layer.  This document describes the use of
>    Hypertext Transfer Protocol (HTTP) as a transport for the protocol.
>
> This should be HyperText
>
> Also, isn't this using HTTPS, not HTTP.
>
>
> S 1.
>    information.  The LIS service applies to access networks employing
>
> This is the first reference to LIS. Please expand.
>
>
>    [I-D.ietf-geopriv-l7-lcp-ps] provides some scenarios in which the
>    Device might rely on its access network to provide location
>
> "the" -> "a"
>
>
>    capable of MIME transport.  This document describes the use of
>    Hypertext Transfer Protocol (HTTP) as a transport for the protocol.
>
> See comments about abstract.
>
>
>
>
> S 4.3.
> I would move this to precede 4.1 and 4.2, since it's orthogonal
> to the value/reference distinction.
>
>
> S 5.1.
>    o  The HELD protocol is a request, response protocol, thus the
>
> I would write request/response.
>
>
> S 6.6.
>    schema Section 7 for a location response message due to XML schema
>
> "schema Section 7" -> "schema in Section 7"
>
>
>
>
>   
Ciao
Hannes

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