Re: [sipcore] 4244bis and privacy

["Mary Barnes" <[e-mail]>]

Yes.

-----Original Message-----
From: Audet, Francois (SC100:3055) 
Sent: Thursday, June 25, 2009 11:37 AM
To: Barnes, Mary (RICH2:AR00); 'Ian Elz'
Cc: 'Christer Holmberg'; 'Hans Erik van Elburg'; 'Shida Schubert';
'[e-mail]'
Subject: RE: 4244bis and privacy

So, let's say A calls B, B forwards to C.

B has privacy turned on.

A calls B. A history-info entry is added with sip:B.

B retargets to C and sets privacy.

I guess that would mean that B's proxy would have to parse the
History-Info and anonymize all entries corresponding to B?

Is this correct? 

> -----Original Message-----
> From: Barnes, Mary (RICH2:AR00)
> Sent: Thursday, June 25, 2009 09:29
> To: Ian Elz
> Cc: Christer Holmberg; Hans Erik van Elburg; Shida Schubert; 
> [e-mail]; Audet, Francois (SC100:3055)
> Subject: RE: 4244bis and privacy
> 
> Hi Ian,
> 
> Responses inline below [MB2].
> 
> Mary.
> 
> -----Original Message-----
> From: Ian Elz [mailto:[e-mail]]
> Sent: Thursday, June 25, 2009 10:13 AM
> To: Barnes, Mary (RICH2:AR00)
> Cc: Christer Holmberg; Hans Erik van Elburg; Shida Schubert; 
> [e-mail]; Audet, Francois (SC100:3055)
> Subject: RE: 4244bis and privacy
> 
> Mary,
> 
> I am a little concerned about one answer that you gave:
> 
> 
> If you have a Privacy header with a value of "none" and a H-I entry 
> with Privacy header parameter with value "history" what is the privacy

> of the individual H-I entry?
> [MB] We did not explicitly address the "none" in RFC 4244, but the 
> general statement is the privacy headers at the request level override

> any at the hi-entry level. [/MB]
>  
> This means that if privacy is required for an individual H-I entry but

> the originating user included "Privacy:none" in the request then there

> is no option to include the real URI in the H-I entry.
> [MB2] I'm confused here - the "none" definition is as you note below, 
> thus "none" prohibits the removal or anonymization of the entries, 
> thus I would think you would fine this functionality desireable. 
> However, this does not prohibit an entity based on policy to anonymize

> (or remove entries if privacy is required for that domain if the 
> entity does not have access to a privacy service). [/MB2]
> 
> This occurs as RFC3323 states in section 4.3: "However, if the Privacy

> header value of 'none' is specified in a message, privacy services 
> MUST NOT perform any privacy function and MUST NOT remove or modify 
> the Privacy header."
> 
> The only option for an intermediate node including a H-I entry where 
> "Privacy:none" is specified and privacy for the H-I URI is required is

> to include an anonymous entry or not include the H-I entry.
> [MB2] If privacy is required then yes, you include anonymous entries 
> or don't include. That's the basic privacy mechanism for privacy 
> levels of "session" "header" and "history" in the R-URI or "history" 
> in the specific entries, as well as when there is a policy for privacy

> for the entries added by a specific domain. The "none" really has no 
> influence on the later case per se. [/MB2]
> 
> In your previous response you stated that we would violate
> RFC3323 if we specified additional behaviour for privacy explicitly 
> stated with a URI -n the H-I entry. I don't believe that this is the 
> case as RFC3323 only considered privacy in a two party scenario and 
> did not consider third party identities being included in a message 
> between two parties. H-I is not the only case where this occurs as the

> Referred-By header when included in the INVITE (or other
> request) which results from the REFER has the same issue.
> [MB2] I can't necessarily disagree on this one (we can debate it 
> either way). But to fix it requires an update to RFC 3323 and 
> shouldn't be something that we want to fix in 4244bis. [/MB2]
> 
> RFC4244 was the first time that there was a recognition that privacy 
> for these individual third party identities may be required. To allow 
> this explicit statement of privacy to be overridden by a generic 
> statement which is applicable to a different user is counterintuitive.
> [MB2] See my comment above. But, as I have consistently said, the idea

> that an entity might want to override the "none" is entirely based on 
> policy and 4244 and 4244bis allow privacy to be applied to the entries

> that are added by that entity if the policy dictates so (and we 
> already say that). [/MB2]
> 
> The original Privacy header is usually included by or on behalf of the

> originating user and should not be allowed to specify the privacy of 
> the original called user, e.g. the 800 number, and prevent this 
> identity being presented if this user does not have the same level of 
> privacy.
> [MB2] As I tried to say in a previous response, a random entity (i.e.,

> one for whom the R-URI is not in a domain under its control) cannot 
> add a privacy header to the Request. Per RFC 3323 an entity may add 
> the header to a request only if it has the appropriate 
> relationship/authorization with the original called user who intiated 
> the request. And, I would find it very surprising if an entity that 
> did have responsibility would apply privacy since that would be 
> counter intuitive and I would hope that SPs would be judicious in 
> specifying the appropriate and inappropriate manner in which the 
> proxies they deploy and interface with privatize the messages. The 
> protocol CANNOT control this behavior and that's why there is the 
> policy clause in 4244 and 4244bis. [/MB2]
> 
> The real issue with the 800 scenario is as you have stated is that the

> answerer will not know the original called identity and will not be 
> able to correctly handle the call. As more generic call centres are 
> used which will answer calls on behalf of many different organizations

> using CTI and the original called identity to have to implement a 
> generic system asking the caller who he originally called appear 
> unprofessional, is inefficient and unproductive.
> [MB2] And, as I noted, it is rare for a call centre to route a call 
> directly to an agent without a user providing some sort of input. Even

> companies like American Airlines, even though they have the info that 
> I enter via the IVR, they still ask some basic questions and there are

> times when they have to reroute me. I don't think we can totally 
> automate things.  And, again, once the call hits the domain that is 
> responsible for that 800 number the entities in that domain have 
> control over how they muck with the R-URI, such that they should be 
> able to use any IVR info to appropriately direct the call - it's not 
> the number that's meaningful, but how the system gets the call to the 
> right user and the additional information they provide as the call is 
> presented to the agent. I would honestly think that having something 
> other than an 800 number show up on the display would be far more 
> useful and in my experience in the systems I developed we're usually 
> talking about CTI interfaces so you have a lot you can do.  And, 
> actually all of this really doesn't matter in that you MUST be able to

> handle this situation independent of the privacy since History-Info is

> optional, you need default behavior assigned. [/MB2]
> 
> We have an opportunity to allow presentation of specific identities 
> and to solve this particular problem so we should take it.
> [MB2] The most we can do is to document the risks/impacts of the use 
> of the Privacy headers at the R-URI level. There is already general 
> text in 4244 and 4244bis that the privacy may impact whether the 
> applications get the information.  And, as I noted before, most 
> commercial systems are using B2BUAs which will allow you far more 
> control over the use of the Privacy headers in the network. But, 
> again, I don't think that's something that should be address in 
> 4244bis.  [/MB2]
> 
> I hope that we can get some wider discussion on this issue so a more 
> general consensus can be obtained.
> 
> Regards
> 
> Ian
> 
> 
> 
> -----Original Message-----
> From: Mary Barnes [mailto:[e-mail]]
> Sent: 24 June 2009 17:27
> To: Ian Elz
> Cc: Christer Holmberg; Hans Erik van Elburg; Shida Schubert; 
> [e-mail]; Francois Audet
> Subject: RE: 4244bis and privacy
> 
> Hi Ian,
> 
> Responses inline below [MB].
> 
> Mary. 
> 
> -----Original Message-----
> From: Ian Elz [mailto:[e-mail]]
> Sent: Wednesday, June 24, 2009 10:37 AM
> To: Barnes, Mary (RICH2:AR00)
> Cc: Christer Holmberg; Hans Erik van Elburg; Shida Schubert; 
> [e-mail]; Audet, Francois (SC100:3055)
> Subject: RE: 4244bis and privacy
> 
> Mary,
> 
> I was not proposing that we change the handling of H-I which is based 
> upon local policy. If that causes an issue for a network operator then

> they can modify their local policy accordingly or arrange with the 
> proxy vendor to modify their equipment to be more flexible with 
> regards to policy.
> 
> Can you clarify for me:
> 
> If you have a Privacy header with either "session" or "header" doe 
> this impact the H-I entries or will only a value of "history" impact 
> the H-I entries?
> [MB] Yes, both "session" and "header" level privacy, consistent with 
> RFC 3323, mandate that entries be anonymized or dropped, with the 
> latter being the recommendation for "session" level privacy. RFC 4244 
> mandated that they be dropped and 4244bis recommends they be 
> anonymized. The original intent for the value of "history" was for the

> tagging of the individual entries, but you end up getting the header 
> level functionality as well. [/MB]
> 
> If you have a Privacy header with a value of "none" and a H-I entry 
> with Privacy header parameter with value "history" what is the privacy

> of the individual H-I entry?
> [MB] We did not explicitly address the "none" in RFC 4244, but the 
> general statement is the privacy headers at the request level override

> any at the hi-entry level. [/MB]
> 
> From reading RFC4244 a Privacy header with value "history" 
> will effectively make all H-I entries private and there is currently 
> no option to  include a H-I Privacy header parameter with value 
> "none".
> [MB] Correct, per my comment above. [/MB]
> 
> H-I at present allows the inclusion of Privacy header parameters to 
> explicitly express privacy for an individual H-I entry but a single 
> node which includes a header "Privacy:
> history" makes all H-I entries private even if this is not the 
> requirements for the specific URI.
> [MB] Correct, but the only node that should add the header is a node 
> which is responsible for the domain associated with the Request URI in

> the incoming request or is authorized to do so. [/MB]
> 
> I will admit that having worked in a telephony environment for a long 
> time I am used to having privacy of identities set on a per number 
> basis and the relative inflexibility of the IETF Privacy header is 
> relatively restrictive as to specifying which identities may be 
> presented and which not.
> [MB] Yes, this is an entirely different paradigm.  I developed 
> telephony s/w for over a decade and this is entirely different - it 
> provides a lot more flexibility, which makes things far, far less 
> deterministic than what you have in telephony switches where your 
> routing and translations are configured for the most part, with just a

> few capabilities for controlling the privacy and it's a closed 
> network.
> 
> With RFC4244/4244bis, there MUST be a mechanism at the UAS or end 
> application that can handle a request that doesn't have the 
> appropriate information either because nodes didn't support 
> History-Info or some random node in the network applied privacy (which

> I think is highly
> unlikely) - this is normative per section 5 of RFC 4244.  So, the 
> worst case scenario I see for this 800 service  (which will get to the

> right UAS but without the exact 800 number that was dialed) is that it

> goes to a default ACD group/customer service agent, etc. who then 
> needs to gather the appropriate information and in my experience this 
> is often an IVR system these days.  So, the service is not broken when

> privacy is applied in an undesireable manner, it's just not optimal.  
> This is something that should be addressed in the target-uri draft 
> which has all the details of how specific services use History-Info.
> One other thing to consider is that most networks that are emulating 
> telephony type features use B2BUAs, which follow the UAS/UAC rules for

> the header rather than the proxy rules, noting that the UAC can set 
> the Privacy header to whatever value it sees as appropriate for the 
> request.
> [/MB]
> 
> 
> Regards
> 
> Ian
> 
> -----Original Message-----
> From: Mary Barnes [mailto:[e-mail]]
> Sent: 24 June 2009 15:48
> To: Ian Elz
> Cc: Christer Holmberg; Hans Erik van Elburg; Shida Schubert; 
> [e-mail]; Francois Audet
> Subject: RE: 4244bis and privacy
> 
> Hi Ian,
> 
> I do not believe we should do the "override" behavior as I think that 
> violates RFC 3323, as the "history" is really a subset of the cases 
> whereby a UAC or proxy would add "session" or "header" to the request.
> And, the latter two cases have the same (undesireable) 
> result.   I agree
> this impacts your services, but we can't mandate that proxies provide 
> information that might violate their local policies and indeed a 
> proxy's local policies can result in the information being anonymized 
> (or removed if they can't
> anonymize) even in the "none" case. 
> 
> I do believe it's reasonable that we strongly recommend that the 
> request level (versus specific hi-entries) not be used and if it is 
> used, the consequence is that some services will not have the 
> information they need - this was the gist of my previous response (to 
> which I did not get any additional feedback). Now, we could add some 
> text that the "none"
> case SHOULD be used (e.g., added by first hop proxy) if it is desired 
> that the information not be subject to privacy restrictions. I do not 
> think it is then particularly useful to add logic around the proxy 
> then being able to tag the entries within their domain as subject to 
> privacy.
> I think that conflicts with the intent of the request level "none".
> However, as I mention above, per the current text, a proxy can (based 
> on local policy) remove entries - so a proxy can capture hi within 
> their domain and not forward any of that information to the next hop 
> in another domain - you already have that functionality.  But, I think

> this introduces the general problem that you might be impacting other 
> services further down the line, which I thought was the problem you 
> were wanting to solve - not specifically your example service but, for

> example, in the case that someone is debugging and they want the 
> entire history, so depending upon the service, this is also 
> undesirable behavior.
> 
> 
> Regards,
> Mary. 
> 
> -----Original Message-----
> From: Ian Elz [mailto:[e-mail]]
> Sent: Wednesday, June 24, 2009 2:57 AM
> To: Barnes, Mary (RICH2:AR00)
> Cc: Christer Holmberg; Hans Erik van Elburg; Shida Schubert; 
> [e-mail]; Audet, Francois (SC100:3055)
> Subject: RE: 4244bis and privacy
> 
> 
>  Mary,
> 
> [I have added the list to this thread for wider comment.]
> 
> In the previous discussions I commented that in RFC4424 that a Privacy

> header with value "history" effectively makes all H-I entries private 
> with the result that the H-I entries may be removed.
> 
> There has now been a comprehensive discussion on indication of the 
> initial 'target' to the final recipient for call handling purposes.
> 
> The main use case related to a freephone example where the answering 
> location may be a call centre where the original freephone number may 
> be required for correct call handling.
> 
> If you now consider the following example (modified from Francois' 
> text in the latest draft - excuse any errors that I may have inserted)
> 
> INVITE sip:sip:[e-mail];user=phone;p=x
> Privacy: history
> History-Info:
> <sip:[e-mail];user=phone;p=x>;index=1;rt;aor  
>        (1)
> History-Info: <sip:[e-mail]>;index=1.1;mp;aor
> (2)
> History-Info: <sip:bob@192.0.2.3>;index=1.1.1;rc
> (3)
> 
> In this case due to the Privacy header all of the H-I entries are 
> considered private and the [phone] will not be delivered to the 
> final destination with the result that call handling may not be 
> correct.
> The Privacy header may have been inserted by any of the nodes which 
> routed the message and inserted a H-I entry.
> 
> If however the H-I was allowed to include a header parameter of 
> "?Privacy=none" in the H-I entry and that an explicit H-I entry 
> privacy value would be considered to have precedence over a Privacy 
> header with a value of "history" then the mapping of the [phone] 
> could be explicitly specified as not private and may be passed on.
> 
> Thus when the mapping from sip:[e-mail] to 
> sip:[e-mail] when H-I entry (2) above is included could 
> also insert the Privacy header parameter in H-I entry (1).
> 
> Thus the message would appear as follows:
> 
> INVITE sip:sip:[e-mail]; user=phone;p=x
> Privacy: history
> History-Info:
> <sip:[e-mail]?Privacy=none;user=phone;p=x>;ind
> ex=1;rt;ao
> r
> History-Info: <sip:[e-mail]>;index=1.1;mp;aor
> History-Info: <sip:bob@192.0.2.3>;index=1.1.1;rc
> 
> This would result in all the H-I entries except (1) being considered 
> private with the result that the =1800... Number is passed for call 
> handling purposes.
> 
> This change is backward compatible with the existing implementation as

> any node using the existing functionality as defined in RFC4244 will 
> continue to be supported.
> 
> The alternative is to remove the ability to include the value 
> "history"
> in the Privacy header and only allow this value in the Privacy header 
> parameter. This alternative is not backward compatible.
> 
> Without this change a single node in the message path which includes a

> header "Privacy: history" will prevent delivery of the aor and thus 
> prevent proper call handling.
> 
> Ian Elz
> 
> 
> 
> -----Original Message-----
> From: Christer Holmberg
> Sent: 23 June 2009 19:40
> To: 'Mary Barnes'; Francois Audet; Hans Erik van Elburg; Shida 
> Schubert
> Cc: Ian Elz
> Subject: RE: 4244bis and privacy
> 
>  
> Hi,
> 
> I include Ian, so he can comment to your resposne himself.
> 
> Regards,
> 
> Christer
> 
> 
> -----Original Message-----
> From: Mary Barnes [mailto:[e-mail]]
> Sent: Tuesday, June 23, 2009 9:40 PM
> To: Christer Holmberg; Francois Audet; Hans Erik van Elburg; Shida 
> Schubert
> Subject: RE: 4244bis and privacy
> 
> Here was the thread of response and the last comment was from Ian that

> he would consider the response:
> http://www.ietf.org/mail-archive/web/sip/current/msg26948.html
> 
> And, there was not agreement on the "none" but rather to qualify the 
> SHOULD NOT forward.  However, in the sipcore-4244bis-00, rather than 
> changing the text such that the headers SHOULD be removed, we 
> recommend that they be anonymized (in section 4.3.3.3.1).  That is 
> entirely consistent with RFC 3324 and thus we have removed the 
> recommendations to remove the headers entirely. However, that changed 
> never got done in section 3.2, so we would need to change this:
>    "Thus, the History- Info header
>    SHOULD NOT be included in Requests where the requestor has 
> indicated
>    a priv-value of Session- or Header-level privacy."
> 
> But, I'm really beginning to be of the mindset that we should just 
> remove all the subsections of section 3 (i.e., leave the text in the 
> upper level section), so we don't have to keep worrying about 
> consistency.
> 
> So, lets either fixt the text in 3.2 or remove altogether and then I 
> think we are really at the point of needing to submit this version so 
> folks that actually have an interest in it can review the updated 
> document.
> 
> Mary. 
> 
> -----Original Message-----
> From: Christer Holmberg [mailto:[e-mail]]
> Sent: Tuesday, June 23, 2009 1:10 PM
> To: Barnes, Mary (RICH2:AR00); Audet, Francois (SC100:3055); Hans Erik

> van Elburg; Shida Schubert
> Subject: 4244bis and privacy
> 
> 
> Hi,
> 
> Below is a comment/proposal which one of my collegues (Ian
> Elz) gave on the list a while ago, when the first version of 4244bis 
> was submitted, but was not incorporated. Do you think it would be 
> useful?
> 
> -------
> 
> While the HI approach to target may solve the problem of being able to

> deliver the target URI to the final destination there is no guarantee 
> that it will actually be delivered.
> 
> The problem arises with how Privacy is defined for HI.
> 
> 4424 defines a new Privacy value "history" which may be placed in 
> either the Privacy header or as a header parameter to the HI entry.
> 
> If one node uses the former option "Privacy: history" then this will 
> make all headers private and will result in all HI entries being 
> removed or made anonymous when the message containing the HI is 
> delivered to the user.
> 
> There is a simple solution to this and that is to also allow the use 
> of the "none" Privacy value as a header parameter in the HI entry. 
> This would explicitly state that no privacy is required to the HI 
> entry and this would override a "history"
> value in the Privacy header.
> 
> I pointed this out to Mary when the 4424bis draft was first published 
> but the change has not been made in the latest draft.
> 
> The change is backward compatible and would not cause an issue with 
> any existing implementations.
> 
> ------
> 
> Regards,
> 
> Christer
> 
> 
> 
> 
>