Network Working Group                                          A. Barbir
Request for Comments: 3838                               Nortel Networks
Category: Informational                                       O. Batuner
                                                             Consultant
                                                                A. Beck
                                                    Lucent Technologies
                                                                T. Chan
                                                                  Nokia
                                                               H. Orman
                                              Purple Streak Development
                                                            August 2004


         Policy, Authorization, and Enforcement Requirements
              of the Open Pluggable Edge Services (OPES)

Status of this Memo

  This memo provides information for the Internet community.  It does
  not specify an Internet standard of any kind.  Distribution of this
  memo is unlimited.

Copyright Notice

  Copyright (C) The Internet Society (2004).

Abstract

  This document describes policy, authorization, and enforcement
  requirements for the selection of the services to be applied to a
  given Open Pluggable Edge Services (OPES) flow.




















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Table of Contents

  1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
  2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  3
  3.  Policy Architecture  . . . . . . . . . . . . . . . . . . . . .  4
      3.1.  Policy Components and Functions  . . . . . . . . . . . .  4
      3.2.  Requirements for Policy Decision Points. . . . . . . . .  5
      3.3.  Requirements for Policy Enforcement Points . . . . . . .  5
  4.  Requirements for Interfaces  . . . . . . . . . . . . . . . . .  6
      4.1.  Service Bindings Requirements  . . . . . . . . . . . . .  7
            4.1.1.  Environment Variables  . . . . . . . . . . . . .  7
            4.1.2.  Requirements for Using State Information . . . .  8
            4.1.3.  Requirements for Passing Information Between
                    Services . . . . . . . . . . . . . . . . . . . .  8
      4.2.  Requirements for Rule and Rules Management . . . . . . .  8
            4.2.1.  Requirements for Rule Providers  . . . . . . . .  8
            4.2.2.  Requirements for Rule Formats and Protocols  . .  9
            4.2.3.  Requirements for Rule Conditions . . . . . . . .  9
            4.2.4.  Requirements for Rule Actions  . . . . . . . . .  9
      4.3.  Requirements for Policy Expression . . . . . . . . . . . 10
  5.  Authentication of Principals and Authorization of Services . . 10
      5.1.  End users, Publishers and Other Considerations . . . . . 11
            5.1.1.  Considerations for End Users . . . . . . . . . . 11
            5.1.2.  Considerations for Publishing Sites. . . . . . . 12
            5.1.3.  Other Considerations . . . . . . . . . . . . . . 12
      5.2.  Authentication . . . . . . . . . . . . . . . . . . . . . 12
      5.3.  Authorization  . . . . . . . . . . . . . . . . . . . . . 13
      5.4.  Integrity and Encryption . . . . . . . . . . . . . . . . 14
            5.4.1.  Integrity and Confidentiality of Authentication
                    and Requests/Responses for Service . . . . . . . 14
            5.4.2.  Integrity and Confidentiality of Application
                    Content  . . . . . . . . . . . . . . . . . . . . 14
      5.5.  Privacy. . . . . . . . . . . . . . . . . . . . . . . . . 14
  6.  Security Considerations  . . . . . . . . . . . . . . . . . . . 15
  7.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 15
      7.1.  Normative References . . . . . . . . . . . . . . . . . . 15
      7.2.  Informative References . . . . . . . . . . . . . . . . . 15
  8.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 16
  9.  Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 16
  10. Full Copyright Statement . . . . . . . . . . . . . . . . . . . 17











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1.  Introduction

  The Open Pluggable Edge Services (OPES) [1]  architecture enables
  cooperative application services (OPES services) between a data
  provider, a data consumer, and zero or more OPES processors.  The
  application services under consideration analyze and possibly
  transform application-level messages exchanged between the data
  provider and the data consumer.  The OPES processor can distribute
  the responsibility of service execution by communicating and
  collaborating with one or more remote callout servers.

  The execution of such services is governed by a set of rules
  installed on the OPES processor.  The rule evaluation can trigger the
  execution of service applications local to the OPES processor or on a
  remote callout server.

  Policies express the goals of an OPES processor as a set of rules
  used to administer, manage, and control access to resources.  The
  requirements in this document govern the behavior of OPES entities in
  determining which of the available services are to be applied to a
  given message, if any.

  The scope of OPES policies described in this document are limited to
  those that describe which services to call and, if appropriate, with
  what parameters.  These policies do not include those that prescribe
  the behavior of the called services.  It is desirable to enable a
  common management framework for specifying policies for both the
  calling of and the behavior of a service.  The integration of such a
  function is the domain of policy administration user interaction
  applications.

  The document is organized as follows: Section 2 considers policy
  framework.  Section 3 discusses requirements for interfaces, while
  section 4 examines authentication of principals and authorization of
  services.

2.  Terminology

  The keywords "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
  "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
  document are to be interpreted as described in [4].  When used with
  the normative meanings, these keywords will be all uppercase.
  Occurrences of these words in lowercase comprise normal prose usage,
  with no normative implications.







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3.  Policy Architecture

  This section describes the architectural policy decomposition
  requirements.  It also describes the requirements for the interfaces
  between the policy components.  Many of the rules here were
  determined under the influence of RFC 3238 [2].

3.1.  Policy Components and Functions

  The policy functions are decomposed into three components: a Rule
  Author, a Policy Decision Point (PDP) [6], and a Policy Enforcement
  Point (PEP) [6].  The Rule Author provides the rules to be used by an
  OPES entity.  These rules control the invocation of services on
  behalf of the rule author.  The PDP and the PEP interpret the
  collected rules and appropriately enforce them.  The decomposition is
  illustrated in Figure 1.

        +--------+                         +--------+
        |  Rule  |                         |  Rule  |
        | Author |          ...            | Author |
        +--------+                         +--------+
             |                                 |
             |                                 |
             |          +----------+           |
             |          |  Policy  |           |  <- PDP Interface
             +--------->| Decision |<----------+
                        |  Point   |
                        +----------+
                            | ^
                            | |
                            | |  <- PEP Interface
                            | |
                            V |
                      +--------------+   ...
                 ---> |    Policy    | --->
                      |  Enforcement |       Data Traffic
                 <--- |    Point     | <---
                      +--------------+


                 Figure 1: Policy Components

  The decomposition of policy control into a PDP and a PEP permit the
  offloading of some tasks to an administrative service that may be
  located on a server separate from the real-time enforcement services
  of the PEP that reside on the OPES processor.





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  The PDP provides for the authentication and authorization of rule
  authors and the validation and compilation of rules.

  The PEP resides in the data filter where the data from an OPES flow
  is evaluated against the compiled rules and appropriate calls to the
  requested services are performed.

  Interfaces between these architectural components are points of
  interoperability.  The interface between rule authors and the policy
  decision points (PDP Interface) MUST use the format that may result
  from the requirements as described in this document.

  The interface between the policy decision points and the policy
  enforcement points (PEP Interface) can be internal to a specific
  vendor implementation of an OPES processor.  Implementations MUST use
  standard interface only if the PDP and the PEP reside on different
  OPES processors.

3.2.  Requirements for Policy Decision Points

  The Policy Decision Point is essentially a policy compiler.  The PDP
  MUST be a service that provides administrative support to the
  enforcement points.  The PDP service MUST authenticate the rule
  authors.

  The PDP MUST verify that the specified rules are within the scope of
  the rule authors authority.  The PDP MUST be a component of the OPES
  Administration Authority.

3.3.  Requirements for Policy Enforcement Points

  In the OPES architecture, the data filter represents a Policy
  Enforcement point (PEP).  At this point, data from an OPES flow is
  evaluated against the compiled rules, and appropriate calls to the
  requested services are performed.

  In the PEP rules MAY chain actions together, where a series of
  services to be called are specified.  Implementation MUST ensure the
  passing of information from one called service to another.
  Implementation MUST NOT prohibit the re-evaluation of a message to
  determine if another service or set of services should be called.

  The execution of an action (i.e., the triggering of a rule) may lead
  to the modification of message property values.  For example, an OPES
  service that under some circumstances converts JPEG images to GIF
  images modifies the content type of the requested web object.





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  Such modification of message property values may change the behavior
  of subsequently performed OPES actions.  The data filter SHOULD act
  on matched rules before it evaluates subsequent rules.  Multiple
  matched rules can be triggered simultaneously if the data filter can
  determine in advance that there are no side effects from the
  execution of any specific rule.

  A data filter MAY evaluate messages several times in the course of
  handling an OPES flow.  The rule processing points MAY be defined by
  administratively defined names.  The definition of such names can
  serve as a selector for policy rules to determine the applicability
  of a rule or a set of rules at each processing point.

  Policy roles ([5] and [6]) SHOULD be used where they aid in the
  development of the OPES policy model.

  Figure 2 expresses a typical message data flow between a data
  consumer application, an OPES processor, and a data provider
  application.  There are four commonly used processing points
  identified by the numbers 1 through 4.

           +--------+       +-----------+       +---------+
           |        |<------|4         3|<------|         |
           | Data   |       |  OPES     |       | Data    |
           |Consumer|       | Processor |       |Provider |
           |  Appl. |------>|1         2|------>| Appl.   |
           +--------+       +-----------+       +---------+


                Figure 2: Processing Execution Points

  Any data filter (PEP) or any administrative (PDP) implementation MUST
  support the four rule processing points.

  o  Data Consumer Request handling role: This involves request
     processing when received from a Data Consumer Application.
  o  OPES Processor Request handling role: This involves request
     processing before forwarding to Data Provider Application.
  o  Data Provider Response handling role: This involves response
     processing when forwarding to Data Consumer Application.
  o  OPES Processor Response handling role: This involves response
     processing when forwarding to Data Consumer Application.

4.  Requirements for Interfaces

  The interface between the policy system and OPES services needs to
  include the ability to pass system state information as well as the
  subject message.



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4.1.  Service Bindings Requirements

  The invoked OPES services MUST be able to be specified in a location
  independent fashion.  That is, the rule authors need not know and
  need not specify the instance of an OPES service in the rules.

  The rule author SHOULD be able to identify the required service at
  the detail level that is appropriate for his or her needs.  The rule
  author SHOULD be able to specify a type of service or be able to
  specify any service that fits a general category of service to be
  applied to its traffic.

  The binding of OPES service names to a specific service MAY be
  distributed between the PDP and the PEP.  As rules are compiled and
  validated by the PDP, they MUST be resolved to a specific
  installations' set of homogeneous OPES service.

  The selection of a specific instance MAY be postponed and left to PEP
  to select at either the rule installation time or at run time.  To
  achieve interoperability, PEP MUST support resolving a generic name
  to a specific instance.  It is possible to use services such as SLP
  or UDDI to resolve generic service names to specific OPES service
  instances.

  The policy system MAY support dynamic discovery of service bindings.
  The rule author may not know specific service bindings, such as
  protocol and parameters, when a rule (as specified on the PDP
  Interface) is general in nature.  The required binding information
  MUST be provided by the PDP and conveyed on the PEP Interface.  A
  service description methodology such as WSDL [8] MUST be present in
  the policy system.

4.1.1.  Environment Variables

  There may be a need to define and support a means for maintaining
  state information that can be used in both condition evaluation and
  action execution.  Depending on the execution environment, OPES
  services MAY have the freedom to define variables that are needed and
  use these variables to further define their service behavior without
  the data filter support.











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4.1.2.  Requirements for Using State Information

  Policy rules MAY specify that state information be used as part of
  the evaluation of the rules against a given message in an OPES flow.
  Thus, the policy system SHOULD support the maintenance of groups that
  can be used in evaluating rule conditions.  Membership in such groups
  can be used as action triggers.

  For example, an authorized site blocking service might conclude that
  a particular user shouldn't be permitted access to a certain web
  site.  Rather than calling the service for each request sent by such
  a user, a rule might be created to determine whether a user is a
  member of blocked users and if a requested site is a member of
  blocked-sites, and then invoke a local blocking service to return an
  appropriate message to the user.

4.1.3.  Requirements for Passing Information Between Services

  Environment variables can be used to pass state information between
  services.  For example, analysis of the request or modifications to
  the request may need to be captured as state information that can be
  passed to other services on the request path or to services on the
  response(s) associated with that request.

  In the PEP, there SHOULD be provisions to enable setting up variables
  when returning from a service call and passing variables to other
  called services based on policy.

4.2.  Requirements for Rule and Rules Management

  This section provides the requirements for rule management.  The
  rules are divided into two groups.  Some rules are provided by the
  data consumer application, and other rules are provided by the data
  provider application.

4.2.1.  Requirements for Rule Providers

  The requirements for rule providers are:

  o  Rule providers MUST be authenticated and authorized for rules that
     apply to their network role.
  o  Rule providers MUST NOT be able to specify rules that are NOT
     within their scope of authority.
  o  Rule providers SHOULD be able to specify only what is needed for
     their services.
  o  Compilation of rules from different sources MUST NOT lead to
     execution of conflicting rules.
  o  The resolution of such rule conflicts is out of scope.



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  o  Rules are assumed to be static and applied to current network
     state.

4.2.2.  Requirements for Rule Formats and Protocols

  It is desirable to choose standard technologies like XML to specify
  the rule language format.

  Rules need to be sent from the rule authors to the OPES
  administrative server for service authorization, rule validation, and
  compilation.  The mechanisms for doing that are out of scope of the
  current work.

  Once the rules are authorized, validated, and compiled by the
  administrative server, the rules need to be sent to the OPES
  processor.  The mechanisms for doing that are out of scope of the
  current work.

4.2.3.  Requirements for Rule Conditions

  Rule conditions MUST be matched against attribute values of the
  encapsulated protocol as well as environment variable values.
  Attribute values of the encapsulated protocol include protocol header
  values and possibly also protocol body values.

  Some OPES services may need to be invoked for all user requests or
  server responses, such as services with logging functionality, for
  example.  The rule system SHOULD allow unconditional rules rather
  than requiring rule authors to specify rule conditions that are
  always true.

4.2.4.  Requirements for Rule Actions

  The rule system MUST allow for the specification of rule actions that
  are triggered if the conditions of a rule are met.  Matched rules
  typically lead to the invocation of local or remote services.  Rule
  actions MUST identify the OPES service that is to be executed for the
  current message request or response.

  Rule actions MAY contain run-time parameters which can be used to
  control the behavior of an OPES service.  If specified, these
  parameters MUST be passed to the executed OPES service.









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4.3.  Requirements for Policy Expression

  OPES processors MUST enforce policy requirements set by data
  consumers and/or data publishers in accordance with the architecture
  [1] and this document.  They cannot do this consistently unless there
  are an unambiguous semantics and representation of the data elements
  mentioned in the policy.  For example, this document mentions
  protection of user "identity" and "profile" information.  If a user
  specifies that his identity must not be shared with other OPES
  administrative trust domains, and later discovers that his family
  name has been shared, he might complain.  If he were told that
  "family names are not considered 'identities' by this site", he would
  probably feel that he had cause for complaint.  Or, he might be told
  that when he selected "do not share identity" on a web form offered
  by the OPES service provider, that this only covered his login name,
  and that a different part of the form had to be filled out to protect
  the family name.  A further breakdown can occur if the configuration
  information provided by such a web form gets translated into
  configuration elements given to an OPES processor, and those
  configuration elements are difficult for a software engineer to
  translate into policy enforcement.  The data elements might have
  confusing names or be split into groupings that are difficult to
  relate to one another.

  The examples illustrate why the OPES policy MUST have definitions of
  data elements, their relationships, and how they relate to
  enforcement.  These semantics of essential items do not require a
  separate protocol, but they MUST be agreed upon by all OPES service
  providers, and the users of OPES services MUST be assured that they
  have the ability to know their settings, to change them if the
  service provider policy allows the changes, and to have reasonable
  assurance that they are enforced with reasonable interpretations.

  The requirements for policy data elements in the OPES specification
  do not have to be all-inclusive, but they MUST cover the minimal set
  of elements that enable the policies that protect the data of end
  users and publishers.

5.  Authentication of Principals and Authorization of Services

  This section considers the authorization and authentication of OPES
  services.









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5.1.  End Users, Publishers and Other Considerations

5.1.1.  Considerations for End Users

  An OPES rule determines which attributes of traffic will trigger the
  application of OPES services.  The author of the service can supply
  rules, but the author cannot supply the necessary part of the rule
  precondition that determines which network users will have the OPES
  services applied for them.  This section discusses how users are
  identified in the rule preconditions, and how users can select and
  deselect OPES services for their traffic, how an OPES service
  provider SHOULD identify the users, and how they determine whether or
  not to add their service selection to an OPES enforcement point.

  An OPES service provider MUST satisfy these major requirements:

  o  Allow all users to request addition, deletion, or blocking of OPES
     services for their traffic (blocking means "do not use this
     service for my traffic").
  o  Prevent untrusted users from causing OPES services to interfere
     with the traffic of other users.
  o  Allow users to see their OPES service profiles and notify them of
     changes.
  o  Keep a log of all profile activity for audit purposes.
  o  Adhere to a privacy policy guarding users' profiles.

  The administrator of the PDP is a trusted party and can set policy
  for individuals or groups using out-of-band communication and
  configuration files.  However, users MUST always be able to query the
  PDP in order to learn what rules apply to their traffic.

  Rules can be deposited in the PDP with no precondition relating to
  network users.  This is the way rules are packaged with an OPES
  service when it is delivered for installation.  The PDP is
  responsible for binding identities to the rules and transmitting them
  to the PEP.  The identity used by the PDP for policy decisions MUST
  be strictly mapped to the identity used by the PEP.  Thus, if a user
  goes through an identification and authentication procedure with the
  PDP and is known by identity "A", and if the PEP uses IP addresses
  for identities, then the PDP MUST provide the PEP with a binding
  between "A" and A's current IP address.










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5.1.2.  Considerations for Publishing Sites

  An OPES service provider acting on behalf of different publishing
  sites SHOULD keep all the above considerations in mind when
  implementing an OPES site.  Because each publishing site may be
  represented by only a single identity, the authentication and
  authorization databases may be easier for the PEP to handle.

5.1.3.  Other Considerations

  Authentication may be necessary between PDP's and PEP's, PEP's and
  callout servers, PEP's and other PEP's, and callout servers and other
  callout servers, for purposes of validating privacy policies.  In any
  case where user data or traffic crosses trust domain boundaries, the
  originating trust domain SHOULD have a policy describing which other
  domains are trusted, and it SHOULD authenticate the domains and their
  policies before forwarding information.

5.2.  Authentication

  When an individual selects (or deselects) an OPES service, the
  individual MUST be authenticated by the OPES service provider.  This
  means that a binding between the user's communication channel and an
  identity known to the service provider is made in a secure manner.
  This SHOULD be done using a strong authentication method with a
  public key certificate for the user; this will be helpful in
  resolving later disputes.  It is recommended that the service
  provider keep a log of all requests for OPES services.  The service
  provider SHOULD use public key certificates to authenticate responses
  to requests.

  The service provider may have trusted users who through explicit or
  implicit contract can assign, remove, or block OPES services for
  particular users.  The trusted users MUST be authenticated before
  being allowed to take actions which will modify the policy base, and
  thus, the actions of the PEP's.

  Because of the sensitivity of user profiles, the PEP Interface
  between the PEP and the PDP MUST use a secure transport protocol.
  The PEP's MUST adhere to the privacy preferences of the users.

  When an OPES service provider accepts an OPES service, there MUST be
  a unique name for the service provided by the entity publishing the
  service.  Users MAY refer to the unique name when requesting a
  service.  The unique name MUST be used when notifying users about
  their service profiles.  PEP's MUST be aware of the unique name for
  each service that can be accessed from their domain.  There MUST be a
  cryptographic binding between the unique name and the entity



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  responsible for the functional behavior of the service, i.e., if it
  is a human language translating service, then the name of company
  that wrote the software SHOULD be bound to the unique name.

5.3.  Authorization

  In addition to requesting or terminating specific services, users MAY
  block particular services, indicating that the services should not be
  applied to their traffic.  The "block all OPES" directive MUST be
  supported on a per user basis.

  A response to a request for an OPES service can be positive or
  negative.  Reasons for a negative response include "service unknown"
  or "service denied by PDP policy".  Positive responses SHOULD include
  the identity of the requestor and the service and the type of
  request.

  As described in the OPES Architecture [1], requests for OPES services
  originate in either the end user or the publisher domain.  The PDP
  bases its authorization decision on the requestor and the domain.
  There are some cases where the decision may be complicated.

  o  The end user has blocked a service, but a trusted user of the PDP
     wants it applied anyway.  In this case, the end user SHOULD
     prevail, unless there are security or legal reasons to leave it in
     place.
  o  The publisher and the end user are in the same domain.  If the
     publisher and end user are both clients of a PDP, can they make
     requests that effect each other's processing?  In this case, the
     PDP MUST have policy rules naming the identities that are allowed
     to set such rules.
  o  The publisher requests a service for an end user.  In this case,
     where the PDP and PEP are in the publisher's administrative
     domain, the publisher has some way of identifying the end user and
     his traffic, and the PDP MUST enable the PEP to enforce the
     policy.  This is allowed, but the PDP MUST use strong methods to
     identify the user and his traffic.  The user MUST be able to
     request and receive information about the service profile that a
     publisher site keeps about him.
  o  The end user requests a service specific to a publisher's identity
     (e.g., nfl.com), but the publisher prohibits the service (e.g.,
     through a "NO OPES" application header).  As in the case above,
     the publisher MUST be able to request and receive profile
     information that a user keeps about a publisher.

  In general, the PDP SHOULD keep its policy base in a manner that
  makes the decision procedure for all cases easy to understand.




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5.4.  Integrity and Encryption

5.4.1.  Integrity and Confidentiality of Authentication and Requests/
       Responses for Service

  The requests and responses SHOULD be cryptographically tied to the
  identities of the requestor and responder, and the messages SHOULD
  NOT be alterable without detection.  A certificate-based digital
  signature is strongly recommended as part of the authentication
  process.  A binding between the request and response SHOULD be
  established using a well-founded cryptographic means, to show that
  the response is made in reply to a specific request.

5.4.2.  Integrity and Confidentiality of Application Content

  As directed by the PEP, content will be transformed in whole or in
  part by OPES services.  This means that end-to-end cryptographic
  protections cannot be used.  This is probably acceptable for the vast
  majority of traffic, but in cases where a lesser form of content
  protection is desirable, hop-by-hop protections can be used instead.
  The requirements for such protections are:

  o  Integrity using shared secrets MUST be used between all processing
     points, end-to-end (i.e., the two ends of a "hop" MUST share a
     secret, but the secret can be different between "hops").  The
     processing points include the callout servers.
  o  Encryption can be requested separately, with the same secret
     sharing requirement between "hops".  When requested, encryption
     applies to all processing points, including callout servers.
  o  The signal for integrity (and optionally encryption) MUST
     originate from either the requestor (in which case it is applied
     to the response as well) or the responder (in which case it covers
     only the response).
  o  The shared secrets MUST be unique (to within a very large
     probabilistic certainty) for each requestor/responder pair.  This
     helps to protect the privacy of end user data from insider attacks
     or configuration errors while it transits the provider's network.

5.5.  Privacy

  The PDP MUST have a privacy policy regarding OPES data such as user
  profiles for services.  Users MUST be able to limit the promulgation
  of their profile data and their identities.

  Supported limitations MUST include:

  o  The ability to prevent Identity from being given to callout
     servers.



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  o  The ability to prevent Profile information from being shared.
  o  The ability to prevent Traffic data from being sent to callout
     servers run by third parties.
  o  The ability to prevent Traffic from particular sites from being
     given to OPES callout servers.

  When an OPES service is provided by a third-party, it MUST have a
  privacy policy and identify itself to upstream and downstream
  parties, telling them how to access its privacy policy.  A mechanism
  is needed to specify these preferences and a protocol to distribute
  them (see section 3.3).

6.  Security Considerations

  This document discusses policy, authorization and enforcement
  requirements of OPES.  In [3]  multiple security and privacy issues
  related to the OPES services are discussed.

7.  References

7.1.  Normative References

  [1]  Barbir, A., Penno, R., Chen, R., Hofmann, M., and H. Orman, "An
       Architecture for Open Pluggable Edge Services (OPES)", RFC 3835,
       August 2004.

  [2]  Floyd, S. and L. Daigle, "IAB Architectural and Policy
       Considerations for Open Pluggable Edge Services", RFC 3238,
       January 2002.

  [3]  Barbir, A., Batuner, O., Srinivas, B., Hofmann, M., and H.
       Orman, "Security Threats and Risks for Open Pluggable Edge
       Services (OPES)", RFC 3837, August 2004.

  [4]  Bradner, S., "Key words for use in RFCs to Indicate Requirement
       Levels", BCP 14, RFC 2119, March 1997.

  [5] Moore, B., Ellesson, E., Strassner, J., and A. Westerinen,
       "Policy Core Information Model -- Version 1 Specification", RFC
       3060, February 2001.

7.2.  Informative References

  [6]  Westerinen, A., Schnizlein, J., Strassner, J., Scherling, M.,
       Quinn, B., Herzog, S., Huynh, A., Carlson, M., Perry, J., and S.
       Waldbusser, "Terminology for Policy-Based Management", RFC 3198,
       November 2001.




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  [7]  Fielding, R., Gettys, J., Mogul, J., Frystyk, H., Masinter, L.,
       Leach, P., and T. Berners-Lee, "Hypertext Transfer Protocol --
       HTTP/1.1", RFC 2616, June 1999.

  [8]  Christensen, et al., Web Services Description Language (WSDL)
       1.1, W3C Note 15 March 2001, http://www.w3.org/TR/wsdl

8.  Acknowledgements

  Many thanks to Andreas Terzis, L. Rafalow (IBM), L. Yang (Intel), M.
  Condry (Intel), Randy Presuhn (Mindspring), and B. Srinivas (Nokia).

9.  Authors' Addresses

  Abbie Barbir
  Nortel Networks
  3500 Carling Avenue
  Nepean, Ontario  K2H 8E9
  Canada
  Phone: +1 613 763 5229
  EMail: [email protected]

  Oskar Batuner
  Consultant
  EMail: [email protected]

  Andre Beck
  Lucent Technologies
  101 Crawfords Corner Road
  Holmdel, NJ  07733
  USA
  EMail: [email protected]

  Tat Chan
  Nokia
  5 Wayside Road
  Burlington, MA  01803
  USA
  EMail: [email protected]

  Hilarie Orman
  Purple Streak Development
  EMail: [email protected]








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10.  Full Copyright Statement

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  to the rights, licenses and restrictions contained in BCP 78, and
  except as set forth therein, the authors retain all their rights.

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  INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
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Acknowledgement

  Funding for the RFC Editor function is currently provided by the
  Internet Society.









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