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Network Working Group                  Internet Architecture Board (IAB)Request for Comments: 3238                                      S. FloydCategory: Informational                                        L. Daigle                                                            January 2002IAB Architectural and Policy Considerations forOpen Pluggable Edge ServicesStatus 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 (2002).  All Rights Reserved.Abstract   This document includes comments and recommendations by the IAB on   some architectural and policy issues related to the chartering of   Open Pluggable Edge Services (OPES) in the IETF.  OPES are services   that would be deployed at application-level intermediaries in the   network, for example, at a web proxy cache between the origin server   and the client.  These intermediaries would transform or filter   content, with the explicit consent of either the content provider or   the end user.1.  Introduction   Open Pluggable Edge Services (OPES) are services that would be   deployed in the network, for example, at a web proxy cache between   the origin server and the client, that would transform or filter   content.  Examples of proposed OPES services include assembling   personalized web pages, adding user-specific regional information to   web pages, virus scanning, content adaptation for clients with   limited bandwidth, language translation, and the like [OPES].   The question of chartering OPES in the IETF ([OPESBOF1], [OPESBOF2],   [OPESBOF3]) and the related controversy in the IETF community   ([Carr01], [CDT01], [Morris01], [Orman01], [Routson01]) have raised   to the fore several architectural and policy issues about robustness   and the end-to-end integrity of data (in terms of the disparities   between what the "origin server" makes available and what the client   receives).  In particular, questions have been raised about the   possible requirements, for a protocol to be developed andIAB                          Informational                      [Page 1]

RFC 3238              IAB Considerations for OPES           January 2002   standardized in the IETF, for that protocol to protect the end-to-end   privacy and integrity of data.  This document attempts to address   some of the architectural and policy issues that have been unresolved   in the chartering of OPES, and to come to some common recommendations   from the IAB regarding these issues.   The purpose of this document is not to recommend specific solutions   for OPES, or even to mandate specific functional requirements.  This   is also not a recommendation to the IESG about whether or not OPES   should be chartered.  Instead, these are recommendations on issues   that any OPES solutions standardized in the IETF should be required   to address, similar to the "Security Considerations" currently   required in IETF documents [RFC2316].  As an example, one way to   address security issues is to show that appropriate security   mechanisms have been provided in the protocol, and another way to   address security issues is to demonstrate that no security issues   apply to this particular protocol.  (Note however that a blanket   sentence that "no security issues are involved" is never considered   sufficient to address security concerns in a protocol with known   security issues.)   This document will try to make our concerns underlying integrity,   privacy, and security as clear as possible.  We recommend that the   IESG require that OPES documents address integrity, privacy, and   security concerns in one way or another, either directly by   demonstrating appropriate mechanisms, or by making a convincing case   that there are no integrity or privacy concerns relevant to a   particular document.   In particular, it seems unavoidable that at some point in the future   some OPES service will perform inappropriately (e.g., a virus scanner   rejecting content that does not include a virus), and some OPES   intermediary will be compromised either inadvertently or with   malicious intent.  Given this, it seems necessary for the overall   architecture to help protect end-to-end data integrity by addressing,   from the beginning of the design process, the requirement of helping   end hosts to detect and respond to inappropriate behavior by OPES   intermediaries.   One of the goals of the OPES architecture must be to maintain the   robustness long cited as one of the overriding goals of the Internet   architecture [Clark88].  Given this, we recommend that the IESG   require that the OPES architecture protect end-to-end data integrity   by supporting end-host detection and response to inappropriate   behavior by OPES intermediaries.  We note that in this case by   "supporting end-host detection", we are referring to supporting   detection by the humans responsible for the end hosts at the content   provider and client.  We would note that many of these concerns aboutIAB                          Informational                      [Page 2]

RFC 3238              IAB Considerations for OPES           January 2002   the ability of end hosts to detect and respond to the inappropriate   behavior of intermediaries could be applied to the architectures for   web caches and content distribution infrastructures even without the   additional complication of OPES.   Each section of the document contains a set of IAB Considerations   that we would recommend be addressed by the OPES architecture.Section 6 summarizes by listing all of these considerations in one   place.   In this document we try to use terminology consistent withRFC 3040   [RFC 3040] and with OPES works in progress.2.  Some history of the controversy about chartering OPES   One view on OPES has been that "OPES is deeply evil and the IETF   should stay far, far away from this hideous abomination" [ODell01].   Others have suggested that "OPES would reduce both the integrity, and   the perception of integrity, of communications over the Internet, and   would significantly increase uncertainly about what might have been   done to content as it moved through the network", and that therefore   the risks of OPES outweigh the benefits [CDT01].  This view of the   risks of OPES was revised in later email, based on the proposals from   [Carr01], "assuming that certain privacy and integrity protections   can be incorporated into the goals of the working group" [Morris01].   One issue concerns the one-party consent model.  In the one-party   consent model, one of the end-nodes (that is, either the content   provider or the end user) is required to explicitly authorize the   OPES service, but authorization is not required from both parties.   [CDT01] comments that relying only on a one-party consent model in   the OPES charter "could facilitate third-party or state-sponsored   censorship of Internet content without the knowledge or consent of   end users", among other undesirable scenarios.   A natural first question is whether there is any architectural   benefit to putting specific services inside the network (e.g., at the   application-level web cache) instead of positioning all services   either at the content provider or the end user.  (Note that we are   asking here whether there is architectural benefit, which is not the   same as asking if there is a business model.)  Client-centric   services suggested for OPES include virus scanning, language   translation, limited client bandwidth adaptation, request filtering,   and adaptation of streaming media, and suggested server-centric   services include location-based services and personalized web pages.IAB                          Informational                      [Page 3]

RFC 3238              IAB Considerations for OPES           January 2002   It seems clear that there can indeed be significant architectural   benefit in providing some OPES services inside the network at the   application-level OPES intermediary.  For example, if some content is   already available from a local or regional web cache, and the end   user requires some transformation (such as adaptation to a limited-   bandwidth path) applied to that data, providing that service at the   web cache itself can prevent the wasted bandwidth of having to   retrieve more data from the content provider, and at the same time   avoid unnecessary delays in providing the service to the end user.   A second question is whether the architectural benefits of providing   services in the middle of the network outweigh the architectural   costs, such as the potential costs concerning data integrity.  This   is similar to the issues considered inRFC 3135 [RFC 3135] of the   relative costs and benefits of placing performance-enhancing proxies   (PEPs) in the middle of a network to address link-related   degradations.  In the case of PEPs, the potential costs include   disabling the end-to-end use of IP layer security mechanisms;   introducing a new possible point of failure that is not under the   control of the end systems; adding increased difficulty in diagnosing   and dealing with failures; and introducing possible complications   with asymmetric routing or mobile hosts.RFC 3135 carefully   considers these possible costs, the mitigations that can be   introduced, and the cases when the benefits of performance-enhancing   proxies to the user are likely to outweigh the costs.  A similar   approach could be applied to OPES services (though we do not attempt   that here).   A third question is whether an OPES service, designed primarily for a   single retrieval action, has an impact on the application layer   addressing architecture.  This is related to the integrity issue   above, but is independent of whether these services are applied in   the middle of the network or at either end.   Most of this document deals with the specific issue of data integrity   with OPES services, including the goal of enabling end hosts to   detect and respond to inappropriate behavior from broken or   compromised OPES intermediaries.   We agree that one-party consent, with one of the end-hosts explicitly   authorizing the OPES service, must be a requirement for OPES to be   standardized in the IETF.   However, as we discuss in the next section of this document, we agree   with [CDT01] that the one-party consent model by itself (e.g., with   one of the end-hosts authorizing the OPES service, and the other   end-host perhaps being unaware of the OPES service) is insufficient   for protecting data integrity in the network.  We also agree withIAB                          Informational                      [Page 4]

RFC 3238              IAB Considerations for OPES           January 2002   [CDT01] that, regardless of the security and authorization mechanisms   standardized for OPES in the IETF, OPES implementations could   probably be modified to circumvent these mechanisms, resulting in the   unauthorized modification of content.  Many of the protocols in the   IETF could be modified for anti-social purposes - transport protocols   could be modified to evade end-to-end congestion control, routing   protocols could be modified to inject invalid routes, web proxy   caches could be used for the unauthorized modification of content   even without OPES, and so on.  None of these seem like compelling   reasons not to standardize transport protocols, routing protocols,   web caching protocols, or OPES itself.  In our view, it means instead   that the infrastructure needs, as much as possible, to be designed to   detect and defend itself against compromised implementations, and   misuses of protocols need to be addressed directly, each in the   appropriate venue.   Mechanisms such as digital signatures, which help users to verify for   themselves that content has not been altered, are a first step   towards the detection of the unauthorized modification of content in   the network.  However, in the case of OPES, additional protection to   ensure the end-to-end integrity of data is desirable as well, for   example, to help end-users to detect cases where OPES intermediaries   were authorized to modify content, but perform inappropriate   modifications.  We would note that mechanisms can *help* end-users to   detect compromised OPES intermediaries in some cases even if they do   not *guarantee* that end-users will be able to detect compromised   OPES intermediaries in all cases.   If OPES is chartered, the OPES working group will also have to   explicitly decide and document whether the OPES architecture must be   compatible with the use of end-to-end encryption by one or more ends   of an OPES-involved session.  If OPES was compatible with end-to-end   encryption, this would effectively ensure that OPES boxes would be   restricted to ones that are known, trusted, explicitly addressed at   the IP layer, and authorized (by the provision of decryption keys) by   at least one of the ends.  Compatibility with end-to-end encryption   would also help to prevent the widespread deployment of yet another   set of services that, to benefit from, require one to keep one's   packet contents in the clear for all to snoop.   IAB Considerations:   (2.1) One-party consent: An OPES framework standardized in the IETF   must require that the use of any OPES service be explicitly   authorized by one of the application-layer end-hosts (that is, either   the content provider or the client).IAB                          Informational                      [Page 5]

RFC 3238              IAB Considerations for OPES           January 2002   (2.2) IP-layer communications: For an OPES framework standardized in   the IETF, the OPES intermediary must be explicitly addressed at the   IP layer by the end user.   We note that (2.2) is not intended to preclude a chain of   intermediaries, with the first intermediary in the chain explicitly   addressed at the IP layer by the end user.3.  End-to-end Integrity   The proposed OPES services have several possible forms, including   server-centric services, such as the dynamic assembling of web pages,   explicitly authorized by the content provider; client-centric   services such as virus scanning or language translation explicitly   authorized by the end user to act on the response from the content   provider; and client-centric services such as privacy-based services   or content-filtering explicitly authorized by the end user to act on   the request from the end user to the content provider.  We consider   the issue of the end-to-end integrity of data separately for these   different classes of services.   For each specific service, the question arises of whether it is   necessary for both the content provider and the end user to be able   to detect and respond to inappropriate behavior by OPES   intermediaries, or if it is sufficient for just one of the two end-   hosts to have this ability.  We don't attempt a general answer, but   we do discuss the issues further in the sections below.3.1.  Data integrity with client-centric OPES services on responses   Why is there any concern about the end-to-end integrity of data in a   client-centric OPES service acting on a response from a content   provider?  If the client requests a service such as virus scanning or   language translation, why is that of any concern to the content   provider one way or another?  One answer is that one of the proper   concerns of the IETF is to design architectures that enable end-hosts   to detect and respond to inappropriate actions in the network.  This   seems of particular importance for powerful devices in the network   such as OPES intermediaries, which are authorized by one of the end-   nodes to act on or transform data in the network, but other than that   are not under the direct control of that end-node.   Consider as an example the services of virus scanning or language   translation.  The end user has reasonable power in detecting and   dealing with imperfect or corrupted virus scanners or language   translators that are under her direct control (e.g., on her own   machine).  The end user knows exactly what program is installed, and   has direct access to the content before and after the service isIAB                          Informational                      [Page 6]

RFC 3238              IAB Considerations for OPES           January 2002   applied.  The end user would have less control over similar services   offered by OPES in the network itself, where the end user's only   control might be the binary one of authorizing or not authorizing the   service.  (We also note that services deployed on the end host in a   self-contained fashion, such as a local virus scanning program, are   not a service in the network, and therefore are not in the province   of the IETF one way or another.)   For a OPES service such as virus scanning or language translation,   the end user could detect a corrupted intermediary, but only through   a "black-box" approach of comparing the input with the output.  This   is also imprecise and requires some effort, compared to the effort   required to detect a corrupted virus scanner installed on one's own   machine.  For example, the user could retrieve the "non-OPES" version   of the content directly from the content provider, if there is a   "non-OPES" version, and compare this with the "OPES" version of the   content available from the OPES intermediary.  However, in the case   of dynamic content, the "non-OPES" version of the content retrieved   by the user directly from the content provider might not necessarily   be the same as the "non-OPES" version of the content considered by   the OPES intermediary.  This limited control by the end user of the   OPES service, and the limited ability of the end user to detect   imperfect or corrupted intermediaries, argues for an architecture   that helps the content provider to detect and respond to imperfect or   corrupted OPES intermediaries as well.   We consider the specific example of virus scanning, authorized by the   end user as an OPES service.  One could imagine virus scanning as a   widely deployed OPES service, augmenting the virus scanning done on   the end host itself.  If I ask for, say, a paper by Steve Bellovin on   security and viruses in the network, and am informed by my authorized   OPES virus-scanning service that this content does not pass the   virus-scan, there are a number of possibilities:   (1) Unknown to Steve, the content (that is, Steve's paper) contains a       harmful virus.   (2) Steve inserted a harmful virus in the content on purpose, with       playful or malicious intent.   (3) The OPES virus scanner can't distinguish between a true harmful       virus, and Steve's paper about harmful viruses.   (4) My local OPES virus scanner has been hacked, with malicious       intent, to reject all content from Steve Bellovin.IAB                          Informational                      [Page 7]

RFC 3238              IAB Considerations for OPES           January 2002   At some point, for some content, some widely-deployed implementation   of some OPES virus scanner is likely to result in problem (3), and   some OPES implementation is likely to be corrupted to result in   problem (4).  Because the end user has limited control over the OPES   virus scanner, the end user also is limited in its ability to detect   problems (3) or (4) in the OPES virus scanner.  In addition, the   content provider is probably the one with the strongest incentive to   detect problems (3) or (4) in the OPES virus scanner.  (The content   provider generally has a strong incentive to detect problem (1) as   well.)  In this case, it seems prudent that the overall OPES   architecture should be carefully designed to prevent the OPES service   of virus scanning, as authorized by the client, from unnecessarily   preventing the distribution of content that in fact does not have   viruses.   Obviously, it is not viable to propose that content providers simply   indicate that some content should be passed to the end user without   virus scanning - the point of virus scanning is for the end user to   exercise control in this regard.  However, if some form of end-system   notification allows the content provider to find out that the content   is being rejected by a virus scanning service instead of being   delivered to the end user, then the content provider (Steve, in this   case) might want to inform end users that this content is known by   the content provider not to pass some OPES virus scanning services.   End users could then make their own decisions about whether or not to   retrieve that content bypassing the OPES virus scanning service,   relying on their own virus scanner or an alternate virus scanning   service for this particular content.  Such end-system notification to   the content provider, if requested, cannot be enforced, and cannot be   relied upon from corrupted intermediaries, but it seems important   nevertheless.   Of course, malicious users can also use their awareness of the virus   scanning service to perfect their ability to construct malicious   viruses that can evade the virus scanning service.  This will be done   anyway, with any virus scanning service, and seems like an acceptable   cost to allow content providers some protection against the vagaries   of imperfect or corrupted OPES services in the network.   Thus, for client-requested services such as virus scanning and   language translation, it is clearly desirable for the origin server   to have notification, if it requests it, that these services are   being performed on its content before the content is sent to the   client.  Any such end-system notification might be accompanied by   reduced performance (in terms of overhead, delays, etc.) for the OPES   service applied to that content.  But some form of end-systemIAB                          Informational                      [Page 8]

RFC 3238              IAB Considerations for OPES           January 2002   notification is clearly necessary if content providers are to be able   to detect and respond to actions by OPES intermediaries that are   deemed inappropriate by the content provider.   Similarly for a client-based OPES service of language translation, it   is clearly desirable for content providers to be able to inform end   users when some content is deemed by the content provider to be   incompatible with language translation.  In this case, the important   issue is not to prevent the OPES language translation from being   performed on the content, but instead to give the content provider   some mechanism to discover the language translation, and to inform   the end user (or more precisely, to inform the end user's host   computer) if the content provider believes that this language   translation is incompatible with this particular content.   IAB Considerations:   (3.1) Notification: The overall OPES framework needs to assist   content providers in detecting and responding to client-centric   actions by OPES intermediaries that are deemed inappropriate by the   content provider.3.2.  Data integrity with server-centric OPES services   What are the concerns, if any, with the end-to-end integrity of data   in a server-centric OPES service such as location-based services?   For example, CNN could authorize a location-based OPES service, where   the OPES intermediary inserts the weather report or news headline of   regional interest into the requested web page.  The same issue of the   detection and response to broken or modified OPES intermediaries   occurs with server-centric OPES as with client-centric OPES services.   We only consider server-centric services on responses, as we are not   aware of any proposals for server-centric OPES services on requests   from the client to the content provider.   How are the end-nodes to detect inappropriate actions from OPES   services authorized by the content provider?  The OPES service is   being performed at an OPES intermediary in the network itself, and   not under the direct control of the content provider; in particular,   the content provider might not have the ability to monitor directly   the output of the OPES intermediary.  One could argue that the   content provider and server-centric OPES intermediary are part of a   single distributed application, and can be responsible on their own   for detecting and dealing with broken or modified OPES   intermediaries, without involving the end user.  But this is   unconvincing, basically arguing that standardizing protocols for   performing OPES services is a network issue properly in the domain of   the IETF, but the ensuring the overall integrity of the service is aIAB                          Informational                      [Page 9]

RFC 3238              IAB Considerations for OPES           January 2002   distributed application matter, and not in the province of the IETF   at all.  It would seem to us that you can't have it both ways.   Simply labeling the content provider and the OPES intermediary as   part of the same distributed application does not give the content   provider the ability to monitor the actions of the OPES intermediary.   However, if the end user receives some form of notification that   these OPES services have been provided, and has some mechanism for   receiving the "non-OPES" content from the content provider without   the OPES intermediary's modifications (if there is such a thing as a   non-OPES version of the content), then the end user is in a better   position to detect and react to inappropriate actions from   compromised or poorly-designed OPES intermediaries.  Thus, it is   clear that some form of end-system notification is required to allow   the end user to detect and respond to broken or modified OPES   intermediaries.  If the end user has notification of action by OPES   intermediaries, it could "veto" an OPES service simply by throwing   the OPES-modified content away.  And if the client wants to talk   directly to the origin server to receive the "non-OPES" version, and   the origin server is configured to allow this, then the OPES   intermediary must be designed to permit this end-to-end   communication.   In addition to concerns about detecting and responding to faulty or   compromised OPES intermediaries, there are purely policy-based   concerns about the integrity of data.  If the content provider looks   at the source IP address from the HTTP request, or tosses a coin, in   order to decide what content to provide, then that is the content   provider's business.  But if there exists a "non-OPES" version of   some content available from the content provider, and also modified   versions available from OPES intermediaries, then it is important   that end users would be able to discover that they are receiving a   modified version from the network, and not the "non-OPES" version   that is also available from the content provider directly.   IAB Considerations:   (3.2) Notification: The overall OPES framework should assist end   users in detecting the behavior of OPES intermediaries, potentially   allowing them to identify imperfect or compromised intermediaries.   (3.3) Non-blocking: If there exists a "non-OPES" version of content   available from the content provider, the OPES architecture must not   prevent users from retrieving this "non-OPES" version from the   content provider.IAB                          Informational                     [Page 10]

RFC 3238              IAB Considerations for OPES           January 20023.3.  Data integrity with client-centric OPES services on requests   There have also been proposals for OPES services authorized by the   client on requests from the client to the content provider.  Examples   include services that remove fields from the HTTP header for added   privacy, and content-filtering services that filter requests based on   the requested URL.  For such services, there is still a need for end   hosts to be assisted in detecting and responding to imperfect or   corrupted intermediaries, but it seems less clear to what extent this   applies to the content provider, and to what extent it applies to the   end user that authorized the service.  The requirements will probably   have to be determined by the OPES and wider IETF communities on a   case-by-case basis for each specific service.4.  Application Layer Addresses   Most application layer addressing revolves around URIs, which, for   the most part, give a structured method to refer to a single data   entity on a remote server.  URIs are universal in that, in principle,   the same result is obtained irrespective of the location of the   client performing the resolution.   Practice often differs from this theory -- ad-strippers remove data   from pages at the client end; web server farms redirect clients to   one of several potential target machines for load-balancing or to   give the user "localized" content.   However, from an architectural standpoint, it is important to be   clear about what is being done here.  In all cases, URI resolution   standards (as defined for individual URI schemes, such as HTTP) apply   unchanged between the client and the OPES intermediary.  What the   intermediary does to fulfill the request is not material to the   discussion, and must produce a result that is compliant with the   applicable URI scheme definition.  In this sense, the OPES   intermediary is the "endpoint" of URI resolution.   In client-centric OPES, the intermediary is resolving the URI on   behalf of the client, and then applying client-requested services to   provide a data response to the client.  The client gets the data it   wanted, but it did not carry out the URI resolution.   In server-centric OPES, the "origin server" cedes its authority to   the intermediary to determine what is the "appropriate" content to   supply for a given URI.   The client may well perform standard URI   resolution, but that reaches no further than the intermediary.   With those distinctions firmly in mind, there are two particular   areas of concern for OPES-like services.IAB                          Informational                     [Page 11]

RFC 3238              IAB Considerations for OPES           January 2002   The first is the consideration of the effect of a series of   interactions, over time and location (i.e., not just one document   retrieval).   Potential problems include inconsistencies in intra-   and inter-document references -- depending on what content is   changed, references from one version of a document might not exist in   a modified target, etc.   The other concern is whether this leads to the creation of content   that is exclusively accessible through the use of an intermediary.   That is, there is no "non-OPES" version.  Either this should not be   allowed, or this would argue for an extension to the Internet   application layer addressing architecture.   IAB Considerations:   (4.1) URI resolution: OPES documentation must be clear in describing   these services as being applied to the result of URI resolution, not   as URI resolution itself.   (4.2) Reference validity: All proposed services must define their   impact on inter- and intra-document reference validity.   (4.3) Any services that cannot be achieved while respecting the above   two considerations may be reviewed as potential requirements for   Internet application addressing architecture extensions, but must not   be undertaken as ad hoc fixes.5.  Privacy   Intermediaries in the middle of the network increase the number of   locations where the privacy of an end-to-end transaction could be   compromised.  Some of these privacy concerns apply to web caches and   CDNs in general as well as specifically to OPES intermediaries.  It   seems a reasonable requirement, for OPES to be chartered in the IETF,   that the issue of providing mechanisms for end users to determine the   privacy policies of OPES intermediaries should be addressed.  These   mechanisms could be quite different for client-centric and server-   centric OPES services.   For a complex issue such as an OPES architecture, which interacts   with protocols from other standards bodies as well as from other IETF   working groups, it seems necessary to keep in mind the overall   picture while, at the same time, breaking out specific parts of the   problem to be standardized in particular working groups.  Thus, a   requirement that the overall OPES architecture address privacy   concerns does not necessarily mean that the mechanisms for this need   to be developed in the IETF, or in the OPES working group (if it is   chartered).IAB                          Informational                     [Page 12]

RFC 3238              IAB Considerations for OPES           January 2002   IAB Considerations:   (5.1) Privacy: The overall OPES framework must provide for mechanisms   for end users to determine the privacy policies of OPES   intermediaries.6.  Summary of IAB Considerations   (2.1) One-party consent: An OPES framework standardized in the IETF   must require that the use of any OPES service be explicitly   authorized by one of the application-layer end-hosts (that is, either   the content provider or the client).   (2.2) IP-layer communications: For an OPES framework standardized in   the IETF, the OPES intermediary must be explicitly addressed at the   IP layer by the end user.   (3.1) Notification: The overall OPES framework needs to assist   content providers in detecting and responding to client-centric   actions by OPES intermediaries that are deemed inappropriate by the   content provider.   (3.2) Notification: The overall OPES framework should assist end   users in detecting the behavior of OPES intermediaries, potentially   allowing them to identify imperfect or compromised intermediaries.   (3.3) Non-blocking: If there exists a "non-OPES" version of content   available from the content provider, the OPES architecture must not   prevent users from retrieving this "non-OPES" version from the   content provider.   (4.1) URI resolution: OPES documentation must be clear in describing   these services as being applied to the result of URI resolution, not   as URI resolution itself.   (4.2) Reference validity: All proposed services must define their   impact on inter- and intra-document reference validity.   (4.3) Any services that cannot be achieved while respecting the above   two considerations may be reviewed as potential requirements for   Internet application addressing architecture extensions, but must not   be undertaken as ad hoc fixes.   (5.1) Privacy: The overall OPES framework must provide for mechanisms   for end users to determine the privacy policies of OPES   intermediaries.IAB                          Informational                     [Page 13]

RFC 3238              IAB Considerations for OPES           January 20027.  Conclusions   This document includes comments and recommendations by the IAB on   some architectural and policy issues related to the chartering of   OPES in the IETF.8.  Acknowledgements   This document has benefited from discussions with members of the IAB   and the IESG, contributors to OPES, John Wroclawski, and others.   However, this is a document of the IAB, and we do not claim that the   other people listed above agree with the contents.9.  References   [Carr01]    Wayne Carr, "Suggested OPES Requirements for Integrity,               Privacy and Security", email to ietf-openproxy@imc.org,               August 16, 2001.  URL "http://www.imc.org/ietf-openproxy/mail-archive/msg00869.html".   [CDT01]     Policy Concerns Raised by Proposed OPES Working Group               Efforts, email to the IESG, from the Center for Democracy               & Technology, August 3, 2001.  URL               "http://www.imc.org/ietf-openproxy/mail-archive/msg00828.html".   [Clark88]   David D. Clark, The Design Philosophy of the DARPA               Internet Protocols, SIGCOMM 1988.   [Morris01]  John Morris, "Re: corrected -  Suggested OPES               Requirements for Integrity, Privacy and Security",               September 28, 2001.  Email to ietf-openproxy@imc.org, URL               "http://www.imc.org/ietf-openproxy/mail-archive/msg00935.html".   [ODell01]   Mike O'Dell, "OPES continuing froth...", Message-Id:               <200107101341.JAA30276@ccr.org>, July 10, 2001, email to               ietf@ietf.org.  URL "http://www1.ietf.org/mail-archive/ietf/Current/msg12650.html".   [OPES]      Open Pluggable Edge Services (OPES) Web Page,               "http://www.ietf-opes.org/".   [OPESBOF1]  OPES BOF, 49th IETF, December 12, 2000.  Agenda:               "http://www.ietf.org/ietf/00dec/opes-agenda.txt".               Minutes:  "http://www.ietf.cnri.reston.va.us/proceedings/00dec/toc.htm#P25_256".IAB                          Informational                     [Page 14]

RFC 3238              IAB Considerations for OPES           January 2002   [OPESBOF2]  OPES BOF, 50th IETF, March 9, 2001.  Minutes:               "http://www.ietf.org/proceedings/01mar/ietf50-40.htm".   [OPESBOF3]  OPES BOF, 51st IETF, August 2001.  Agenda:               "http://www.ietf.org/ietf/01aug/opes.txt".  Minutes:               "http://www.ietf.org/proceedings/01aug/minutes/OPES.HTM".   [Orman01]   Hilarie Orman, "Data Integrity for Open Pluggable               Services", email to ietf-openproxy@imc.org, August 15,               2001.  URL "http://www.imc.org/ietf-openproxy/mail-archive/msg00865.html".   [RFC 2316]  Bellovin, S., "Report of the IAB Security Architecture               Workshop",RFC 2316, April 1998.   [RFC2401]   Kent, S. and R. Atkinson, "Security Architecture for the               Internet Protocol",RFC 2401, November 1998.   [RFC 3040]  Cooper, I., Melve, I. and G. Tomlinson, "Internet Web               Replication and Caching Taxonomy",RFC 3040, January               2001.   [RFC 3135]  Border, J., Kojo, M., Griner, J., Montenegro, G. and Z.               Shelby, "Performance Enhancing Proxies Intended to               Mitigate Link-Related Degradations",RFC 3135, June 2001.   [Routson01] Joyce Routson, IETF's Edge Standards Controversy, July               11, 2001, Stardust CDN Week.  URL               "http://www.stardust.com/cdnweek/articles/2001/07/09/opes.htm".10.  Security Considerations   This document does not propose any new protocols, and therefore does   not involve any security considerations in that sense.  However,   throughout this document there are discussions of the privacy and   integrity issues of OPES services and the architectural requirements   created by those issues.11.  IANA Considerations   There are no IANA considerations regarding this document.IAB                          Informational                     [Page 15]

RFC 3238              IAB Considerations for OPES           January 2002Authors' Addresses   Internet Architecture Board   EMail:  iab@iab.org   Membership at time this document was completed:   Harald Alvestrand   Ran Atkinson   Rob Austein   Fred Baker   Steve Bellovin   Brian Carpenter   Jon Crowcroft   Leslie Daigle   Steve Deering   Sally Floyd   Geoff Huston   John Klensin   Henning SchulzrinneIAB                          Informational                     [Page 16]

RFC 3238              IAB Considerations for OPES           January 200212.  Full Copyright Statement   Copyright (C) The Internet Society (2002).  All Rights Reserved.   This document and translations of it may be copied and furnished to   others, and derivative works that comment on or otherwise explain it   or assist in its implementation may be prepared, copied, published   and distributed, in whole or in part, without restriction of any   kind, provided that the above copyright notice and this paragraph are   included on all such copies and derivative works.  However, this   document itself may not be modified in any way, such as by removing   the copyright notice or references to the Internet Society or other   Internet organizations, except as needed for the purpose of   developing Internet standards in which case the procedures for   copyrights defined in the Internet Standards process must be   followed, or as required to translate it into languages other than   English.   The limited permissions granted above are perpetual and will not be   revoked by the Internet Society or its successors or assigns.   This document and the information contained herein is provided on an   "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING   TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING   BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION   HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.Acknowledgement   Funding for the RFC Editor function is currently provided by the   Internet Society.IAB                          Informational                     [Page 17]