< draft-ietf-simple-presence-09.txt   draft-ietf-simple-presence-10.txt >
Internet Engineering Task Force SIMPLE WG Internet Engineering Task Force SIMPLE WG
Internet Draft J. Rosenberg Internet Draft J. Rosenberg
dynamicsoft dynamicsoft
draft-ietf-simple-presence-09.txt draft-ietf-simple-presence-10.txt
December 6, 2002 January 31, 2003
Expires: June 2003 Expires: July 2003
A Presence Event Package for the Session Initiation Protocol (SIP) A Presence Event Package for the Session Initiation Protocol (SIP)
STATUS OF THIS MEMO STATUS OF THIS MEMO
This document is an Internet-Draft and is in full conformance with This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026. all provisions of Section 10 of RFC2026.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that Task Force (IETF), its areas, and its working groups. Note that
skipping to change at page 2, line 12 skipping to change at page 2, line 12
notification framework. This protocol is also compliant with the notification framework. This protocol is also compliant with the
Common Presence Profile (CPP) framework. Common Presence Profile (CPP) framework.
Table of Contents Table of Contents
1 Introduction ........................................ 3 1 Introduction ........................................ 3
2 Terminology ......................................... 3 2 Terminology ......................................... 3
3 Definitions ......................................... 3 3 Definitions ......................................... 3
4 Overview of Operation ............................... 5 4 Overview of Operation ............................... 5
5 Usage of Presence URIs .............................. 6 5 Usage of Presence URIs .............................. 6
6 Presence Event Package .............................. 7 6 Presence Event Package .............................. 8
6.1 Package Name ........................................ 7 6.1 Package Name ........................................ 8
6.2 Event Package Parameters ............................ 7 6.2 Event Package Parameters ............................ 8
6.3 SUBSCRIBE Bodies .................................... 8 6.3 SUBSCRIBE Bodies .................................... 8
6.4 Subscription Duration ............................... 8 6.4 Subscription Duration ............................... 9
6.5 NOTIFY Bodies ....................................... 8 6.5 NOTIFY Bodies ....................................... 9
6.6 Notifier Processing of SUBSCRIBE Requests ........... 9 6.6 Notifier Processing of SUBSCRIBE Requests ........... 10
6.6.1 Authentication ...................................... 9 6.6.1 Authentication ...................................... 10
6.6.2 Authorization ....................................... 10 6.6.2 Authorization ....................................... 11
6.7 Notifier Generation of NOTIFY Requests .............. 11 6.7 Notifier Generation of NOTIFY Requests .............. 12
6.8 Subscriber Processing of NOTIFY Requests ............ 12 6.8 Subscriber Processing of NOTIFY Requests ............ 13
6.9 Handling of Forked Requests ......................... 12 6.9 Handling of Forked Requests ......................... 13
6.10 Rate of Notifications ............................... 13 6.10 Rate of Notifications ............................... 14
6.11 State Agents ........................................ 13 6.11 State Agents ........................................ 14
6.11.1 Aggregation, Authentication, and Authorization ...... 13 6.11.1 Aggregation, Authentication, and Authorization ...... 14
6.11.2 Migration ........................................... 14 6.11.2 Migration ........................................... 15
7 Learning Presence State ............................. 15 7 Learning Presence State ............................. 16
7.1 Co-location ......................................... 15 7.1 Co-location ......................................... 16
7.2 REGISTER ............................................ 15 7.2 REGISTER ............................................ 16
7.3 Uploading Presence Documents ........................ 16 7.3 Uploading Presence Documents ........................ 17
8 Example Message Flow ................................ 16 8 Example Message Flow ................................ 17
9 Security Considerations ............................. 19 9 Security Considerations ............................. 20
9.1 Confidentiality ..................................... 19 9.1 Confidentiality ..................................... 20
9.2 Message Integrity and Authenticity .................. 20 9.2 Message Integrity and Authenticity .................. 21
9.3 Outbound Authentication ............................. 20 9.3 Outbound Authentication ............................. 22
9.4 Replay Prevention ................................... 21 9.4 Replay Prevention ................................... 22
9.5 Denial of Service Attacks Against Third Parties ..... 21 9.5 Denial of Service Attacks Against Third Parties ..... 22
9.6 Denial Of Service Attacks Against Servers ........... 22 9.6 Denial Of Service Attacks Against Servers ........... 23
10 IANA Considerations ................................. 22 10 IANA Considerations ................................. 23
11 Contributors ........................................ 22 11 Contributors ........................................ 23
12 Acknowledgements .................................... 24 12 Acknowledgements .................................... 25
13 Authors Addresses ................................... 24 13 Authors Addresses ................................... 25
14 Normative References ................................ 25 14 Normative References ................................ 25
15 Informative References .............................. 25 15 Informative References .............................. 26
1 Introduction 1 Introduction
Presence, also known as presence information, conveys the ability and Presence, also known as presence information, conveys the ability and
willingness of a user to communicate across a set of devices. RFC willingness of a user to communicate across a set of devices. RFC
2778 [10] defines a model and terminology for describing systems that 2778 [10] defines a model and terminology for describing systems that
provide presence information. In that model, a presence service is a provide presence information. In that model, a presence service is a
system that accepts, stores, and distributes presence information to system that accepts, stores, and distributes presence information to
interested parties, called watchers. A presence protocol is a interested parties, called watchers. A presence protocol is a
protocol for providing a presence service over the Internet or any IP protocol for providing a presence service over the Internet or any IP
skipping to change at page 7, line 7 skipping to change at page 7, line 7
accomplished by sending a SUBSCRIBE request with an immediate accomplished by sending a SUBSCRIBE request with an immediate
expiration. expiration.
5 Usage of Presence URIs 5 Usage of Presence URIs
A presentity is identified in the most general way through a presence A presentity is identified in the most general way through a presence
URI [3], which is of the form pres:user@domain. These URIs are URI [3], which is of the form pres:user@domain. These URIs are
protocol independent. They are resolved to protocol specific URIs, protocol independent. They are resolved to protocol specific URIs,
such as a SIP or SIPS URI, through domain-specific mapping policies. such as a SIP or SIPS URI, through domain-specific mapping policies.
It is very possible that a user will have both a SIP (and/or SIPS)
URI and a pres URI to identify both themself and other users. This
leads to questions about how these URI relate and which are to be
used.
In some instances, a user starts with one URI format, such as the
pres URI, and learns a URI in a different format through some
protocol means. As an example, a SUBSCRIBE request sent to a pres URI
will result in learning a SIP or SIPS URI for the presentity from the
Contact header field of the 200 OK to the SUBSCRIBE request. As
another example, a DNS mechanism might be defined that would allow
lookup of a pres URI to obtain a SIP or SIPS URI. In cases where one
URI is learned from another through protocol means, those means will
often provide some kind of scoping that limit the lifetime of the
learned URI. DNS, for example, provides a TTL which would limit the
scope of the URI. These scopes are very useful to avoid stale or
conflicting URIs for identifying the same resource. To ensure that a
user can always determine whether a learned URI is still valid, it is
RECOMMENDED that systems which provide lookup services for presence
URIs have some kind of scoping mechanism.
If a subscriber is only aware of the protocol-independent pres URI If a subscriber is only aware of the protocol-independent pres URI
for a presentity, it follows the procedures defined in [5]. These for a presentity, it follows the procedures defined in [5]. These
procedures will result in the placement of the pres URI in the procedures will result in the placement of the pres URI in the
Request-URI of the SIP request, followed by the usage of the DNS Request-URI of the SIP request, followed by the usage of the DNS
procedures defined in [5] to determine the host to send the SIP procedures defined in [5] to determine the host to send the SIP
request to. Of course, a local outbound proxy may alternatively be request to. Of course, a local outbound proxy may alternatively be
used, as specified in RFC 3261 [1]. If the subscriber is aware of used, as specified in RFC 3261 [1]. If the subscriber is aware of
both the protocol-independent pres URI and the SIP or SIPS URI for both the protocol-independent pres URI and the SIP or SIPS URI for
the same presentity, it SHOULD use the SIP or SIPS URI. the same presentity, and both are valid (as discussed above) it
SHOULD use the pres URI format. Of course, if the subscriber only
knows the SIP URI for the presentity, that URI is used, and standard
RFC 3261 processing will occur.
SUBSCRIBE messages also contain logical identifiers that define the SUBSCRIBE messages also contain logical identifiers that define the
originator and recipient of the subscription (the To and From header originator and recipient of the subscription (the To and From header
fields). These SHOULD contain SIP or SIPS URIs whenever possible, but fields). These headers can take either a pres or SIP URI. When the
MAY contain a pres URI if a SIP or SIPS URI is not known or subscriber is aware of both a pres and SIP URI for its own identity,
available. it SHOULD use the pres URI in the From header field. Similarly, when
the subscriber is aware of both a pres and a SIP URI for the desired
presentity, it SHOULD use the pres URI in the To header field.
The usage of the pres URI instead of the SIP URI within the SIP
message supports interoperability through gateways to other CPP-
compliant systems. It provides a protocol-independent form of
identification which can be passed between systems. Without such an
identity, gateways would be forced to map SIP URIs into the
addressing format of other protocols. Generally, this is done by
converting the SIP URI to the form <foreign-protocol-scheme>:<encoded
SIP URI>@<gateway>. This is commonly done in email systems, and has
many known problems. The usage of the pres URI is a SHOULD, and not a
MUST, to allow for cases where it is known that there are no gateways
present, or where the usage of the pres URI will cause
interoperability problems with SIP components that do not support the
pres URI.
The Contact, Record-Route and Route fields do not identify logical The Contact, Record-Route and Route fields do not identify logical
entities, but rather concrete ones used for SIP messaging. SIP [1] entities, but rather concrete ones used for SIP messaging. SIP [1]
specifies rules for their construction. specifies rules for their construction.
6 Presence Event Package 6 Presence Event Package
The SIP event framework [2] defines a SIP extension for subscribing The SIP event framework [2] defines a SIP extension for subscribing
to, and receiving notifications of, events. It leaves the definition to, and receiving notifications of, events. It leaves the definition
of many aspects of these events to concrete extensions, known as of many aspects of these events to concrete extensions, known as
skipping to change at page 8, line 4 skipping to change at page 8, line 39
The name of this package is "presence". As specified in RFC 3265 [2], The name of this package is "presence". As specified in RFC 3265 [2],
this value appears in the Event header field present in SUBSCRIBE and this value appears in the Event header field present in SUBSCRIBE and
NOTIFY requests. NOTIFY requests.
Example: Example:
Event: presence Event: presence
6.2 Event Package Parameters 6.2 Event Package Parameters
The SIP event framework allows event packages to define additional The SIP event framework allows event packages to define additional
parameters carried in the Event header field. This package, presence, parameters carried in the Event header field. This package, presence,
does not define any additional parameters. does not define any additional parameters.
6.3 SUBSCRIBE Bodies 6.3 SUBSCRIBE Bodies
A SUBSCRIBE request MAY contain a body. The purpose of the body A SUBSCRIBE request MAY contain a body. The purpose of the body
depends on its type. Subscriptions will normally not contain bodies. depends on its type. Subscriptions will normally not contain bodies.
The Request-URI, which identifies the presentity, combined with the The Request-URI, which identifies the presentity, combined with the
event package name, is sufficient for presence. event package name, is sufficient for presence.
We anticipate that document formats could be defined to act as One type of body that can be included in a SUBSCRIBE request is a
filters for subscriptions. These filters would request that only filter document. These filters request that only certain presence
certain presence events generate notifications, or would ask for a events generate notifications, or would ask for a restriction on the
restriction on the set of data returned in NOTIFY requests. For set of data returned in NOTIFY requests. For example, a presence
example, a presence filter might specify that the notifications filter might specify that the notifications should only be generated
should only be generated when the status of the user's instant inbox when the status of the user's instant inbox [10] changes. It might
[10] changes. It might also say that the content of these also say that the content of these notifications should only contain
notifications should only contain the status of the instant inbox. the status of the instant inbox. Filter documents are not specified
in this document, and at the time of writing, are expected to be the
subject of future standardization activity.
Honoring of these filters is at the policy discretion of the PA. Honoring of these filters is at the policy discretion of the PA.
If the SUBSCRIBE request does not contain a body, this tells the PA If the SUBSCRIBE request does not contain a filter, this tells the PA
that no filter is to be applied. The PA SHOULD send NOTIFY requests that no filter is to be applied. The PA SHOULD send NOTIFY requests
at the discretion of its own policy. at the discretion of its own policy.
6.4 Subscription Duration 6.4 Subscription Duration
User presence changes as a result of many events. Some examples are: User presence changes as a result of many events. Some examples are:
o Turning on and off of a cell phone o Turning on and off of a cell phone
o Modifying the registration from a softphone o Modifying the registration from a softphone
skipping to change at page 9, line 10 skipping to change at page 10, line 4
6.5 NOTIFY Bodies 6.5 NOTIFY Bodies
As described in RFC 3265 [2], the NOTIFY message will contain bodies As described in RFC 3265 [2], the NOTIFY message will contain bodies
that describe the state of the subscribed resource. This body is in a that describe the state of the subscribed resource. This body is in a
format listed in the Accept header field of the SUBSCRIBE, or a format listed in the Accept header field of the SUBSCRIBE, or a
package-specific default if the Accept header field was omitted from package-specific default if the Accept header field was omitted from
the SUBSCRIBE. the SUBSCRIBE.
In this event package, the body of the notification contains a In this event package, the body of the notification contains a
presence document. This document describes the presence of the presence document. This document describes the presence of the
presentity that was subscribed to. All subscribers MUST support the presentity that was subscribed to. All subscribers and notifiers MUST
"application/cpim-pidf+xml" presence data format described in [6]. support the "application/cpim-pidf+xml" presence data format
The subscribe request MAY contain an Accept header field. If no such described in [6]. The subscribe request MAY contain an Accept header
header field is present, it has a default value of field. If no such header field is present, it has a default value of
"application/cpim-pidf+xml". If the header field is present, it MUST "application/cpim-pidf+xml". If the header field is present, it MUST
include "application/cpim-pidf+xml", and MAY include any other types include "application/cpim-pidf+xml", and MAY include any other types
capable of representing user presence. capable of representing user presence.
6.6 Notifier Processing of SUBSCRIBE Requests 6.6 Notifier Processing of SUBSCRIBE Requests
Based on the proxy routing procedures defined in the SIP Based on the proxy routing procedures defined in the SIP
specification, the SUBSCRIBE request will arrive at a presence agent specification, the SUBSCRIBE request will arrive at a presence agent
(PA). This subsection defines package-specific processing at the PA (PA). This subsection defines package-specific processing at the PA
of a SUBSCRIBE request. General processing rules for requests are of a SUBSCRIBE request. General processing rules for requests are
skipping to change at page 9, line 36 skipping to change at page 10, line 30
User presence is highly sensitive information. Because the User presence is highly sensitive information. Because the
implications of divulging presence information can be severe, strong implications of divulging presence information can be severe, strong
requirements are imposed on the PA regarding subscription processing, requirements are imposed on the PA regarding subscription processing,
especially related to authentication and authorization. especially related to authentication and authorization.
6.6.1 Authentication 6.6.1 Authentication
A presence agent MUST authenticate all subscription requests. This A presence agent MUST authenticate all subscription requests. This
authentication can be done using any of the mechanisms defined in RFC authentication can be done using any of the mechanisms defined in RFC
3261 [1]. 3261 [1]. Note that digest is mandatory to implement, as specified in
RFC 3261.
In single-domain systems, where the subscribers all have shared In single-domain systems, where the subscribers all have shared
secrets with the PA, the combination of digest authentication over secrets with the PA, the combination of digest authentication over
Transport Layer Security (TLS) [7] provides a secure and workable Transport Layer Security (TLS) [7] provides a secure and workable
solution for authentication. This use case is described in Section solution for authentication. This use case is described in Section
26.3.2.1 of RFC 3261 [1]. 26.3.2.1 of RFC 3261 [1].
In inter-domain scenarios, establishing an authenticated identity of In inter-domain scenarios, establishing an authenticated identity of
the subscriber is harder. It is anticipated that authentication will the subscriber is harder. It is anticipated that authentication will
often be established through transitive trust. SIP mechanisms for often be established through transitive trust. SIP mechanisms for
skipping to change at page 20, line 48 skipping to change at page 21, line 45
It is important for the message recipient to ensure that the message It is important for the message recipient to ensure that the message
contents are actually what was sent by the originator, and that the contents are actually what was sent by the originator, and that the
recipient of the message be able to determine who the originator recipient of the message be able to determine who the originator
really is. This applies to both requests and responses of SUBSCRIBE really is. This applies to both requests and responses of SUBSCRIBE
and NOTIFY. NOTIFY requests are particularly important. Without and NOTIFY. NOTIFY requests are particularly important. Without
authentication and integrity, presence documents could be forged or authentication and integrity, presence documents could be forged or
modified, fooling the watcher into believing incorrect presence modified, fooling the watcher into believing incorrect presence
information. information.
To deal with this problem, SIPs authentication and message integrity RFC 3261 provides many mechanisms to provide these features. In order
features can be used. SIP provides http digest for authentication, for the PA to authenticate the watcher, it MAY use HTTP Digest
and S/MIME for authentication and integrity. (Section 22 of RFC 3261). As a result, all watchers MUST support HTTP
Digest. This is a redundant requirement, however, since all SIP user
agents are mandated to support it by RFC 3261. To provide
authenticity and integrity services, a watcher MAY use the SIPS
scheme when subscribing to the presentity. To support this, all PA
MUST support TLS and SIPS as if they were a proxy (see Section 26.3.1
of RFC 3261).
Furthermore, SMIME MAY be used for integrity and authenticity of
SUBSCRIBE and NOTIFY requests. This is described in Section 23 of RFC
3261.
9.3 Outbound Authentication 9.3 Outbound Authentication
When local proxies are used for transmission of outbound messages, When local proxies are used for transmission of outbound messages,
proxy authentication is RECOMMENDED. This is useful to verify the proxy authentication is RECOMMENDED. This is useful to verify the
identity of the originator, and prevent spoofing and spamming at the identity of the originator, and prevent spoofing and spamming at the
originating network. originating network.
9.4 Replay Prevention 9.4 Replay Prevention
Replay attacks can be used by an attacker to fool a watcher into Replay attacks can be used by an attacker to fool a watcher into
believing an outdated presence state for a presentity. For example, a believing an outdated presence state for a presentity. For example, a
document describing a presentity as being "offline" can be replayed, document describing a presentity as being "offline" can be replayed,
fooling watchers into thinking that the user is never online. This fooling watchers into thinking that the user is never online. This
may effectively block communications with the presentity. may effectively block communications with the presentity.
SIP S/MIME can provide message integrity and authentication over SIP SIP S/MIME can provide message integrity and authentication over SIP
request bodies. This capability can be used to prevent these replay request bodies. Watchers and PAs MAY implement S/MIME signatures to
attacks. When it is used for that purpose, the presence document prevent these replay attacks. When it is used for that purpose, the
carried in the NOTIFY request MUST contain a timestamp. In the case presence document carried in the NOTIFY request MUST contain a
of PIDF, this is accomplished using the timestamp element, as timestamp. In the case of PIDF, this is accomplished using the
described in Section 6 of [6]. Tuples whose timestamp is older than timestamp element, as described in Section 6 of [6]. Tuples whose
the timestamp of the most recently received presence document SHOULD timestamp is older than the timestamp of the most recently received
be considered stale, and discarded. presence document SHOULD be considered stale, and discarded.
Finally, HTTP digest authentication MAY be used to prevent replay Finally, HTTP digest authentication (which MUST be implemented by
attacks, when there is a shared secret between the PA and the watchers and PAs) MAY be used to prevent replay attacks, when there
watcher. In such a case, the watcher can challenge the NOTIFY is a shared secret between the PA and the watcher. In such a case,
requests with the auth-int quality of protection. the watcher can challenge the NOTIFY requests with the auth-int
quality of protection.
9.5 Denial of Service Attacks Against Third Parties 9.5 Denial of Service Attacks Against Third Parties
Denial of Service (DOS) attacks are a critical problem for an open, Denial of Service (DOS) attacks are a critical problem for an open,
inter-domain, presence protocol. Unfortunately, presence is a good inter-domain, presence protocol. Unfortunately, presence is a good
candidate for Distributed DoS (DDOS) attacks because of its candidate for Distributed DoS (DDOS) attacks because of its
amplification properties. A single SUBSCRIBE message could generate a amplification properties. A single SUBSCRIBE message could generate a
nearly unending stream of notifications, so long as a suitably nearly unending stream of notifications, so long as a suitably
dynamic source of presence data can be found. Thus, a simple way to dynamic source of presence data can be found. Thus, a simple way to
launch an attack against a target is to send subscriptions to a large launch an attack against a target is to send subscriptions to a large
skipping to change at page 24, line 22 skipping to change at page 25, line 31
13 Authors Addresses 13 Authors Addresses
Jonathan Rosenberg Jonathan Rosenberg
dynamicsoft dynamicsoft
72 Eagle Rock Avenue 72 Eagle Rock Avenue
First Floor First Floor
East Hanover, NJ 07936 East Hanover, NJ 07936
email: jdrosen@dynamicsoft.com email: jdrosen@dynamicsoft.com
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.
14 Normative References 14 Normative References
[1] J. Rosenberg, H. Schulzrinne, G. Camarillo, A. Johnston, J. [1] J. Rosenberg, H. Schulzrinne, G. Camarillo, A. R. Johnston, J.
Peterson, R. Sparks, M. Handley, and E. Schooler, "SIP: session Peterson, R. Sparks, M. Handley, and E. Schooler, "SIP: session
initiation protocol," RFC 3261, Internet Engineering Task Force, June initiation protocol," RFC 3261, Internet Engineering Task Force, June
2002. 2002.
[2] A. B. Roach, "Session initiation protocol (sip)-specific event [2] A. B. Roach, "Session initiation protocol (sip)-specific event
notification," RFC 3265, Internet Engineering Task Force, June 2002. notification," RFC 3265, Internet Engineering Task Force, June 2002.
[3] D. Crocker et al. , "Common profile: Presence," Internet Draft, [3] D. H. Crocker and J. Peterson, "Common profile: Presence,"
Internet Engineering Task Force, Oct. 2002. Work in progress. internet draft, Internet Engineering Task Force, Dec. 2002. Work in
progress.
[4] S. Bradner, "Key words for use in RFCs to indicate requirement [4] S. Bradner, "Key words for use in rfcs to indicate requirement
levels," RFC 2119, Internet Engineering Task Force, Mar. 1997. levels," RFC 2119, Internet Engineering Task Force, Mar. 1997.
[5] D. Crocker et al. , "Address resolution for instant messaging [5] D. H. Crocker and J. Peterson, "Address resolution for instant
and presence," Internet Draft, Internet Engineering Task Force, Oct. messaging and presence," internet draft, Internet Engineering Task
2002. Work in progress. Force, Dec. 2002. Work in progress.
[6] H. Sugano and S. Fujimoto, "Common presence and instant messaging [6] H. Sugano, S. Fujimoto, et al. , "Common presence and instant
(CPIM)presence information data format," Internet Draft, Internet messaging (cpim)presence information data format," internet draft,
Engineering Task Force, Nov. 2002. Work in progress. Internet Engineering Task Force, Jan. 2003. Work in progress.
[7] T. Dierks and C. Allen, "The TLS protocol version 1.0," RFC 2246, [7] T. Dierks and C. Allen, "The TLS protocol version 1.0," RFC 2246,
Internet Engineering Task Force, Jan. 1999. Internet Engineering Task Force, Jan. 1999.
[8] J. Rosenberg, "A session initiation protocol (SIP)event [8] J. Rosenberg, "A watcher information event template-package for
template-package for watcher information," Internet Draft, Internet the session initiation protocol (SIP)," internet draft, Internet
Engineering Task Force, May 2002. Work in progress. Engineering Task Force, Dec. 2002. Work in progress.
[9] H. Schulzrinne and J. Rosenberg, "Session initiation protocol [9] H. Schulzrinne and J. Rosenberg, "Session initiation protocol
(SIP) caller preferences and callee capabilities," Internet Draft, (SIP) caller preferences and callee capabilities," internet draft,
Internet Engineering Task Force, Nov. 2002. Work in progress. Internet Engineering Task Force, Nov. 2002. Work in progress.
15 Informative References 15 Informative References
[10] M. Day, J. Rosenberg, and H. Sugano, "A model for presence and [10] M. Day, J. Rosenberg, and H. Sugano, "A model for presence and
instant messaging," RFC 2778, Internet Engineering Task Force, Feb. instant messaging," RFC 2778, Internet Engineering Task Force, Feb.
2000. 2000.
[11] J. Peterson, "Enhancements for authenticated identity management [11] J. Peterson, "Enhancements for authenticated identity management
in the session initiation protocol (SIP)," Internet Draft, Internet in the session initiation protocol (SIP)," internet draft, Internet
Engineering Task Force, Oct. 2002. Work in progress. Engineering Task Force, Oct. 2002. Work in progress.
[12] P. Calhoun et al. , "Diameter base protocol," Internet Draft, [12] P. Calhoun et al. , "Diameter base protocol," internet draft,
Internet Engineering Task Force, Oct. 2002. Work in progress. Internet Engineering Task Force, Jan. 2003. Work in progress.
[13] M. Day, S. Aggarwal, G. Mohr, and J. Vincent, "Instant messaging [13] M. Day, S. Aggarwal, G. Mohr, and J. Vincent, "Instant messaging
/ presence protocol requirements," RFC 2779, Internet Engineering / presence protocol requirements," RFC 2779, Internet Engineering
Task Force, Feb. 2000. Task Force, Feb. 2000.
[14] P. Gutmann, "Password-based encryption for CMS," RFC 3211, [14] P. Gutmann, "Password-based encryption for CMS," RFC 3211,
Internet Engineering Task Force, Dec. 2001. Internet Engineering Task Force, Dec. 2001.
Intellectual Property Statement
The IETF takes no position regarding the validity or scope of any
intellectual property or other rights that might be claimed to
pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights
might or might not be available; neither does it represent that it
has made any effort to identify any such rights. Information on the
IETF's procedures with respect to rights in standards-track and
standards-related documentation can be found in BCP-11. Copies of
claims of rights made available for publication and any assurances of
licenses to be made available, or the result of an attempt made to
obtain a general license or permission for the use of such
proprietary rights by implementors or users of this specification can
be obtained from the IETF Secretariat.
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights which may cover technology that may be required to practice
this standard. Please address the information to the IETF Executive
Director.
Full Copyright Statement
Copyright (c) The Internet Society (2003). 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.
 End of changes. 28 change blocks. 
112 lines changed or deleted 142 lines changed or added

This html diff was produced by rfcdiff 1.48. The latest version is available from http://tools.ietf.org/tools/rfcdiff/