PCP Working Group T. Reddy
Internet-Draft P. Patil
Intended status: Standards Track D. Wing
Expires: August 29, 2013 R. Penno
Cisco
February 25, 2013
PCP Authentication Requirements
draft-reddy-pcp-auth-req-01
Abstract
In an attempt to reach consensus on a PCP authentication mechanism,
this document describes requirements for PCP authentication. It is
hoped this can serve as the basis for a comparison of PCP
authentication mechanisms.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on August 29, 2013.
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described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Requirements . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Third Party Authorization . . . . . . . . . . . . . . . . . . . 5
5. Other recommendations . . . . . . . . . . . . . . . . . . . . . 6
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6
7. Security Considerations . . . . . . . . . . . . . . . . . . . . 6
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6
8.1. Normative References . . . . . . . . . . . . . . . . . . . 6
8.2. Informative References . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 7
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1. Introduction
This document derives requirements for PCP Authentication from PCP
deployment scenarios and scope described in PCP-base
[I-D.ietf-pcp-base] and other PCP drafts. The document focuses on
requirements and does not make a suggestion on the authentication
mechanism to be used to satisfy requirements.
2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
3. Requirements
REQ-1: PCP client and server MUST provide client authentication.
The client could be a host running a PCP client or middle box
(e.g., NAT) running a PCP Proxy.
* The identity details of the client could be used by the PCP
server to grant access to certain PCP opcodes or PCP options.
For example GUESTS would not be permitted to use MAP opcode,
ADMINISTRATOR is only permitted to use THIRD_PARTY option.
* The identity details of the client could be used for auditing.
PCP Authentication MUST also generate message authentication key
for integrity protection of PCP request and response.
REQ-2: PCP Servers MUST be able to indicate that a request will not
be processed without authentication.
REQ-3: PCP allows a server to send multiple responses. To properly
support that model with authentication, a client that sends an
authenticated request MUST be able to verify the integrity and
origin of an subsequent unsolicited response should it choose to
do so.
REQ-4: PCP allows a server to send multiple responses. If the
original request/response exchange was authenticated, a server
MUST be able to send a subsequent authenticated unsolicited
Response.
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REQ-5: PCP allows a server to send multiple responses. If the
server wants to send an unsolicited message, but the previous
security association has expired, the server MUST be able to
trigger re-authentication with the client.
REQ-6: Clients that have authenticated with the server MUST verify
the integrity of the contents of all unsolicited responses.
REQ-7: If there are circumstances where PCP responses do not include
integrity related to a current security association, then those
messages MUST NOT be trusted without soliciting an integrity
protected version.
REQ-8: It is important that PCP not leak privacy information between
the PCP client and the PCP server(s). Thus, the PCP
authentication MUST NOT exchange the PCP clients authentication
credentials in clear text. For example, exchanging the PCP
username in clear text would violate this requirement.
REQ-9: Confidentiality of the PCP messages is OPTIONAL for PCP
request and response of opcodes MAP, PEER, ANNOUNCE and options
THIRD_PARTY, PREFER_FAILURE and FILTER explained in PCP-base
[I-D.ietf-pcp-base]. Other PCP drafts MUST evaluate if
confidentiality is OPTIONAL or not for new PCP opcodes and options
introduced.
REQ-10: The authentication mechanism SHOULD be immune to passive
dictionary attacks.
REQ-11: PCP Authentication MUST ensure that an attacker snopping the
PCP messages cannot guess the SA.
REQ-12: To ease troubleshooting and ensure fate sharing, the PCP
authentication and PCP messages MUST be multiplexed over the same
port.
REQ-13: PCP authentication MUST accommodate authentication between
administrative domains. For example, a PCP client may wish to
communicate directly to an ISP's PCP server, even though the in-
home CPE router does not support PCP. In this scenario the PCP
client needs to directly authenticate with the ISP's PCP server.
REQ-14: PCP client MUST be able to ascertain that it is talking to
the right PCP server, especially when PCP server is located in a
different administrative domain.
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REQ-15: For the scenarios described in REQ-13, PCP authentication
mechanism MUST be functional across address and port translation,
including NAPT64 and NAPT44.
REQ-16: If a PCP client and server desire authentication then a PCP
proxy, that modifies PCP request/response before forwarding
messages, MUST validate message integrity of PCP messages from the
PCP server and client respectively.
+------------+ |
| PCP Client |-----+ |
+--(Host 1)--+ | +-----------+ | +----------+
+---| | | | |
| PCP Proxy |-------|PCP Server|
+---| | | | |
+------------+ | +-----------+ | +----------+
| PCP Client |-----+ |
+--(Host 2)--+ possible boundary
<- Home side | ISP side ->
REQ-17: PCP Proxy must also ensure message integrity after updating
the PCP message for cases described in sections 6 and 7 of
[I-D.ietf-pcp-proxy].
REQ-18: PCP authentication SHOULD support a mechanism where only one
PCP client on the host will authenticate with the PCP server and
any other PCP clients SHOULD be able to reuse the previously
negotiated key for integrity protection. For example, multiple
applications on the host like BitTorrent [BitTorrent],
WebRTC[I-D.ietf-rtcweb-overview]/SIP [RFC3261] using PCP.
REQ-19: All else equal, it is RECOMMENDED to choose a widely
deployed authentication technique with known security properties
rather than inventing a new authentication mechanism.
REQ-20: Changes in PCP to accommodate authentication SHOULD be
minimal so that updates and additions to the authentication
mechanism have no bearing on modifying PCP.
4. Third Party Authorization
In addition to two party authentication that has been discussed in
this draft, a mechanism for third party authorization must also be
supported. This is required in cases where a third party authorizes
the use of a resource on a PCP server for a desired PCP client. For
example, a PCP request to a PCP capable firewall authorized by a SIP
proxy rather than by virtue of the end user making the PCP request.
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The PCP server is to permit a PCP MAP request if a user is making a
SIP call with the Enterprise SIP server, otherwise do not allow MAP
request from that particular user. In this scenario the first party
is the user, second party is the PCP server (which is also the
firewall) and the third party is the SIP Server, where the user is
authorized to use MAP request only when making a call using the
trusted SIP Server.
5. Other recommendations
o Upon receiving a challenge with a certain REALM, if the PCP client
does not have credentials for that REALM, it SHOULD attempt to use
the username GUEST and password GUEST. The GUEST credentials are
expected to be configured on infrastructure where PCP
authentication is not necessary, but such guest users are given
some (minimal) authorization to use PCP. This addresses the
problem when the client is visiting foreign networks like hotel,
hot spot etc where it may gain access to the network but does not
know the credentials to authenticate to the ISP's PCP server when
the in-home CPE router does not support PCP and the PCP client
needs to directly authenticate with the ISP's PCP server (REQ-14).
6. IANA Considerations
This document does not require any action from IANA.
7. Security Considerations
This document does not define an architecture nor a protocol; as such
it does not raise any security concerns.
8. References
8.1. Normative References
[I-D.ietf-pcp-base]
Wing, D., Cheshire, S., Boucadair, M., Penno, R., and P.
Selkirk, "Port Control Protocol (PCP)",
draft-ietf-pcp-base-29 (work in progress), November 2012.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
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8.2. Informative References
[BitTorrent]
"Cohen, B., "The BitTorrent Protocol Specification Version
11031", February 2008.", September 2012.
[I-D.ietf-pcp-proxy]
Boucadair, M., Penno, R., and D. Wing, "Port Control
Protocol (PCP) Proxy Function", draft-ietf-pcp-proxy-02
(work in progress), February 2013.
[I-D.ietf-rtcweb-overview]
Alvestrand, H., "Overview: Real Time Protocols for Brower-
based Applications", draft-ietf-rtcweb-overview-06 (work
in progress), February 2013.
[RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
A., Peterson, J., Sparks, R., Handley, M., and E.
Schooler, "SIP: Session Initiation Protocol", RFC 3261,
June 2002.
Authors' Addresses
Tirumaleswar Reddy
Cisco Systems, Inc.
Cessna Business Park, Varthur Hobli
Sarjapur Marathalli Outer Ring Road
Bangalore, Karnataka 560103
India
Email: tireddy@cisco.com
Prashanth Patil
Cisco Systems, Inc.
Bangalore
India
Email: praspati@cisco.com
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Dan Wing
Cisco Systems, Inc.
170 West Tasman Drive
San Jose, California 95134
USA
Email: dwing@cisco.com
Reinaldo Penno
Cisco Systems, Inc.
170 West Tasman Drive
San Jose, California 95134
USA
Email: repenno@cisco.com
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