PCP Authentication Requirements
Author(s): Reinaldo Penno, Dan Wing, Prashanth Patil, Tirumaleswar Reddy
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....
PCP Working Group T. Reddy Internet-Draft P. Patil Intended status: Standards Track D. Wing Expires: January 11, 2014 R. Penno Cisco July 10, 2013 PCP Authentication Requirements draft-reddy-pcp-auth-req-04 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. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on January 11, 2014. Copyright Notice Copyright (c) 2013 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as Reddy, et al. Expires January 11, 2014 [Page 1] Internet-Draft PCP Auth Requirements July 2013 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 . . . . . . . . . . . . . . . . . . . . . 7 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7 7. Security Considerations . . . . . . . . . . . . . . . . . . . . 7 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7 8.1. Normative References . . . . . . . . . . . . . . . . . . . 7 8.2. Informative References . . . . . . . . . . . . . . . . . . 7 Appendix A. Change History . . . . . . . . . . . . . . . . . . . . 8 A.1. Change from -01 to -02 . . . . . . . . . . . . . . . . . . 8 A.2. Change from -02 to -03 . . . . . . . . . . . . . . . . . . 8 A.3. Change from -03 to -04 . . . . . . . . . . . . . . . . . . 8 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8 Reddy, et al. Expires January 11, 2014 [Page 2] Internet-Draft PCP Auth Requirements July 2013 1. Introduction This document derives requirements for PCP Authentication from PCP deployment scenarios and scope described in [RFC6887] 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]. This note uses terminologies defined in [RFC4949] such as realm, security association, identity, credential etc. 3. Requirements REQ-1: PCP MUST provide client authentication. PCP client and server MUST also be able to mutually authenticate. Mutual authentication is especially necessary when the PCP server is located in a different administrative domain from the PCP client. Credentials to gain access to the network could be different from the credentials used to authenticate with the PCP server. * 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 might not be permitted to use the MAP opcode and only ADMINISTRATOR might be permitted to use the THIRD_PARTY option. * The identity details of the client could be used for auditing. REQ-2: PCP Authentication MUST generate security association for integrity protection of PCP request and response. This and all subsequent requirements are not applicable to multicast PCP responses like ANNOUNCE. REQ-3: A PCP server MUST be able to indicate that a request will not be processed without authentication. REQ-4: If a PCP client authenticates with a PCP server, A. The client MUST be able to verify the integrity and origin of responses from the server. Reddy, et al. Expires January 11, 2014 [Page 3] Internet-Draft PCP Auth Requirements July 2013 B. The server MUST be able to send authenticated unsolicited responses. C. If a PCP response does not include integrity related to a current security association, then those messages MUST NOT be trusted without soliciting an integrity protected version. D. The server MUST be able to trigger reauthentication with the client. The unsolicited message for authentication trigger MUST be integrity protected if there is a valid unexpired SA. REQ-5: It is important that PCP not leak privacy information between the PCP client and PCP server, A. The authentication mechanism MUST be able to keep credentials hidden from eavesdroppers on path between the client and server. B. 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 as explained in [RFC6887]. Other PCP drafts MUST evaluate if confidentiality is OPTIONAL for new PCP opcodes and options introduced. C. PCP authentication SHOULD be immune to passive dictionary attacks. D. PCP Authentication MUST ensure that an attacker snooping PCP messages cannot guess the SA. REQ-6: To ease troubleshooting and ensure fate sharing, PCP authentication and PCP messages MUST be multiplexed over the same port. REQ-7: 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-8: For the scenarios described in REQ-7, the PCP authentication mechanism MUST be functional across address and port translation, including NAPT64 and NAPT44. REQ-9: A PCP proxy that modifies PCP messages SHOULD have the ability to independently authenticate with the PCP client and PCP server. The presence of a PCP proxy hence requires two separately authenticates SAs. As a consequence, the PCP proxy: Reddy, et al. Expires January 11, 2014 [Page 4] Internet-Draft PCP Auth Requirements July 2013 +------------+ | | PCP Client |-----+ | +--(Host 1)--+ | +-----------+ | +----------+ +---| | | | | | PCP Proxy |-------|PCP Server| +---| | | | | +------------+ | +-----------+ | +----------+ | PCP Client |-----+ | +--(Host 2)--+ possible boundary <- Home side | ISP side -> A. MUST be able to validate message integrity of PCP messages from the PCP server and client respectively. B. MUST be able to ensure message integrity after updating the PCP message for cases described in sections 6 and 7 of [I-D.ietf-pcp-proxy]. The PCP proxy MUST also permit authentication on only one side of the proxy. For example, a customer premises host may not authenticate with the PCP proxy but the PCP proxy may authenticate with the PCP server. REQ-10: It is RECOMMENDED that PCP authentication support a mechanism where authentication on one port MUST be usable on other ports without requiring another authentication exchange for other ports. For example, there could multiple applications on the host like BitTorrent [BitTorrent], WebRTC[I-D.ietf-rtcweb-overview]/SIP [RFC 3261] using PCP. Multiple authentication exchanges increase load on the PCP server and chatter on the network. For example, if 'N' messages are to be exchanged for PCP authentication and 'M' independent applications implement their own PCP client, a total of N*M messages have to be exchanged and 'M' number of SAs maintained for each host. REQ-11: It is RECOMMENDED to choose a widely deployed authentication technique with known security properties rather than inventing a new authentication mechanism. REQ-12: Changes in PCP to accommodate authentication SHOULD be minimal so that updates and additions to the authentication mechanism have minimal bearing on modifying PCP. 4. Third Party Authorization REQ-13: In addition to a two party authentication that has been discussed in this draft, a mechanism for third party authorization Reddy, et al. Expires January 11, 2014 [Page 5] Internet-Draft PCP Auth Requirements July 2013 MUST also be supported. This is applicable in cases where a third party authorizes the use of a resource on a PCP server for a desired PCP client. For example, as depicted in Figure 1 , 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. The PCP server is to permit a PCP MAP request from the PCP client if the user is making a SIP call with the Enterprise or a trusted SIP server in 3rd party network, 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. ========================= | SIP Server | ========================= | 3rd Party Network | | ================== | WAN |-----+-+----+---+----+-+--- ================== | | | | | | | +-------+-------+ | | Firewall - | | | PCP Server | | +-------+-------+ | | | | | Network A | | Network B -+-+-----+-----------+-+-----+-------- -----+-+-------+------ | | +-+------+ +--------+ | Alice | | Bob | +--------+ +--------+ Users : Alice, Bob Figure 1: WebRTC server in a different administrative domain Reddy, et al. Expires January 11, 2014 [Page 6] Internet-Draft PCP Auth Requirements July 2013 5. Other recommendations REQ-14: There SHOULD be support for a means to provide integrity protection without user authentication, i.e., an anonymous client should be able to verify a PCP server using server-side-only auth and as a consequence obtain an SA which will be used for PCP message integrity. For example, a client visiting foreign networks such as a hotel, hot spot etc where the client may gain access to the network but does not know the credentials to authenticate with the PCP server. The negotiation of SA should be secure such that the SA is only known to the anonymous client and PCP server. 6. IANA Considerations This document does not require any action from IANA. 7. Security Considerations This entire document is about security considerations for PCP. 8. References 8.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC2119, March 1997. [RFC4949] Shirey, R., "Internet Security Glossary, Version 2", RFC4949, August 2007. [RFC6887] Wing, D., Cheshire, S., Boucadair, M., Penno, R., and P. Selkirk, "Port Control Protocol (PCP)", RFC6887, April 2013. 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-03 (work in progress), June 2013. Reddy, et al. Expires January 11, 2014 [Page 7] Internet-Draft PCP Auth Requirements July 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. [RFC 3261] 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. Appendix A. Change History A.1. Change from -01 to -02 o Requirements reorganized based on commonality o New requirement 3(c(2)) added. A.2. Change from -02 to -03 o Merged REQ-1 and REQ-7 o Updated Section 5 "Other recommendations" A.3. Change from -03 to -04 o Updated REQ-4, REQ-9 and REQ-14. Authors' Addresses Tirumaleswar Reddy Cisco Systems, Inc. Cessna Business Park, Varthur Hobli Sarjapur Marathalli Outer Ring Road Bangalore, Karnataka 560103 India Email: email@example.com Reddy, et al. Expires January 11, 2014 [Page 8] Internet-Draft PCP Auth Requirements July 2013 Prashanth Patil Cisco Systems, Inc. Bangalore India Email: firstname.lastname@example.org Dan Wing Cisco Systems, Inc. 170 West Tasman Drive San Jose, California 95134 USA Email: email@example.com Reinaldo Penno Cisco Systems, Inc. 170 West Tasman Drive San Jose, California 95134 USA Email: firstname.lastname@example.org Reddy, et al. Expires January 11, 2014 [Page 9]