INTERNET-DRAFTInternet Engineering Task Force (IETF) L. Fang, Ed.Intended Status: InformationalRequest for Comments: 6941 CiscoExpires: August 25, 2013Category: Informational B. Niven-Jenkins, Ed. ISSN: 2070-1721 Velocix S. Mansfield, Ed. Ericsson R. Graveman, Ed. RFG SecurityFebruary 25,April 2013MPLS-TPMPLS Transport Profile (MPLS-TP) Security Frameworkdraft-ietf-mpls-tp-security-framework-09Abstract This document provides a security framework forMultiprotocol Label Switchingthe MPLS Transport Profile (MPLS-TP). MPLS-TP extends MPLS technologies and introduces newOAMOperations, Administration, and Maintenance (OAM) capabilities, atransport- orientedtransport-oriented path protection mechanism, and strong emphasis on static provisioning supported by network management systems. This document addresses the security aspects relevant in the context of MPLS-TP specifically. It describes potential securitythreats, security requirements for MPLS-TP, andthreats as well as mitigation proceduresforrelated to MPLS-TP networks and to MPLS-TP interconnection to other MPLS and GMPLS networks. This document is built onRFC5920 "MPLSRFC 5920 ("Security Framework for MPLS and GMPLSsecurity framework"Networks") by providing additional security considerationswhichthat are applicable to the MPLS-TP extensions. All the security considerations fromRFC5920RFC 5920 are assumed to apply. This document is a product of a joint Internet Engineering Task Force (IETF) / International Telecommunication Union Telecommunication Standardization Sector (ITU-T) effort to include an MPLS Transport Profile within the IETF MPLS andPWE3Pseudowire Emulation Edge-to-Edge (PWE3) architectures to support the capabilities and functionality of a packet transport network. Status ofthisThis Memo ThisInternet-Draftdocument issubmitted to IETF in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documentsnot an Internet Standards Track specification; it is published for informational purposes. This document is a product of the Internet Engineering Task Force(IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. Internet-Drafts are draft documents valid for a maximum(IETF). It represents the consensus ofsix monthsthe IETF community. It has received public review andmay be updated, replaced, or obsoletedhas been approved for publication byotherthe Internet Engineering Steering Group (IESG). Not all documentsatapproved by the IESG are a candidate for anytime. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The listlevel of Internet Standard; see Section 2 of RFC 5741. Information about the currentInternet-Drafts can be accessed at http://www.ietf.org/1id-abstracts.html The liststatus ofInternet-Draft Shadow Directories canthis document, any errata, and how to provide feedback on it may beaccessedobtained athttp://www.ietf.org/shadow.htmlhttp://www.rfc-editor.org/info/rfc6941. Copyrightand LicenseNotice 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 described in the Simplified BSD License. Table of Contents 1. Introduction. . . . . . . . . . . . . . . . . . . . . . . . . 3....................................................3 1.1. Terminology. . . . . . . . . . . . . . . . . . . . . . . . 3................................................3 2. Security Reference Models. . . . . . . . . . . . . . . . . . . 4.......................................4 2.1. Security Reference Model 1. . . . . . . . . . . . . . . . 4.................................5 2.2. Security Reference Model 2. . . . . . . . . . . . . . . . 6.................................6 3. Security Threats. . . . . . . . . . . . . . . . . . . . . . . 8................................................9 4. Defensive Techniques. . . . . . . . . . . . . . . . . . . . . 9...........................................10 5. Security Considerations. . . . . . . . . . . . . . . . . . . . 10........................................12 6.IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 11 7.Acknowledgements. . . . . . . . . . . . . . . . . . . . . . . 11 8................................................13 7. References. . . . . . . . . . . . . . . . . . . . . . . . . . 11 8.1......................................................13 7.1. Normative References. . . . . . . . . . . . . . . . . . . 11 8.2.......................................13 7.2. Informative References. . . . . . . . . . . . . . . . . . 11 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 12 Contributors' Addresses . . . . . . . . . . . . . . . . . . . . . 12....................................13 Contributors ......................................................14 1. Introduction This document provides a security framework forMultiprotocol Label Switchingthe MPLS Transport Profile (MPLS-TP). As defined inMPLS-TP Requirements"Requirements of an MPLS Transport Profile" [RFC5654] andMPLS-TP"A Framework for MPLS in Transport Networks" [RFC5921], MPLS-TP uses a subset of MPLS features and introduces extensions to reflect the characteristics of the transport technology. The additional functionalityincludeincludes in-band OAM, transport-oriented path protection and recovery mechanisms, and new OAM capabilities that were developed for MPLS-TP but that also apply togeneralMPLS and GMPLS. There is strong emphasis in MPLS-TP on static provisioning support throughnetwork management systems (NMS)Network Management Systems (NMSs) orOperationOperational Support Systems(OSS).(OSSs). This document is built onRFC 5920[RFC5920] by providing additional security considerationswhichthat are applicable to the MPLS-TP extensions. The security models, threats,requirements,and defense techniques previously defined in [RFC5920] are assumed to apply to generalaspectaspects of MPLS-TP. This document is a product of a joint Internet Engineering Task Force (IETF) / International Telecommunication Union Telecommunication Standardization Sector (ITU-T) effort to include an MPLS Transport Profile within the IETF MPLS and PWE3 architectures to support the capabilities and functionality of a packet transport network. Readers can refer to [RFC5654] and [RFC5921] for MPLS-TPterminologies,terminologies and to [RFC5920] for security terminologieswhichthat are relevant to MPLS and GMPLS. 1.1. Terminology Term Definition ------ ----------------------------------------------- AC Attachment Circuit BFD Bidirectional Forwarding Detection CECustomer-Edge deviceCustomer Edge DoS Denial of Service G-ACh Generic Associated Channel GAL G-ACh Label GMPLS GeneralizedMulti-ProtocolMultiprotocol Label Switching IP Internet Protocol LDP Label Distribution Protocol LSP Label Switched Path NMS Network Management System MPLSMultiProtocolMultiprotocol Label Switching MPLS-TPMultiProtocol Label SwitchingMPLS Transport Profile MS-PW Multi-Segment Pseudowire OAM Operations, Administration, and Maintenance PEProvider-Edge deviceProvider Edge PSN Packet-Switched Network PW Pseudowire S-PE PW Switching Provider Edge SP Service Provider SS-PW Single-Segment Pseudowire T-PE PW Terminating Provider Edge 2. Security Reference Models This section defines reference models for security in MPLS-TP networks. The models are built on the architecture ofMPLS-TPMPLS-TP, as defined in [RFC5921]. The placement ofService Provider (SP)SP boundaries plays an important role in determining the security models for any particular deployment. This document defines a trusted zone as being where a single SP has total operational control over that part of the network. A primary concern is about security aspects that relate to breaches of security from the "outside" of a trusted zone to the "inside" of this zone. 2.1. Security Reference Model 1 In reference model 1, a single SP has total control of thePE/T-PE"PE/T-PE toPE/T-PEPE/T-PE" part of the MPLS-TP network. Security reference model 1(a)Anshows an MPLS-TP network withSingle SegmentSingle-Segment Pseudowire (SS-PW) from PE1 to PE2. The trusted zone is PE1 toPE2PE2, as illustrated in Figure 1. |<-------------- Emulated Service ---------------->| | | | |<-------Pseudo Wire ------>|Pseudowire ------->| | | | | | | | |<-- PSN Tunnel -->| | | | v v v v | v AC +----+ +----+ AC v +-----+ | | PE1|==================| PE2| | +-----+ | |----------|............PW1.............|----------| | | CE1 | | | | | | | | CE2 | | |----------|............PW2.............|----------| | +-----+ ^ | | |==================| | | ^ +-----+ ^ | +----+ +----+ | | ^ | | Provider Edge 1 Provider Edge 2 | | | | | | Customer | |Customer Edge 1 | |Edge 2 | | Native service Native service ---Untrusted--- >|<------- Trusted Zone ----->|<---Untrusted---- Figure 1. MPLS-TP Security Model 1(a) Security reference model 1(b)Anshows an MPLS-TP network with Multi-Segment Pseudowire (MS-PW) from T-PE1 to T-PE2. The trusted zone is T-PE1 toT-PE2T-PE2, as illustrated in Figure 2. Native |<-------------Pseudowire------------>| Native Service | | Service (AC) | |<- PSN ->| |<- PSN ->| | (AC) | v v v v v v | | +-----+ +-----+ +-----+ | +----+ | |T-PE1|=========|S-PE1|=========|T-PE2| | +----+ | |------|......PW.Seg't1.......PW.Seg't3......|-------| | | CE1| | | | | | | | | |CE2 | | |------|......PW.Seg't2.......PW.Seg't4......|-------| | +----+ | | |=========| |=========| | | +----+ ^ +-----+ ^ +-----+ ^ +-----+ ^ | | | | | TP LSP TP LSP | | | |<----------------- Emulated Service ---------------->| -Untrusted->|<---------- Trusted Zone ----------->|<-Untrusted-- Figure 2. MPLS-TP Security Model 1(b) 2.2. Security Reference Model 2 In reference model 2, a single SP does not have the end-to-end control of the segment from PE/T-PE to PE/T-PE.Some S-PE(s), T-PE(s)A given S-PE or T-PE may be under the control ofother SPs, or theanother SP, that SP's customers, or its partners. In this case, the MPLS-TP network is not contained within a single trusted zone. SecurityReference Modelreference model 2(a)Anshows an MPLS-TP network with Multi-Segment Pseudowire (MS-PW) from T-PE1 to T-PE2. The trusted zone is T-PE1 to S-PE1, as illustrated in Figure 3. Native |<-------------Pseudowire------------>| Native Service | | Service (AC) | |<--PSN-->| |<--PSN-->| | (AC) | V V V V V V | | +-----+ +-----+ +-----+ | +----+ | |T-PE1|=========|S-PE1|=========|T-PE2| | +----+ | |------|......PW.Seg't1.......PW.Seg't3......|------| | | CE1| | | | | | | | | |CE2 | | |------|......PW.Seg't2.......PW.Seg't4......|------| | +----+ | | |=========| |=========| | | +----+ ^ +-----+ ^ +-----+ ^ +-----+ ^ | | | | | TP LSP TP LSP | | | |<---------------- Emulated Service --------------->| Untrusted-->|<-- Trusted Zone---->|<---------Untrusted-------- Figure 3. MPLS-TP Security Model 2(a) SecurityReference Modelreference model 2(b)Anshows an MPLS-TP network with Multi-Segment Pseudowire (MS-PW) from T-PE1 to T-PE2. The trusted zone is the S-PE1 only, as illustrated in Figure 4. Native |<-------------Pseudowire------------>| Native Service | | Service (AC) | |<--PSN-->| |<--PSN-->| | (AC) | V V V V V V | | +-----+ +-----+ +-----+ | +----+ | |T-PE1|=========|S-PE1|=========|T-PE2| | +----+ | |------|......PW.Seg't1.......PW.Seg't3......|------| | | CE1| | | | | | | | | |CE2 | | |------|......PW.Seg't2.......PW.Seg't4......|------| | +----+ | | |=========| |=========| | | +----+ ^ +-----+ ^ +-----+ ^ +-----+ ^ | | | | | TP LSP TP LSP | | | |<---------------- Emulated Service --------------->| --------Untrusted---------->|<--->|<-------Untrusted---------- Trusted Zone Figure 4. MPLS-TP Security Model 2(b) SecurityReference Modelreference model 2(c)Anshows an MPLS-TP network with Multi-Segment Pseudowire (MS-PW) from differentService ProvidersSPs with inter-provider PW connections. The trusted zone is T-PE1 to S-PE3, as illustrated in Figure 5. Native |<--------------------- PW15 ------------------>| Native Layer | | Layer Service | |<PSN13>| |<PSN3X>| |<PSNXZ>| | Service (AC1) V V LSP V V LSP V V LSP V V (AC2) | +-----+ +-+ +-----+ +-----+ +-+ +-----+ | +---+ | |T-PE1| | | |S-PE3| |S-PEX| | | |T-PEZ| | +---+ | | | | |=======| |=======| |=======| | | | | |CE1|----|........PW1........|..PW3..|........PW5........|---|CE2| | | | | |=======| |=======| |=======| | | | | +---+ | 1 | |2| | 3 | | X | |Y| | Z | +---+ +-----+ +-+ +-----+ +-----+ +-+ +-----+ |<--Subnetwork 123->| |<--Subnetwork XYZ->| Untrusted>|<-- Trusted Zone-->|<-------------Untrusted------------- Figure 5. MPLS-TP Security Model 2(c) In general, the boundaries of a trusted zone must be carefully defined when analyzing the security properties of each individual network. The security boundaries determine which reference model should be applied to a given network topology. 3. Security Threats This section discusses various network security threats that are unique to MPLS-TP and may endanger MPLS-TP networks. Attackstoagainst a GAL or G-ACh mayinclude:include the following: - GAL or BFD label manipulation, which includes insertion of false labels and modification, deletion, or replay of messages. - DoSattackattacks through in-band OAM by generating excessive G-ACh/GAL and BFD messageswhichthat consume significant bandwidth and potentially cause congestion. These attacks can cause unauthorized protection switchover, inability torestore,restore one or more LSPs, or loss of network connectivity. Whenaan NMS is used for LSP setup,theattackstoon the NMS can cause the aboveeffecteffects as well. Although this is not unique to MPLS-TP, MPLS-TPnetworknetworks can be particularly vulnerable to NMSattackattacks, due to the fact that static provisioning throughNMSNMSs is a commonly used model. In the static provisioning model, a compromised NMS can potentially be comparable to acomprisedcompromised control plane plus acomprisedcompromised management plane in the dynamic controlled network model. Attacksto NMSon NMSs may come from either externalattackers,attackers or insiders. Outside attacks are initiated outside of the trusted zone by unauthorizeduserusers of the MPLS-TPnetwork management systems.NMSs. Insiderattack isattacks are initiated from insideofthe trusted zone by an entitywiththat has authorized access to the managementsystems,systems but that performs unapprovedharmfulfunctions that are harmful to the MPLS-TP networks. These attacks maybedirectlytargeted totarget theNMS, orNMS; they may also take place via the compromised communication channels between the NMS and the network devices that are being provisioned, or throughtheuser accessof the usersto the provisioning tools.TheThis type of security threat may include disclosure of information, generating false OAM messages, taking down MPLS-TP LSPs, connecting to the wrong MPLS-TP tunnelend points,endpoints, and DoS attackstoon theMPLS- TPMPLS-TP networks. There are other more generic securitythreat,threats, suchas: Unauthorizedas unauthorized observation of data traffic (including traffic pattern analysis),modification,modification or deletion of a provider's or user's data,as well asand replay or insertion of inauthentic data into a provider's or user's data stream. These types of attacks apply to MPLS-TP traffic regardless of how the LSP or PW is setupup, in asimilarway that is similar to how they apply to MPLS traffic regardless of how the LSP is set up. More details on theabove mentioned threatabove-mentioned threats are documented in [RFC5920].TheSuch threats maybe resultingresult from malicious behavior or accidentalerrors.errors: Example 1:AttackAttacks from users: Users of the MPLS-TP network may attack the network infrastructure or attack other users. Example 2:AttackAttacks from insiders: Employees of the operators may attack the MPLS-TP network, especially throughNMS.NMSs. Example 3:AttackAttacks frominter-connectinginterconnecting SPs or other partners: Other SPs may attack the MPLS-TP network, particularly through theinter- providerinter-provider connections. Example 4:AttackAttacks as the result ofoperationoperational errors:OperationOperations staff may fail to followtheoperational procedures or may make operational mistakes. 4. Defensive Techniques The defensive techniques presented in this document and in [RFC5920] are intended to describe methods by which some security threats can be addressed. They are not intended as requirements for all MPLS-TP deployments. The specific operational environment determines the security requirements for any instance of MPLS-TP. Therefore, protocol designers should provide a full set of securitycapabilities, whichcapabilities that can be selected and used where appropriate. The MPLS-TP provider should determine the applicability of these techniques to the provider's specific service offerings, and the end user may wish to assess the value of these techniques to the user's service requirements. Authentication is the primary defense technique to mitigate the risk of the MPLS-TP securitythreat "GALthreats discussed in Section 3 (GAL or BFD labelmanipulation",manipulation, and"DoS attackDoS attacks through in-bandOAM" discussed in Section 3.OAM). Authentication refers to methods to ensure that message sources are properly identified by the MPLS-TP devices with which they communicate. Authentication includes the following: - entity authentication for identityverification,verification - management systemauthentication,authentication - peer-to-peerauthentication,authentication - message integrity and replay detection to ensure the validity of messagestreams,streams - network-based access controls such as packet filtering andfirewalls,firewalls - host-based accesscontrols, isolation, aggregation,controls - isolation - aggregation - protection against denial ofservice, andservice - eventlogging. Wherelogging Section 5.2 of [RFC5920] describes these techniques where they apply to MPLS and GMPLS ingeneral, they are described in Section 5.2 of [RFC5920].general. In addition to authentication, the following defense should also be considered in order to protect MPLS-TPnetworks.networks: - Use ofIsolated Infrastructureisolated infrastructure for MPLS-TP One way to protect the MPLS-TP infrastructurenetworkis to use dedicated network resources to provide MPLS-TP transport services. For example, in security model 2 (Section 2.2), the potential risk of attacks on the S-PE1 or T-PE1 in the trusted zone may be reduced by using non-IP-based communication paths, so that the paths in the trusted zone cannot be reached from the outside via IP. - Verification ofConnectivityconnectivity To protect against deliberate or accidental misconnection, mechanisms can be put in place to verify both end-to-end connectivity and segment-by-segment resources. These mechanisms can trace the routes of LSPs in both the control plane and the data plane. Note that the connectivity verification tools are now developed for general MPLS networks as well. The defense techniquesarethat apply generally to MPLS/GMPLS are not detailedhere,here; see [RFC5920] for details regarding these techniques. For example: 1)Authentication: including Management System Authentication, Peer-to-PeerAuthentication,Cryptographic Techniquesincluding management system authentication, peer-to-peer authentication, and cryptographic techniques forAuthenticating Identity;authenticating identity 2) AccessControl Techniques;control techniques 3) Use ofAggregated Infrastructure;aggregated infrastructure 4) Mitigation ofDenial of Service Attacks;denial-of-service attacks 5) Monitoring,Detection,detection, andReportingreporting ofSecurity Attacks. Readers can refer to [RFC5920] for details.security attacks It is important to point out the following security defensetechniques whichtechniques, as they are particularly critical forNMSNMSs, due to the strong emphasis on static provisioning supported byNMSNMSs in MPLS-TPdeployment.deployments. These techniquesinclude: Entityinclude the following: - entity authentication for identityverification,verification - encryption forconfidentiality,confidentiality - message integrity and replay detection to ensure the validity of messagestreams, as well as usersstreams - user access control andevents loggingevent logging, which must be applied forNMSNMSs and provisioningapplications.applications 5. Security Considerations Security considerations constitute the sole subject of this document and hence are discussed throughout. This document evaluatesMPLS-TP specificsecurity risksandspecific to MPLS-TP, as well as mitigation mechanismswhichthat may be used to counterthepotential threats. All of the techniques presented here involve mature and widely implemented technologies that are practical to implement. It is meant to assist equipment vendors and serviceproviders,providers who must ultimately decide what threats to protect against in any given configuration or serviceofferingoffering, from a customer's perspective as well as from a service provider's perspective. 6.IANA Considerations This document contains no new IANA considerations. 7.Acknowledgements The authors wish to thank the following people: Joel Halpern and Gregory Mirsky for their review comments and contributions to this document,thankMach Chen for his review and suggestions,thankAdrian Farrel for his RoutingADArea Director review and detailed comments,thankLoa Andersson for his continued support and guidance as the MPLS WGco-Chair,co-chair, andthankDan Romascanu and Barry Leiba for their helpful comments during IESG review.8.7. References8.1.7.1. Normative References [RFC5654] Niven-Jenkins, B., Ed., Brungard, D., Ed., Betts, M., Ed., Sprecher, N., and S. Ueno, "Requirements of an MPLS Transport Profile", RFC 5654, September 2009. [RFC5920] Fang, L., Ed., "Security Framework for MPLS and GMPLS Networks", RFC 5920, July 2010.8.2.7.2. Informative References [RFC5921] Bocci, M., Ed., Bryant, S., Ed., Frost, D., Ed., Levrau, L., and L. Berger, "A Framework for MPLS in Transport Networks", RFC 5921, July 2010. Contributors Raymond Zhang Alcatel-Lucent 750D Chai Chee Road Singapore 469004 EMail: raymond.zhang@alcatel-lucent.com Nabil Bitar Verizon 40 Sylvan Road Waltham, MA 02145 US EMail: nabil.bitar@verizon.com Masahiro Daikoku KDDI Corporation 3-11-11 Iidabashi, Chiyodaku, Tokyo Japan EMail: ms-daikoku@kddi.com Lei Wang Lime Networks Strandveien 30, 1366 Lysaker Norway EMail: lei.wang@limenetworks.no Henry Yu TW Telecom 10475 Park Meadow Drive Littleton, CO 80124 US EMail: henry.yu@twtelecom.com Authors' Addresses Luyuan Fang (editor) Cisco Systems 111 Wood Ave. South Iselin, NJ08830,08830 USEmail:EMail: lufang@cisco.com Ben Niven-Jenkins (editor) Velocix 326 Cambridge Science Park Milton Road Cambridge CB40WG,0WG UKEmail:EMail: ben@niven-jenkins.co.uk Scott Mansfield (editor) Ericsson 300 Holger Way San Jose, CA95134,95134 USEmail:EMail: scott.mansfield@ericsson.com Richard F. Graveman (editor) RFG Security, LLC 15 Park Avenue Morristown, NJ07960,07960 USEmail:EMail: rfg@acm.orgContributors' Addresses Raymond Zhang Alcatel-Lucent 750D Chai Chee Road Singapore 469004 Email: raymond.zhang@alcatel-lucent.com Nabil Bitar Verizon 40 Sylvan Road Waltham, MA 02145, US Email: nabil.bitar@verizon.com Masahiro Daikoku KDDI Corporation 3-11-11 Iidabashi, Chiyodaku, Tokyo, Japan Email: ms-daikoku@kddi.com Lei Wang Lime Networks Strandveien 30, 1366 Lysaker, Norway Email: lei.wang@limenetworks.no Henry Yu TW Telecom 10475 Park Meadow Drive Littleton, CO 80124, US Email: henry.yu@twtelecom.com