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Versions: (draft-fang-mpls-tp-security-framework) 00 01 02 03 04 05 06 07 09 RFC 6941

Internet Engineering Task Force                             L. Fang, Ed.
Internet-Draft                                             Cisco Systems
Intended status: Informational                     B. Niven-Jenkins, Ed.
Expires: January 14, 2013                                        Velocix
                                                       S. Mansfield, Ed.
                                                                Ericsson
                                                        R. Graveman, Ed.
                                                            RFG Security
                                                           July 14, 2012



                       MPLS-TP Security Framework
                draft-ietf-mpls-tp-security-framework-04

Abstract

   This document provides a security framework for Multiprotocol Label
Switching Transport Profile (MPLS-TP).  MPLS-TP extends MPLS
technologies and introduces new OAM capabilities, a transport-
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 security threats,
security requirements for MPLS-TP, and mitigation procedures for
MPLS-TP networks and MPLS-TP interconnection to other MPLS and GMPLS
networks.

   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 functionalities of a packet transport network.

   This Informational Internet-Draft is aimed at achieving IETF
Consensus before publication as an RFC and will be subject to an IETF
Last Call.

   [RFC Editor, please remove this note before publication as an RFC and
insert the correct Streams Boilerplate to indicate that the published
RFC has IETF Consensus.]







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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
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   This Internet-Draft will expire on January 15, 2013.

Copyright Notice

   Copyright (c) 2012 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.


















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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
     1.1.  Background and Motivation  . . . . . . . . . . . . . . . .  4
     1.2.  Scope  . . . . . . . . . . . . . . . . . . . . . . . . . .  4
     1.3.  Requirement Language . . . . . . . . . . . . . . . . . . .  5
     1.4.  Terminology  . . . . . . . . . . . . . . . . . . . . . . .  6
     1.5.  Structure of the document  . . . . . . . . . . . . . . . .  7
   2.  Security Reference Models  . . . . . . . . . . . . . . . . . .  7
     2.1.  Security Reference Model 1 . . . . . . . . . . . . . . . .  7
     2.2.  Security Reference Model 2 . . . . . . . . . . . . . . . .  9
     2.3.  Security Reference Model 3 . . . . . . . . . . . . . . . . 12
     2.4.  Trusted Zone Boundaries  . . . . . . . . . . . . . . . . . 13
   3.  Security Threats . . . . . . . . . . . . . . . . . . . . . . . 14
     3.1.  Attacks on the Control Plane . . . . . . . . . . . . . . . 16
     3.2.  Attacks on the Data Plane  . . . . . . . . . . . . . . . . 17
   4.  Security Requirements for MPLS-TP  . . . . . . .   . . . . . . 17
   5.  Defensive Techniques for MPLS-TP Networks  . . . . . . . . . . 19
     5.1.  Authentication . . . . . . . . . . . . . . . . . . . . . . 19
       5.1.1.  Management System Authentication . . . . . . . . . . . 20
       5.1.2.  Peer-to-Peer Authentication  . . . . . . . . . . . . . 20
       5.1.3.  Cryptographic Techniques for Authenticating
               Identity . . . . . . . . . . . . . . . . . . . . . . . 20
     5.2.  Access Control Techniques  . . . . . . . . . . . . . . . . 20
     5.3.  Use of Isolated Infrastructure . . . . . . . . . . . . . . 21
     5.4.  Use of Aggregated Infrastructure . . . . . . . . . . . . . 21
     5.5.  Mitigation of Denial of Service Attacks  . . . . . . . . . 21
     5.6.  Verification of Connectivity . . . . . . . . . . . . . . . 21
   6.  Monitoring, Detection, and Reporting of Security Attacks . . . 22
   7.  Security Considerations  . . . . . . . . . . . . . . . . . . . 22
   8.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 23
   9.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 23
     9.1.  Normative References . . . . . . . . . . . . . . . . . . . 23
     9.2.  Informative References . . . . . . . . . . . . . . . . . . 23
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 24














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1.  Introduction

1.1.  Background and Motivation

   This document provides a security framework for Multiprotocol Label
Switching Transport Profile (MPLS-TP).

   The MPLS-TP Requirements and MPLS-TP Framework are defined in
[RFC5654] and [RFC5921], respectively.  The intent of MPLS-TP
development is to address the needs for transport evolution and the
fast-growing bandwidth demand accelerated by new packet-based services
and multimedia applications, from Ethernet Services, Layer 2 and Layer 3
VPNs, and triple play to Mobile Access Network (RAN) backhaul, etc.
MPLS-TP is based on MPLS technologies to take advantage of this
technology's maturity, and maintaining the transport characteristics of
MPLS is an MPLS-TP requirement.

   To focus on meeting transport requirements, MPLS-TP uses a subset of
MPLS features and introduces extensions to reflect the characteristics
of the transport technology.  The added functionalities include in-band
OAM, transport-oriented path protection and recovery mechanisms, etc.
There is strong emphasis on static provisioning supported by network
management systems (NMS) or Operation Support Systems (OSS). MPLS-TP and
MPSL without TP also need to interwork.

   The security aspects of the extensions particularly designed for
MPLS-TP need to be addressed.  The security models, threats,
requirements, and defense techniques previously defined in [RFC5920]
can be applied to reuse existing functionality in MPLS and GMPLS but
are not sufficient to cover the TP extensions.

   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.

1.2.  Scope

   This document addresses the security aspects specific to MPLS-TP.  It
defines security models that apply to various MPLS-TP deployment
scenarios, identifies potential security threats and mitigation
procedures for MPLS-TP networks and MPLS-TP interconnection to GMPLS or
MPLS networks without TP, and provides security requirements for
MPLS-TP. Inter-AS and Inter-provider security for MPLS-TP to MPLS-TP
connections or MPLS-TP to MPLS connections without TP are discussed,
because these connections present higher security risks than connections
for Intra-AS MPLS-TP.

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   The general security analysis and guidelines for MPLS and GMPLS are
addressed in [RFC5920], and the content of [RFC5920] that has no new
impact on MPLS-TP is not repeated in this document.  Other general
security issues regarding transport networks that are not specific to
MPLS-TP are also found elsewhere.  Readers may also refer to the
"Security Best Practices Efforts and Documents" Opsec Effort [opsec-
efforts] and "Security Mechanisms for the Internet" [RFC3631] (if there
are linkages to the Internet in the applications) for general network
operations security considerations.  This document does not define the
specific mechanisms or methods that must be implemented to satisfy the
security requirements.

   The issues and areas addressed with respect to MPLS-TP security are:

o  Attacks against G-Ach integrity, availability, or confidentiality

o  Misuse of G-Ach to attack data plane resources

o  ID spoofing attacks

o  Attacks against the loopback mechanism and Authentication TLV

o  Attacks against the network management system (NMS)

o  NMS and CP interaction vulnerabilities

o  MIP and MEP assignment and attacks on these mechanisms

o  Topology discovery vulnerabilities

o  Data plane authentication (using G-Ach or by other means)

o  Label authentication

o  DoS attacks on the data plane

o  Performance monitoring vulnerabilities

1.3.  Requirement Language

   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].  Although
this document is not a protocol specification, the use of this
language clarifies the instructions to protocol designers producing
solutions that satisfy the requirements set out in this document.



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1.4.  Terminology

   This document uses MPLS, MPLS-TP, and security terminology.
Detailed definitions and additional terminology for MPLS-TP may be
found in [RFC5654] and [RFC5921]. MPLS/GMPLS security-related
terminology can be found in [RFC5920].

o  AC: Attachment Circuit

o  BFD: Bidirectional Forwarding Detection

o  CE: Customer-Edge device

o  DoS: Denial of Service

o  DDoS: Distributed Denial of Service

o  GAL: Generic Alert Label

o  G-ACh: Generic Associated Channel

o  GMPLS: Generalized Multi-Protocol Label Switching

o  LDP: Label Distribution Protocol

o  LSP: Label Switched Path

o  MCC: Management Communication Channel

o  MEP: Maintenance End Point

o  MIP: Maintenance Intermediate Point

o  MPLS: MultiProtocol Label Switching

o  OAM: Operations, Administration, and Management

o  PE: Provider-Edge device

o  PSN: Packet-Switched Network

o  PW: Pseudowire

o  RSVP: Resource Reservation Protocol

o  RSVP-TE: Resource Reservation Protocol with Traffic Engineering
      Extensions

o S-PE: Switching Provider Edge

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o  SCC: Signaling Communication Channel

o  SSH: Secure Shell

o  TE: Traffic Engineering

o  TLS: Transport Layer Security

o  T-PE: Terminating Provider Edge

o  VPN: Virtual Private Network

o  WG: Working Group of IETF

o  WSS: Web Services Security

1.5.  Structure of the document

   Section 1: Introduction

   Section 2: MPLS-TP Security Reference Models

   Section 3: Security Threats

   Section 4: Security Requirements

   Section 5: Defensive and mitigation techniques and procedures

2.  Security Reference Models

   This section defines reference models for security in MPLS-TP
networks.

   The models are built on the architecture of MPLS-TP defined in
[RFC5921].  The Service Provider (SP) boundaries play 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 the PE/T-PE to
PE/T-PE part of the MPLS-TP network.


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   Security reference model 1(a)

   An MPLS-TP network with Single Segment Pseudowire (SS-PW) from PE to
PE.  The trusted zone is PE1 to PE2 as illustrated in MPLS-TP Security
Model 1 (a) (Figure 1).

          |<-------------- Emulated Service ---------------->|
          |                                                  |
          |          |<------- Pseudo Wire ------>|          |
          |          |                            |          |
          |          |    |<-- 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----

                       MPLS-TP Security Model 1 (a)

                                 Figure 1

Security reference model 1(b)

   An MPLS-TP network with Multi-Segment Pseudowire (MS-PW) from T-PE to
T-PE.  The trusted zone is T-PE1 to T-PE2 in this model as illustrated
in MPLS-TP Security Model 1 (b) (Figure 2).












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            Native  |<------------Pseudowire----------->|  Native
            Service |        PSN             PSN        |  Service
             (AC)   |    |<-cloud->|     |<-cloud->|    |   (AC)
               |    V    V         V     V         V    V     |
               |    +----+         +----+          +----+     |
        +----+ |    |TPE1|=========|SPE1|==========|TPE2|     | +----+
        |    |------|.....PW.Seg't1......PW.Seg't3..... |-------|    |
        | CE1| |    |    |         |    |          |    |     | |CE2 |
        |    |------|.....PW.Seg't2......PW.Seg't4..... |-------|    |
        +----+ |    |    |=========|    |==========|    |     | +----+
             ^      +----+    ^    +----+     ^    +----+       ^
             |                |               |                 |
             |              TP LSP            TP LSP            |
             |                                                  |
             |<---------------- Emulated Service -------------->|

    -- Untrusted-->|<---------- Trusted Zone ---------->|<--Untrusted--


                       MPLS-TP Security Model 1 (b)

                                 Figure 2

2.2.  Security Reference Model 2

   In reference model 2, a single SP does not have total control
of the PE/T-PE to PE/T-PE part of the MPLS-TP network. S-PE and T-PE may
be under the control of different SPs, or their customers or may not be
trusted for some other reason.  The MPLS-TP network is not contained
within a single trusted zone.

   Security Reference Model 2(a)

   An MPLS-TP network with Multi-Segment Pseudowire (MS-PW) from T-PE to
T-PE.  The trusted zone is T-PE1 to S-PE, as illustrated in MPLS-TP
Security Model 2 (a) (Figure 3).











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            Native  |<------------Pseudowire----------->|  Native
            Service |         PSN              PSN      |  Service
             (AC)   |    |<cloud->|     |<-cloud-->|    |   (AC)
               |    V    V        V     V          V    V     |
               |    +----+         +----+          +----+     |
        +----+ |    |TPE1|=========|SPE1|==========|TPE2|     | +----+
        |    |------|.....PW.Seg't1......PW.Seg't3..... |-------|    |
        | CE1| |    |    |         |    |          |    |     | |CE2 |
        |    |------|.....PW.Seg't2......PW.Seg't4..... |-------|    |
        +----+ |    |    |=========|    |==========|    |     | +----+
             ^      +----+    ^    +----+     ^    +----+       ^
             |                |               |                 |
             |              TP LSP            TP LSP            |
             |                                                  |
             |<---------------- Emulated Service -------------->|

    -- Untrusted-->|<-- Trusted Zone -->|<---------Untrusted--------

                       MPLS-TP Security Model 2 (a)

                                 Figure 3

   Security Reference Model 2(b)

   An MPLS-TP network with Multi-Segment Pseudowire (MS-PW) from T-PE to
T-PE.  The trusted zone is the S-PE, as illustrated in MPLS-TP
Security Model 2 (b) (Figure 4).






















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            Native  |<------------Pseudowire-------------->|  Native
            Service |         PSN              PSN         |  Service
             (AC)   |    |<cloud->|     |<-cloud-->|    |   (AC)
               |    V    V        V     V          V    V     |
               |    +----+         +----+          +----+     |
        +----+ |    |TPE1|=========|SPE1|==========|TPE2|     | +----+
        |    |------|.....PW.Seg't1......PW.Seg't3.... .|-------|    |
        | CE1| |    |    |         |    |          |    |     | |CE2 |
        |    |------|.....PW.Seg't2......PW.Seg't4..... |-------|    |
        +----+ |    |    |=========|    |==========|    |     | +----+
             ^      +----+    ^    +----+     ^    +----+       ^
             |                |               |                 |
             |              TP LSP            TP LSP            |
             |                                                  |
             |<---------------- Emulated Service -------------->|

    --------Untrusted------------>|<--->|< ------Untrusted--------
                                  Trusted
                                    Zone

                       MPLS-TP Security Model 2 (b)

                                 Figure 4

   Security Reference Model 2(c)

   An MPLS-TP network with Multi-Segment Pseudowire (MS-PW) from
different Service Providers with inter-provider PW connections.  The
trusted zone is T-PE1 to S-PE3, as illustrated in MPLS-TP Security
Model 2 (c) (Figure 5).



















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   Native  |<-------------------- PW15 --------------------->| Native
    Layer  |                                                 |  Layer
  Service  |    |<-PSN13->|    |<-PSN3X->|    |<-PSNXZ->|    | Service
     (AC1) V    V   LSP   V    V   LSP   V    V   LSP   V    V  (AC2)
           +----+   +-+   +----+         +----+   +-+   +----+
  +---+    |TPE1|   | |   |SPE3|         |SPEX|   | |   |TPEZ|   +---+
  |   |    |    |=========|    |=========|    |=========|    |   |   |
  |CE1|----|........PW1........|...PW3...|........PW5........|---|CE2|
  |   |    |    |=========|    |=========|    |=========|    |   |   |
  +---+    | 1  |   |2|   | 3  |         | X  |   |Y|   | Z  |   +---+
           +----+   +-+   +----+         +----+   +-+   +----+

           |<- Subnetwork 123->|         |<- Subnetwork XYZ->|

Untrusted->|<- Trusted Zone - >|<-------------Untrusted---------------

                       MPLS-TP Security Model 2 (c)

                                 Figure 5

2.3.  Security Reference Model 3

An MPLS-TP network with a Transport LSP from PE1 to PE2.  The trusted
zone is PE1 to PE2 as illustrated in MPLS-TP Security Model 3 (a)
(Figure 6), where the two PEs and the devices in between them are
under control of a single service operator.





















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            |<------------- Client Network Layer --------------->|
            |                                                    |
            |          |<----------- Packet --------->|          |
            |          |         Transport Service    |          |
            |          |                              |          |
            |          |                              |          |
            |          |          Transport           |          |
            |          |    |<------ LSP ------->|    |          |
            |          V    V                    V    V          |
            V    AC    +----+      +-----+       +----+     AC   V
      +-----+    |     | PE1|=======\   /========| PE2|     |    +-----+
      |     |----------|..Svc LSP1.| \ / |............|----------|     |
      | CE1 |    |     |    |      |  X  |       |    |     |    | CE2 |
      |     |----------|..Svc LSP2.| / \ |............|----------|     |
      +-----+  ^ |     |    |=======/   \========|    |     | ^  +-----+
            ^  |       +----+  ^   +-----+       +----+     | |  ^
            |  |      Provider |       ^         Provider     |  |
            |  |       Edge 1  |       |          Edge 2      |  |
      Customer |               |    P Router                  | Customer
       Edge 1  |             TE LSP                           |  Edge 2
               |                                              |
               |                                              |
         Native service                                 Native service

   -----Untrusted---- >|< ------ Trusted Zone ------ >|<---Untrusted----

                       MPLS-TP Security Model 3 (a)

                                 Figure 6

2.4.  Trusted-Zone Boundaries

   The boundaries of a trusted zone should be carefully defined when
analyzing the security properties of each individual network. As
illustrated above, the security boundaries determine which
reference model should be applied to analyze use cases.

   A key requirement of MPLS-TP networks is that the security of a
trusted zone MUST NOT be compromised by interconnecting one SP's
MPLS-TP or MPLS infrastructure with another SP's core devices, T-PE
devices, or end users.

   In addition, neighboring nodes in the network may be trusted or
untrusted.  Neighbors may also be authorized or unauthorized.  Even
though a neighbor may be authorized for communication, it may not be
trusted.  For example, when connecting with another provider's S-PE
to set up Inter-AS LSPs, the other provider is considered to be
untrusted but may be authorized for communication.

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                +---------------+        +----------------+
                |               |        |                |
                |    MPLS-TP   S-PE1----S-PE3  MPLS-TP    |
        CE1--T-PE1   Network    |        |     Network  T-PE2--CE2
                |    Provider  S-PE2----S-PE4  Provider   |
                |       A       |        |        B       |
                +---------------+        +----------------+

           For Provider A:
                   Trusted Zone: Provider A MPLS-TP network
                   Trusted neighbors: T-PE1, S-PE1, S-PE2
                   Authorized but untrusted neighbor: Provider B
                   Unauthorized and untrusted neighbors: CE2

               MPLS-TP trusted zone and authorized neighbor

                                 Figure 7
3.  Security Threats

   This section lists various network security threats that may
endanger MPLS-TP networks.  It emphasizes threats that are new to
MPLS-TP networks or affect MPLS-TP networks in new ways.

   A successful attack on a particular MPLS-TP network or on a SP's
MPLS-TP infrastructure may cause one or more of the following
adverse effects:

   1.  Observation (including traffic pattern analysis), modification,
       or deletion of a provider's or user's data, as well as 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 set up in a similar way to how
       they apply to MPLS traffic regardless how the LSP is set up.

   2.  Compromised GAL label or BFD messaging:

       a.  GAL label or BFD label manipulation, which includes insertion
           of false labels or messages and modification, deletion, or
           replay of GAL labels or messages.

       b.  DoS attack through in-band OAM G-ACh/GAL and BFD messages.

       c.  Attacks via G-ACh to cause protection switchover,
           restoration, or locking of a transport connection.

   3.  Disruption of a provider's or user's connectivity, or degradation
       of a provider's service quality.



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       a.  Attacks against a SP's connectivity:

           +  In the case in which an NMS is used for LSP setup, the
              attacks occur through attacks on the NMS.

           +  In the case in which dynamic provisioning is used, the
              attacks occur on the dynamic control plane.  Most aspects
              of these are addressed in [RFC5920].

        b.  Attacks against user's connectivity.  These are similar to
            PE/CE attacks against access in typical MPLS networks and
            are addressed in [RFC5920].

   4.  Probes of a provider's network to determine its configuration,
       capacity, or usage.  These can occur through attacks against an
       NMS in the case of static provisioning or attacks against the
       control plane in dynamic MPLS-TP networks. They can also result
       from combined attacks.

   It is helpful to consider that threats, whether resulting from
malicious behavior or accidental errors, may come from different
sources or categories of attackers.  For example, they may come from:

o  Users of the MPLS-TP network itself, who may attack the network or
   other users. These other users' services may be provided by the
   same or a different MPLS-TP core.

o  The MPLS-TP SP or its employees.

o  Other persons who obtain physical access to a MPLS-TP SP's site.

o  Other persons who use social engineering to influence the behavior
   of a SP's personnel.

o  Outsiders, e.g., attackers from the other sources, including the
   Internet (if connectivity can be obtained).

o  Other SPs in the case of MPLS-TP inter-provider connection.  The
   other provider may or may not be using MPLS-TP.

o  Those who create, deliver, install, and maintain hardware or software
   for network equipment.

   Security is a tradeoff between cost and risk, so it is useful to
consider the likelihood of different attacks, the cost of preventing
them, and the possible damage resulting from their occurrence.  There is
at least a perceived difference in the likelihood of most types of
attacks being successfully mounted in different environments, such as:


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o  An MPLS-TP network inter-connected with another provider's core

o  An MPLS-TP configuration inter-connected with the public Internet,
   e.g., for control or management functions

   Most types of attacks become easier to mount and hence more likely as
the shared infrastructure via which service is provided expands from
a single SP to multiple cooperating SPs to the global Internet.
Attacks that may not be of sufficient likeliness to warrant concern
in a closely controlled environment often merit defensive measures in
broader, more open environments.  Even though surveys show that 40% to
60% of attacks originate from insiders, in closed communities, it is
often practical to identify and to deal with misbehavior after the fact:
employee misbehavoir can be corrected, for example.

   The following sections list specific types of exploits that threaten
MPLS-TP networks.

3.1.  Attacks on the Control Plane

   This category includes attacks that may compromise the availability
of control plane capabilities, the integrity of these operations, and,
potentially, the confidentiality of these operations for either in-
band (G-ACh) or out-of-band (GMPLS) configurations.  Attacks against
GMPLS include attacks against its constituent protocols (i.e., RSVP-TE,
LDP, OSPFv2, or PCEP). Attacks against G-ACh may be directed against the
label mechanism (GAL) or any of the encapsulated signaling or management
protocols (SCC, MCC, OAM, or protection).  The following attacks may
target the provisioning, management, or survivability functions of the
control plane:

o  Improper MPLS-TP LSP or PW creation or deletion. This may result from
   a failure of control plane authentication or authorization mechanisms
   or compromise of control plane traffic.  One result might be improper
   cross-connection of different users' traffic.

o  Improper use of MPLS-TP protection and restoration capabilities. This
   also may result from a failure of control plane authentication or
   authorization mechanisms or compromise of control plane traffic.

o  Unauthorized observation of control plane traffic, which includes
   information about a SP's MPLS-TP configuration, equipment, or users.

o  Denial of service attacks on the control plane or use of the control
   plane to carry out denial of service attacks against the data plane.

o  Attacks on the SP's MPLS-TP equipment or software. These may occur
   during the normal lifecycle of the equipment and software or via
   management interfaces or other points of entry. These include social
   engineering attacks on the SP's infrastructure.

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3.2.  Attacks on the Data Plane

   The general MPLS data plane attacks apply to MPLS-TP as well. These
include the following:

o  Denial of service, misconnection, loss of bandwidth, or other
   service disruptions.

o  Unauthorized observation of data traffic, including LSP or PW
   message interception and traffic pattern analysis.

o  Modification or deletion of data traffic, which may include
   insertion of inauthentic data traffic (spoofing or replay).

   MPLS-TP supports data plane switching (e.g., from working to
protect-path when a failure is detected) without the involvement of
control plane or management system. Therefore, data plane attacks can
potentially cause serious network instability.


4.  Security Requirements for MPLS-TP

   This section covers requirements for securing an MPLS-TP network
infrastructure.  The MPLS-TP network can be operated without a
control plane or via dynamic control plane protocols.  The security
requirements related to MPLS-TP OAM, recovery mechanisms, MPLS-TP
interconnection with other technologies, and operations specific to
MPLS-TP are addressed in this section.

   A service provider may deploy the security options best fitting
its network operations. This document does not mandate that MPLS-TP
network operators must configure and use technical mechanisms to
satisfy all of the security requirements listed in this document.

   These requirements are focused on: 1) how to protect the MPLS-TP
network from various attacks originating outside the trusted zone,
including those from network users, both accidental and malicious; 2)
prevention of operational errors resulting from misconfiguration
within the trusted zone.

R01: MPLS-TP MUST support the physical and logical separation of the
     data plane from the control plane and the management plane.
     That is, if the control plane, management plane, or both are
     attacked and cannot function normally, the data plane should
     continue to forward packets without being impacted.


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R02: MPLS-TP MUST support static provisioning of MPLS-TP LSPs and PWs
     without using control protocols (with or without a NMS).  This is
     particularly important in cases where components of the
     provisioning process are not in the trusted zone (security model
     2(a) and security model 2(b), where some or all T-PEs are not in
     the trusted zone and the inter-provider cases in security model
     2(c), where the connecting S-PE is not in the trusted zone; see
     Figures 3, 4, and 5).

R03: MPLS-TP MUST support the IP loopback and non-IP path options that
     use the path ID compatible with ITU-T transport-based operations.

R04: MPLS-TP MUST support authentication, integrity, and replay
     protection for any control protocol used in an MPLS-TP network.

R05: MPLS-TP SHOULD support confidentiality, algorithm agility, and key
     management for any control protocol used in an MPLS-TP network.

R06: MPLS-TP MUST support authentication, integrity, and replay
     protection for dynamic MPLS network inter-connection protocols.

R07: MPLS-TP SHOULD support confidentiality, algorithm agility, and key
     management for dynamic MPLS network inter-connection protocols.

R08: MPLS-TP MUST support mechanisms to mitigate denial of service
     (DoS) attacks carried out over any control plane protocol or
     management protocol, including OAM and G-ACh, whether in-band
     or out-of band. This applies to denial-of-service attacks against
     the control or management protocol itself or against the data
     channel.

R09: MPLS-TP MUST provide secure ways to support Service Providers'
     requirements for hiding their infrastructure in all reference
     models using static configuration or a dynamic control plane, help
     to reduce risk of SP networks be attacked, (e.g. DoS attack).

R10: MPLS-TP SHOULD provide protection from operational errors.  The
     extensive use of static provisioning with or without a NMS
     increases the likelihood of operational errors that result in
     misconfigurations that may compromise user's data, system security,
     or network security is greater.

R11: MPLS-TP MUST support event logging and auditing.  Logging and
     auditing capabilities provide critical resources for tracking
     down problems and repairing the damage after a security incident.

Management security requirements are covered in [RFC5951]. This document
mandates protocol security, access controls, and protection against
denial of service attacks for all management protocols. [RFC3871]
contains guidelines on appropriately strong and open cryptography.


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R12: MPLS-TP MUST support authentication, integrity, and replay
     protection for the management communication channel (MCC) and all
     network traffic and protocols used to support management functions.
     This includes protocols used for configuration, monitoring,
     Configuration backup, logging, time synchronization,
     authentication, and routing.

R13: MPLS-TP SHOULD support confidentiality, algorithm agility, and key
     management for the management communication channel (MCC) and all
     network traffic and protocols used to support management functions.
     This includes protocols used for configuration, monitoring,
     Configuration backup, logging, time synchronization,
     authentication, and routing.

R14: The MCC MUST support access controls by protocol and port number.

5.  Defensive Techniques for MPLS-TP Networks

   The defensive techniques presented in this document 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 security capabilities, which 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.

   The techniques discussed here include entity authentication for
identity verification, encryption for confidentiality, message integrity
and replay detection to ensure the validity of message streams, network-
based access controls such as packet filtering and firewalls, host-based
access controls, isolation, aggregation, protection against denial of
service, and event logging. Where these techniques apply to MPLS and
GMPLS in general, they are described in Section 5.2 of [RFC5920]. The
remainder of this section covers aspects that apply particularly to
MPLS-TP.

5.1.  Authentication

   To prevent security issues arising from impersonation, masquerade,
some denial-of-service attacks, or from malicious or accidental
misconfiguration, it is critical that MPLS-TP devices should accept
connections or control messages only from known sources.  Authentication
refers to methods for ensuring that the identities of message sources
are properly verified by the devices with which they communicate.
This section focuses on scenarios in which sender authentication is
required and recommends authentication mechanisms for these scenarios.

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5.1.1.  Management System Authentication

   Management system authentication includes the authentication of a PE
to a centrally-managed network management or directory server when
directory-based auto-discovery is used.  It also includes authentication
of a CE to the configuration server when a configuration server system
is used.  This type of authentication should be bi-directional. The PE
or CE needs to be certain it is communicating with the right server.

5.1.2.  Peer-to-Peer Authentication

   Peer-to-peer authentication includes peer authentication for network
control protocols and other peer authentication (e.g., authentication
of one IPsec security gateway by another).

   Authentication should be bi-directional, including S-PE, T-PE, PE, or
CE to authentication to a configuration server so that a PE or CE can be
certain it is communicating with the right server.

5.1.3.  Cryptographic Techniques for Authenticating Identity

   Cryptographic techniques offer several mechanisms for authenticating
the identity of devices or individuals.  These include the use of
shared secret keys, one-time keys generated by accessory devices or
software, user-ID and password pairs, and a variety of public-private
key systems.  Some of these use digital certificates binding a user's
name and public key. One method of using digital certificates is within
a hierarchical Certification Authority system.

5.2.  Access Control Techniques

   Many of the security issues related to management interfaces can be
addressed through the use of authentication as described in Section
5.1. However, additional security may be provided by controlling access
to management interfaces or to specific resources with an access control
model. In addition to identification and authentication, access control
deals with authorization.

SNMP security efforts have focused on access control models. For the
Most recent version of SNMP security, see the work of the ISMS WG.

   The Optical Internetworking Forum has worked on protecting interfaces
to management systems with TLS, SSH, IPsec, WSS, etc.  See Security for
Management Interfaces to Network Elements [OIF-SMI-03.0].

   Management interfaces, especially console ports on MPLS-TP devices,
may be configured so they are only accessible out-of-band, through a
system which is physically or logically separated from the rest of
the MPLS-TP infrastructure.

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   Where management interfaces are accessible in-band within the MPLS-TP
domain, filtering or firewalling techniques can be used to restrict
unauthorized in-band traffic from having access to management
interfaces.  Depending on device capabilities, these filtering or
firewalling techniques can be configured either on other devices
through which the traffic might pass, or on the individual MPLS-TP
devices themselves.

5.3.  Use of Isolated Infrastructure

   One way to protect the infrastructure used for support of MPLS-TP is
to separate the resources for support of MPLS-TP services from the
resources used for other purposes. For example, in security model 2
(Section 2.2), the potential risk of attacks on the S-PE or T-PE in the
trusted zone may be reduced by using non-IP-based communication paths.

5.4.  Use of Aggregated Infrastructure

   In general, it is not feasible to use a completely separate set of
resources for support of each service.  In fact, one of the main
reasons for MPLS-TP enabled services is to allow sharing of resources
between multiple services and multiple users.  Thus, even if certain
services use a separate network from Internet services, nonetheless
there will still be multiple MPLS-TP users sharing the same network
resources.

   In general, the use of aggregated infrastructure allows the service
provider to benefit from stochastic multiplexing of multiple bursty
flows, and also may in some cases thwart traffic pattern analysis by
combining the data from multiple users.  However, service providers
must minimize security risks introduced from any individual service
or individual users.

5.5.  Mitigatoion of Denial of Service Attacks

It is possible to lessen the potential and impact of denial-of-service
attacks by using secure protocols, turning off unnecessary processes,
logging and monitoring, and using ingress filtering.  See [RFC4732]
for background on denial-of-service attacks in the context of the
Internet.

5.6.  Verification of Connectivity

To protect against deliberate or accidental misconnection,
mechanisms can be put in place to verify both end-to-end connectivity
and hop-by-hop resources.  These mechanisms can trace the routes of
LSPs in both the control plane and the data plane.




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6.  Monitoring, Detection, and Reporting of Security Attacks

   MPLS-TP networks and services may be subject to attacks from a
variety of security threats.  Many types of threats are described
in the Security Requirements (Section 4) section of this document.
The defensive techniques described in this document and elsewhere
provide significant levels of protection from many of these threats.
However, in addition to employing defensive techniques silently to
protect against attacks, MPLS-TP services can also add value for
both providers and customers by implementing security monitoring
systems to detect and report on any security attacks, regardless
of whether the attacks are effective.

   Attackers often begin by probing and analyzing defenses, so systems
that can detect and properly report these early stages of attacks can
provide significant benefits.

   Information concerning attack incidents, especially if available
quickly, can be useful in defending against further attacks.  It can
be used to help identify attackers or their specific targets at an
early stage.  This knowledge about attackers and targets can be used
to strengthen defenses against specific attacks or attackers, or to
improve the defenses for specific targets on an as-needed basis.
Information collected on attacks may also be useful in identifying
and developing defenses against novel attack types.

Also, extensive logging of normal processing, error conditions, and
security events can be an invaluable source of information for tracking
down attacks, recovering from them, and determining how to prevent
future attacks.  Different methods may be appropriate from case to case,
and in fact comparing the same or similar information obtained in
different ways (e.g., with syslog and SNMP) sometimes reveals subtle
security flaws or actual intrusions. Implementations should also pay
attention to the security of the logs themselves.

7.  Security Considerations

   Security considerations constitute the sole subject of this document
and hence are discussed throughout.

   The document describes a variety of defensive techniques that may be
used to counter the potential threats.  All of the techniques
presented involve mature and widely implemented technologies that are
practical to implement.






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   The document evaluates MPLS-TP security requirements from a
customer's perspective as well as from a service provider's
perspective.  These sections re-evaluate the identified threats from
the perspectives of the various stakeholders and are meant to assist
equipment vendors and service providers, who must ultimately decide
what threats to protect against in any given configuration or service
offering.

8.  IANA Considerations

   This document contains no new IANA considerations.

9.  References

9.1.  Normative References

[RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
           Requirement Levels", BCP 14, RFC 2119, March 1997.

[RFC3871]  Jones, G., "Operational Security Requirements for Large
           Internet Service Provider (ISP) IP Network
           Infrastructure", RFC 3871, September 2504.

[RFC4732]  Handley, M., Rescorla, E., and IAB, "Internet Denial-of-
           Service Considerations", RFC 4732, December 2006.

[RFC5654]  Niven-Jenkins, B., Brungard, D., Betts, M., Sprecher, N.,
           and S. Ueno, "Requirements of an MPLS Transport Profile",
           RFC 5654, September 2509.

[RFC5951]  Lam, K., Mansfield, S., and E. Gray, "Network Management
           Requirements for MPLS-based Transport Networks", RFC 5951,
           September 2510.

9.2.  Informative References

[OIF-SMI-03.0]
           Optical Internetworking Forum, "Security for Management
           Interfaces to Network Elements", OIF OIF-SMI-03.0,
           November 2011.

[RFC3631]  Bellovin, S., Schiller, J., and C. Kaufman, "Security
           Mechanisms for the Internet", RFC 3631, December 2003.

[RFC5920]  Fang, L., "Security Framework for MPLS and GMPLS
           Networks", RFC 5920, July 2010.



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[RFC5921]  Bocci, M., Bryant, S., Frost, D., Levrau, L., and L.
           Berger, "A Framework for MPLS in Transport Networks",
           RFC 5921, July 2010.

[opsec-efforts]
           "Security Best Practices Efforts and Documents",
           IETF draft-ietf-opsec-efforts-18.txt, April 2012.

Authors' Addresses

   Luyuan Fang (editor)
   Cisco Systems
   111 Wood Ave. South
   Iselin, NJ 08830
   US
   Email: lufang@cisco.com


   Ben Niven-Jenkins (editor)
   Velocix
   326 Cambridge Science Park
   Milton Road
   Cambridge CB4 0WG
   UK
   Email: ben@niven-jenkins.co.uk


   Scott Mansfield (editor)
   Ericsson
   300 Holger Way
   San Jose, CA 95134
   US
   Email: scott.mansfield@ericsson.com


   Richard F. Graveman (editor)
   RFG Security, LLC
   15 Park Avenue
   Morristown, NJ 07960
   US
   Email: rfg@acm.org



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   Raymond Zhang
   Alcatel-Lucent
   701 Middlefield Road
   Mountain View, CA 94043
   US
   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




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