Internet Engineering Task Force L. Fang, Ed.
Internet-Draft Cisco Systems Inc.
Intended status: Informational B. Niven-Jenkins, Ed.
Expires: November 17, 2011 Velocix
S. Mansfield, Ed.
Ericsson
May 16, 2011
MPLS-TP Security Framework
draft-ietf-mpls-tp-security-framework-01
Abstract
This document provides a security framework for Multiprotocol Label
Switching Transport Profile (MPLS-TP). Extended from MPLS
technologies, MPLS-TP introduces new OAM capabilities, transport
oriented path protection mechanism, and strong emphasis on static
provisioning supported by network management systems. This document
addresses the security aspects that are relevant in the context of
MPLS-TP specifically. It describes the security requirements for
MPLS-TP; potential securities threats and migration procedures for
MPLS-TP networks and MPLS-TP inter-connection to 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.]
Fang, et al. Expires November 17, 2011 [Page 1]
Internet-Draft MPLS-TP Security Framework May 2011
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 November 17, 2011.
Copyright Notice
Copyright (c) 2011 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.
Fang, et al. Expires November 17, 2011 [Page 2]
Internet-Draft MPLS-TP Security Framework May 2011
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 Requirements for MPLS-TP . . . . . . . . . . . . . . 14
4. Security Threats . . . . . . . . . . . . . . . . . . . . . . . 16
4.1. Attacks on the Control Plane . . . . . . . . . . . . . . . 18
4.2. Attacks on the Data Plane . . . . . . . . . . . . . . . . 18
5. Defensive Techniques for MPLS-TP Networks . . . . . . . . . . 19
5.1. Authentication . . . . . . . . . . . . . . . . . . . . . . 19
5.1.1. Management System Authentication . . . . . . . . . . . 19
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. Service Provider Quality Control Processes . . . . . . . . 21
5.6. Verification of Connectivity . . . . . . . . . . . . . . . 21
6. Monitoring, Detection, and Reporting of Security Attacks . . . 21
7. Security Considerations . . . . . . . . . . . . . . . . . . . 22
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 22
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 22
9.1. Normative References . . . . . . . . . . . . . . . . . . . 22
9.2. Informative References . . . . . . . . . . . . . . . . . . 23
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 23
Fang, et al. Expires November 17, 2011 [Page 3]
Internet-Draft MPLS-TP Security Framework May 2011
1. Introduction
1.1. Background and Motivation
This document provides a security framework for Multiprotocol Label
Switching Transport Profile (MPLS-TP).
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, the fast growing bandwidth
demand accelerated by new packet based services and multimedia
applications, from Ethernet Services, Layer 2 and Layer 3 VPNS,
triple play to Mobile Access Network (RAN) backhaul, etc. MPLS-TP is
based on MPLS technologies to take advantage of the technology
maturity, and it is required to maintain the transport
characteristics.
Focused on meeting transport requirements, MPLS-TP uses a subset of
MPLS features, and introduces extensions to reflect the transport
technology characteristics. 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 System (NMS) or Operation Support System (OSS).
There are also needs for MPLS-TP and MPLS interworking.
The security aspects for the new extensions which are particularly
designed for MPLS-TP need to be addressed. The security models,
requirements, threat and defense techniques previously defined in
[RFC5921] can be used for the re-use of the existing functionalities
in MPLS and GMPLS, but not sufficient to cover the new 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 functionalities of a packet transport network.
1.2. Scope
This document addresses the security aspects that are specific to
MPLS-TP. It intends to provide the security requirements for
MPLS-TP; define security models which apply to various MPLS-TP
deployment scenarios; identify the potential security threats and
mitigation procedures for MPLS-TP networks and MPLS-TP inter-
connection to MPLS or GMPLS networks. Inter-AS and Inter-provider
security for MPLS-TP to MPLS-TP connections or MPLS-TP to MPLS
connections are discussed, where connections present higher security
risk factors than connections for Intra-AS MPLS-TP.
Fang, et al. Expires November 17, 2011 [Page 4]
Internet-Draft MPLS-TP Security Framework May 2011
The general security analysis and guidelines for MPLS and GMPLS are
addressed in [RFC5920], the content which has no new impact to
MPLS-TP will not be repeated in this document. Other general
security issues regarding transport networks that are not specific to
MPLS-TP are also out of scope. 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 operation security considerations. This document
does not intend to define the specific mechanisms/methods that must
be implemented to satisfy the security requirements.
Issues/Areas to be addressed:
o G-Ach (control plane attack, DoS attack, message intercept, etc.)
o Spoofing ID
o Loopback
o NMS attack
o NMS and CP interaction
o MIP/MEP assignment and attacks
o Topology discovery
o Data plane authentication
o Label authentication
o DoS attack in Data Plane
o Performance Monitoring
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.
Fang, et al. Expires November 17, 2011 [Page 5]
Internet-Draft MPLS-TP Security Framework May 2011
1.4. Terminology
This document uses MPLS, MPLS-TP, and Security specific terminology.
Detailed definitions and additional terminology for MPLS-TP may be
found in [RFC5654], [RFC5921], and MPLS/GMPLS security related
terminology in [RFC5920].
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
Fang, et al. Expires November 17, 2011 [Page 6]
Internet-Draft MPLS-TP Security Framework May 2011
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 Requirements
Section 4: Security Threats
Section 5: Defensive/Mitigation techniques/procedures
2. Security Reference Models
This section defines a reference model 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
the 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 the reference model 1, a single SP has total control of PE/T-PE to
PE/T-PE of the MPLS-TP network.
Fang, et al. Expires November 17, 2011 [Page 7]
Internet-Draft MPLS-TP Security Framework May 2011
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).
Fang, et al. Expires November 17, 2011 [Page 8]
Internet-Draft MPLS-TP Security Framework May 2011
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 the reference model 2, a single SP does not have the total control
of PE/T-PE to PE/T-PE 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).
Fang, et al. Expires November 17, 2011 [Page 9]
Internet-Draft MPLS-TP Security Framework May 2011
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).
Fang, et al. Expires November 17, 2011 [Page 10]
Internet-Draft MPLS-TP Security Framework May 2011
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).
Fang, et al. Expires November 17, 2011 [Page 11]
Internet-Draft MPLS-TP Security Framework May 2011
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).
Fang, et al. Expires November 17, 2011 [Page 12]
Internet-Draft MPLS-TP Security Framework May 2011
|<------------- 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 from the above, the security boundaries determine which
reference model should be applied to the use case analysis.
A key requirement of MPLS-TP networks is that the security of the
trusted zone MUST NOT be compromised by interconnecting one SP's
MPLS-TP or MPLS infrastructure with another SP's core, 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.
Fang, et al. Expires November 17, 2011 [Page 13]
Internet-Draft MPLS-TP Security Framework May 2011
+---------------+ +----------------+
| | | |
| 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 neighbors: CE2
MPLS-TP trusted zone and authorized neighbor
Figure 7
3. Security Requirements for MPLS-TP
This section covers security requirements for securing MPLS-TP
network infrastructure. The MPLS-TP network can be operated without
a control plane or via dynamic control planes protocols. The
security requirements related to new MPLS-TP OAM, recovery
mechanisms, MPLS-TP and MPLS interconnection, and MPLS-TP specific
operational requirements will be addressed in this section.
A service provider may choose the implementation options which are
the best fit for his/her network operation. This document does not
state that a MPLS/GMPLS network must fulfill all security
requirements listed to be secure.
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.
o MPLS-TP MUST support the physical and logical separation of data
plane from the control plane and management plane. That is, if
the control plane or/and management plane are attacked and cannot
function normally, the data plane should continue to forward
packets without being impacted.
o MPLS-TP MUST support static provisioning of MPLS-TP LSP and PW
with or without NMS/OSS, without using control protocols. This is
particularly important in the case of security model 2(a)
Fang, et al. Expires November 17, 2011 [Page 14]
Internet-Draft MPLS-TP Security Framework May 2011
(Figure 3) and security model 2(b) (Figure 4) where some or all
T-PEs are not in the trusted zone, and in the inter-provider cases
in security model 2(c) (Figure 5) when the connecting S-PE is in
the untrusted zone.
o MPLS-TP MUST support non-IP path options in addition to IP
loopback option. Non-IP path options when used in security model
2 (Section 2.2) may help to lower the potential risk of attack on
the S-PE/T-PE in the trusted zone.
o MPLS-TP MUST support authentication of any control protocol used
for an MPLS-TP network, as well as for MPLS-TP network to dynamic
MPLS network inter-connection.
o MPLS-TP MUST support mechanisms to prevent Denial of Service (DOS)
attacks via any in-band OAM or G-ACh/GAL.
o MPLS-TP MUST support hiding of the Service Provider infrastructure
for all reference models regardless of whether the network(s) are
using static configuration or a dynamic control plane.
o Security management requirements from [RFC5951]:
* MPLS-TP MUST support management communication channel (MCC)
security.
* Secure communication channels MUST be supported for all network
traffic and protocols used to support management functions.
This MUST include protocols used for configuration, monitoring,
configuration backup, logging, time synchronization,
authentication, and routing.
* The MCC MUST support application protocols that provide
confidentiality and data integrity protection.
* The MCC MUST support the use of open cryptographic algorithms
[RFC3871].
* The MCC MUST support authentication to ensure that management
connectivity and activity is only from authenticated entities.
* The MCC MUST support port access control.
* Distributed Denial of Service: It is possible to lessen the
impact and potential for DoS and DDoS by using secure
protocols, turning off unnecessary processes, logging and
monitoring, and ingress filtering. [RFC4732] provides
background on DOS in the context of the Internet.
Fang, et al. Expires November 17, 2011 [Page 15]
Internet-Draft MPLS-TP Security Framework May 2011
o MPLS-TP MUST provide protection from operational error. Due to
the extensive use of static provisioning with or without NMS and
OSS, the prevention of configuration errors should be addressed as
major security requirements.
4. Security Threats
This section discusses the various network security threats that may
endanger MPLS-TP networks. The discussion is limited to those
threats that are unique to MPLS-TP networks or that affect MPLS-TP
networks in unique 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 ill
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 non-authentic 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. Attacks on GAL label, BFD messages:
1. GAL label or BFD label manipulation: including insertion of
false label or messages, or modification, or removal the GAL
labels or messages by attackers.
2. DOS attack through in-band OAM G-ACH/GAL, and BFD messages.
3. Disruption of a provider's and/or user's connectivity, or
degradation of a provider's service quality.
1. Provider connectivity attacks:
+ In the case of NMS is used for LSP set-up, the attacks
would be through the attack of NMS.
+ In the case of dynamic is used for dynamic provisioning,
the attack would be on dynamic control plane. Most
aspects are addressed in [RFC5920].
2. User connectivity attack. This would be similar as PE/CE
access attack in typical MPLS networks, addressed in
[RFC5920].
Fang, et al. Expires November 17, 2011 [Page 16]
Internet-Draft MPLS-TP Security Framework May 2011
4. Probing a provider's network to determine its configuration,
capacity, or usage. These types of attack can happen through NMS
attacks in the case of static provisioning, or through control
plane attacks as in dynamic MPLS networks. It can also be
combined attacks.
It is useful to consider that threats, whether malicious or
accidental, may come from different categories of sources. For
example they may come from:
o Other users whose services are provided by the same MPLS-TP core.
o The MPLS-TP SP or persons working for it.
o Other persons who obtain physical access to a MPLS-TP SP's site.
o Other persons who use social engineering methods to influence the
behavior of a SP's personnel.
o Users of the MPLS-TP network itself.
o Others, e.g., attackers from the other sources, Internet if
connected.
o Other SPs in the case of MPLS-TP Inter-provider connection. The
provider may or may not be using MPLS-TP.
o Those who create, deliver, install, and maintain software for
network equipment.
Given that security is generally a tradeoff between expense and risk,
it is also useful to consider the likelihood of different attacks
occurring. There is at least a perceived difference in the
likelihood of most types of attacks being successfully mounted in
different environments, such as:
o A MPLS-TP network inter-connecting with another provider's core
o A MPLS-TP configuration transiting the public Internet
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. In closed communities, it is often
practical to deal with misbehavior after the fact: an employee can be
disciplined, for example.
Fang, et al. Expires November 17, 2011 [Page 17]
Internet-Draft MPLS-TP Security Framework May 2011
The following sections discuss specific types of exploits that
threaten MPLS-TP networks.
4.1. Attacks on the Control Plane
o MPLS-TP LSP creation by an unauthorized element
o LSP message interception
o Attacks on G-Ach
o Attacks against LDP
o Attacks against RSVP-TE
o Attacks against GMPLS
o Denial of Service Attacks on the Network Infrastructure
o Attacks on the SP's MPLS/GMPLS Equipment via Management Interfaces
o Social Engineering Attacks on the SP's Infrastructure
o Cross-Connection of Traffic between Users
o Attacks against Routing Protocols
o Other Attacks on Control Traffic
4.2. Attacks on the Data Plane
This category encompasses attacks on the provider's or end user's
data. Note that from the MPLS-TP network end user's point of view,
some of this might be control plane traffic, e.g. routing protocols
running from user site A to user site B via IP or non-IP connections,
which may be some type of VPN.
o Unauthorized Observation of Data Traffic
o Modification of Data Traffic
o Insertion of Inauthentic Data Traffic: Spoofing and Replay
o Unauthorized Deletion of Data Traffic
o Unauthorized Traffic Pattern Analysis
Fang, et al. Expires November 17, 2011 [Page 18]
Internet-Draft MPLS-TP Security Framework May 2011
o Denial of Service Attacks
o Misconnection
5. Defensive Techniques for MPLS-TP Networks
The defensive techniques discussed 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
implementations. 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 operational
environment determines the security requirements. Therefore,
protocol designers need to provide a full set of security services,
which can be used where appropriate.
The techniques discussed here include encryption, authentication,
filtering, firewalls, access control, isolation, aggregation, and
others.
5.1. Authentication
To prevent security issues arising from some DoS attacks or from
malicious or accidental misconfiguration, it is critical that devices
in the MPLS-TP should only accept connections or control messages
from valid sources. Authentication refers to methods to ensure that
message sources are properly identified by the MPLS-TP devices with
which they communicate. This section focuses on identifying the
scenarios in which sender authentication is required and recommends
authentication mechanisms for these scenarios.
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.
Authentication should be bi-directional, including PE or CE to
configuration server authentication for PE or CE to be certain it is
communicating with the right server.
Fang, et al. Expires November 17, 2011 [Page 19]
Internet-Draft MPLS-TP Security Framework May 2011
5.1.2. Peer-to-Peer Authentication
Peer-to-peer authentication includes peer authentication for network
control protocols and other peer authentication (i.e., authentication
of one IPsec security gateway by another).
Authentication should be bi-directional, including S-PE, T-PE, PE or
CE to configuration server authentication for PE or CE to 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 range of public-private
key systems. Another approach is to use a hierarchical Certification
Authority system to provide digital certificates.
5.2. Access Control Techniques
Most of the security issues related to management interfaces can be
addressed through the use of authentication techniques as described
in the section on authentication. However, additional security may
be provided by controlling access to management interfaces in other
ways.
The Optical Internetworking Forum has done relevant work on
protecting such interfaces with TLS, SSH, Kerberos, IPsec, WSS, etc.
See Security for Management Interfaces to Network Elements
[OIF-SMI-01.0], and Addendum to the Security for Management
Interfaces to Network Elements [OIF-SMI-02.1]. See also the work in
the ISMS WG.
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.
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.
Fang, et al. Expires November 17, 2011 [Page 20]
Internet-Draft MPLS-TP Security Framework May 2011
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.
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. Service Provider Quality Control Processes
5.6. Verification of Connectivity
In order 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.
6. Monitoring, Detection, and Reporting of Security Attacks
MPLS-TP network and service may be subject to attacks from a variety
of security threats. Many threats are described in the Security
Requirements (Section 3) Section of this document. Many of the
defensive techniques described in this document and elsewhere provide
significant levels of protection from a variety of 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
Fang, et al. Expires November 17, 2011 [Page 21]
Internet-Draft MPLS-TP Security Framework May 2011
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.
7. Security Considerations
Security considerations constitute the sole subject of this memo and
hence are discussed throughout.
The document describes a variety of defensive techniques that may be
used to counter the suspected threats. All of the techniques
presented involve mature and widely implemented technologies that are
practical to implement.
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 2004.
[RFC4732] Handley, M., Rescorla, E., and IAB, "Internet Denial-of-
Fang, et al. Expires November 17, 2011 [Page 22]
Internet-Draft MPLS-TP Security Framework May 2011
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 2009.
[RFC5951] Lam, K., Mansfield, S., and E. Gray, "Network Management
Requirements for MPLS-based Transport Networks", RFC 5951,
September 2010.
9.2. Informative References
[OIF-SMI-01.0]
Optical Internetworking Forum, "Security for Management
Interfaces to Network Elements", OIF OIF-SMI-01.0,
Sept 2003.
[OIF-SMI-02.1]
Optical Internetworking Forum, "Addendum to the Security
for Management Interfaces to Network Elements", OIF OIF-
SMI-02.1, March 2006.
[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.
[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-08.txt, June 2008.
Authors' Addresses
Luyuan Fang (editor)
Cisco Systems Inc.
111 Wood Ave. South
Iselin, NJ 08830
US
Email: lufang@cisco.com
Fang, et al. Expires November 17, 2011 [Page 23]
Internet-Draft MPLS-TP Security Framework May 2011
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
Raymond Zhang
British Telecom
BT Center
81 Newgate Street
London EC1A 7AJ
Uk
Email: raymond.zhang@bt.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
Fang, et al. Expires November 17, 2011 [Page 24]
Internet-Draft MPLS-TP Security Framework May 2011
Lei Wang
Telenor
Telenor Norway
Office Snaroyveien
1331 Fornedbu
Norway
Email: lei.wang@telenor.com
Henry Yu
TW Telecom
10475 Park Meadow Drive
Littleton, CO 80124
US
Email: henry.yu@twtelecom.com
Fang, et al. Expires November 17, 2011 [Page 25]
