Network Working Group Luyuan Fang (Ed) Internet Draft Michael Behringer Category: Informational Cisco Systems, Inc. Expires: August 2007 Ross Callon Juniper Networks J. L. Le Roux France Telecom Raymond Zhang British Telecom Paul Knight Nortel Yaakov Stein RAD Data Communications February 2007 Security Framework for MPLS and GMPLS Networks draft-fang-mpls-gmpls-security-framework-00.txt Status of this Memo This memo provides information for the Internet community. It does not specify an Internet standard of any kind. Distribution of this memo is unlimited. Internet-Drafts are working documents 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 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." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. IPR Disclosure Acknowledgement By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Copyright Notice Copyright (C) The IETF Trust (2007). Fang, et al. Informational 1 MPLS/GMPLS Security framework February 2007 Abstract This document provides a security framework for Multiprotocol Label Switching (MPLS) and Generalized Multiprotocol Label Switching (GMPLS) Networks (MPLS and GMPLS are described in [RFC3031] and [RFC3945]). This document addresses the security aspects that are relevant in the context of MPLS and GMPLS. It describes the security threats, the related defensive techniques, and the mechanisms for detection and reporting. This document gives emphasis to RSVP-TE and LDP security considerations, as well as Inter-AS and Inter-provider security considerations for building and maintaining MPLS and GMPLS networks across different domains or different Service Providers. Table of Contents 1. Introduction..................................................3 1.1. Structure of This Document.................................4 1.2. Contributors...............................................5 2. Terminology...................................................5 2.1. Terminology................................................5 2.2. Acronyms and Abbreviations.................................7 3. Security Reference Models.....................................7 4. Security Threats..............................................9 4.1. Attacks on the Control Plane..............................10 4.2. Attacks on the Data Plane.................................13 5. Defensive Techniques for MPLS/GMPLS Networks.................15 5.1. Cryptographic techniques..................................16 5.2. Authentication............................................24 5.3. Access Control techniques.................................25 5.4. Use of Isolated Infrastructure............................29 5.5. Use of Aggregated Infrastructure..........................30 5.6. Service Provider Quality Control Processes................30 5.7. Deployment of Testable MPLS/GMPLS Service.................31 6. Monitoring, Detection, and Reporting of Security Attacks.....31 7. Service Provider General Security Requirements...............32 7.1. Protection within the Core Network........................32 7.2. Protection on the User Access Link........................36 7.3. General Requirements for MPLS/GMPLS Providers.............38 8. Inter-provider Security Requirements.........................38 8.1. Control Plane Protection..................................39 Fang, et al. Informational 2 MPLS/GMPLS Security framework February 2007 8.2. Data Plane Protection.....................................43 9. Security Considerations......................................44 10. IANA Considerations........................................45 11. Normative References.......................................45 12. Informational References...................................46 13. Author's Addresses.........................................47 14. Acknowledgement............................................49 Conventions used in this document 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 [RFC 2119]. 1. Introduction Security is an important aspect of all networks, MPLS and GMPLS networks being no exception. MPLS and GMPLS are described in [RFC3031] [RFC3945]. Various security considerations have been addressed in each of the many RFCs that address on MPLS and GMPLS technologies, but there has not been a single document which provides general security considerations. The motivation for creating this document is to provide a comprehensive and consistent security framework for MPLS and GMPLS networks. Each individual document may point to this document for general security considerations in addition to providing the security considerations which are specific to the particular technologies the document is describing. In this document, we first describe the security threats that are relevant in the context of MPLS and GMPLS, and the defensive techniques that can be used to combat those threats. We consider security issues deriving both from malicious or incorrect behavior of users and other parties and from negligent or incorrect behavior of the providers. An important part of security defense is the detection and report of a security attack, which is also addressed in this document. We then discuss the possible service provider security requirements in a MPLS or GMPLS environment. The users have expectations that need to be met on the security characteristics of MPLS or GMPLS networks. These will include the security requirements for MPLS and GMPLS supporting equipments, and the provider operation security Fang, et al. Informational 3 MPLS/GMPLS Security framework February 2007 requirements. The service providers must protect their network infrastructure, and make it secure to the level required to provide services over their MPLS or GMPLS networks. Inter-As and Inter-provider security are discussed with special emphasis, since the security risk factors are higher with inter- provider connections. Depending on different MPLS or GMPLS techniques used, the degree of risk and the mitigation methodologies vary. This document discusses the security aspects and requirements for certain basic MPLS and GMPLS techniques and inter-connection models. This document does not attempt to cover all current and future MPLS and GMPLS technologies, since it is not within the scope of this document to analyze the security properties of specific technologies. It is important to clarify that, in this document; we limit ourselves to describing the providers' security requirements that pertain to MPLS and GMPLS networks. Readers may refer to the "Security Best Practices Efforts and Documents" [opsec effort] and "Security Mechanisms for the Internet" [RFC3631] for general network operation security considerations. It is not our intention, however, to formulate precise "requirements" on each specific technology in terms of defining the mechanisms and techniques that must be implemented to satisfy such security requirements. 1.1. Structure of This Document This document is organized as follows. In Section 2, we define the terminology used in the document. In section 3, we define the security reference models for security in MPLS/GMPLS networks, which we use in the rest of the document. In Section 4, we describe the security threats that are specific of MPLS and GMPLS. In Section 5, we review defense techniques that may be used against those threats. In Section 6, we describe how attacks may be detected and reported. In Section 7, we describe security requirements that the provider may have in order to guarantee the security of the network infrastructure to provide MPLS/GMPLS services. In section 8, we discuss Inter-provider security requirements. Finally, in Section 9, we discuss security considerations of this document. This document has used relevant content from RFC 4111 "Security Framework of Provider Provisioned VPN" [RFC4111], and "MPLS InterCarrier Interconnect Technical Specification" [MFA MPLS ICI] in the Inter-provider security discussion. We acknowledge the authors of these documents for the valuable information and text. Fang, et al. Informational 4 MPLS/GMPLS Security framework February 2007 1.2. Contributors As the design team members of MPLS security Framework, the following made significant contributions to this document. Nabil Bitar, Verizon Monique Morrow, Cisco systems, Inc. Jerry Ash, AT&T 2. Terminology 2.1. Terminology This document uses MPLS and GMPLS specific terminology. Definitions and details about MPLS and GMPLS terminology can be found in [RFC3031] and [RFC3945]. The most important definitions are repeated in this section, for other definitions the reader is referred to [RFC3031] and [RFC3945]. CE: Customer Edge device. A Customer Edge device is a router or a switch in the customer network interfacing with the Service Provider's network. Forwarding equivalence class (FEC): A group of IP packets which are forwarded in the same manner (e.g., over the same path, with the same forwarding treatment) Label: A short fixed length physically contiguous identifier which is used to identify a FEC, usually of local significance. Label switched hop: the hop between two MPLS nodes, on which forwarding is done using labels. Label switched path (LSP): The path through one or more LSRs at one level of the hierarchy followed by a packets in a particular FEC. Label switching router (LSR): an MPLS node which is capable of forwarding native L3 packets Layer 2: the protocol layer under layer 3 (which therefore offers the services used by layer 3). Forwarding, when done by the swapping of short fixed length labels, occurs at layer 2 regardless of whether the label being examined is an ATM VPI/VCI, a frame relay DLCI, or an MPLS label. Fang, et al. Informational 5 MPLS/GMPLS Security framework February 2007 Layer 3: the protocol layer at which IP and its associated routing protocols operate link layer synonymous with layer 2. Loop detection: a method of dealing with loops in which loops are allowed to be set up, and data may be transmitted over the loop, but the loop is later detected. Loop prevention: a method of dealing with loops in which data is never transmitted over a loop. Label stack: an ordered set of labels. Merge point: a node at which label merging is done MPLS domain: a contiguous set of nodes which operate MPLS routing and forwarding and which are also in one Routing or Administrative Domain. MPLS edge node: an MPLS node that connects an MPLS domain with a node which is outside of the domain, either because it does not run MPLS, and/or because it is in a different domain. Note that if an LSR has a neighboring host which is not running MPLS, that that LSR is an MPLS edge node. P: Provider Router. The Provider Router is a router in the Service Provider's core network that does not have interfaces directly towards the customer. A P router is used to interconnect the PE routers. MPLS egress node: an MPLS edge node in its role in handling traffic as it leaves an MPLS domain MPLS ingress node: an MPLS edge node in its role in handling traffic as it enters an MPLS domain MPLS label: a label which is carried in a packet header, and which represents the packet's FEC MPLS node: a node which is running MPLS. An MPLS node will be aware of MPLS control protocols, will operate one or more L3 routing protocols, and will be capable of forwarding packets based on labels. An MPLS node may optionally be also capable of forwarding native L3 packets. MultiProtocol Label Switching (MPLS): an IETF working group and the effort associated with the working group Fang, et al. Informational 6 MPLS/GMPLS Security framework February 2007 PE: Provider Edge device. The Provider Edge device is the equipment in the Service Provider's network that interfaces with the equipment in the customer's network. SP: Service Provider. VPN: Virtual Private Network. Restricted communication between a set of sites, making use of an IP backbone which is shared by traffic that is not going to or coming from those sites. [RFC4110]. 2.2. Acronyms and Abbreviations AS Autonomous System ASBR Autonomous System Border Router ATM Asynchronous Transfer Mode BGP Border Gateway Protocol FEC Forwarding Equivalence Class GMPLS Generalized Multi-Protocol Label Switching IGP Interior Gateway Protocol IP Internet Protocol LDP Label Distribution Protocol L2 Layer 2 L3 Layer 3 LSP Label Switched Path LSR Label Switching Router MPLS MultiProtocol Label Switching MP-BGP Multi-Protocol BGP PCE Path Calculation Element PSN Packet-Switched Network RSVP-TE Resource Reservation Protocol with Traffic Engineering Extensions TTL Time-To-Live VPN Virtual Private Network 3. Security Reference Models This section defines a reference model for security in MPLS/GMPLS networks. A MPLS/GMPLS core network is defined here as the central network infrastructure (P and PE routers). A MPLS/GMPLS core network consists of one or more SP networks. All network elements in the core are under the operational control of one or more MPLS/GMPLS service providers. Even if the MPLS/GMPLS core is provided by several service providers, towards the end users it appears as a single zone of trust. However, when several service providers Fang, et al. Informational 7 MPLS/GMPLS Security framework February 2007 provide together an MPLS/GMPLS core, each SP still needs to secure itself against the other SPs. A MPLS/GMPLS end user is a company, institution or residential client of the SP. This document defines each MPLS in a single domain a trusted zone. 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. Figure 1 depicts the concept of trusted zones within the MPLS/GMPLS framework. /-------------\ +------------+ / \ +------------+ | MPLS/GMPLS +---/ \--------+ MPLS | | user | MPLS/GMPLS Core | user | | site +---\ /XXX-----+ site | +------------+ \ / XXX +------------+ \-------------/ | | | | | +------\ +--------/ "Internet" MPLS/GMPLS Core with user connections and Internet connection Figure 1: The MPLS/GMPLS trusted zone model The trusted zone defined is the MPLS/GMPLS core/network in a single AS within a single Service Provider. In principle the trusted zones should be separate; however, typically MPLS core networks also offer Internet access, in which case a transit point (marked with "XXX" in the figure 1) is defined. In the case of MPLS/GMPLS inter-provider connection, the trusted zone ends at the ASBR (marked with "B" in the figure 2) of the considered AS/provider. A key requirement of MPLS and GMPLS networks is that the security of the trusted zone not be compromised by interconnecting the MPLS/GMPLS core infrastructure with another provider core (MPLS/GMPLS or non-MPLS/GMPLS), Internet, or end user access. In addition, neighbors may be trusted or untrusted. Neighbors may be authorized or unauthorized. Even though a neighbor may be authorized for communication, it may not be trusted. For example, Fang, et al. Informational 8 MPLS/GMPLS Security framework February 2007 when connecting with another provider ASBRs to set up inter-AS LSPs, the other provider is considered as an untrusted but authorized neighbor. +---------------+ +----------------+ | | | | | MPLS/GMPLS ASBR1----ASBR3 MPLS/GMPLS | CE1--PE1 Network | | Network PE2--CE2 | Provider A ASBR2----ASBR4 Provider B | | | | | +---------------+ +----------------+ For Provider A: Trusted Zone: Provider A MPSL/GMPLS network Trusted neighbor: PE1, ASBR1, ASBR2 Authorized but untrusted neighbor: provider B Unauthorized neighbor: CE1, CE2 Figure 2. MPLS/GMPLS trusted zone and authorized neighbor Security against threats that originate within the same trusted zone as their targets (for example, attacks from within the core network) is outside the scope of this document. Also outside the scope are all aspects of network security which are independent of whether a network is a MPLS/GMPLS network (for example, attacks from the Internet to a user web-server which is connected through the MPLS/GMPLS network will not be considered here, unless the way the MPLS/GMPLS network is provisioned could make a difference to the security of this user server). 4. Security Threats This section discusses the various network security threats that may endanger MPLS/GMPLS networks. The discussion is limited to those threats that are unique to MPLS/GMPLS networks, or that affect MPLS/GMPLS network in unique ways. A successful attack on a particular MPLS/GMPLS network or on a service provider's MPLS/GMPLS infrastructure may cause one or more of the following ill effects: - Observation, modification, or deletion of provider/user data. - Replay of provider/user data. Fang, et al. Informational 9 MPLS/GMPLS Security framework February 2007 - Injection of non-authentic data into a provider/user traffic stream. - Traffic pattern analysis on provider/user traffic. - Disruption of provider/user connectivity. - Degradation of provider service quality. It is useful to consider that threats, whether malicious or accidental, may come from different categories of sources. For example they may come from: - Other users whose services are provided by the same MPLS/GMPLS core. - The MPLS/GMPLS service provider or persons working for it. - Other persons who obtain physical access to a MPLS/GMPLS service provider site. - Other persons who use social engineering methods to influence behavior of service provider personnel. - Users of the MPLS/GMPLS network itself, i.e. intra-VPN threats. (Such threats are beyond the scope of this document.) - Others i.e. attackers from the Internet at large. - Other service provider in the case of MPLS/GMPLS Inter-provider connection. The core of the other provider may or may not be using MPLS/GMPLS core. Given that security is generally a compromise 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: - A MPLS/GMPLS inter-connecting with another provider's core - A MPLS/GMPLS 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 service provider to multiple cooperating providers 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. The following sections discuss specific types of exploits that threaten MPLS/GMPLS networks. 4.1. Attacks on the Control Plane This category encompasses attacks on the control structures operated by the service provider with MPLS/GMPLS cores. Fang, et al. Informational 10 MPLS/GMPLS Security framework February 2007 4.1.1. LSP creation by an unauthorized element The unauthorized element can be a local CE or a router in another domain. An unauthorized element can generate MPLS signaling messages. At the least, this can result in extra control plane and forwarding state, and if successful, network bandwidth could be reserved unnecessarily. 4.1.2. LSP message interception This threat might be accomplished by monitoring network traffic, although it would require physical intrusion. If successful, it could provide information leading to label spoofing attacks. It also raises confidentiality issues. 4.1.3. Attacks against RSVP-TE RSVP-TE, described in [RFC3209], is the control protocol used to set up GMPLS and traffic engineered MPLS tunnels. There are two major types of attacks against an MPLS domain based on RSVP-TE. The attacker may set up numerous unauthorized LSPs, or may send a storm of RSVP messages in a DoS attack. It has been demonstrated that unprotected routers running RSVP can be effectively disabled by both types of DoS attacks. These attacks may even be combined, by using the unauthorized LSPs to transport additional RSVP (or other) messages across routers where they might otherwise be filtered out. RSVP attacks can be launched against adjacent routers at the border with the attacker, or against non-adjacent routers within the MPLS domain, if there is no effective mechanism to filter them out. 4.1.4. Attacks against LDP LDP, described in [RFC3036], is the control protocol used to set up non-TE MPLS tunnels. There are two significant types of attack against LDP. An unauthorized network element can establish an LDP session by sending LDP Hello and LDP Init messages, leading to the potential setup of an LSP, as well as accompanying LDP state table consumption. Even without successfully established LSPs, an attacker can launch a DoS attack in the form of a storm of LDP Hello messages and/or LDP TCP Syn messages, leading to high CPU utilization on the target router. Fang, et al. Informational 11 MPLS/GMPLS Security framework February 2007 4.1.5. Denial of Service Attacks on the Network Infrastructure DoS attacks could be accomplished through an MPLS signaling storm, resulting in high CPU utilization and possibly leading to control plane resource starvation. Control plane DOS attacks can be mounted specifically against the mechanisms the service provider uses to provide various services, or against the general infrastructure of the service provider e.g. P routers or shared aspects of PE routers. (Attacks against the general infrastructure are within the scope of this document only if the attack happens in relation with the MPLS/GMPLS infrastructure, otherwise is not MPLS/GMPLS-specific issue.) The attacks described in the following sections may each have denial of service as one of their effects. Other DOS attacks are also possible. 4.1.6. Attacks on the Service Provider MPLS/GMPLS Equipment Via Management Interfaces This includes unauthorized access to service provider infrastructure equipment, for example to reconfigure the equipment or to extract information (statistics, topology, etc.) pertaining to the network. 4.1.7. Social Engineering Attacks on the Service Provider Infrastructure Attacks in which the service provider network is reconfigured or damaged, or in which confidential information is improperly disclosed, may be mounted through manipulation of service provider personnel. These types of attacks are MPLS/GMPLS-specific if they affect MPLS/GMPLS-serving mechanisms. 4.1.8. Cross-connection of Traffic Between Users This refers to the event where expected isolation between separate users (who may be VPN users) is breached. This includes cases such as: - A site being connected into the "wrong" VPN. - Traffic being replicated and sent to an unauthorized user. - Two or more VPNs being improperly merged together. - A point-to-point VPN connecting the wrong two points. Fang, et al. Informational 12 MPLS/GMPLS Security framework February 2007 - Any packet or frame being improperly delivered outside the VPN to which it belongs. Mis-connection or cross-connection of VPNs may be caused by service provider or equipment vendor error, or by the malicious action of an attacker. The breach may be physical (e.g. PE-CE links mis- connected) or logical (improper device configuration). Anecdotal evidence suggests that the cross-connection threat is one of the largest security concerns of users (or would-be users). 4.1.9. Attacks Against User Routing Protocols This encompasses attacks against underlying routing protocols that are run by the service provider and that directly support the MPLS/GMPLS core. (Attacks against the use of routing protocols for the distribution of backbone (non-VPN) routes are beyond the scope of this document.) Specific attacks against popular routing protocols have been widely studied and described in [Beard]. 4.1.10. Other Attacks on Control Traffic Besides routing and management protocols (covered separately in the previous sections) a number of other control protocols may be directly involved in delivering the services by the MPLS/GMPLS core. These include but may not be limited to: - MPLS signaling (LDP, RSVP-TE) discussed above in subsections 4.1.4 and 4.1.3 - PCE signaling - IPsec signaling (IKE) - L2TP - BGP-based membership discovery - Database-based membership discovery (e.g. RADIUS-based) Attacks might subvert or disrupt the activities of these protocols, for example via impersonation or DOS attacks. 4.2. Attacks on the Data Plane This category encompasses attacks on the provider or end user's data. Note that from the MPLS/GMPLS network end user's point of view, some of this might be control plane traffic, e.g. routing protocols running from the user site A to the user site B via an L2 or L3 connection which may be some type of VPN. Fang, et al. Informational 13 MPLS/GMPLS Security framework February 2007 4.2.1. Unauthorized Observation of Data Traffic This refers to "sniffing" provider/end user packets and examining their contents. This can result in exposure of confidential information. It can also be a first step in other attacks (described below) in which the recorded data is modified and re- inserted, or re-inserted as-is. 4.2.2. Modification of Data Traffic This refers to modifying the contents of packets as they traverse the MPLS/GMPLS core. 4.2.3. Insertion of Non-Authentic Data Traffic: Spoofing and Replay This refers to the insertion (or "spoofing") into the user packets that do not belong there, with the objective of having them accepted by the recipient as legitimate. Also included in this category is the insertion of copies of once-legitimate packets that have been recorded and replayed. 4.2.4. Unauthorized Deletion of Data Traffic This refers to causing packets to be discarded as they traverse the MPLS/GMPLS networks. This is a specific type of Denial of Service attack. 4.2.5. Unauthorized Traffic Pattern Analysis This refers to "sniffing" provider/user packets and examining aspects or meta-aspects of them that may be visible even when the packets themselves are encrypted. An attacker might gain useful information based on the amount and timing of traffic, packet sizes, source and destination addresses, etc. For most users, this type of attack is generally considered to be significantly less of a concern than the other types discussed in this section. 4.2.6. Denial of Service Attacks Denial of Service (DOS) attacks are those in which an attacker attempts to disrupt or prevent the use of a service by its legitimate users. Taking network devices out of service, modifying their configuration, or overwhelming them with requests for service are several of the possible avenues for DOS attack. Overwhelming the network with requests for service, otherwise known as a "resource exhaustion" DOS attack, may target any resource in Fang, et al. Informational 14 MPLS/GMPLS Security framework February 2007 the network e.g. link bandwidth, packet forwarding capacity, session capacity for various protocols, CPU power, and so on. DOS attacks of the resource exhaustion type can be mounted against the data plane of a particular provider or end-user by attempting to insert (spoofing) an overwhelming quantity of non-authentic data into the provider/end user network from the outside of the trusted zone. Potential results might be to exhaust the bandwidth available to that provider/end user or to overwhelm the cryptographic authentication mechanisms of the provider or end user. Data plane resource exhaustion attacks can also be mounted by overwhelming the service provider's general (MPLS/GMPLS- independent) infrastructure with traffic. These attacks on the general infrastructure are not usually a MPLS/GMPLS-specific issue, unless the attack is mounted by another MPLS/GMPLS network user from a privileged position. (E.g. a MPLS/GMPLS network user might be able to monopolize network data plane resources and thus disrupt other users.) 5. Defensive Techniques for MPLS/GMPLS 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/GMPLS implementations. The MPLS/GMPLS 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 encryption, authentication, filtering, firewalls, access control, isolation, aggregation, and other techniques. Nothing is ever 100% secure. Defense therefore involves protecting against those attacks that are most likely to occur and/or that have the most dire consequences if successful. For those attacks that are protected against, absolute protection is seldom achievable; more often it is sufficient just to make the cost of a successful attack greater than what the adversary will be willing to expend. Successfully defending against an attack does not necessarily mean the attack must be prevented from happening or from reaching its target. In many cases the network can instead be designed to withstand the attack. For example, the introduction of non- authentic packets could be defended against by preventing their Fang, et al. Informational 15 MPLS/GMPLS Security framework February 2007 introduction in the first place, or by making it possible to identify and eliminate them before delivery to the MPLS/GMPLS user's system. The latter is frequently a much easier task. 5.1. Cryptographic techniques MPLS/GMPLS defenses against a wide variety of attacks can be enhanced by the proper application of cryptographic techniques. These are the same cryptographic techniques which are applicable to general network communications. In general, these techniques can provide confidentiality (encryption) of communication between devices, authentication of the identities of the devices, and can ensure that it will be detected if the data being communicated is changed during transit. Several aspects of authentication are addressed in some detail in a separate "Authentication" section. Encryption adds complexity to a service, and thus it may not be a standard offering within every user service. There are a few reasons why encryption may not be a standard offering within every user service. Encryption adds an additional computational burden to the devices performing encryption and decryption. This may reduce the number of user connections which can be handled on a device or otherwise reduce the capacity of the device, potentially driving up the provider's costs. Typically, configuring encryption services on devices adds to the complexity of the device configuration and adds incremental labor cost. Packet sizes are typically increased when the packets are secured, increasing the network traffic load and adding to the likelihood of packet fragmentation with its increased overhead. (This packet length increase can often be mitigated to some extent by data compression techniques, but at the expense of additional computational burden.) Finally, some providers may employ enough other defensive techniques, such as physical isolation or filtering/firewall techniques, that they may not perceive additional benefit from encryption techniques. The trust model among the MPLS/GMPLS user, the MPLS/GMPLS provider, and other parts of the network is a key element in determining the applicability of encryption for any specific MPLS/GMPLS implementation. In particular, it determines where encryption should be applied: - If the data path between the user's site and the provider's PE is not trusted, then encryption may be used on the PE-CE link. - If some part of the backbone network is not trusted, particularly in implementations where traffic may travel Fang, et al. Informational 16 MPLS/GMPLS Security framework February 2007 across the Internet or multiple provider networks, then the PE-PE traffic may be encrypted. - If the user does not trust any zone outside of its premises, it may require end-to-end or CE-CE encryption service. This service fits within the scope of this MPLS/GMPLS security framework when the CE is provisioned by the MPLS/GMPLS provider. - If the user requires remote access to a its site from a system at a location which is not a customer location (for example, access by a traveler) there may be a requirement for encrypting the traffic between that system and an access point or at a customer site. If the MPLS/GMPLS provider provides the access point, then the customer must cooperate with the provider to handle the access control services for the remote users. These access control services are usually implemented using encryption, as well. Although CE-CE encryption provides confidentiality against third- party interception, if the MPLS/GMPLS provider has complete management control over the CE (encryption) devices, then it may be possible for the provider to gain access to the user's traffic or internal network. Encryption devices can potentially be configured to use null encryption, bypass encryption processing altogether, or provide some means of sniffing or diverting unencrypted traffic. Thus an implementation using CE-CE encryption needs to consider the trust relationship between the MPLS/GMPLS user and provider. MPLS/GMPLS users and providers may wish to negotiate a service level agreement (SLA) for CE-CE encryption that will provide an acceptable demarcation of responsibilities for management of encryption on the CE devices. The demarcation may also be affected by the capabilities of the CE devices. For example, the CE might support some partitioning of management, a configuration lock-down ability, or allow both parties to verify the configuration. In general, the MPLS/GMPLS user needs to have a fairly high level of trust that the MPLS/GMPLS provider will properly provision and manage the CE devices, if the managed CE-CE model is used. 5.1.1. IPsec in MPLS/GMPLS IPsec [RFC4301] [RFC4302] [RFC4305] [RFC4306] [RFC2411] is the security protocol of choice for encryption at the IP layer (Layer 3). IPsec provides robust security for IP traffic between pairs of devices. Non-IP traffic must be converted to IP (e.g. by encapsulation) in order to exploit IPsec. Fang, et al. Informational 17 MPLS/GMPLS Security framework February 2007 In the MPLS/GMPLS model, IPsec can be employed to protect IP traffic between PEs, between a PE and a CE, or from CE to CE. CE- to-CE IPsec may be employed in either a provider-provisioned or a user-provisioned model. Likewise, encryption of data which is performed within the user's site is outside the scope of this document, since it is simply handled as user data by the MPLS/GMPLS core. IPsec does not itself specify an encryption algorithm. It can use a variety of encryption algorithms, with various key lengths, such as AES encryption. There are trade-offs between key length, computational burden, and the level of security of the encryption. A full discussion of these trade-offs is beyond the scope of this document. In practice, any currently recommended IPsec encryption offers enough security to substantially reduce the likelihood of being directly targeted by an attacker; other weaker links in the chain of security are likely to be attacked first. MPLS/GMPLS users may wish to use a Service Level Agreement (SLA) specifying the Service Provider's responsibility for ensuring data confidentiality, rather than analyzing the specific encryption techniques used in the MPLS/GMPLS service. For many of the MPLS/GMPLS provider's network control messages and some user requirements, cryptographic authentication of messages without encryption of the contents of the message may provide acceptable security. Using IPsec, authentication of messages is provided by the Authentication Header (AH) or through the use of the Encapsulating Security Protocol (ESP) with authentication only. Where control messages require authentication but do not use IPsec, then other cryptographic authentication methods are available. Message authentication methods currently considered to be secure are based on hashed message authentication codes (HMAC) [RFC2104] implemented with a secure hash algorithm such as Secure Hash Algorithm 1 (SHA-1) [RFC3174]. The currently recommended mechanism to provide a combination of confidentiality, data origin authentication, and connectionless integrity is the use of AES in CCM (Counter with CBC-MAC) mode (AES-CCM) [AES-CCM], with an explicit initialization vector (IV), as the IPsec ESP. MPLS/GMPLS which provide differentiated services based on traffic type may encounter some conflicts with IPsec encryption of traffic. Since encryption hides the content of the packets, it may not be possible to differentiate the encrypted traffic in the same manner as unencrypted traffic. Although DiffServ markings are copied to Fang, et al. Informational 18 MPLS/GMPLS Security framework February 2007 the IPsec header and can provide some differentiation, not all traffic types can be accommodated by this mechanism. 5.1.2. Encryption for device configuration and management For configuration and management of MPLS/GMPLS devices, encryption and authentication of the management connection at a level comparable to that provided by IPsec is desirable. Several methods of transporting MPLS/GMPLS device management traffic offer security and confidentiality. - Secure Shell (SSH) offers protection for TELNET [STD-8] or terminal-like connections to allow device configuration. - SNMP v3 [STD62] provides encrypted and authenticated protection for SNMP-managed devices. - Transport Layer Security (TLS) [RFC4346] and the closely-related Secure Sockets Layer (SSL) are widely used for securing HTTP- based communication, and thus can provide support for most XML- and SOAP-based device management approaches. - As of 2004, there is extensive work proceeding in several organizations (OASIS, W3C, WS-I, and others) on securing device management traffic within a "Web Services" framework, using a wide variety of security models, and providing support for multiple security token formats, multiple trust domains, multiple signature formats, and multiple encryption technologies. - IPsec provides the services with security and confidentiality at the network layer. With regards to device management, its current use is primarily focused on in-band management of user- managed IPsec gateway devices. 5.1.3. Cryptographic techniques for MPLS Pseudowires 5.1.4. 5.1.3 Security Considerations for MPLS Pseudowires In addition to IP traffic, MPLS networks may be used to transport other services such as Ethernet, ATM, frame relay, and TDM. This is done by setting up pseudowires (PWs) that tunnel the native service through the MPLS core by encapsulating at the edges. The PWE architecture is defined in [RFC3985]. Fang, et al. Informational 19 MPLS/GMPLS Security framework February 2007 PW tunnels may be set up using the PWE control protocol based on LDP [RFC4447], and thus security considerations for LDP will most likely be applicable to the PWE3 control protocol as well. PW user packets contain at least one MPLS label (the PW label) and may contain one or more MPLS tunnel labels. After the label stack there is a four-byte control word (which is optional for some PW types), followed by the native service payload. It must be stressed that encapsulation of MPLS PW packets in IP for the purpose of enabling use of IPsec mechanisms is not a valid option. The PW client traffic may be secured by use of mechanisms beyond the scope of this document. 5.1.5. End-to-end vs. hop-by-hop encryption tradeoffs in MPLS/GMPLS In MPLS/GMPLS, encryption could potentially be applied to the MPLS/GMPLS traffic at several different places. This section discusses some of the tradeoffs in implementing encryption in several different connection topologies among different devices within a MPLS/GMPLS network. Encryption typically involves a pair of devices which encrypt the traffic passing between them. The devices may be directly connected (over a single "hop"), or there may be intervening devices which transport the encrypted traffic between the pair of devices. The extreme cases involve using encryption between every adjacent pair of devices along a given path (hop-by-hop), or using encryption only between the end devices along a given path (end-to- end). To keep this discussion within the scope of this document, the latter ("end-to-end") case considered here is CE-to-CE rather than fully end-to-end. Figure 3 depicts a simplified topology showing the Customer Edge (CE) devices, the Provider Edge (PE) devices, and a variable number (three are shown) of Provider core (P) devices which might be present along the path between two sites in a single VPN, operated by a single service provider (SP). Site_1---CE---PE---P---P---P---PE---CE---Site_2 Figure 3: Simplified topology traversing through MPLS/GMPLS core Fang, et al. Informational 20 MPLS/GMPLS Security framework February 2007 Within this simplified topology, and assuming that P devices are not to be involved with encryption, there are four basic feasible configurations for implementing encryption on connections among the devices: 1) Site-to-site (CE-to-CE) - Encryption can be configured between the two CE devices, so that traffic will be encrypted throughout the SP's network. 2) Provider edge-to-edge (PE-to-PE) - Encryption can be configured between the two PE devices. Unencrypted traffic is received at one PE from the customer's CE, then it is encrypted for transmission through the SP's network to the other PE, where it is decrypted and sent to the other CE. 3) Access link (CE-to-PE) - Encryption can be configured between the CE and PE, on each side (or on only one side). 4) Configurations 2 and 3 above can also be combined, with encryption running from CE to PE, then PE to PE, then PE to CE. Among the four feasible configurations, key tradeoffs in considering encryption include: - Vulnerability to link eavesdropping - assuming an attacker can observe the data in transit on the links, would it be protected by encryption? - Vulnerability to device compromise - assuming an attacker can get access to a device (or freely alter its configuration), would the data be protected? - Complexity of device configuration and management - given the number of sites per VPN customer as Nce and the number of PEs participating in a given VPN as Npe, how many device configurations need to be created or maintained, and how do those configurations scale? - Processing load on devices - how many encryption or decryption operations must be done given P packets? - This influences considerations of device capacity and perhaps end-to-end delay. - Ability of SP to provide enhanced services (QoS, firewall, intrusion detection, etc.) - Can the SP inspect the data in order to provide these services? Fang, et al. Informational 21 MPLS/GMPLS Security framework February 2007 These tradeoffs are discussed for each configuration, below: 1) Site-to-site (CE-to-CE) Link eavesdropping - protected on all links Device compromise - vulnerable to CE compromise Complexity - single administration, responsible for one device per site (Nce devices), but overall configuration per VPN scales as Nce**2 Processing load - on each of two CEs, each packet is either encrypted or decrypted (2P) Enhanced services - severely limited; typically only Diffserv markings are visible to SP, allowing some QoS services 2) Provider edge-to-edge (PE-to-PE) Link eavesdropping - vulnerable on CE-PE links; protected on SP's network links Device compromise - vulnerable to CE or PE compromise Complexity - single administration, Npe devices to configure. (Multiple sites may share a PE device so Npe is typically much less than Nce.) Scalability of the overall configuration depends on the PPVPN type: If the encryption is separate per VPN context, it scales as Npe**2 per customer VPN. If the encryption is per-PE, it scales as Npe**2 for all customer VPNs combined. Processing load - on each of two PEs, each packet is either encrypted or decrypted (2P) Enhanced services - full; SP can apply any enhancements based on detailed view of traffic 3) Access link (CE-to-PE) Link eavesdropping - protected on CE-PE link; vulnerable on SP's network links Device compromise - vulnerable to CE or PE compromise Complexity - two administrations (customer and SP) with device configuration on each side (Nce + Npe devices to configure) but since there is no mesh the overall configuration scales as Nce. Processing load - on each of two CEs, each packet is either encrypted or decrypted, plus on each of two PEs, each packet is either encrypted or decrypted (4P) Enhanced services - full; SP can apply any enhancements based on detailed view of traffic 4) Combined Access link and PE-to-PE (essentially hop-by-hop) Link eavesdropping - protected on all links Fang, et al. Informational 22 MPLS/GMPLS Security framework February 2007 Device compromise - vulnerable to CE or PE compromise Complexity - two administrations (customer and SP) with device configuration on each side (Nce + Npe devices to configure). Scalability of the overall configuration depends on the PPVPN type: If the encryption is separate per VPN context, it scales as Npe**2 per customer VPN. If the encryption is per-PE, it scales as Npe**2 for all customer VPNs combined. Processing load - on each of two CEs, each packet is either encrypted or decrypted, plus on each of two PEs, each packet is both encrypted and decrypted (6P) Enhanced services - full; SP can apply any enhancements based on detailed view of traffic Given the tradeoffs discussed above, a few conclusions can be made: - Configurations 2 and 3 are subsets of 4 that may be appropriate alternatives to 4 under certain threat models; the remainder of these conclusions compare 1 (CE-to-CE) vs. 4 (combined access links and PE-to-PE). - If protection from link eavesdropping is most important, then configurations 1 and 4 are equivalent. - If protection from device compromise is most important and the threat is to the CE devices, both cases are equivalent; if the threat is to the PE devices, configuration 1 is best. - If reducing complexity is most important, and the size of the network is very small, configuration 1 is the best. Otherwise configuration 4 is the best because rather than a mesh of CE devices it requires a smaller mesh of PE devices. Also under some PPVPN approaches the scaling of 4 is further improved by sharing the same PE-PE mesh across all VPN contexts. The scaling advantage of 4 may be increased or decreased in any given situation if the CE devices are simpler to configure than the PE devices, or vice- versa. - If the overall processing load is a key factor, then 1 is best. - If the availability of enhanced services support from the SP is most important, then 4 is best. As a quick overall conclusion, CE-to-CE encryption provides greater protection against device compromise but this comes at the cost of enhanced services and at the cost of operational complexity due to the Order(n**2) scaling of a larger mesh. Fang, et al. Informational 23 MPLS/GMPLS Security framework February 2007 This analysis of site-to-site vs. hop-by-hop encryption tradeoffs does not explicitly include cases of multiple providers cooperating to provide a PPVPN service, public Internet VPN connectivity, or remote access VPN service, but many of the tradeoffs will be similar. 5.2. Authentication In order to prevent security issues from some Denial-of-Service attacks or from malicious misconfiguration, it is critical that devices in the MPLS/GMPLS 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/GMPLS 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. Cryptographic techniques (authentication and encryption) do not protect against some types of denial of service attacks, specifically resource exhaustion attacks based on CPU or bandwidth exhaustion. In fact, the processing required to decrypt and/or check authentication may in some cases increase the effect of these resource exhaustion attacks. Cryptographic techniques may however, be useful against resource exhaustion attacks based on exhaustion of state information (e.g., TCP SYN attacks). The MPLS user plane, as presently defined, is not amenable to source authentication as there are no source identifiers in the MPLS packet to authenticate. The MPLS label is only locally meaningful, and identifies a downstream semantic rather than an upstream source. When the MPLS payload carries identifiers that may be authenticated (e.g., IP packets), authentication may be carried out at the client level, but this does not help the MPLS service provider as these client identifiers belong to an external non-trusted network. 5.2.1. Management System Authentication Management system authentication includes the authentication of a PE to a centrally-managed directory server, when directory-based Fang, et al. Informational 24 MPLS/GMPLS Security framework February 2007 "auto-discovery" is used. It also includes authentication of a CE to the configuration server, when a configuration server system is used. 5.2.2. Peer-to-peer Authentication Peer-to-peer authentication includes peer authentication for network control protocols (e.g. LDP, BGP, etc.), and other peer authentication (i.e. authentication of one IPsec security gateway by another). 5.2.3. 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 Certificate Authority system to provide digital certificates. This section describes or provides references to the specific cryptographic approaches for authenticating identity. These approaches provide secure mechanisms for most of the authentication scenarios required in securing a MPLS/GMPLS network. 5.3. Access Control techniques Access control techniques include packet-by-packet or packet-flow- by-packet-flow access control by means of filters and firewalls, as well as by means of admitting a "session" for a control/signaling/management protocol. Enforcement of access control by isolated infrastructure addresses is discussed in another section of this document. In this document, we distinguish between filtering and firewalls based primarily on the direction of traffic flow. We define filtering as being applicable to unidirectional traffic, while a firewall can analyze and control both sides of a conversation. There are two significant corollaries of this definition: - Routing or traffic flow symmetry: A firewall typically requires routing symmetry, which is usually enforced by locating a firewall where the network topology assures that both sides of a Fang, et al. Informational 25 MPLS/GMPLS Security framework February 2007 conversation will pass through the firewall. A filter can operate upon traffic flowing in one direction, without considering traffic in the reverse direction. - Statefulness: Since it receives both sides of a conversation, a firewall may be able to interpret a significant amount of information concerning the state of that conversation, and use this information to control access. A filter can maintain some limited state information on a unidirectional flow of packets, but cannot determine the state of the bi-directional conversation as precisely as a firewall. 5.3.1. Filtering It is relatively common for routers to filter data packets. That is, routers can look for particular values in certain fields of the IP or higher level (e.g., TCP or UDP) headers. Packets which match the criteria associated with a particular filter may either be discarded or given special treatment. In discussing filters, it is useful to separate the Filter Characteristics which may be used to determine whether a packet matches a filter from the Packet Actions which are applied to those packets which match a particular filter. o Filter Characteristics Filter characteristics are used to determine whether a particular packet or set of packets matches a particular filter. In many cases filter characteristics may be stateless. A stateless filter is one which determines whether a particular packet matches a filter based solely on the filter definition, normal forwarding information (such as the next hop for a packet), and the characteristics of that individual packet. Typically stateless filters may consider the incoming and outgoing logical or physical interface, information in the IP header, and information in higher layer headers such as the TCP or UDP header. Information in the IP header to be considered may for example include source and destination IP address, Protocol field, Fragment Offset, and TOS field. Filters also may consider fields in the TCP or UDP header such as the Port fields as well as the SYN field in the TCP header. Stateful filtering maintains packet-specific state information, to aid in determining whether a filter has been met. For example, a device might apply stateless filters to the first fragment of a fragmented IP packet. If the filter matches, then the data unit ID may be remembered and other fragments of the same packet may then be considered to match the same filter. Stateful filtering is more Fang, et al. Informational 26 MPLS/GMPLS Security framework February 2007 commonly done in firewalls, although firewall technology may be added to routers. o Actions based on Filter Results If a packet, or a series of packets, matches a specific filter, then there are a variety of actions which may be taken based on that filter match. Examples of such actions include: - Discard In many cases filters may be set to catch certain undesirable packets. Examples may include packets with forged or invalid source addresses, packets which are part of a DOS or DDOS attack, or packets which are trying to access resources which are not permitted (such as network management packets from an unauthorized source). Where such filters are activated, it is common to silently discard the packet or set of packets matching the filter. The discarded packets may of course also be counted and/or logged. - Set CoS A filter may be used to set the Class of Service associated with the packet. - Count packets and/or bytes - Rate Limit In some cases the set of packets which match a particular filter may be limited to a specified bandwidth. In this case packets and/or bytes would be counted, and would be forwarded normally up to the specified limit. Excess packets may be discarded, or may be marked (for example by setting a "discard eligible" bit in the IP ToS field or the MPLS EXP field). - Forward and Copy It is useful in some cases to forward some set of packets normally, but to also send a copy to a specified other address or interface. For example, this may be used to implement a lawful intercept capability, or to feed selected packets to an Intrusion Detection System. o Other Issues related to Use of Packet Filters There may be a very wide variation in the performance impact of filtering. This may occur both due to differences between Fang, et al. Informational 27 MPLS/GMPLS Security framework February 2007 implementations, and also due to differences between types or numbers of filters deployed. For filtering to be useful, the performance of the equipment has to be acceptable in the presence of filters. The precise definition of "acceptable" may vary from service provider to service provider, and may depend upon the intended use of the filters. For example, for some uses a filter may be turned on all the time in order to set CoS, to prevent an attack, or to mitigate the effect of a possible future attack. In this case it is likely that the service provider will want the filter to have minimal or no impact on performance. In other cases, a filter may be turned on only in response to a major attack (such as a major DDOS attack). In this case a greater performance impact may be acceptable to some service providers. A key consideration with the use of packet filters is that they can provide few options for filtering packets carrying encrypted data. Since the data itself is not accessible, only packet header information or other unencrypted fields can be used for filtering. 5.3.2. Firewalls Firewalls provide a mechanism for control over traffic passing between different trusted zones in the MPLS/GMPLS model, or between a trusted zone and an untrusted zone. Firewalls typically provide much more functionality than filters, since they may be able to apply detailed analysis and logical functions to flows, and not just to individual packets. They may offer a variety of complex services, such as threshold-driven denial-of-service attack protection, virus scanning, acting as a TCP connection proxy, etc. As with other access control techniques, the value of firewalls depends on a clear understanding of the topologies of the MPLS/GMPLS core network, the user networks, and the threat model. Their effectiveness depends on a topology with a clearly defined inside (secure) and outside (not secure). Firewalls may be applied to help protect MPLS/GMPLS core network functions from attacks originating from the Internet or from MPLS/GMPLS user sites, but typically other defensive techniques will be used for this purpose. Where firewalls are employed as a service to protect user VPN sites from the Internet, different VPN users, and even different sites of a single VPN user, may have varying firewall requirements. The Fang, et al. Informational 28 MPLS/GMPLS Security framework February 2007 overall PPVPN logical and physical topology, along with the capabilities of the devices implementing the firewall services, will have a significant effect on the feasibility and manageability of such varied firewall service offerings. Another consideration with the use of firewalls is that they can provide few options for handling packets carrying encrypted data. Since the data itself is not accessible, only packet header information, other unencrypted fields, or analysis of the flow of encrypted packets can be used for making decisions on accepting or rejecting encrypted traffic. 5.3.3. Access Control to management interfaces 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. Management interfaces, especially console ports on MPLS/GMPLS devices, may be configured so they are only accessible out-of-band, through a system which is physically and/or logically separated from the rest of the MPLS/GMPLS infrastructure. Where management interfaces are accessible in-band within the MPLS/GMPLS 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/GMPLS devices themselves. 5.4. Use of Isolated Infrastructure One way to protect the infrastructure used for support of MPLS/GMPLS is to separate the resources for support of MPLS/GMPLS services from the resources used for other purposes (such as support of Internet services). In some cases this may make use of physically separate equipment for VPN services, or even a physically separate network. For example, PE-based L3 VPNs may be run on a separate backbone not connected to the Internet, or may make use of separate edge routers from those used to support Internet service. Private IP addresses Fang, et al. Informational 29 MPLS/GMPLS Security framework February 2007 (local to the provider and non-routable over the Internet) are sometimes used to provide additional separation. 5.5. 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/GMPLS enabled services is to allow sharing of resources between multiple users, including multiple VPNs, etc. Thus even if certain services make use of a separate network from Internet services, nonetheless there will still be multiple MPLS/GMPLS users sharing the same network resources. In some cases MPLS/GMPLS services will share the use of network resources with Internet services or other services. It is therefore important for MPLS/GMPLS services to provide protection between resource utilization by different users. Thus a well-behaved MPLS/GMPLS user should be protected from possible misbehavior by other users. This requires that limits are placed on the amount of resources which can be used by any one VPN. For example, both control traffic and user data traffic may be rate limited. In some cases or in some parts of the network where a sufficiently large number of queues are available each VPN (and optionally each VPN and CoS within the VPN) may make use of a separate queue. Control-plane resources such as link bandwidth as well as CPU and memory resources may be reserved on a per-VPN basis. The techniques which are used to provision resource protection between multiple users served by the same infrastructure can also be used to protect MPLS/GMPLS networks and services from Internet services. 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. 5.6. Service Provider Quality Control Processes Deployment of provider-provisioned VPN services in general requires a relatively large amount of configuration by the service provider. For example, the service provider needs to configure which VPN each site belongs to, as well as QoS and SLA guarantees. This large amount of required configuration leads to the possibility of misconfiguration. Fang, et al. Informational 30 MPLS/GMPLS Security framework February 2007 It is important for the service provider to have operational processes in place to reduce the potential impact of misconfiguration. CE to CE authentication may also be used to detect misconfiguration when it occurs. 5.7. Deployment of Testable MPLS/GMPLS Service. This refers to solutions that can be readily tested to make sure they are configured correctly. E.g. for a point-point connection, checking that the intended connectivity is working pretty much ensures that there is not connectivity to some unintended site. 6. Monitoring, Detection, and Reporting of Security Attacks MPLS/GMPLS network and service may be subject to attacks from a variety of security threats. Many threats are described in another part 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 silently employing defensive techniques to protect against attacks, MPLS/GMPLS services can also add value for both providers and customers by implementing security monitoring systems which detect and report on any security attacks which occur, regardless of whether the attacks are effective. Attackers often begin by probing and analyzing defenses, so systems which 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 and/or their specific targets at an early stage. This knowledge about attackers and targets can be used to further strengthen defenses against specific attacks or attackers, or improve the defensive services 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. Monitoring systems used to detect security attacks in MPLS/GMPLS will typically operate by collecting information from the Provider Edge (PE), Customer Edge (CE), and/or Provider backbone (P) devices. Security monitoring systems should have the ability to actively retrieve information from devices (e.g., SNMP get) or to passively receive reports from devices (e.g., SNMP notifications). The specific information exchanged will depend on the capabilities of the devices and on the type of VPN technology. Particular care Fang, et al. Informational 31 MPLS/GMPLS Security framework February 2007 should be given to securing the communications channel between the monitoring systems and the MPLS/GMPLS devices. The CE, PE, and P devices should employ efficient methods to acquire and communicate the information needed by the security monitoring systems. It is important that the communication method between MPLS/GMPLS devices and security monitoring systems be designed so that it will not disrupt network operations. As an example, multiple attack events may be reported through a single message, rather than allowing each attack event to trigger a separate message, which might result in a flood of messages, essentially becoming a denial-of-service attack against the monitoring system or the network. The mechanisms for reporting security attacks should be flexible enough to meet the needs of MPLS/GMPLS service providers, MPLS/GMPLS customers, and regulatory agencies, if applicable. The specific reports will depend on the capabilities of the devices, the security monitoring system, the type of VPN, and the service level agreements between the provider and customer. 7. Service Provider General Security Requirements In this section, we discuss the security requirements that the provider may have in order to secure its MPLS/GMPLS network infrastructure, including LDP and RSVP-TE specific requirements. The MPLS/GMPLS service provider requirements defined here are the requirements for the MPLS/GMPLS core in the reference model. The core network can be implemented with different types of network technologies, and each core network may use different technologies to provide the various services to users with different levels of offered security. Therefore, a MPLS/GMPLS service provider may fulfill any number of the security requirements listed in this section. This document does not state that a MPLS/GMPLS network must fulfill all of these requirements to be secure. These requirements are focused on: 1) how to protect the MPLS/GMPLS core from various attacks outside the core including network users, both accidentally and maliciously, 2) how to protect the end users. 7.1. Protection within the Core Network 7.1.1. Control Plane Protection - General - Protocol authentication within the core: Fang, et al. Informational 32 MPLS/GMPLS Security framework February 2007 The network infrastructure must support mechanisms for authentication of the control plane. In MPLS/GMPLS core is used, LDP sessions may be authenticated by use TCP MD5, in addition, IGP and BGP authentication should also be considered. For a core providing Layer 2 services, PE to PE authentication may also be used via IPsec. With the cost of authentication coming down rapidly, the application of control plane authentication may not increase the cost of implementation for providers significantly, and will help to improve the security of the core. If the core is dedicated to MPLS/GMPLS enabled services and without any interconnects to third parties then this may reduce the requirement for authentication of the core control plane. - Elements protection Here we discuss means to hide the provider's infrastructure nodes. A MPLS/GMPLS provider may make the infrastructure routers (P and PE routers) unreachable from outside users and unauthorized internal users. For example, separate address space may be used for the infrastructure loopbacks. Normal TTL propagation may be altered to make the backbone look like one hop from the outside, but caution needs to be taken for loop prevention. This prevents the backbone addresses from being exposed through trace route; however this must also be assessed against operational requirements for end to end fault tracing. An Internet backbone core may be re-engineered to make Internet routing an edge function, for example, using MPLS label switching for all traffic within the core and possibly make the Internet a VPN within the PPVPN core itself. This helps to detach Internet access from PPVPN services. Separating control plane, data plane, and management plane functionality in terms of hardware and software may be implemented on the PE devices to improve security. This may help to limit the problems when attacked in one particular area, and may allow each plane to implement additional security measurement separately. PEs are often more vulnerable to attack than P routers, since PEs cannot be made unreachable to outside users by their very nature. Access to core trunk resources can be controlled on a per user basis by the application of inbound rate-limiting/shaping, this can Fang, et al. Informational 33 MPLS/GMPLS Security framework February 2007 be further enhanced on a per Class of Service basis (see section 8.2.3) In the PE, using separate routing processes for different services, for example, Internet and PPVPN service may help to improve the PPVPN security and better protect VPN customers. Furthermore, if the resources, such as CPU and Memory, may be further separated based on applications, or even individual VPNs, it may help to provide improved security and reliability to individual VPN customers. 7.1.2. Control plane protection with RSVP-TE - RSVP Security Tools Isolation of the trusted domain is an important security mechanism with respect to RSVP, to ensure that an untrusted element cannot access a router of the trusted domain. Though isolation is limited by the need to allow ASBR-ASBR communication for inter-AS LSPs. Isolation mechanisms might be bypassed by Router Alert IP packets. - A solution would consists in disabling the RSVP router alert mode and dropping all IP packets with the router alert option, or also to drop on an interface all incoming IP packets with port 46, which requires an access-list at the IP port level) or spoofed IP packets if anti-spoofing is not activated. RSVP security can be strengthened by deactivating RSVP on interfaces with neighbors who are not authorized to use RSVP, to protect against adjacent CE-PE attacks. However, this does not really protect against DoS attacks, and does not protect against attacks on non-adjacent routers. It has been demonstrated that substantial CPU resources are consumed simply by processing received RSVP packets, even if the RSVP process is deactivated for the specific interface on which the RSVP message is received. RSVP neighbor filtering at the protocol level, to restrict the set of neighbors that can send RSVP messages to a given router, protects against non-adjacent attacks. However, this does not protect against DoS attacks, and does not effectively protect against spoofing of the source address of RSVP packets, if the filter relies on the neighbor's address within the RSVP message. RSVP neighbor filtering at the data plane level (access list to accept IP packet with port 46, only for specific neighbors). This requires Router Alert mode to be deactivated. This does not protect against spoofing. - Authentication for RSVP messages Fang, et al. Informational 34 MPLS/GMPLS Security framework February 2007 One of the most powerful tools for protection against RSVP-based attacks is the use of authentication for RSVP messages, based on a secure message hash using a key shared by RSVP neighbors. This protects against LSP creation attacks, at the expense of consuming significant CPU resources for digest computation. In addition, if the neighboring RSVP speaker is compromised, it could be used to launch attacks using authenticated RSVP messages. Another valuable tool is RSVP message pacing, to limit the number of RSVP messages sent to a given neighbor during a given period. This allows blocking DoS attack propagation. In order to ensure continued effective operation of the MPLS router even in the case of an attack which is able to bypass packet filtering mechanisms such as Access Control Lists in the data plane, it is important that routers have some mechanisms to limit the impact of the attack. There should be a mechanism to rate limit the amount of control plane traffic addressed to the router, per interface. This should be configurable on a per-protocol basis, (and, ideally, on a per sender basis) to avoid an attacked protocol, or a given sender blocking all communications. This requires the ability to filter and limit the rate of incoming messages of particular protocols, such as RSVP (filtering at the IP port level), and particular senders). In addition, there should be a mechanism to limit CPU and memory capacity allocated to RSVP, so as to protect other control plane elements. In order to limit the memory allocation, it will probably be necessary to limit the number of LSPs which can be set up. - limit the impact of an attack on control plane resources In order to ensure continued effective operation of the MPLS router even in the case of an attack which is able to bypass packet filtering mechanisms such as Access Control Lists in the data plane, it is important that routers have some mechanisms to limit the impact of the attack. There should be a mechanism to rate limit the amount of control plane traffic addressed to the router, per interface. This should be configurable on a per-protocol basis, (and, ideally, on a per sender basis) to avoid an attacked protocol, or a given sender blocking all communications. This requires the ability to filter and limit the rate of incoming messages of particular protocols, such as RSVP (filtering at the IP port level, and particular senders). In addition, there should be a mechanism to limit CPU and memory capacity allocated to RSVP, so as to protect other control plane elements. In order to limit the memory allocation, it will probably be necessary to limit the number of LSPs which can be set up. Fang, et al. Informational 35 MPLS/GMPLS Security framework February 2007 7.1.3. Control plane protection with LDP The approaches to protect MPLS routers against LDP-based attacks are very similar to those for RSVP, including isolation, protocol deactivation on specific interfaces, filtering of LDP neighbors at the protocol level, filtering of LDP neighbors at the data plane level (access list that filter the TCP & UDP LDP ports), authentication with message digest, rate limiting of LDP messages per protocol per sender and limiting all resources which might be allocated to LDP-related tasks. 7.1.4. Data Plane Protection IPsec technologies can provide - encryption of secure provider or user data. In today's MPLS/GMPLS, ATM, or Frame Relay networks, encryption is not provided as a basic feature. Mechanisms described in section 5 can be used to secure the MPLS data plane to secure the data carried over MPLS core. 7.2. Protection on the User Access Link Peer / Neighbor protocol authentication may be used to enhance security. For example, BGP MD5 authentication may be used to enhance security on PE-CE links using eBGP. In the case of Inter- provider connection, authentication / encryption mechanisms between ASes, such as IPsec, may be used. WAN link address space separation for different services (e.g. VPN and non-VPN) may be implemented to improve security in order to protect each service if multiple services are provided on the same PE platform. Firewall / Filtering: access control mechanisms can be used to filter out any packets destined for the service provider's infrastructure prefix or eliminate routes identified as illegitimate routes. Rate limiting may be applied to the user interface/logical interfaces against DDOS bandwidth attack. This is very helpful when the PE device is supporting both multi-services, especially when supporting VPN and Internet Services on the same physical interfaces through different logical interfaces. Fang, et al. Informational 36 MPLS/GMPLS Security framework February 2007 7.2.1. Link Authentication Authentication mechanisms can be employed to validate site access to the network via fixed or logical (e.g. L2TP, IPsec) connections. Where the user wishes to hold the 'secret' associated to acceptance of the access and site into the VPN, then provider solutions require the flexibility for either direct authentication by the PE itself or interaction with a customer authentication server. Mechanisms are required in the latter case to ensure that the interaction between the PE and the customer authentication server is controlled e.g. limiting it simply to an exchange in relation to the authentication phase and with other attributes e.g. RADIUS optionally being filtered. 7.2.2. Access Routing Mechanisms may be used to provide control at a routing protocol level e.g. RIP, OSPF, BGP between the CE and PE. Per neighbor and per VPN routing policies may be established to enhance security and reduce the impact of a malicious or non-malicious attack on the PE, in particular the following mechanisms should be considered: - Limiting the number of prefixes that may be advertised on a per access basis into the PE. Appropriate action may be taken should a limit be exceeded e.g. the PE shutting down the peer session to the CE - Applying route dampening at the PE on received routing updates - Definition of a per VPN prefix limit after which additional prefixes will not be added to the VPN routing table. In the case of Inter-provider connection, access protection, link authentication, and routing policies as described above may be applied. Both inbound and outbound firewall/filtering mechanism between ASes may be applied. Proper security procedures must be implemented in Inter-provider VPN interconnection to protect the providers' network infrastructure and their customer VPNs. This may be custom designed for each Inter-Provider VPN peering connection, and must be agreed by both providers. 7.2.3. Access QoS MPLS/GMPLS providers offering QoS enabled services require mechanisms to ensure that individual accesses are validated against their subscribed QOS profile and as such gain access to core resources that match their service profile. Mechanisms such as per Class of service rate limiting/traffic shaping on ingress to the MPLS/GMPLS core are one option in providing this level of control. Fang, et al. Informational 37 MPLS/GMPLS Security framework February 2007 Such mechanisms may require the per Class of Service profile to be enforced either by marking, remarking or discard of traffic outside of profile. 7.2.4. Customer service monitoring tools End users requiring visibility of the specific statistics on the core e.g. routing table, interface status, QoS statistics, impose requirements for mechanisms at the PE to both validate the incoming user and limit the views available to that particular user. Mechanisms should also be considered to ensure that such access cannot be used a means of a DOS attack (either malicious or accidental) on the PE itself. This could be accomplished through either separation of these resources within the PE itself or via the capability to rate-limit on a per physical/logical connection basis such traffic. 7.3. General Requirements for MPLS/GMPLS Providers The MPLS/GMPLS providers must support the users' security requirements as listed in Section 7. Depending on the technologies used, these requirements may include: - User control plane separation - routing isolation - Protection against intrusion, DOS attacks and spoofing - Access Authentication - Techniques highlighted through this document identify methodologies for the protection of resources and MPLS/GMPLS infrastructure. Equipment hardware/software bugs leading to breaches in security are not within the scope of this document. 8. Inter-provider Security Requirements This section discusses security capabilities that are important at the MPLS/GMPLS Inter-provider connections, and at devices (including ASBR routers) which support the Inter-provider connections. The security capabilities stated in this section should be considered as complementary to security considerations addressed in the individual protocol specifications and/or security frameworks. Security vulnerabilities and exposures may be propagated across multiple networks because of security vulnerabilities arising in one peer's network. Threats to security originate from accidental, Fang, et al. Informational 38 MPLS/GMPLS Security framework February 2007 administrative and intentional sources. Intentional threats include events such as spoofing and Denial of Service (DoS) attacks. The level and nature of threats, as well as security and availability requirements, may vary over time and from network to network. This section therefore discusses capabilities that need to be available in equipment deployed for support of the MPLS-ICI. Whether any particular capability is used in any one specific instance of the ICI is up to the service providers managing the provider edge equipment offering/using the ICI services. 8.1. Control Plane Protection This section discusses capabilities for control plane protection, including protection of routing, signaling, and OAM capabilities. 8.1.1. Authentication of Signaling Sessions Authentication of signaling sessions (i.e., BGP, LDP and RSVP-TE) and routing sessions (e.g., BGP) as well as OAM sessions across domain boundaries. Equipment must be able to support exchange of all protocol messages over a single IPsec tunnel, with NULL encryption and authentication, between the peering ASBRs. Support for TCP MD5 authentication for LDP and BGP and for RSVP-TE authentication must also be provided. Mechanisms to authenticate and validate a dynamic setup request MUST be available. For instance, if dynamic signaling of a TE-LSP or PW is crossing a domain boundary, there must be a way to detect whether the LSP source is who he claims to be and that he is allowed to connect to the destination. MD5 authentication support for all TCP-based protocols within the scope of the MPLS-ICI (i.e., LDP signaling, and BGP routing) and MD5 authentication for the RSVP-TE Integrity Object MUST be provided to interoperate with current practices. Equipment SHOULD be able to support exchange of all signaling and routing (LDP, RSVP-TE, and BGP) protocol messages over a single IPSec in tunnel or transport mode with authentication but with NULL encryption, between the peering ASBRs. IPSec, if supported, must be supported with HMAC-MD-5 and optionally SHA-1. It is expected that authentication algorithms will evolve over time and support can be updated as needed. OAM Operations across the MPLS-ICI could also be the source of security threats on the provider infrastructure as well as the service offered over the MPLS-ICI. A large volume of OAM messages could overwhelm the processing capabilities of an ASBR if the ASBR is not probably protected. Maliciously-generated OAM messages could Fang, et al. Informational 39 MPLS/GMPLS Security framework February 2007 also be used to bring down an otherwise healthy service (e.g., MPLS Pseudo Wire), and therefore effecting service security. MPLS-ping does not support authentication today and that support should be subject for future considerations. Bidirectional Forwarding Detection (BFD) however, does have support for carrying an authentication object. It also supports Time-To-Live (TTL) processing as anti-replay measure. Implementations conformant to this MPLS-ICI should support BFD authentication using MD-5 and must support the procedures for TTL processing. 8.1.2. Protection against DoS attacks in the Control Plane Ability to prevent signaling and routing DOS attacks on the control plane per interface and provider. Such prevention may be provided by rate-limiting signaling and routing messages that can be sent by a peer provider according to a traffic profile and by guarding against malformed packets. Equipment MUST provide the ability to filter signaling, routing, and OAM packets destined for the device, and MUST provide the ability to rate limit such packets. Packet filters SHOULD be capable of being separately applied per interface, and SHOULD have minimal or no performance impact. For example, this allows an operator to filter or rate-limit signaling, routing, and OAM messages that can be sent by a peer provider and limit such traffic to a traffic profile. In the presence of a control plane DoS attack against an ASBR, the router SHOULD guarantee sufficient resources to allow network operators to execute network management commands to take corrective action, such as turning on additional filters or disconnecting an interface which is under attack. DoS attacks on the control plane SHOULD NOT adversely affect data plane performance. Equipment which supports BGP MUST support the ability to limit the number of BGP routes received from any particular peer. Furthermore, in the case of IPVPN, a router MUST be able to limit the number of routes learned from a BGP peer per IPVPN. In the case that a device has multiple BGP peers, it SHOULD be possible for the limit to vary between peers. 8.1.3. Protection against Malformed Packets Equipment SHOULD be robust in the presence of malformed protocol packets. For example, malformed routing, signaling, and OAM packets should be treated in accordance to the relevant protocol specification. Fang, et al. Informational 40 MPLS/GMPLS Security framework February 2007 8.1.4. Ability to Enable/Disable Specific Protocols Ability to drop any signaling or routing protocol messages when these messages are to be processed by the ASBR but the corresponding protocol is not enabled on that interface. Equipment must allow an administrator to enable or disable a protocol (default protocol is disabled unless administratively enable) on an interface basis. Equipment MUST be able to drop any signaling or routing protocol messages when these messages are to be processed by the ASBR but the corresponding protocol is not enabled on that interface. This dropping SHOULD NOT adversely affect data plane or control plane performance. 8.1.5. Protection Against Incorrect Cross Connection Capability of detecting and locating faults in an LSP cross-connect MUST be provided. Such faults cause security violations as they result in directing traffic to the wrong destinations. This capability may rely on OAM functions. Equipment MUST support MPLS LSP Ping [RFC4379]. This MAY be used to verify end to end connectivity for the LSP (e.g., PW, TE Tunnel, VPN LSP, etc), and to verify PE to PE connectivity for L3 VPN services. When routing information is advertised from one domain to the other, there MUST be mechanisms that enable operators to guard against situations that result in traffic hijacking, black-holing, resource stealing (e.g., number of routes), etc. For instance, in the IPVPN case, an operator must be able to block routes based on associated route target attributes. In addition, mechanisms must exist to verify whether a route advertised by a peer for a given VPN is actually a valid route and whether the VPN has a site attached or reachable through that domain. Equipment (ASBRs and RRs) which supports operation of BGP MUST allow a means to restrict which Route Target attributes are sent to and accepted from a BGP peer across an ICI. Equipment (ASBRs, RRs) SHOULD also be able to inform the peer regarding which Route Target attributes it will accept from the peer. This is due to the fact that a peer which sends an incorrect Route Target can result in incorrect cross-connection of VPNs. Also, sending inappropriate route targets to a peer may disclose confidential information. Further Security Consideration for inter-provider BGP/MPLS IPVPN operations are discussed in the IPVPN Annex. Fang, et al. Informational 41 MPLS/GMPLS Security framework February 2007 8.1.6. Protection Against Spoofed Updates and Route Advertisements Equipment MUST support signaling and routing. Equipment MUST support route filtering of routes received via a BGP peer sessions by applying policies that include one or more the following: AS path, BGP next hop, standard community and/or extended community. 8.1.7. Protection of Confidential Information Ability to identify and prohibit messages that can reveal confidential information about network operation (e.g., performance OAM messages, MPLS-ping messages). Service Providers must have the flexibility of handling these messages at the ASBR. Equipment SHOULD provide the ability to identify and prohibit messages that can reveal confidential information about network operation (e.g., performance OAM messages, LSP Traceroute messages). Service Providers must have the flexibility of handling these messages at the ASBR. For example, equipment supporting LSP Traceroute MAY limit which addresses replies can be sent to. Note: This capability should be used with care. For example, if a service provider chooses to prohibit the exchange of LSP PING messages at the ICI, it may make it more difficult to debug incorrect cross-connection of LSPs or other problems. A provider may decide to progress these messages if they are incoming from a trusted provider and are targeted to specific agreed-on addresses. Another provider may decide to traffic police, reject or apply policies to these messages. Solutions must enable providers to control the information that is relayed to another provider about the path that an LSP takes. For example, in RSVP-TE record route object or MPLS-ping trace, a provider must be able to control the information contained in corresponding messages when sent to another provider. 8.1.8. Protection Against over-provisioned number of RSVP-TE LSPs and bandwidth reservation In addition to the control plane protection mechanisms listed in the previous section on Control plane protection with RSVP-TE, the ASBR needs mechanisms to both limit the number of LSPs that can be set up by other domains and to limit the amount of bandwidth that can be reserved. A provider's ASBR may deny the LSPs set up request or the bandwidth reservation request sent by another provider's the limits are reached. Fang, et al. Informational 42 MPLS/GMPLS Security framework February 2007 8.2. Data Plane Protection 8.2.1. Protection against DoS in the Data Plane This is provided earlier in this document. 8.2.2. Protection against Label Spoofing Verification that a label received across an interconnect was actually assigned to the provider across the interconnect. If the label was not assigned to the provider, the packet MUST be dropped. Equipment MUST be able to verify that a label received across an interconnect was actually assigned to an LSP arriving from the provider across that interconnect. If the label was not assigned to an LSP which arrives at this router from the correct neighboring provider, the packet MUST be dropped. This verification can be applied to the top label only. The top label is the received top label and every label that is exposed by label popping to be used for forwarding decisions. Equipment MUST provide the capability of dropping MPLS-labeled packets if all labels in the stack are not processed. This provides carriers the capability of guaranteeing that every label that enters its domain from another carrier was actually assigned to that carrier. The following requirements are not directly reflected in this document but must be used as guidance for addressing further work. Solutions MUST NOT force operators to reveal reachability information to routers within their domains. ||< AS1 >| Traffic flow direction is from SP2 to SP1 Usually, the transit label used by ASBR2 is allocated by ASBR1 which in turn advertises to ASB2 (downstream unsolicited or on- demand) and this label is used for a service context (VPN label, PW VC label, etc.) and this LSP is normally terminated at a forwarding table belonging to the service instance on PE (PE1) in SP1. In the example above, ASBR1 would not know if the label of an incoming packet from ASBR2 over the interconnect is VPN label or PSN label for AS1. So it is possible (though rare) that ASBR2 can be tempered such that the incoming label could match a PSN label (e.g., LDP) in AS1 - then this LSP would end up on the global plane of an infrastructure router (P or PE1) - this could invite a unidirectional attack on that P or PE1 the LSP terminates. To mitigate this threat, we SHOULD be able to do a forwarding path look-up for the label on an incoming packet from a interconnect in a LFIB space that is only intended for its own service context or provide a mechanism on the data plane that would ensure the incoming labels are what ASBR1 has allocated and advertised. Similar concept has been proposed in "Requirements for Multi- Segment Pseudowire Emulation Edge-to-Edge (PWE3)" [PW-REQ]. 9. Security Considerations Security considerations constitute the sole subject of this memo and hence are discussed throughout. Here we recap what has been presented and explain at a very high level the role of each type of consideration in an overall secure MPLS/GMPLS system. The document describes a number of potential security threats. Some of these threats have already been observed occurring in running networks; others are largely theoretical at this time. DOS attacks and intrusion Attacks from the Internet against service provider infrastructure have been seen to occur. DOS "attacks" (typically not malicious) have also been seen in which CE equipment overwhelms PE equipment with high quantities or rates of packet traffic or routing Fang, et al. Informational 44 MPLS/GMPLS Security framework February 2007 information. Operational/provisioning errors are cited by service providers as one of their prime concerns. 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 describes the importance of detecting, monitoring, and reporting attacks, both successful and unsuccessful. These activities are essential for "understanding one's enemy", mobilizing new defenses, and obtaining metrics about how secure the MPLS/GMPLS network is. As such they are vital components of any complete PPVPN security system. The document evaluates MPLS/GMPLS security requirements from a customer perspective as well as from a service provider 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 equipment or service offering. 10. IANA Considerations TBD. 11. Normative References [RFC3031] E. Rosen, A. Viswanathan, R. Callon, "Multiprotocol Label Switching Architecture", RFC 3031, January 2001. [RFC3945] E. Mannie, "Generalized Multi-Protocol Label Switching (GMPLS) Architecture", RFC 3945, October 2004. [RFC3036] Andersson, et al., "LDP Specification", January 2001. [RFC3209] Awduche, et al., "RSVP-TE: Extensions to RSVP for LSP Tunnels", December 2001. [RFC4301] S. Kent, K. Seo, "Security Architecture for the Internet Protocol," December 2005. [RFC4302] S. Kent, "IP Authentication Header," December 2005. Fang, et al. Informational 45 MPLS/GMPLS Security framework February 2007 [RFC4305] D. Eastlake 3rd, "Cryptographic Algorithm Implementation Requirements for Encapsulating Security Payload (ESP) and Authentication Header (AH)", December 2005. [RFC4306] C. Kaufman, "Internet Key Exchange (IKEv2) Protocol",December 2005. [RFC4346] T. Dierks and E. Rescorla, "The Transport Layer Security (TLS) Protocol, Version 1.1," April 2006. [RFC4379] K. Kompella and G. Swallow, "Detecting Multi-Protocol Label Switched (MPLS) Data Plane Failures", February 2006. [RFC4447] Martini, et al., "Pseudowire Setup and Maintenance Using the Label Distribution Protocol (LDP)", April 2006. [STD62] "Simple Network Management Protocol, Version 3," RFCs 3411- 3418, December 2002. [STD-8] J. Postel and J. Reynolds, "TELNET Protocol Specification", STD 8, May 1983. 12. Informational References [AES-CCM] Housley, R., "Using AES CCM Mode With IPsec ESP", draft- ietf-ipsec-ciph-aes-ccm-05.txt, work in progress, November 2003. [RFC 2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997 [Beard] D. Beard and Y. Yang, "Known Threats to Routing Protocols," draft-beard-rpsec-routing-threats-00.txt, Oct. 2002. (Note, this is now approved as RFC, no number yet, http://www.ietf.org/internet- drafts/draft-ietf-rpsec-routing-threats-06.txt. [RFC2104] H. Krawczyk, M. Bellare, R. Canetti, "HMAC: Keyed-Hashing for Message Authentication," February 1997. [RFC2411] R. Thayer, N. Doraswamy, R. Glenn, "IP Security Document Roadmap," November 1998. [RFC3174] D. Eastlake, 3rd, and P. Jones, "US Secure Hash Algorithm 1 (SHA1)," September 2001. Fang, et al. Informational 46 MPLS/GMPLS Security framework February 2007 [RFC3985] S. Bryant and P. Pate, "Pseudo Wire Emulation Edge-to- Edge (PWE3) Architecture", March 2005. [RFC4111] L. Fang, "Security Framework of Provider Provisioned VPN", RFC 4111, July 2005. [RFC3631] S. Bellovin, C. Kaufman, J. Schiller, "Security Mechanisms for the Internet," December 2003. [RFC4110] R. Callon and M. Suzuki, "A Framework for Layer 3 Provider-Provisioned Virtual Private Networks (PPVPNs), July 2005. [MFA MPLS ICI] N. Bitar, "MPLS InterCarrier Interconnect Technical Specification", MFA2006.109.01, August 2006. [opsec efforts] C. Lonvick and D. Spak, "Security Best Practices Efforts and Documents", draft-ietf-opsec-efforts-05.txt, December 2006. [PW-REQ] N. Bitar, M. Bocci, L. Martini, "Requirements for Multi- Segment Pseudowire Emulation Edge-to-Edge", draft-ietf-pwe3-ms-pw- requirements-04.txt. 13. Author's Addresses Luyuan Fang Cisco Systems, Inc. 300 Beaver Brook Road Boxborough, MA 01719 USA EMail: lufang@cisco.com Michael Behringer Cisco Systems, Inc. Village d'Entreprises Green Side 400, Avenue Roumanille, Batiment T 3 06410 Biot, Sophia Antipolis FRANCE Email: mbehring@cisco.com Ross Callon Juniper Networks 10 Technology Park Drive Westford, MA 01886 Fang, et al. Informational 47 MPLS/GMPLS Security framework February 2007 USA Email: rcallon@juniper.net Jean-Louis Le Roux France Telecom 2, avenue Pierre-Marzin 22307 Lannion Cedex FRANCE Email: jeanlouis.leroux@francetelecom.com Raymond Zhang British Telecom 2160 E. Grand Ave. El Segundo, CA 90025 USA Email: raymond.zhang@bt.com Paul Knight Nortel 600 Technology Park Drive Billerica, MA 01821 EMail: paul.knight@nortel.com Yaakov (Jonathan) Stein RAD Data Communications 24 Raoul Wallenberg St., Bldg C Tel Aviv 69719 ISRAEL Email: yaakov_s@rad.com Intellectual Property The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. Fang, et al. Informational 48 MPLS/GMPLS Security framework February 2007 Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf- ipr@ietf.org. Full Copyright Statement Copyright (C) The IETF Trust (2007). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. Disclaimer This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 14. Acknowledgement Funding for the RFC Editor function is provided by the IETF Administrative Support Activity (IASA). Fang, et al. Informational 49