Internet Engineering Task Force (IETF)                   M. Jethanandani
Request for Comments: 6952                             Ciena Corporation
Category: Informational                                         K. Patel
ISSN: 2070-1721                                       Cisco Systems, Inc
                                                                L. Zheng
                                                     Huawei Technologies
                                                                May 2013
Internet Engineering Task Force (IETF)                   M. Jethanandani
Request for Comments: 6952                             Ciena Corporation
Category: Informational                                         K. Patel
ISSN: 2070-1721                                       Cisco Systems, Inc
                                                                L. Zheng
                                                     Huawei Technologies
                                                                May 2013

Analysis of BGP, LDP, PCEP, and MSDP Issues According to the Keying and Authentication for Routing Protocols (KARP) Design Guide




This document analyzes TCP-based routing protocols, the Border Gateway Protocol (BGP), the Label Distribution Protocol (LDP), the Path Computation Element Communication Protocol (PCEP), and the Multicast Source Distribution Protocol (MSDP), according to guidelines set forth in Section 4.2 of "Keying and Authentication for Routing Protocols Design Guidelines", RFC 6518.

本文件根据本协议第4.2节规定的指南,分析基于TCP的路由协议、边界网关协议(BGP)、标签分发协议(LDP)、路径计算元素通信协议(PCEP)和多播源分发协议(MSDP)“路由协议设计指南的键控和认证”,RFC 6518。

Status of This Memo


This document is not an Internet Standards Track specification; it is published for informational purposes.


This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Not all documents approved by the IESG are a candidate for any level of Internet Standard; see Section 2 of RFC 5741.

本文件是互联网工程任务组(IETF)的产品。它代表了IETF社区的共识。它已经接受了公众审查,并已被互联网工程指导小组(IESG)批准出版。并非IESG批准的所有文件都适用于任何级别的互联网标准;见RFC 5741第2节。

Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at


Copyright Notice


Copyright (c) 2013 IETF Trust and the persons identified as the document authors. All rights reserved.

版权所有(c)2013 IETF信托基金和确定为文件作者的人员。版权所有。

This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents ( in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License.

本文件受BCP 78和IETF信托有关IETF文件的法律规定的约束(自本文件出版之日起生效。请仔细阅读这些文件,因为它们描述了您对本文件的权利和限制。从本文件中提取的代码组件必须包括信托法律条款第4.e节中所述的简化BSD许可证文本,并提供简化BSD许可证中所述的无担保。

Table of Contents


   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Abbreviations . . . . . . . . . . . . . . . . . . . . . .   4
   2.  Current Assessment of BGP, LDP, PCEP, and MSDP  . . . . . . .   5
     2.1.  Transport Layer . . . . . . . . . . . . . . . . . . . . .   5
     2.2.  Keying Mechanisms . . . . . . . . . . . . . . . . . . . .   6
     2.3.  BGP . . . . . . . . . . . . . . . . . . . . . . . . . . .   7
     2.4.  LDP . . . . . . . . . . . . . . . . . . . . . . . . . . .   7
       2.4.1.  Spoofing Attacks  . . . . . . . . . . . . . . . . . .   7
       2.4.2.  Denial-of-Service Attacks . . . . . . . . . . . . . .   8
     2.5.  PCEP  . . . . . . . . . . . . . . . . . . . . . . . . . .   8
     2.6.  MSDP  . . . . . . . . . . . . . . . . . . . . . . . . . .  10
   3.  Optimal State for BGP, LDP, PCEP, and MSDP  . . . . . . . . .  10
     3.1.  LDP . . . . . . . . . . . . . . . . . . . . . . . . . . .  10
   4.  Gap Analysis for BGP, LDP, PCEP, and MSDP . . . . . . . . . .  11
     4.1.  LDP . . . . . . . . . . . . . . . . . . . . . . . . . . .  12
     4.2.  PCEP  . . . . . . . . . . . . . . . . . . . . . . . . . .  13
   5.  Transition and Deployment Considerations  . . . . . . . . . .  13
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .  13
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  14
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  14
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .  14
     8.2.  Informative References  . . . . . . . . . . . . . . . . .  14
   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Abbreviations . . . . . . . . . . . . . . . . . . . . . .   4
   2.  Current Assessment of BGP, LDP, PCEP, and MSDP  . . . . . . .   5
     2.1.  Transport Layer . . . . . . . . . . . . . . . . . . . . .   5
     2.2.  Keying Mechanisms . . . . . . . . . . . . . . . . . . . .   6
     2.3.  BGP . . . . . . . . . . . . . . . . . . . . . . . . . . .   7
     2.4.  LDP . . . . . . . . . . . . . . . . . . . . . . . . . . .   7
       2.4.1.  Spoofing Attacks  . . . . . . . . . . . . . . . . . .   7
       2.4.2.  Denial-of-Service Attacks . . . . . . . . . . . . . .   8
     2.5.  PCEP  . . . . . . . . . . . . . . . . . . . . . . . . . .   8
     2.6.  MSDP  . . . . . . . . . . . . . . . . . . . . . . . . . .  10
   3.  Optimal State for BGP, LDP, PCEP, and MSDP  . . . . . . . . .  10
     3.1.  LDP . . . . . . . . . . . . . . . . . . . . . . . . . . .  10
   4.  Gap Analysis for BGP, LDP, PCEP, and MSDP . . . . . . . . . .  11
     4.1.  LDP . . . . . . . . . . . . . . . . . . . . . . . . . . .  12
     4.2.  PCEP  . . . . . . . . . . . . . . . . . . . . . . . . . .  13
   5.  Transition and Deployment Considerations  . . . . . . . . . .  13
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .  13
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  14
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  14
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .  14
     8.2.  Informative References  . . . . . . . . . . . . . . . . .  14
1. Introduction
1. 介绍

In their "Report from the IAB Workshop on Unwanted Traffic March 9-10, 2006" [RFC4948], the Internet Architecture Board (IAB) described an attack on core routing infrastructure as an ideal attack that would inflict the greatest amount of damage and suggested steps to tighten the infrastructure against the attack. Four main steps were identified for that tightening:


1. Create secure mechanisms and practices for operating routers.

1. 创建操作路由器的安全机制和实践。

2. Clean up the Internet Routing Registry (IRR) repository, and secure both the database and the access, so that it can be used for routing verifications.

2. 清理Internet路由注册表(IRR)存储库,确保数据库和访问的安全,以便可以将其用于路由验证。

3. Create specifications for cryptographic validation of routing message content.

3. 为路由消息内容的加密验证创建规范。

4. Secure the routing protocols' packets on the wire.

4. 在线路上保护路由协议的数据包。

In order to secure the routing protocols, this document performs an initial analysis of the current state of four TCP-based protocols -- BGP [RFC4271], LDP [RFC5036], PCEP [RFC5440], and MSDP [RFC3618] -- according to the requirements of the KARP Design Guidelines [RFC6518]. Section 4.2 of that document uses the term "state", which will be referred to as the "state of the security method". Thus, a term like "Define Optimal State" would be referred to as "Define Optimal State of the Security Method".


This document builds on several previous efforts into routing security:


o "Issues with Existing Cryptographic Protection Methods for Routing Protocols" [RFC6039], describes issues with existing cryptographic protection methods for routing protocols.

o “路由协议现有加密保护方法的问题”[RFC6039]描述了路由协议现有加密保护方法的问题。

o Analysis of OSPF Security According to the KARP Design Guide [RFC6863] analyzes Open Shortest Path First (OSPF) security according to the KARP Design Guide.

o 根据KARP设计指南分析OSPF安全[RFC6863]根据KARP设计指南分析开放最短路径优先(OSPF)安全。

Section 2 of this document looks at the current state of the security method for the four routing protocols: BGP, LDP, PCEP, and MSDP. Section 3 examines what the optimal state of the security method would be for the four routing protocols according to the KARP Design Guidelines [RFC6518], and Section 4 does an analysis of the gap between the existing state of the security method and the optimal state of the security method for the protocols and suggests some areas where improvement is needed.


1.1. Abbreviations
1.1. 缩写

AES - Advanced Encryption Standard


AO - Authentication Option


AS - Autonomous System


BGP - Border Gateway Protocol


CMAC - Cipher-Based Message Authentication Code


DoS - Denial of Service


GTSM - Generalized Time-to-Live (TTL) Security Mechanism


HMAC - Hash-Based MAC


KARP - Key and Authentication for Routing Protocols


KDF - Key Derivation Function


KEK - Key Encrypting Key


KMP - Key Management Protocol


LDP - Label Distribution Protocol


LSR - Label Switching Routers


MAC - Message Authentication Code


MKT - Master Key Table


MSDP - Multicast Source Distribution Protocol


MD5 - Message Digest Algorithm 5


OSPF - Open Shortest Path First


PCEP - Path Computation Element Communication Protocol


PCC - Path Computation Client


PCE - Path Computation Element


SHA - Secure Hash Algorithm


TCP - Transmission Control Protocol


TTL - Time-to-Live


UDP - User Datagram Protocol


WG - Working Group


2. Current Assessment of BGP, LDP, PCEP, and MSDP

This section assesses the transport protocols for any authentication or integrity mechanisms used by the protocol. It describes the current security mechanisms, if any, used by BGP, LDP, PCEP, and MSDP.


2.1. Transport Layer
2.1. 传输层

At the transport layer, routing protocols are subject to a variety of DoS attacks, as outlined in "Internet Denial-of-Service Considerations" [RFC4732]. Such attacks can cause the routing protocol to become congested, resulting in the routing updates being supplied too slowly to be useful. In extreme cases, these attacks prevent routers from converging after a change.


Routing protocols use several methods to protect themselves. Those that use TCP as a transport protocol use access lists to accept packets only from known sources. These access lists also help protect edge routers from attacks originating outside the protected domain. In addition, for edge routers running the External Border Gateway Protocol (eBGP), TCP LISTEN is run only on interfaces on which its peers have been discovered or via which routing sessions are expected (as specified in router configuration databases).


"Generalized TTL Security Mechanism (GTSM)" [RFC5082] describes a generalized Time-to-Live (TTL) security mechanism to protect a protocol stack from CPU-utilization-based attacks. TCP Robustness [RFC5961] recommends some TCP-level mitigations against spoofing attacks targeted towards long-lived routing protocol sessions.


Even when BGP, LDP, PCEP, and MSDP sessions use access lists, they are vulnerable to spoofing and man-in-the-middle attacks. Authentication and integrity checks allow the receiver of a routing protocol update to know that the message genuinely comes from the node that claims to have sent it and to know whether the message has been modified. Sometimes routers can be subjected to a large number of authentication and integrity requests, exhausting connection resources on the router in a way that could lead to the denial of genuine requests.


TCP MD5 [RFC2385] has been obsoleted by TCP-AO [RFC5925]. However, it is still widely used to authenticate TCP-based routing protocols such as BGP. It provides a way for carrying a MD5 digest in a TCP segment. This digest is computed using information known only to the endpoints, and this ensures authenticity and integrity of messages. The MD5 key used to compute the digest is stored locally on the router. This option is used by routing protocols to provide for session-level protection against the introduction of spoofed TCP segments into any existing TCP streams, in particular, TCP Reset segments. TCP MD5 does not provide a generic mechanism to support key rollover. It also does not support algorithm agility.

TCP MD5[RFC2385]已被TCP-AO[RFC5925]淘汰。然而,它仍然被广泛用于验证基于TCP的路由协议,如BGP。它提供了一种在TCP段中承载MD5摘要的方法。此摘要是使用仅端点已知的信息计算的,这确保了消息的真实性和完整性。用于计算摘要的MD5密钥本地存储在路由器上。路由协议使用此选项提供会话级保护,以防止将伪造的TCP段引入任何现有TCP流,特别是TCP重置段。TCP MD5不提供支持密钥翻转的通用机制。它也不支持算法敏捷性。

The Message Authentication Codes (MACs) used by TCP MD5 are considered too weak both because of the use of the hash function and because of the way the secret key used by TCP MD5 is managed. Furthermore, TCP MD5 does not support any algorithm agility. TCP-AO [RFC5925] and its companion document Cryptographic Algorithms for TCP-AO [RFC5926], describe steps towards correcting both the MAC weakness and the management of secret keys. Those steps require that two MAC algorithms be supported. They are HMAC-SHA-1-96, as specified in HMAC [RFC2104], and AES-128-CMAC-96, as specified in NIST-SP800-38B [NIST-SP800-38B]. Cryptographic research suggests that both these MAC algorithms are fairly secure. By supporting multiple MAC algorithms, TCP-AO supports algorithm agility. TCP-AO also allows additional MACs to be added in the future.

由于使用哈希函数和TCP MD5使用的密钥的管理方式,TCP MD5使用的消息身份验证码(MAC)被认为太弱。此外,TCP MD5不支持任何算法敏捷性。TCP-AO[RFC5925]及其配套文件TCP-AO加密算法[RFC5926]描述了纠正MAC弱点和密钥管理的步骤。这些步骤要求支持两种MAC算法。它们是HMAC[RFC2104]中规定的HMAC-SHA-1-96和NIST-SP800-38B[NIST-SP800-38B]中规定的AES-128-CMAC-96。密码研究表明,这两种MAC算法都相当安全。通过支持多种MAC算法,TCP-AO支持算法敏捷性。TCP-AO还允许将来添加其他MAC。

2.2. Keying Mechanisms
2.2. 键控机构

For TCP-AO [RFC5925], there is no Key Management Protocol (KMP) used to manage the keys that are employed to generate the MAC. TCP-AO talks about coordinating keys derived from the Master Key Table (MKT) between endpoints and allows for a master key to be configured manually or for it to be managed via an out-of-band mechanism.


It should be noted that most routers configured with static keys have not seen the key changed ever. The common reason given for not changing the key is the difficulty in coordinating the change between pairs of routers when using TCP MD5. It is well known that the longer the same key is used, the greater the chance that it can be guessed or exposed, e.g., when an administrator with knowledge of the keys leaves the company.

应该注意的是,大多数配置了静态密钥的路由器从未见过密钥发生变化。给出的不更改密钥的常见原因是在使用TCP MD5时难以协调路由器对之间的更改。众所周知,使用同一密钥的时间越长,其被猜测或暴露的可能性就越大,例如,当了解密钥的管理员离开公司时。

For point-to-point key management, the IKEv2 protocol [RFC5996] provides for automated key exchange under a Security Association (SA) and can be used for a comprehensive KMP solution for routers. IKEv2 can be used for both IPsec SAs [RFC4301] and other types of SAs. For example, Fibre Channel SAs [RFC4595] are currently negotiated with IKEv2. Using IKEv2 to negotiate TCP-AO is a possible option.

对于点对点密钥管理,IKEv2协议[RFC5996]提供了安全关联(SA)下的自动密钥交换,并可用于路由器的综合KMP解决方案。IKEv2可用于IPsec SAs[RFC4301]和其他类型的SAs。例如,光纤通道SAs[RFC4595]目前正在与IKEv2协商。使用IKEv2协商TCP-AO是一种可能的选择。

2.3. BGP
2.3. BGP

All BGP communications take place over TCP. Therefore, all security vulnerabilities for BGP can be categorized as relating to the security of the transport protocol itself, or to the compromising of individual routers and the data they handle. This document examines the issues for the transport protocol, while the SIDR Working Group (WG) looks at ways to sign and secure the data exchanged in BGP as described in "An Infrastructure to Support Secure Internet Protocol" [RFC6480].


2.4. LDP
2.4. 自民党

"Security Framework for MPLS and GMPLS Networks" [RFC5920] outlines security aspects that are relevant in the context of MPLS and GMPLS. It describes the security threats, the related defensive techniques, and the mechanism for detection and reporting.


Section 5 of LDP [RFC5036] states that LDP is subject to two different types of attacks: spoofing and denial-of-service attacks.


2.4.1. Spoofing Attacks
2.4.1. 欺骗攻击

A spoofing attack against LDP can occur both during the discovery phase and during the session communication phase.

在发现阶段和会话通信阶段都可能发生针对LDP的欺骗攻击。 Discovery Exchanges using UDP 使用UDP的发现交换

Label Switching Routers (LSRs) indicate their willingness to establish and maintain LDP sessions by periodically sending Hello messages. Reception of a Hello message serves to create a new "Hello adjacency", if one does not already exist, or to refresh an existing one.


There are two variants of the discovery mechanism. A Basic Discovery mechanism is used to discover LSR neighbors that are directly connected at the link level, and an Extended Discovery mechanism is used by LSRs that are more than one hop away.


Unlike all other LDP messages, the Hello messages are sent using UDP. This means that they cannot benefit from the security mechanisms available with TCP. LDP [RFC5036] does not provide any security mechanisms for use with Hello messages except for some configuration that may help protect against bogus discovery events. These configurations include directly connected links and interfaces. Routers that do not use directly connected links have to use the Extended Discovery mechanism and will not be able to use configuration to protect against bogus discovery events.


Spoofing a Hello packet for an existing adjacency can cause the adjacency to time out and result in termination of the associated session. This can occur when the spoofed Hello message specifies a small Hold Time, causing the receiver to expect Hello messages within this interval, while the true neighbor continues sending Hello messages at the lower, previously agreed to frequency.


Spoofing a Hello packet can also cause the LDP session to be terminated. This can occur when the spoofed Hello specifies a different Transport Address from the previously agreed one between neighbors. Spoofed Hello messages are observed and reported as a real problem in production networks.

欺骗Hello数据包也会导致LDP会话终止。当伪造的Hello指定的传输地址与邻居之间先前约定的传输地址不同时,可能会发生这种情况。伪造的Hello消息在生产网络中被观察到并报告为一个实际问题。 Session Communication using TCP 使用TCP的会话通信

LDP, like other TCP-based routing protocols, specifies use of the TCP MD5 Signature Option to provide for the authenticity and integrity of session messages. As stated in Section 2.1 of this document and in Section 2.9 of LDP [RFC5036], MD5 authentication is considered too weak for this application as outlined in MD5 and HMAC-MD5 Security Considerations [RFC6151]. It also does not support algorithm agility. A stronger hashing algorithm, e.g., SHA1, which is supported by TCP-AO [RFC5925], could be deployed to take care of the weakness.

与其他基于TCP的路由协议一样,LDP指定使用TCP MD5签名选项来提供会话消息的真实性和完整性。如本文件第2.1节和LDP[RFC5036]第2.9节所述,MD5认证对于MD5和HMAC-MD5安全注意事项[RFC6151]中所述的应用程序来说太弱。它也不支持算法敏捷性。可以部署TCP-AO[RFC5925]支持的更强大的散列算法,例如SHA1,以解决该弱点。

Alternatively, one could move to using TCP-AO, which provides for stronger MAC algorithms, makes it easier to set up manual keys, and protects against replay attacks.


2.4.2. Denial-of-Service Attacks
2.4.2. 拒绝服务攻击

LDP is subject to Denial-of-Service (DoS) attacks both in discovery mode and session mode. The potential targets are documented in Section 5.3 of LDP [RFC5036].


2.5. PCEP
2.5. PCEP

For effective selection by Path Computation Clients (PCCs), a PCC needs to know the location of Path Computation Elements (PCEs) in its domain along with some information relevant for PCE selection. Such PCE information could be learned through manual configuration, on each PCC, along with the capabilities of the PCE or automatically through a PCE discovery mechanism as outlined in Requirements for PCE Discovery [RFC4674].


Attacks on PCEP [RFC5440] may result in damage to active networks. These include computation responses, which if changed can cause protocols like RSVP-TE [RFC3209] to set up suboptimal or


inappropriate LSPs. In addition, PCE itself can be a target for a variety of DoS attacks. Such attacks can cause path computations to be supplied too slowly to be of any value, particularly as it relates to recovery or establishment of LSPs.


Finally, PCE discovery, as outlined in OSPF Protocol Extensions for PCE Discovery [RFC5088] and IS-IS Protocol Extensions for PCE Discovery [RFC5089], is a significant feature for the successful deployment of PCEP in large networks. These mechanisms allow PCC to discover the existence of PCEs within the network. If the discovery mechanism is compromised, it will impair the ability of the nodes to function as described below.


As RFC 5440 states, PCEP (which makes use of TCP as a transport) could be the target of the following attacks:

如RFC 5440所述,PCEP(利用TCP作为传输)可能成为以下攻击的目标:

o Spoofing (PCC or PCE implementation)

o 欺骗(PCC或PCE实施)

o Snooping (message interception)

o 窥探(消息截获)

o Falsification

o 伪造

o Denial of Service

o 拒绝服务

In inter-Autonomous System (inter-AS) scenarios where PCE-to-PCE communication is required, attacks may be particularly significant with commercial implications as well as service-level agreement implications.


Additionally, snooping of PCEP requests and responses may give an attacker information about the operation of the network. By viewing the PCEP messages, an attacker can determine the pattern of service establishment in the network and can know where traffic is being routed, thereby making the network susceptible to targeted attacks and the data within specific LSPs vulnerable.


Ensuring PCEP communication privacy is of key importance, especially in an inter-AS context, where PCEP communication endpoints do not reside in the same AS. An attacker that intercepts a PCE message could obtain sensitive information related to computed paths and resources.


At the time PCEP was documented in [RFC5440], TCP-AO had not been fully specified. Therefore, [RFC5440] mandates that PCEP implementations include support for TCP MD5 and that use of the function should be configurable by the operator. [RFC5440] also describes the vulnerabilities and weaknesses of TCP MD5 as noted in this document. [RFC5440] goes on to state that PCEP implementations

在[RFC5440]中记录PCEP时,尚未完全指定TCP-AO。因此,[RFC5440]要求PCEP实现包括对TCP MD5的支持,并且该功能的使用应由操作员配置。[RFC5440]还描述了本文档中提到的TCP MD5的漏洞和弱点。[RFC5440]接着指出PCEP实施

should include support for TCP-AO as soon as that specification is complete. Since TCP-AO [RFC5925] has now been published, new PCEP implementations should fully support TCP-AO.


2.6. MSDP
2.6. MSDP

Similar to BGP and LDP, the Multicast Source Distribution Protocol (MSDP) uses TCP MD5 [RFC2385] to protect TCP sessions via the TCP MD5 option. But with a weak MD5 authentication, TCP MD5 is not considered strong enough for this application. It also does not support algorithm agility.

与BGP和LDP类似,多播源分发协议(MSDP)使用TCP MD5[RFC2385]通过TCP MD5选项保护TCP会话。但是,由于MD5身份验证较弱,因此认为TCP MD5对于该应用程序不够强大。它也不支持算法敏捷性。

MSDP advocates imposing a limit on the number of source address and group addresses (S,G) that can be cached within the protocol in order to mitigate state explosion due to any denial of service and other attacks.


3. Optimal State for BGP, LDP, PCEP, and MSDP

The ideal state of the security method for BGP, LDP, PCEP, and MSDP protocols is when they can withstand any of the known types of attacks. The protocols also need to support algorithm agility, i.e., they must not hardwire themselves to one algorithm.


Additionally, the KMP for the routing sessions should help negotiate unique, pair-wise random keys without administrator involvement. It should also negotiate Security Association (SA) parameters required for the session connection, including key lifetimes. It should keep track of those lifetimes and negotiate new keys and parameters before they expire and do so without administrator involvement. In the event of a breach, including when an administrator with knowledge of the keys leaves the company, the keys should be changed immediately.


The DoS attacks for BGP, LDP, PCEP, and MSDP are attacks to the transport protocol -- TCP for the most part, and UDP in case of the discovery phase of LDP. TCP and UDP should be able to withstand any of the DoS scenarios by dropping packets that are attack packets in a way that does not impact legitimate packets.


The routing protocols should provide a mechanism to authenticate the routing information carried within the payload, and administrators should enable it.


3.1. LDP
3.1. 自民党

To mitigate LDP's current vulnerability to spoofing attacks, LDP needs to be upgraded such that an implementation is able to determine the authenticity of the neighbors sending the Hello message.


Labels are similar to routing information, which is distributed in the clear. However, there is currently no requirement that the labels be encrypted. Such a requirement is out of scope for this document.


Similarly, it is important to ensure that routers exchanging labels are mutually authenticated, and that there are no rogue peers or unauthenticated peers that can compromise the stability of the network.


4. Gap Analysis for BGP, LDP, PCEP, and MSDP

This section outlines the differences between the current state of the security methods for routing protocols and the desired state of the security methods as outlined in Section 4.2 of the KARP Design Guidelines [RFC6518]. As that document states, these routing protocols fall into the category of one-to-one peering messages and will use peer keying protocols. This section covers issues that are common to the four protocols, leaving protocol-specific issues to sub-sections.


At a transport level, these routing protocols are subject to some of the same attacks that TCP applications are subject to. These include DoS and spoofing attacks. "Internet Denial-of-Service Considerations" [RFC4732] outlines some solutions. "Defending TCP Against Spoofing Attacks" [RFC4953] recommends ways to prevent spoofing attacks. In addition, the recommendations in [RFC5961] should also be followed and implemented to strengthen TCP.


Routers lack comprehensive key management and keys derived that they can use to authenticate data. As an example, TCP-AO [RFC5925], talks about coordinating keys derived from the Master Key Table (MKT) between endpoints, but the MKT itself has to be configured manually or through an out-of-band mechanism. Also, TCP-AO does not address the issue of connectionless reset, as it applies to routers that do not store MKT across reboots.


Authentication, integrity protection, and encryption all require the use of keys by sender and receiver. An automated KMP, therefore has to include a way to distribute key material between two endpoints with little or no administrative overhead. It has to cover automatic key rollover. It is expected that authentication will cover the packet, i.e., the payload and the TCP header, and will not cover the frame, i.e., the layer 2 header.


There are two methods of automatic key rollover. Implicit key rollover can be initiated after a certain volume of data gets exchanged or when a certain time has elapsed. This does not require


explicit signaling nor should it result in a reset of the TCP connection in a way that the links/adjacencies are affected. On the other hand, explicit key rollover requires an out-of-band key signaling mechanism. It can be triggered by either side and can be done anytime a security parameter changes, e.g., an attack has happened, or a system administrator with access to the keys has left the company. An example of this is IKEv2 [RFC5996], but it could be any other new mechanisms also.


As stated earlier, TCP-AO [RFC5925] and its accompanying document, Cryptographic Algorithms for TCP-AO [RFC5926], require that two MAC algorithms be supported, and they are HMAC-SHA-1-96, as specified in HMAC [RFC2104], and AES-128-CMAC-96, as specified in NIST-SP800-38B [NIST-SP800-38B]. Therefore, TCP-AO meets the algorithm agility requirement.


There is a need to protect authenticity and validity of the routing/ label information that is carried in the payload of the sessions. However, that is outside the scope of this document and is being addressed by the SIDR WG. Similar mechanisms could be used for intra-domain protocols.


Finally, replay protection is required. The replay mechanism needs to be sufficient to prevent an attacker from creating a denial of service or disrupting the integrity of the routing protocol by replaying packets. It is important that an attacker not be able to disrupt service by capturing packets and waiting for replay state to be lost.


4.1. LDP
4.1. 自民党

As described in LDP [RFC5036], the threat of spoofed Basic Hellos can be reduced by only accepting Basic Hellos on interfaces that LSRs trust, employing GTSM [RFC5082], and ignoring Basic Hellos not addressed to the "all routers on this subnet" multicast group. Spoofing attacks via Targeted Hellos are potentially a more serious threat. An LSR can reduce the threat of spoofed Extended Hellos by filtering them and accepting Hellos from sources permitted by access lists. However, performing the filtering using access lists requires LSR resources, and the LSR is still vulnerable to the IP source address spoofing. Spoofing attacks can be solved by being able to authenticate the Hello messages, and an LSR can be configured to only accept Hello messages from specific peers when authentication is in use.


LDP Hello Cryptographic Authentication [HELLO-CRYPTO] suggest a new Cryptographic Authentication TLV that can be used as an authentication mechanism to secure Hello messages.

LDP Hello Cryptographic Authentication[Hello-CRYPTO]提出了一种新的加密身份验证TLV,可以用作保护Hello消息的身份验证机制。

4.2. PCEP
4.2. PCEP

Path Computation Element (PCE) discovery, according to [RFC5440], is a significant feature for the successful deployment of PCEP in large networks. This mechanism allows a Path Computation Client (PCC) to discover the existence of suitable PCEs within the network without the necessity of configuration. It should be obvious that, where PCEs are discovered and not configured, the PCC cannot know the correct key to use. There are different approaches to retain some aspect of security, but all of them require use of a keys and a keying mechanism, the need for which has been discussed above.


5. Transition and Deployment Considerations
5. 过渡和部署注意事项

As stated in the KARP Design Guidelines [RFC6518], it is imperative that the new authentication, security mechanisms, and key management protocol support incremental deployment, as it is not feasible to deploy the new routing protocol authentication mechanism overnight.


Typically, authentication and security in a peer-to-peer protocol requires that both parties agree to the mechanisms that will be used. If an agreement is not reached, the setup of the new mechanism will fail or will be deferred. Upon failure, the routing protocols can fall back to the mechanisms that were already in place, e.g., use static keys if that was the mechanism in place. The fallback should be configurable on a per-node or per-interface basis. It is usually not possible for one end to use the new mechanism while the other end uses the old. Policies can be put in place to retry upgrading after a said period of time, so that manual coordination is not required.


If the automatic KMP requires use of Public Key Infrastructure Certificates [RFC5280] to exchange key material, the required Certificate Authority (CA) root certificates may need to be installed to verify the authenticity of requests initiated by a peer. Such a step does not require coordination with the peer, except to decide which CA authority will be used.


6. Security Considerations
6. 安全考虑

This section describes security considerations that BGP, LDP, PCEP, and MSDP should try to meet.


As with all routing protocols, they need protection from both on-path and off-path blind attacks. A better way to protect them would be with per-packet protection using a cryptographic MAC. In order to provide for the MAC, keys are needed.


The routing protocols need to support algorithm agility, i.e., they must not hardwire themselves to one algorithm.


Once keys are used, mechanisms are required to support key rollover. They should cover both manual and automatic key rollover. Multiple approaches could be used. However, since the existing mechanisms provide a protocol field to identify the key as well as management mechanisms to introduce and retire new keys, focusing on the existing mechanism as a starting point is prudent.


Furthermore, it is strongly suggested that these routing protocols support algorithm agility. It has been proven that algorithms weaken over time. Supporting algorithm agility assists in smooth transitions from old to new algorithms.


7. Acknowledgements
7. 致谢

We would like to thank Brian Weis for encouraging us to write this document, and thanks to Anantha Ramaiah and Mach Chen for providing comments on it.

我们要感谢Brian Weis鼓励我们编写本文件,并感谢Anantha Ramaiah和Mach Chen对本文件的评论。

8. References
8. 工具书类
8.1. Normative References
8.1. 规范性引用文件

[RFC5926] Lebovitz, G. and E. Rescorla, "Cryptographic Algorithms for the TCP Authentication Option (TCP-AO)", RFC 5926, June 2010.

[RFC5926]Lebovitz,G.和E.Rescorla,“TCP认证选项(TCP-AO)的加密算法”,RFC 5926,2010年6月。

[RFC6518] Lebovitz, G. and M. Bhatia, "Keying and Authentication for Routing Protocols (KARP) Design Guidelines", RFC 6518, February 2012.

[RFC6518]Lebovitz,G.和M.Bhatia,“路由协议的键控和认证(KARP)设计指南”,RFC 6518,2012年2月。

[RFC6863] Hartman, S. and D. Zhang, "Analysis of OSPF Security According to the Keying and Authentication for Routing Protocols (KARP) Design Guide", RFC 6863, March 2013.

[RFC6863]Hartman,S.和D.Zhang,“根据路由协议键控和认证(KARP)设计指南分析OSPF安全性”,RFC 6863,2013年3月。

8.2. Informative References
8.2. 资料性引用

[HELLO-CRYPTO] Zheng, L., Chen, M., and M. Bhatia, "LDP Hello Cryptographic Authentication", Work in Progress, January 2013.

[HELLO-CRYPTO]Zheng,L.,Chen,M.,和M.Bhatia,“LDP HELLO加密认证”,正在进行的工作,2013年1月。

[NIST-SP800-38B] Dworking, , "Recommendation for Block Cipher Modes of Operation: The CMAC Mode for Authentication", May 2005.


[RFC2104] Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed-Hashing for Message Authentication", RFC 2104, February 1997.

[RFC2104]Krawczyk,H.,Bellare,M.,和R.Canetti,“HMAC:用于消息认证的键控哈希”,RFC 2104,1997年2月。

[RFC2385] Heffernan, A., "Protection of BGP Sessions via the TCP MD5 Signature Option", RFC 2385, August 1998.

[RFC2385]Heffernan,A.,“通过TCP MD5签名选项保护BGP会话”,RFC 2385,1998年8月。

[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V., and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP Tunnels", RFC 3209, December 2001.

[RFC3209]Awduche,D.,Berger,L.,Gan,D.,Li,T.,Srinivasan,V.,和G.Swallow,“RSVP-TE:LSP隧道RSVP的扩展”,RFC 3209,2001年12月。

[RFC3618] Fenner, B. and D. Meyer, "Multicast Source Discovery Protocol (MSDP)", RFC 3618, October 2003.


[RFC4271] Rekhter, Y., Li, T., and S. Hares, "A Border Gateway Protocol 4 (BGP-4)", RFC 4271, January 2006.

[RFC4271]Rekhter,Y.,Li,T.,和S.Hares,“边境网关协议4(BGP-4)”,RFC 42712006年1月。

[RFC4301] Kent, S. and K. Seo, "Security Architecture for the Internet Protocol", RFC 4301, December 2005.

[RFC4301]Kent,S.和K.Seo,“互联网协议的安全架构”,RFC 43012005年12月。

[RFC4595] Maino, F. and D. Black, "Use of IKEv2 in the Fibre Channel Security Association Management Protocol", RFC 4595, July 2006.

[RFC4595]Maino,F.和D.Black,“在光纤通道安全关联管理协议中使用IKEv2”,RFC 45952006年7月。

[RFC4674] Le Roux, J.L., "Requirements for Path Computation Element (PCE) Discovery", RFC 4674, October 2006.

[RFC4674]Le Roux,J.L.,“路径计算元素(PCE)发现的要求”,RFC 4674,2006年10月。

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

[RFC4732]Handley,M.,Rescorla,E.,IAB,“互联网拒绝服务注意事项”,RFC 4732,2006年12月。

[RFC4948] Andersson, L., Davies, E., and L. Zhang, "Report from the IAB workshop on Unwanted Traffic March 9-10, 2006", RFC 4948, August 2007.

[RFC4948]Andersson,L.,Davies,E.,和L.Zhang,“IAB 2006年3月9日至10日不必要交通研讨会报告”,RFC 4948,2007年8月。

[RFC4953] Touch, J., "Defending TCP Against Spoofing Attacks", RFC 4953, July 2007.

[RFC4953]Touch,J.“保护TCP免受欺骗攻击”,RFC 4953,2007年7月。

[RFC5036] Andersson, L., Minei, I., and B. Thomas, "LDP Specification", RFC 5036, October 2007.

[RFC5036]Andersson,L.,Minei,I.,和B.Thomas,“LDP规范”,RFC 5036,2007年10月。

[RFC5082] Gill, V., Heasley, J., Meyer, D., Savola, P., and C. Pignataro, "The Generalized TTL Security Mechanism (GTSM)", RFC 5082, October 2007.

[RFC5082]Gill,V.,Heasley,J.,Meyer,D.,Savola,P.,和C.Pignataro,“广义TTL安全机制(GTSM)”,RFC 5082,2007年10月。

[RFC5088] Le Roux, JL., Vasseur, JP., Ikejiri, Y., and R. Zhang, "OSPF Protocol Extensions for Path Computation Element (PCE) Discovery", RFC 5088, January 2008.

[RFC5088]Le Roux,JL.,Vasseur,JP.,Ikejiri,Y.,和R.Zhang,“路径计算元素(PCE)发现的OSPF协议扩展”,RFC 5088,2008年1月。

[RFC5089] Le Roux, JL., Vasseur, JP., Ikejiri, Y., and R. Zhang, "IS-IS Protocol Extensions for Path Computation Element (PCE) Discovery", RFC 5089, January 2008.

[RFC5089]Le Roux,JL.,Vasseur,JP.,Ikejiri,Y.,和R.Zhang,“路径计算元素(PCE)发现的IS-IS协议扩展”,RFC 5089,2008年1月。

[RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S., Housley, R., and W. Polk, "Internet X.509 Public Key Infrastructure Certificate and Certificate Revocation List (CRL) Profile", RFC 5280, May 2008.

[RFC5280]Cooper,D.,Santesson,S.,Farrell,S.,Boeyen,S.,Housley,R.,和W.Polk,“Internet X.509公钥基础设施证书和证书撤销列表(CRL)配置文件”,RFC 52802008年5月。

[RFC5440] Vasseur, JP. and JL. Le Roux, "Path Computation Element (PCE) Communication Protocol (PCEP)", RFC 5440, March 2009.

[RFC5440]Vasseur,JP。和JL。Le Roux,“路径计算元件(PCE)通信协议(PCEP)”,RFC 54402009年3月。

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

[RFC5920]方,L,“MPLS和GMPLS网络的安全框架”,RFC 5920,2010年7月。

[RFC5925] Touch, J., Mankin, A., and R. Bonica, "The TCP Authentication Option", RFC 5925, June 2010.

[RFC5925]Touch,J.,Mankin,A.,和R.Bonica,“TCP认证选项”,RFC 59252010年6月。

[RFC5961] Ramaiah, A., Stewart, R., and M. Dalal, "Improving TCP's Robustness to Blind In-Window Attacks", RFC 5961, August 2010.

[RFC5961]Ramaiah,A.,Stewart,R.,和M.Dalal,“提高TCP对窗口盲攻击的鲁棒性”,RFC 59612010年8月。

[RFC5996] Kaufman, C., Hoffman, P., Nir, Y., and P. Eronen, "Internet Key Exchange Protocol Version 2 (IKEv2)", RFC 5996, September 2010.

[RFC5996]Kaufman,C.,Hoffman,P.,Nir,Y.,和P.Eronen,“互联网密钥交换协议版本2(IKEv2)”,RFC 59962010年9月。

[RFC6039] Manral, V., Bhatia, M., Jaeggli, J., and R. White, "Issues with Existing Cryptographic Protection Methods for Routing Protocols", RFC 6039, October 2010.

[RFC6039]Manral,V.,Bhatia,M.,Jaeggli,J.,和R.White,“路由协议现有加密保护方法的问题”,RFC 6039,2010年10月。

[RFC6151] Turner, S. and L. Chen, "Updated Security Considerations for the MD5 Message-Digest and the HMAC-MD5 Algorithms", RFC 6151, March 2011.

[RFC6151]Turner,S.和L.Chen,“MD5消息摘要和HMAC-MD5算法的更新安全注意事项”,RFC 61512011年3月。

[RFC6480] Lepinski, M. and S. Kent, "An Infrastructure to Support Secure Internet Routing", RFC 6480, February 2012.

[RFC6480]Lepinski,M.和S.Kent,“支持安全互联网路由的基础设施”,RFC 6480,2012年2月。

Authors' Addresses


Mahesh Jethanandani Ciena Corporation 1741 Technology Drive San Jose, CA 95110 USA


   Phone: +1 (408) 436-3313
   Phone: +1 (408) 436-3313

Keyur Patel Cisco Systems, Inc 170 Tasman Drive San Jose, CA 95134 USA


   Phone: +1 (408) 526-7183
   Phone: +1 (408) 526-7183

Lianshu Zheng Huawei Technologies China


   Phone: +86 (10) 82882008
   Phone: +86 (10) 82882008