draft-ietf-karp-routing-tcp-analysis-05.txt   draft-ietf-karp-routing-tcp-analysis-06.txt 
Routing Working Group M. Jethanandani Routing Working Group M. Jethanandani
Internet-Draft Ciena Corporation Internet-Draft Ciena Corporation
Intended status: Informational K. Patel Intended status: Informational K. Patel
Expires: April 21, 2013 Cisco Systems, Inc Expires: June 8, 2013 Cisco Systems, Inc
L. Zheng L. Zheng
Huawei Technologies Huawei Technologies
October 18, 2012 December 5, 2012
Analysis of BGP, LDP, PCEP and MSDP Issues According to KARP Design Analysis of BGP, LDP, PCEP and MSDP Issues According to KARP Design
Guide Guide
draft-ietf-karp-routing-tcp-analysis-05.txt draft-ietf-karp-routing-tcp-analysis-06.txt
Abstract Abstract
This document analyzes Border Gateway Protocol (BGP) [RFC4271], Label This document analyzes TCP based routing protocols, Border Gateway
Distribution Protocol (LDP) [RFC5036], Path Computation Element Protocol (BGP) [RFC4271], Label Distribution Protocol (LDP)
Protocol (PCEP) [RFC5440] and Multicast Source Distribution Protocol [RFC5036], Path Computation Element Protocol (PCEP) [RFC5440], and
(MSDP) [RFC3618] according to guidelines set forth in section 4.2 of Multicast Source Distribution Protocol (MSDP) [RFC3618] according to
Keying and Authentication for Routing Protocols Design Guidelines guidelines set forth in section 4.2 of Keying and Authentication for
[RFC6518]. Routing Protocols Design Guidelines [RFC6518].
Status of this Memo Status of this Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on April 21, 2013. This Internet-Draft will expire on June 8, 2013.
Copyright Notice Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the Copyright (c) 2012 IETF Trust and the persons identified as the
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Conventions Used in This Document . . . . . . . . . . . . 3 1.1. Abbreviations . . . . . . . . . . . . . . . . . . . . . . 4
1.2. Abbreviations . . . . . . . . . . . . . . . . . . . . . . 4
2. Current Assessment of BGP, LDP, PCEP and MSDP . . . . . . . . 5 2. Current Assessment of BGP, LDP, PCEP and MSDP . . . . . . . . 5
2.1. Transport layer . . . . . . . . . . . . . . . . . . . . . 5 2.1. Transport layer . . . . . . . . . . . . . . . . . . . . . 5
2.2. Keying mechanisms . . . . . . . . . . . . . . . . . . . . 6 2.2. Keying mechanisms . . . . . . . . . . . . . . . . . . . . 6
2.3. LDP . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 2.3. LDP . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.3.1. Spoofing attacks . . . . . . . . . . . . . . . . . . . 6 2.3.1. Spoofing attacks . . . . . . . . . . . . . . . . . . . 7
2.3.2. Privacy Issues . . . . . . . . . . . . . . . . . . . . 7 2.3.2. Privacy Issues . . . . . . . . . . . . . . . . . . . . 8
2.3.3. Denial of Service Attacks . . . . . . . . . . . . . . 8 2.3.3. Denial of Service Attacks . . . . . . . . . . . . . . 8
2.4. PCEP . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 2.4. PCEP . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.5. MSDP . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 2.5. MSDP . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3. Optimal State for BGP, LDP, PCEP, and MSDP . . . . . . . . . . 10 3. Optimal State for BGP, LDP, PCEP, and MSDP . . . . . . . . . . 10
3.1. LDP . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 3.1. LDP . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
4. Gap Analysis for BGP, LDP, PCEP and MSDP . . . . . . . . . . . 11 4. Gap Analysis for BGP, LDP, PCEP and MSDP . . . . . . . . . . . 11
4.1. LDP . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 4.1. LDP . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
4.2. PCEP . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 4.2. PCEP . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
5. Transition and Deployment Considerations . . . . . . . . . . . 13 5. Transition and Deployment Considerations . . . . . . . . . . . 14
6. Security Considerations . . . . . . . . . . . . . . . . . . . 14 6. Security Considerations . . . . . . . . . . . . . . . . . . . 15
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 15 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 16 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 17
8.1. Normative References . . . . . . . . . . . . . . . . . . . 16 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 18
8.2. Informative References . . . . . . . . . . . . . . . . . . 16 9.1. Normative References . . . . . . . . . . . . . . . . . . . 18
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 18 9.2. Informative References . . . . . . . . . . . . . . . . . . 18
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 20
1. Introduction 1. Introduction
In March 2006 the Internet Architecture Board (IAB) in its "Unwanted In March 2006, the Internet Architecture Board (IAB) described an
Internet Traffic" workshop documented in Report from the IAB workshop attack on core routing infrastructure as an ideal attack that would
on Unwanted Traffic March 9-10, 2006 [RFC4948] described an attack on inflict the greatest amount of damage, in their Report from the IAB
core routing infrastructure as an ideal attack with the most amount workshop on Unwanted Traffic March 9-10, 2006 [RFC4948], and suggests
of damage. Four main steps were identified for that tightening: 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. Create secure mechanisms and practices for operating routers.
2. Clean up the Internet Routing Registry [IRR] repository, and 2. Clean up the Internet Routing Registry (IRR) repository, and
securing both the database and the access, so that it can be used securing both the database and the access, so that it can be used
for routing verifications. for routing verifications.
3. Create specifications for cryptographic validation of routing 3. Create specifications for cryptographic validation of routing
message content. message content.
4. Secure the routing protocols' packets on the wire. 4. Secure the routing protocols' packets on the wire.
In order to secure the routing protocols this document performs an In order to secure the routing protocols this document performs an
initial analysis of the current state of BGP, LDP, PCEP and MSDP initial analysis of the current state of TCP based protocols
according to the requirements of KARP Design Guidelines [RFC6518]. including BGP, LDP, PCEP, and MSDP according to the requirements of
Section 4.2 of the document uses the term "state" which will be KARP Design Guidelines [RFC6518]. Section 4.2 of the document uses
referred to as the "state of the security method". Thus a term like the term "state" which will be referred to as the "state of the
"Define Optimal State" would be referred to as "Define Optimal State security method". Thus a term like "Define Optimal State" would be
of the Security Method". This document builds on several previous referred to as "Define Optimal State of the Security Method". This
analysis efforts into routing security. The OPSEC working group document builds on several previous analysis efforts into routing
published Issues with existing Cryptographic Protection Methods for security.
Routing Protocols [RFC6039] an analysis of cryptographic issues with
routing protocols and Analysis of OSPF Security According to KARP
Design Guide [draft-ietf-karp-ospf-analysis-03].
Section 2 of this document looks at the current state of security The OPSEC working group published Issues with existing Cryptographic
Protection Methods for Routing Protocols [RFC6039], an analysis of
cryptographic issues with routing protocols and Analysis of OSPF
Security According to KARP Design Guide
[draft-ietf-karp-ospf-analysis-03].
Section 2 of this document looks at the current state of the security
method for the four routing protocols, BGP, LDP, PCEP and MSDP. method for the four routing protocols, BGP, LDP, PCEP and MSDP.
Section 3 examines what the optimal state of the security method Section 3 examines what the optimal state of the security method
would be for the four routing protocols according to KARP Design would be for the four routing protocols, according to KARP Design
Guidelines [RFC6518] and Section 4 does a analysis of the gap between Guidelines [RFC6518] and Section 4 does a analysis of the gap between
the existing state of the security method and the optimal state of the existing state of the security method and the optimal state of
the security method for protocols and suggests some areas where the security method for protocols and suggests some areas where
improvement is needed. improvement is needed.
1.1. Conventions Used in This Document 1.1. Abbreviations
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 RFC 2119 [RFC2119].
1.2. Abbreviations
AS - Autonomous Systems AS - Autonomous Systems
BGP - Border Gateway Protocol BGP - Border Gateway Protocol
DoS - Denial of Service DoS - Denial of Service
GTSM - Generalized TTL Security Mechanism GTSM - Generalized TTL Security Mechanism
KARP - Key and Authentication for Routing Protocols KARP - Key and Authentication for Routing Protocols
skipping to change at page 5, line 14 skipping to change at page 5, line 14
2. Current Assessment of BGP, LDP, PCEP and MSDP 2. Current Assessment of BGP, LDP, PCEP and MSDP
This section assesses the transport protocols for any authentication This section assesses the transport protocols for any authentication
or integrity mechanisms used by the protocol. It describes the or integrity mechanisms used by the protocol. It describes the
current security mechanisms if any used by BGP, LDP, PCEP and MSDP. current security mechanisms if any used by BGP, LDP, PCEP and MSDP.
2.1. Transport layer 2.1. Transport layer
At a transport layer, routing protocols are subject to a variety of At a transport layer, routing protocols are subject to a variety of
DoS attacks as outlined in Internet Denial-of-Service Considerations DoS attacks, as outlined in Internet Denial-of-Service Considerations
[RFC4732]. Such attacks can cause the routing protocol to become [RFC4732]. Such attacks can cause the routing protocol to become
congested with the result that routing updates are supplied too congested with the result that routing updates are supplied too
slowly to be useful. In extreme cases, these attacks prevent routers slowly to be useful. In extreme cases, these attacks prevent routers
from converging after a change. from converging after a change.
Routing protocols use several methods to protect themselves. Those Routing protocols use several methods to protect themselves. Those
that use TCP as a transport protocol use access lists to accept that use TCP as a transport protocol use access lists to accept
packets only from known sources. These access lists also help packets only from known sources. These access lists also help
protect edge routers from attacks originating from outside the protect edge routers from attacks originating outside the protected
protected domain. In addition for edge routers running eBGP, TCP domain. In addition, for edge routers running eBGP, TCP LISTEN is
LISTEN is run only on interfaces on which its peers have been run only on interfaces on which its peers have been discovered or via
discovered or via which routing sessions are expected (as specified which routing sessions are expected (as specified in router
in router configuration databases). configuration databases).
Generalized TTL Security Mechanism (GTSM) [RFC5082] describes a Generalized TTL Security Mechanism (GTSM) [RFC5082] describes a
generalized Time to Live (TTL) security mechanism to protect a generalized Time to Live (TTL) security mechanism to protect a
protocol stack from CPU-utilization based attacks.TCP Robustness protocol stack from CPU-utilization based attacks.TCP Robustness
[RFC5961] recommends some TCP level mitigations against spoofing [RFC5961] recommends some TCP level mitigations against spoofing
attacks targeted towards long-lived routing protocol sessions. attacks targeted towards long-lived routing protocol sessions.
Even when BGP, LDP, PCEP and MSDP sessions use access lists they are Even when BGP, LDP, PCEP and MSDP sessions use access lists, they are
vulnerable to spoofing and man in the middle attacks. Authentication vulnerable to spoofing and man in the middle attacks. Authentication
and integrity checks allow the receiver of a routing protocol update and integrity checks allow the receiver of a routing protocol update
to know that the message genuinely comes from the node that purports to know that the message genuinely comes from the node that claims to
to have sent it, and to know whether the message has been modified. have sent it, and to know whether the message has been modified.
Sometimes routers can be subjected to a large number of Sometimes routers can be subjected to a large number of
authentication and integrity requests, exhausting connection authentication and integrity requests, exhausting connection
resources on the router in a way that deny genuine requests. resources on the router in a way that could lead to deny genuine
requests.
TCP MD5 [RFC2385] has been obsoleted by TCP-AO [RFC5925]. However it TCP MD5 [RFC2385] has been obsoleted by TCP-AO [RFC5925]. However,
is still widely used to authenticate TCP based routing protocols such it is still widely used to authenticate TCP based routing protocols
as BGP. It provides a way for carrying a MD5 digest in a TCP such as BGP. It provides a way for carrying a MD5 digest in a TCP
segment. This digest acts like a signature for that segment, segment. This digest acts like a signature for that segment,
computed using information known only to the connection end points. computed using information known only to the connection end points.
The MD5 key used to compute the digest is stored locally on the The MD5 key used to compute the digest is stored locally on the
router. This option is used by routing protocols to provide for router. This option is used by routing protocols to provide for
session level protection against the introduction of spoofed TCP session level protection against the introduction of spoofed TCP
segments into any existing TCP streams, in particular TCP Reset segments into any existing TCP streams, in particular TCP Reset
segments. TCP MD5 does not provide a generic mechanism to support segments. TCP MD5 does not provide a generic mechanism to support
key roll-over. key roll-over.
The Message Authentication Codes (MACs) used by the TCP MD5 option is The Message Authentication Codes (MACs) used by TCP MD5 option, is
considered too weak both because of the use of the hash function and 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. TCP-AO because of the way the secret key used by TCP MD5 is managed. TCP-AO
[RFC5925] and its companion document Crypto Algorithms for TCP-AO [RFC5925], and its companion document Crypto Algorithms for TCP-AO
[RFC5926] describe steps towards correcting both the MAC weakness and [RFC5926], describe steps towards correcting both the MAC weakness
the management of secret keys. For MAC it specifies two MAC and the management of secret keys. For MAC it requires that two MAC
algorithms that MUST be supported. They are HMAC-SHA-1-96 as algorithms be supported. They are HMAC-SHA-1-96 as specified in HMAC
specified in HMAC [RFC2104] and AES-128-CMAC-96 as specified in NIST- [RFC2104], and AES-128-CMAC-96 as specified in NIST-SP800-38B
SP800-38B [NIST-SP800-38B]. Cryptographic research suggests that [NIST-SP800-38B]. Cryptographic research suggests that both these
both these MAC algorithms defined are fairly secure. TCP-AO allows MAC algorithms defined are fairly secure. TCP-AO allows additional
additional MACs to be added in the future. MACs to be added in the future.
2.2. Keying mechanisms 2.2. Keying mechanisms
For TCP-AO [RFC5925] there is no Key Management Protocol (KMP) used For TCP-AO [RFC5925] there is no Key Management Protocol (KMP) used
to manage the keys that are employed to generate the Message to manage the keys that are employed to generate the Message
Authentication Code (MAC). TCP-AO allows for a master key to be Authentication Code (MAC). TCP-AO talks about coordinating keys
configured manually or for it to be managed via a out of band derived from Master Key Table (MKT) between endpoints and allows for
mechanism. a master key to be configured manually or for it to be managed via a
out of band mechanism.
It should be noted that most routers configured with static keys have It should be noted that most routers configured with static keys have
not seen the key changed ever. The common reason given for not not seen the key changed ever. The common reason given for not
changing the key is the difficulty in coordinating the change between changing the key is the difficulty in coordinating the change between
pairs of routers when using TCP MD5. It is well known that the 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 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 guessed or exposed e.g. when an administrator with knowledge of the
keys leaves the company. keys leaves the company.
For point-to-point key management IKEv2 [RFC5996] provides for For point-to-point key management IKEv2 [RFC5996] protocol provides
automated key exchange under a SA and can be used for a comprehensive for automated key exchange under a SA, and can be used for a
Key Management Protocol (KMP) solution. comprehensive Key Management Protocol (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.
2.3. LDP 2.3. LDP
Section 5 of LDP [RFC5036] states that LDP is subject to two Section 5 of LDP [RFC5036] states that LDP is subject to two
different types of attacks: spoofing, and denial of service attacks. different types of attacks: spoofing, and denial of service attacks.
In addition, LDP distributes labels in the clear, enabling hackers to In addition, LDP distributes labels in the clear, enabling hackers to
see what labels are being distributed. The attacker can use that see what labels are being distributed. The attacker can use that
information to spoof a connection and distribute a different set of information to spoof a connection and distribute a different set of
labels causing traffic to be dropped. labels causing traffic to be dropped.
2.3.1. Spoofing attacks 2.3.1. Spoofing attacks
A spoofing attack against LDP can occur both during the discovery A spoofing attack against LDP can occur both during the discovery
phase and during the session communication phase. phase and during the session communication phase.
2.3.1.1. Discovery exchanges using UDP 2.3.1.1. Discovery exchanges using UDP
Label Switching Routers (LSRs) indicate their willingness to Label Switching Routers (LSRs) indicate their willingness to
establish and maintain LDP sessions by periodically sending Hello establish and maintain LDP sessions by periodically sending Hello
messages. Receipt of a Hello message serves to create a new "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 adjacency", if one does not already exist, or to refresh an existing
one. one.
Unlike all other LDP messages, the Hello messages are sent using UDP. Unlike all other LDP messages, the Hello messages are sent using UDP.
This means that they cannot benefit from the security mechanisms This means that they cannot benefit from the security mechanisms
available with TCP. LDP [RFC5036] does not provide any security available with TCP. LDP [RFC5036] does not provide any security
mechanisms for use with Hello messages except for some configuration mechanisms for use with Hello messages except for some configuration
which may help protect against bogus discovery events. These which may help protect against bogus discovery events. These
configurations include directly connected links and interfaces. configurations include directly connected links and interfaces.
Routers that do not use directly connected links have to use Extended Routers that do not use directly connected links have to use Extended
skipping to change at page 7, line 39 skipping to change at page 7, line 45
Spoofing a Hello packet can also cause the LDP session to be Spoofing a Hello packet can also cause the LDP session to be
terminated. This can occur when the spoofed Hello specifies a terminated. This can occur when the spoofed Hello specifies a
different Transport Address from the previously agreed one between different Transport Address from the previously agreed one between
neighbors. Spoofed Hello messages are observed and reported as real neighbors. Spoofed Hello messages are observed and reported as real
problem in production networks. problem in production networks.
2.3.1.2. Session communication using TCP 2.3.1.2. Session communication using TCP
LDP like other TCP based routing protocols specifies use of the TCP LDP like other TCP based routing protocols specifies use of the TCP
MD5 Signature Option to provide for the authenticity and integrity of MD5 Signature Option to provide for the authenticity and integrity of
session messages. As stated above, MD5 authentication is considered session messages. As stated in section 2.1, MD5 authentication is
too weak for this application. A stronger hashing algorithm e.g considered too weak for this application. A stronger hashing
SHA1, which is supported by TCP-AO [RFC5925] could be deployed to algorithm e.g SHA1, which is supported by TCP-AO [RFC5925] could be
take care of the weakness. deployed to take care of the weakness.
Alternatively, one could move to using TCP-AO which provides for Alternatively, one could move to using TCP-AO which provides for
stronger MACs, makes it easier to setup manual keys and protects stronger MAC algorithms, makes it easier to setup manual keys and
against replays. protects against replay attacks.
2.3.2. Privacy Issues 2.3.2. Privacy Issues
LDP provides no mechanism for protecting the privacy of label LDP provides no mechanism for protecting the privacy of label
distribution. The security requirements of label distribution are distribution. Labels, like routing information are distributed in
similar to other routing protocols that need to distribute routing the clear. There is currently no requirement for labels to be
information. encrypted and that work is outside the scope of the KARP working
group.
2.3.3. Denial of Service Attacks 2.3.3. Denial of Service Attacks
LDP is subject to Denial of Service (DoS) attacks both in its LDP is subject to Denial of Service (DoS) attacks both in its
discovery mode and in session mode. These are documented in Section discovery mode and in session mode. These are documented in Section
5.3 of LDP [RFC5036]. 5.3 of LDP [RFC5036].
2.4. PCEP 2.4. PCEP
Attacks on PCEP [RFC5440] may result in damage to active networks. Attacks on PCEP [RFC5440] may result in damage to active networks.
skipping to change at page 8, line 40 skipping to change at page 8, line 48
o Denial of Service o Denial of Service
In inter-Autonomous Systems (AS) scenarios where PCE-to-PCE In inter-Autonomous Systems (AS) scenarios where PCE-to-PCE
communication is required, attacks may be particularly significant communication is required, attacks may be particularly significant
with commercial as well as service-level agreement implications. with commercial as well as service-level agreement implications.
Additionally, snooping of PCEP requests and responses may give an Additionally, snooping of PCEP requests and responses may give an
attacker information about the operation of the network. By viewing attacker information about the operation of the network. By viewing
the PCEP messages an attacker can determine the pattern of service the PCEP messages an attacker can determine the pattern of service
establishment in the network and can know where traffic is being establishment in the network, and can know where traffic is being
routed, thereby making the network susceptible to targeted attacks routed, thereby making the network susceptible to targeted attacks
and the data within specific LSPs vulnerable. and the data within specific LSPs vulnerable.
Ensuring PCEP communication privacy is of key importance, especially Ensuring PCEP communication privacy is of key importance, especially
in an inter-AS context, where PCEP communication end-points do not in an inter-AS context, where PCEP communication end-points do not
reside in the same AS. An attacker that intercepts a PCE message reside in the same AS. An attacker that intercepts a PCE message
could obtain sensitive information related to computed paths and could obtain sensitive information related to computed paths and
resources. resources.
2.5. MSDP 2.5. MSDP
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The routing protocols should provide a mechanism to authenticate the The routing protocols should provide a mechanism to authenticate the
routing information carried within the payload. routing information carried within the payload.
3.1. LDP 3.1. LDP
To harden LDP against its current vulnerability to spoofing attacks, To harden LDP against its current vulnerability to spoofing attacks,
LDP needs to be upgraded such that an implementation is able to LDP needs to be upgraded such that an implementation is able to
determine the authenticity of the neighbors sending the Hello determine the authenticity of the neighbors sending the Hello
message. message.
There is currently no requirement to protect the privacy of label Labels are similar to routing information which is distributed in the
distribution as labels are carried in the clear like other routing clear. It is important to ensure that routers exchanging labels are
information. mutually authenticated, and that there are no rogue peers or
unauthenticated peers that can compromise the stability of the
network. However, there is currently no requirement that the labels
be encrypted.
4. Gap Analysis for BGP, LDP, PCEP and MSDP 4. Gap Analysis for BGP, LDP, PCEP and MSDP
This section outlines the differences between the current state of This section outlines the differences between the current state of
the security methods for routing protocols and the desired state of the security methods for routing protocols, and the desired state of
the security methods as outlined in section 4.2 of KARP Design the security methods as outlined in section 4.2 of KARP Design
Guidelines [RFC6518]. As that document states, these routing Guidelines [RFC6518]. As that document states, these routing
protocols fall into the category of one-to-one peering messages and protocols fall into the category of one-to-one peering messages and
will use peer keying protocol. It covers issues that are common to will use peer keying protocol. It covers issues that are common to
the four protocols in this section, leaving protocol specific issues the four protocols in this section, leaving protocol specific issues
to sub-sections. to sub-sections.
At a transport level these routing protocols are subject to some of At a transport level these routing protocols are subject to some of
the same attacks that TCP applications are subject to. These include the same attacks that TCP applications are subject to. These include
DoS and spoofing attacks. Internet Denial-of-Service Considerations DoS and spoofing attacks. Internet Denial-of-Service Considerations
[RFC4732] outlines some solutions. Defending TCP Against Spoofing [RFC4732] outlines some solutions. Defending TCP Against Spoofing
Attacks [RFC4953] recommends ways to prevent spoofing attacks. In Attacks [RFC4953] recommends ways to prevent spoofing attacks. In
addition Improving TCP's Robustness to Blind In-Window Attacks. addition, the recommendations in [RFC5961] should also be followed
[RFC5961] should also be followed and implemented to strengthen TCP. and implemented to strengthen TCP.
Routers lack comprehensive key management and keys derived from it Routers lack comprehensive key management and keys derived from it
that they can use to authenticate data. As an example TCP-AO that they can use to authenticate data. As an example TCP-AO
[RFC5925], talks about coordinating keys derived from Master Key [RFC5925], talks about coordinating keys derived from Master Key
Table (MKT) between endpoints, but the MKT itself has to be Table (MKT) between endpoints, but the MKT itself has to be
configured manually or through an out of band mechanism. Also TCP-AO configured manually or through an out of band mechanism. Also TCP-AO
does not address the issue of connectionless reset, as it applies to does not address the issue of connectionless reset, as it applies to
routers that do not store MKT across reboots. routers that do not store MKT across reboots.
Authentication, tamper protection, and encryption all require the use Authentication, tamper protection, and encryption all require the use
skipping to change at page 11, line 49 skipping to change at page 11, line 49
There are two methods of automatic key rollover. Implicit key There are two methods of automatic key rollover. Implicit key
rollover can be initiated after certain volume of data gets exchanged rollover can be initiated after certain volume of data gets exchanged
or when a certain time has elapsed. This does not require explicit 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 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, way that the links/adjacencies are affected. On the other hand,
explicit key rollover requires an out of band key signaling explicit key rollover requires an out of band key signaling
mechanism. It can be triggered by either side and can be done mechanism. It can be triggered by either side and can be done
anytime a security parameter changes e.g. an attack has happened, or anytime a security parameter changes e.g. an attack has happened, or
a system administrator with access to the keys has left the company. 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 An example of this is IKEv2 [RFC5996], but it could be any other new
mechanisms also. mechanisms also.
As stated earlier TCP-AO [RFC5925] and its accompanying document As stated earlier TCP-AO [RFC5925], and its accompanying document
Crypto Algorithms for TCP-AO [RFC5926] suggest that two MAC Crypto Algorithms for TCP-AO [RFC5926], requires that two MAC
algorithms that MUST be supported are HMAC-SHA-1-96 as specified in 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 HMAC [RFC2104], and AES-128-CMAC-96 as specified in NIST-SP800-38B
[NIST-SP800-38B]. [NIST-SP800-38B].
There is a need to protect authenticity and validity of the routing/ There is a need to protect authenticity and validity of the routing/
label information that is carried in the payload of the sessions. label information that is carried in the payload of the sessions.
However, that is outside the scope of this document and is being However, that is outside the scope of this document and is being
addressed by SIDR WG. Similar mechanisms could be used for intra- addressed by SIDR WG. Similar mechanisms could be used for intra-
domain protocols. 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. LDP
As described in LDP [RFC5036], the threat of spoofed Basic Hellos can As described in LDP [RFC5036], the threat of spoofed Basic Hellos can
be reduced by only accepting Basic Hellos on interfaces that LSRs be reduced by only accepting Basic Hellos on interfaces that LSRs
trust, employing GTSM [RFC5082] and ignoring Basic Hellos not trust, employing GTSM [RFC5082] and ignoring Basic Hellos not
addressed to the "all routers on this subnet" multicast group. addressed to the "all routers on this subnet" multicast group.
Spoofing attacks via Targeted Hellos are potentially a more serious Spoofing attacks via Targeted Hellos are potentially a more serious
threat. An LSR can reduce the threat of spoofed Extended Hellos by threat. An LSR can reduce the threat of spoofed Extended Hellos by
filtering them and accepting Hellos from sources permitted by an filtering them and accepting Hellos from sources permitted by an
access lists. However, performing the filtering using access lists access lists. However, performing the filtering using access lists
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is in use. is in use.
LDP Hello Cryptographic Authentication LDP Hello Cryptographic Authentication
[draft-zheng-mpls-ldp-hello-crypto-auth-04] suggest a new [draft-zheng-mpls-ldp-hello-crypto-auth-04] suggest a new
Cryptographic Authentication TLV that can be used as an Cryptographic Authentication TLV that can be used as an
authentication mechanism to secure Hello messages. authentication mechanism to secure Hello messages.
4.2. PCEP 4.2. PCEP
Path Computation Element (PCE) discovery according to its RFC Path Computation Element (PCE) discovery according to its RFC
[RFC5440] is a significant feature for the successful deployment of [RFC5440], is a significant feature for the successful deployment of
PCEP in large networks. This mechanism allows a Path Computation PCEP in large networks. This mechanism allows a Path Computation
Client (PCC) to discover the existence of suitable PCEs within the Client (PCC) to discover the existence of suitable PCEs within the
network without the necessity of configuration. It should be obvious network without the necessity of configuration. It should be obvious
that, where PCEs are discovered and not configured, the PCC cannot that, where PCEs are discovered and not configured, the PCC cannot
know the correct key to use. There are different approaches to 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 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. and a keying mechanism, the need for which has been discussed above.
5. Transition and Deployment Considerations 5. Transition and Deployment Considerations
As stated in KARP Design Guidelines [RFC6518] it is imperative that As stated in KARP Design Guidelines [RFC6518], it is imperative that
the new authentication and security mechanisms defined support the new authentication and security mechanisms defined support
incremental deployment, as it is not feasible to deploy the new incremental deployment, as it is not feasible to deploy the new
routing protocol authentication mechanism overnight. routing protocol authentication mechanism overnight.
Typically authentication and security in a peer-to-peer protocol Typically, authentication and security in a peer-to-peer protocol
requires that both parties agree to the mechanisms that will be used. 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 If an agreement is not reached the setup of the new mechanism will
fail or will be deferred. Upon failure, the routing protocols can fail or will be deferred. Upon failure, the routing protocols can
fallback to the mechanisms that were already in place e.g. use static fallback to the mechanisms that were already in place e.g. use static
keys if that was the mechanism in place. It is usually not possible keys if that was the mechanism in place. It is usually not possible
for one end to use the new mechanism while the other end uses the 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 old. Policies can be put in place to retry upgrading after a said
period of time, so a manual coordination is not required. period of time, so a manual coordination is not required.
If the automatic KMP requires use of public/private keys to exchange If the automatic KMP requires use of public/private keys to exchange
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This section describes security considerations that BGP, LDP, PCEP This section describes security considerations that BGP, LDP, PCEP
and MSDP should try to meet. and MSDP should try to meet.
As with all routing protocols, they need protection from both on-path 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 and off-path blind attacks. A better way to protect them would be
with per-packet protection using a cryptographic MAC. In order to with per-packet protection using a cryptographic MAC. In order to
provide for the MAC, keys are needed. provide for the MAC, keys are needed.
Once keys are used, mechanisms are required to support key rollover. Once keys are used, mechanisms are required to support key rollover.
This should cover both manual and automatic key rollover. Multiple This should cover both manual and automatic key rollover. Multiple
approaches could be used. However since the existing mechanisms approaches could be used. However, since the existing mechanisms
provide a protocol field to identify the key as well as management provide a protocol field to identify the key as well as management
mechanisms to introduce and retire new keys, focusing on the existing mechanisms to introduce and retire new keys, focusing on the existing
mechanism as a starting point is prudent. mechanism as a starting point is prudent.
Finally, replay protection is required. The replay mechanism needs 7. IANA Considerations
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.
7. Acknowledgements None.
8. Acknowledgements
We would like to thank Brian Weis for encouraging us to write this We would like to thank Brian Weis for encouraging us to write this
draft and to Anantha Ramaiah and Mach Chen for providing comments on draft, and to Anantha Ramaiah and Mach Chen for providing comments on
it. it.
8. References 9. References
8.1. Normative References
[RFC2385] Heffernan, A., "Protection of BGP Sessions via the TCP MD5 9.1. Normative References
Signature Option", RFC 2385, August 1998.
[RFC5926] Lebovitz, G. and E. Rescorla, "Cryptographic Algorithms [RFC5926] Lebovitz, G. and E. Rescorla, "Cryptographic Algorithms
for the TCP Authentication Option (TCP-AO)", RFC 5926, for the TCP Authentication Option (TCP-AO)", RFC 5926,
June 2010. June 2010.
[RFC6518] Lebovitz, G. and M. Bhatia, "Keying and Authentication for [RFC6518] Lebovitz, G. and M. Bhatia, "Keying and Authentication for
Routing Protocols (KARP) Design Guidelines", RFC 6518, Routing Protocols (KARP) Design Guidelines", RFC 6518,
February 2012. February 2012.
[draft-ietf-karp-threats-reqs] 9.2. Informative References
Lebovitz, G. and M. Bhatia, "KARP Threats and
Requirements", March 2012.
8.2. Informative References
[NIST-SP800-38B] [NIST-SP800-38B]
Dworking, "Recommendation for Block Cipher Modes of Dworking, "Recommendation for Block Cipher Modes of
Operation: The CMAC Mode for Authentication", May 2005. Operation: The CMAC Mode for Authentication", May 2005.
[RFC2104] Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed- [RFC2104] Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed-
Hashing for Message Authentication", RFC 2104, Hashing for Message Authentication", RFC 2104,
February 1997. February 1997.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2409] Harkins, D. and D. Carrel, "The Internet Key Exchange [RFC2385] Heffernan, A., "Protection of BGP Sessions via the TCP MD5
(IKE)", RFC 2409, November 1998. Signature Option", RFC 2385, August 1998.
[RFC3547] Baugher, M., Weis, B., Hardjono, T., and H. Harney, "The
Group Domain of Interpretation", RFC 3547, July 2003.
[RFC3618] Fenner, B. and D. Meyer, "Multicast Source Discovery [RFC3618] Fenner, B. and D. Meyer, "Multicast Source Discovery
Protocol (MSDP)", RFC 3618, October 2003. Protocol (MSDP)", RFC 3618, October 2003.
[RFC4271] Rekhter, Y., Li, T., and S. Hares, "A Border Gateway [RFC4271] Rekhter, Y., Li, T., and S. Hares, "A Border Gateway
Protocol 4 (BGP-4)", RFC 4271, January 2006. Protocol 4 (BGP-4)", RFC 4271, January 2006.
[RFC4301] Kent, S. and K. Seo, "Security Architecture for the
Internet Protocol", RFC 4301, December 2005.
[RFC4595] Maino, F. and D. Black, "Use of IKEv2 in the Fibre Channel
Security Association Management Protocol", RFC 4595,
July 2006.
[RFC4732] Handley, M., Rescorla, E., and IAB, "Internet Denial-of- [RFC4732] Handley, M., Rescorla, E., and IAB, "Internet Denial-of-
Service Considerations", RFC 4732, December 2006. Service Considerations", RFC 4732, December 2006.
[RFC4948] Andersson, L., Davies, E., and L. Zhang, "Report from the [RFC4948] Andersson, L., Davies, E., and L. Zhang, "Report from the
IAB workshop on Unwanted Traffic March 9-10, 2006", IAB workshop on Unwanted Traffic March 9-10, 2006",
RFC 4948, August 2007. RFC 4948, August 2007.
[RFC4953] Touch, J., "Defending TCP Against Spoofing Attacks", [RFC4953] Touch, J., "Defending TCP Against Spoofing Attacks",
RFC 4953, July 2007. RFC 4953, July 2007.
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