draft-ietf-mpls-ldp-hello-crypto-auth-08.txt   draft-ietf-mpls-ldp-hello-crypto-auth-09.txt 
Network Working Group L. Zheng Network Working Group L. Zheng
Internet-Draft M. Chen Internet-Draft M. Chen
Intended status: Standards Track Huawei Technologies Intended status: Standards Track Huawei Technologies
Expires: December 4, 2014 M. Bhatia Expires: December 20, 2014 M. Bhatia
Alcatel-Lucent Ionos Networks
June 2, 2014 June 18, 2014
LDP Hello Cryptographic Authentication LDP Hello Cryptographic Authentication
draft-ietf-mpls-ldp-hello-crypto-auth-08.txt draft-ietf-mpls-ldp-hello-crypto-auth-09.txt
Abstract Abstract
This document introduces a new optional Cryptographic Authentication This document introduces a new optional Cryptographic Authentication
TLV that LDP can use to secure its Hello messages. It secures the TLV that LDP can use to secure its Hello messages. It secures the
Hello messages against spoofing attacks and some well known attacks Hello messages against spoofing attacks and some well known attacks
against the IP header. This document describes a mechanism to secure against the IP header. This document describes a mechanism to secure
the LDP Hello messages using National Institute of Standards and the LDP Hello messages using Hashed Message Authentication Code
Technology (NIST) Secure Hash Standard family of algorithms. (HMAC) with National Institute of Standards and Technology (NIST)
Secure Hash Standard family of algorithms.
Requirements Language Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119]. document are to be interpreted as described in RFC 2119 [RFC2119].
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
skipping to change at page 1, line 43 skipping to change at page 1, line 44
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 December 4, 2014. This Internet-Draft will expire on December 20, 2014.
Copyright Notice Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the Copyright (c) 2014 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
skipping to change at page 2, line 24 skipping to change at page 2, line 29
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Cryptographic Authentication TLV . . . . . . . . . . . . . . 4 2. Cryptographic Authentication TLV . . . . . . . . . . . . . . 4
2.1. Optional Parameter for Hello Message . . . . . . . . . . 4 2.1. Optional Parameter for Hello Message . . . . . . . . . . 4
2.2. LDP Security Association . . . . . . . . . . . . . . . . 4 2.2. LDP Security Association . . . . . . . . . . . . . . . . 4
2.3. Cryptographic Authentication TLV Encoding . . . . . . . . 6 2.3. Cryptographic Authentication TLV Encoding . . . . . . . . 6
2.4. Sequence Number Wrap . . . . . . . . . . . . . . . . . . 8 2.4. Sequence Number Wrap . . . . . . . . . . . . . . . . . . 8
3. Cryptographic Authentication Procedure . . . . . . . . . . . 8 3. Cryptographic Authentication Procedure . . . . . . . . . . . 8
4. Cross Protocol Attack Mitigation . . . . . . . . . . . . . . 8 4. Cross Protocol Attack Mitigation . . . . . . . . . . . . . . 9
5. Cryptographic Aspects . . . . . . . . . . . . . . . . . . . . 8 5. Cryptographic Aspects . . . . . . . . . . . . . . . . . . . . 9
5.1. Preparing the Cryptographic Key . . . . . . . . . . . . . 9 5.1. Preparing the Cryptographic Key . . . . . . . . . . . . . 9
5.2. Computing the Hash . . . . . . . . . . . . . . . . . . . 9 5.2. Computing the Hash . . . . . . . . . . . . . . . . . . . 10
5.3. Result . . . . . . . . . . . . . . . . . . . . . . . . . 10 5.3. Result . . . . . . . . . . . . . . . . . . . . . . . . . 10
6. Processing Hello Message Using Cryptographic Authentication . 10 6. Processing Hello Message Using Cryptographic Authentication . 10
6.1. Transmission Using Cryptographic Authentication . . . . . 10 6.1. Transmission Using Cryptographic Authentication . . . . . 10
6.2. Receipt Using Cryptographic Authentication . . . . . . . 10 6.2. Receipt Using Cryptographic Authentication . . . . . . . 11
7. Security Considerations . . . . . . . . . . . . . . . . . . . 11 7. Operational Considerations . . . . . . . . . . . . . . . . . 12
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 8. Security Considerations . . . . . . . . . . . . . . . . . . . 12
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 12 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 12 10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 13
10.1. Normative References . . . . . . . . . . . . . . . . . . 13 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 14
10.2. Informative References . . . . . . . . . . . . . . . . . 13 11.1. Normative References . . . . . . . . . . . . . . . . . . 14
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 14 11.2. Informative References . . . . . . . . . . . . . . . . . 14
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15
1. Introduction 1. Introduction
The Label Distribution Protocol (LDP) [RFC5036] sets up LDP sessions The Label Distribution Protocol (LDP) [RFC5036] sets up LDP sessions
that run between LDP peers. The peers could either be directly that run between LDP peers. The peers could either be directly
connected at the link level or could be multiple hops away. An LDP connected at the link level or could be multiple hops away. An LDP
Label Switching Router (LSR) could either be configured with the Label Switching Router (LSR) could either be configured with the
identity of its peers or could discover them using LDP Hello identity of its peers or could discover them using LDP Hello
messages. These messages are sent encapsulated in UDP addressed to messages. These messages are sent encapsulated in UDP addressed to
"all routers on this subnet" or to a specific IP address. Periodic "all routers on this subnet" or to a specific IP address. Periodic
Hello messages are also used to maintain the relationship between LDP Hello messages are also used to maintain the relationship between LDP
peers necessary to keep the LDP session active. peers necessary to keep the LDP session active.
Since the Hello messages are sent using UDP and not TCP, these Since the Hello messages are sent using UDP and not TCP, these
messages cannot use the security mechanisms defined for TCP messages cannot use the security mechanisms defined for TCP
[RFC5926]. While some configuration guidance is given in [RFC5036] [RFC5926]. While some configuration guidance is given in [RFC5036]
to help protect against false discovery messages, it does not provide to help protect against false discovery messages, it does not provide
an explicit security mechanism to protect the Hello messages. an explicit security mechanism to protect the Hello messages.
Spoofing a Hello packet for an existing adjacency can cause the valid Spoofing a Hello message for an existing adjacency can cause the
adjacency to time out and in turn can result in termination of the valid adjacency to time out and in turn can result in termination of
associated session. This can occur when the spoofed Hello specifies the associated session. This can occur when the spoofed Hello
a smaller Hold Time, causing the receiver to expect Hellos within specifies a smaller Hold Time, causing the receiver to expect Hellos
this smaller interval, while the true neighbor continues sending within this smaller interval, while the true neighbor continues
Hellos at the previously agreed lower frequency. Spoofing a Hello sending Hellos at the previously agreed lower frequency. Spoofing a
packet can also cause the LDP session to be terminated directly, Hello message can also cause the LDP session to be terminated
which can occur when the spoofed Hello specifies a different directly, which can occur when the spoofed Hello specifies a
Transport Address, other than the previously agreed one between different Transport Address, other than the previously agreed one
neighbors. Spoofed Hello messages have been observed and reported as between neighbors. Spoofed Hello messages have been observed and
a real problem in production networks [RFC6952]. reported as a real problem in production networks [RFC6952].
For Link Hello, [RFC5036] states that the threat of spoofed Hellos For Link Hello, [RFC5036] states that the threat of spoofed Hellos
can be reduced by accepting Hellos only on interfaces to which LSRs can be reduced by accepting Hellos only on interfaces to which LSRs
that can be trusted are directly connected, and ignoring Hellos not that can be trusted are directly connected, and ignoring Hellos not
addressed to the "all routers on this subnet" multicast group. The addressed to the "all routers on this subnet" multicast group. The
Generalized TTL Security Mechanism (GTSM) provides a simple and Generalized TTL Security Mechanism (GTSM) provides a simple and
reasonably robust defense mechanism for Link Hello [RFC6720], but it reasonably robust defense mechanism for Link Hello [RFC6720], but it
does not secure against packet spoofing attack or replay does not secure against packet spoofing attack or replay
attack[RFC5082]. attack[RFC5082].
skipping to change at page 3, line 44 skipping to change at page 3, line 48
spoofed Targeted Hellos by filtering them and accepting only those spoofed Targeted Hellos by filtering them and accepting only those
originating at sources permitted by an access list. However, originating at sources permitted by an access list. However,
filtering using access lists requires LSR resource, and does not filtering using access lists requires LSR resource, and does not
prevent IP-address spoofing. prevent IP-address spoofing.
This document introduces a new Cryptographic Authentication TLV which This document introduces a new Cryptographic Authentication TLV which
is used in LDP Hello messages as an optional parameter. It enhances is used in LDP Hello messages as an optional parameter. It enhances
the authentication mechanism for LDP by securing the Hello message the authentication mechanism for LDP by securing the Hello message
against spoofing attack. It also introduces a cryptographic sequence against spoofing attack. It also introduces a cryptographic sequence
number carried in the Hello messages that can be used to protect number carried in the Hello messages that can be used to protect
against replay attacks. The LSRs could be configured to only accept against replay attacks.
Hello messages from specific peers when authentication is in use.
Using this Cryptographic Authentication TLV, one or more secret keys Using this Cryptographic Authentication TLV, one or more secret keys
(with corresponding Security Association (SA) IDs) are configured in (with corresponding Security Association (SA) IDs) are configured in
each system. For each LDP Hello message, the key is used to generate each system. For each LDP Hello message, the key is used to generate
and verify a HMAC Hash that is stored in the LDP Hello message. For and verify a HMAC Hash that is stored in the LDP Hello message. For
cryptographic hash function, this document proposes to use SHA-1, cryptographic hash function, this document proposes to use SHA-1,
SHA-256, SHA-384, and SHA-512 defined in US NIST Secure Hash Standard SHA-256, SHA-384, and SHA-512 defined in US NIST Secure Hash Standard
(SHS) [FIPS-180-3]. The HMAC authentication mode defined in (SHS) [FIPS-180-3]. The HMAC authentication mode defined in
[RFC2104] is used. Of the above, implementations MUST include [RFC2104] is used. Of the above, implementations MUST include
support for at least HMAC-SHA-256 and SHOULD include support for support for at least HMAC-SHA-256 and SHOULD include support for
HMAC-SHA-1 and MAY include support for either of HMAC-SHA-384 or HMAC-SHA-1 and MAY include support for HMAC-SHA-384 and HMAC-SHA-512.
HMAC-SHA-512.
2. Cryptographic Authentication TLV 2. Cryptographic Authentication TLV
2.1. Optional Parameter for Hello Message 2.1. Optional Parameter for Hello Message
[RFC5036] defines the encoding for the Hello message. Each Hello [RFC5036] defines the encoding for the Hello message. Each Hello
message contains zero or more Optional Parameters, each encoded as a message contains zero or more Optional Parameters, each encoded as a
TLV. Three Optional Parameters are defined by [RFC5036]. This TLV. Three Optional Parameters are defined by [RFC5036]. This
document defines a new Optional Parameter: the Cryptographic document defines a new Optional Parameter: the Cryptographic
Authentication parameter. Authentication parameter.
skipping to change at page 4, line 41 skipping to change at page 4, line 44
An LDP Security Association (SA) contains a set of parameters shared An LDP Security Association (SA) contains a set of parameters shared
between any two legitimate LDP speakers. between any two legitimate LDP speakers.
Parameters associated with an LDP SA are as follows: Parameters associated with an LDP SA are as follows:
o Security Association Identifier (SA ID) o Security Association Identifier (SA ID)
This is a 32-bit unsigned integer used to uniquely identify an LDP This is a 32-bit unsigned integer used to uniquely identify an LDP
SA between two LDP peers, as manually configured by the network SA between two LDP peers, as manually configured by the network
operator (or, in the future, possibly by some key management operator (or, possibly by some key management protocol specified
protocol specified by the IETF) . by the IETF in the future) .
The receiver determines the active SA by looking at the SA ID The receiver determines the active SA by looking at the SA ID
field in the incoming Hello message. field in the incoming Hello message.
The sender, based on the active configuration, selects an SA to The sender, based on the active configuration, selects an SA to
use and puts the correct SA ID value associated with the SA in the use and puts the correct SA ID value associated with the SA in the
LDP Hello message. If multiple valid and active LDP SAs exist for LDP Hello message. If multiple valid and active LDP SAs exist for
a given interface, the sender may use any of those SAs to protect a given interface, the sender may use any of those SAs to protect
the packet. the packet.
skipping to change at page 6, line 30 skipping to change at page 6, line 33
the KeyStopGenerate time of the old key. Any unspecified values are the KeyStopGenerate time of the old key. Any unspecified values are
encoded as Zero. encoded as Zero.
Key storage SHOULD persist across a system restart, warm or cold, to Key storage SHOULD persist across a system restart, warm or cold, to
avoid operational issues. In the event that the last key associated avoid operational issues. In the event that the last key associated
with an interface expires, it is unacceptable to revert to an with an interface expires, it is unacceptable to revert to an
unauthenticated condition, and not advisable to disrupt routing. unauthenticated condition, and not advisable to disrupt routing.
Therefore, the router SHOULD send a "last Authentication Key Therefore, the router SHOULD send a "last Authentication Key
expiration" notification to the network manager and treat the key as expiration" notification to the network manager and treat the key as
having an infinite lifetime until the lifetime is extended, the key having an infinite lifetime until the lifetime is extended, the key
is deleted by network management, or a new key is configured is deleted by network management, or a new key is configured.
2.3. Cryptographic Authentication TLV Encoding 2.3. Cryptographic Authentication TLV Encoding
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0|0| Auth (TBD1) | Length | |0|0| Auth (TBD1) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Security Association ID | | Security Association ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Cryptographic Sequence Number (High Order 32 Bits) | | Cryptographic Sequence Number (High Order 32 Bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Cryptographic Sequence Number (Low Order 32 Bits) | | Cryptographic Sequence Number (Low Order 32 Bits) |
skipping to change at page 7, line 7 skipping to change at page 7, line 24
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
| Authentication Data (Variable) | | Authentication Data (Variable) |
~ ~ ~ ~
| | | |
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- Type: TBD1, Cryptographic Authentication - Type: TBD1, Cryptographic Authentication
- Length: Specifying the length in octets of the value field. - Length: Specifying the length in octets of the value field,
including the Security Association ID and Cryptographic Sequence
Number fields.
- Security Association ID: 32 bit field that maps to the - Security Association ID: 32 bit field that maps to the
authentication algorithm and the secret key used to create the authentication algorithm and the secret key used to create the
message digest carried in LDP payload. message digest carried in LDP payload.
Though the SA ID implies the algorithm, the HMAC output size should Though the SA ID implies the algorithm, the HMAC output size should
not be used by implementers as an implicit hint, because additional not be used by implementers as an implicit hint, because additional
algorithms may be defined in the future that have the same output algorithms may be defined in the future that have the same output
size. size.
- Cryptographic Sequence Number: 64-bit strictly increasing sequence - Cryptographic Sequence Number: 64-bit strictly increasing sequence
number that is used to guard against replay attacks. The 64-bit number that is used to guard against replay attacks. The 64-bit
sequence number MUST be incremented for every LDP Hello packet sent sequence number MUST be incremented for every LDP Hello message sent
by the LDP router. Upon reception, the sequence number MUST be by the LDP router. Upon reception, the sequence number MUST be
greater than the sequence number in the last LDP Hello packet greater than the sequence number in the last LDP Hello message
accepted from the sending LDP neighbor. Otherwise, the LDP packet is accepted from the sending LDP neighbor. Otherwise, the LDP message
considered a replayed packet and dropped. is considered a replayed packet and dropped. The Cryptographic
Sequence Number is a single space per LDP router.
LDP routers implementing this specification MUST use existing LDP routers implementing this specification MUST use existing
mechanisms to preserve the sequence number's strictly increasing mechanisms to preserve the sequence number's strictly increasing
property for the deployed life of the LDP router (including cold property for the deployed life of the LDP router (including cold
restarts). One mechanism for accomplishing this could be to use the restarts). One mechanism for accomplishing this could be to use the
high-order 32 bits of the sequence number as a boot count that is high-order 32 bits of the sequence number as a boot count that is
incremented anytime the LDP router loses its sequence number state. incremented anytime the LDP router loses its sequence number state.
Techniques such as sequence number space partitioning described above Techniques such as sequence number space partitioning described above
or non-volatile storage preservation can be used but are beyond the or non-volatile storage preservation can be used but are beyond the
scope of this specification. Sequence number wrap is described in scope of this specification. Sequence number wrap is described in
Section 2.4. Section 2.4.
- Authentication Data: - Authentication Data:
This field carries the digest computed by the Cryptographic This field carries the digest computed by the Cryptographic
Authentication algorithm in use. The length of the Authentication Authentication algorithm in use. The length of the Authentication
Data varies based on the cryptographic algorithm in use, which is Data varies based on the cryptographic algorithm in use, which is
skipping to change at page 8, line 8 skipping to change at page 8, line 27
Auth type Length Auth type Length
--------------- ---------- --------------- ----------
HMAC-SHA1 20 bytes HMAC-SHA1 20 bytes
HMAC-SHA-256 32 bytes HMAC-SHA-256 32 bytes
HMAC-SHA-384 48 bytes HMAC-SHA-384 48 bytes
HMAC-SHA-512 64 bytes HMAC-SHA-512 64 bytes
2.4. Sequence Number Wrap 2.4. Sequence Number Wrap
When incrementing the sequence number for each transmitted LDP When incrementing the sequence number for each transmitted LDP
packet, the sequence number should be treated as an unsigned 64-bit message, the sequence number should be treated as an unsigned 64-bit
value. If the lower order 32-bit value wraps, the higher order value. If the lower order 32-bit value wraps, the higher order
32-bit value should be incremented and saved in non-volatile storage. 32-bit value should be incremented and saved in non-volatile storage.
If the LDP router is deployed long enough that the 64-bit sequence If the LDP router is deployed long enough that the 64-bit sequence
number wraps, all keys, independent of key distribution mechanism number wraps, all keys, independent of key distribution mechanism
MUST be reset. This is done to avoid the possibility of replay MUST be reset. This is done to avoid the possibility of replay
attacks. Once the keys have been changed, the higher order sequence attacks. Once the keys have been changed, the higher order sequence
number can be reset to 0 and saved to non-volatile storage. number can be reset to 0 and saved to non-volatile storage.
3. Cryptographic Authentication Procedure 3. Cryptographic Authentication Procedure
skipping to change at page 10, line 23 skipping to change at page 10, line 43
being used. being used.
This also means that the use of hash functions with larger output This also means that the use of hash functions with larger output
sizes will also increase the size of the LDP message as transmitted sizes will also increase the size of the LDP message as transmitted
on the wire. on the wire.
6. Processing Hello Message Using Cryptographic Authentication 6. Processing Hello Message Using Cryptographic Authentication
6.1. Transmission Using Cryptographic Authentication 6.1. Transmission Using Cryptographic Authentication
Prior to transmitting the Hello message, the Length in the Prior to transmitting the LDP Hello message, the Length in the
Cryptographic Authentication TLV header is set as per the Cryptographic Authentication TLV header is set as per the
authentication algorithm that is being used. It is set to 24 for authentication algorithm that is being used. It is set to 24 for
HMAC-SHA-1, 36 for HMAC-SHA-256, 52 for HMAC-SHA-384 and 68 for HMAC- HMAC-SHA-1, 36 for HMAC-SHA-256, 52 for HMAC-SHA-384 and 68 for HMAC-
SHA-512. SHA-512.
The Security Association ID field is set to the ID of the current The Security Association ID field is set to the ID of the current
authentication key. The HMAC Hash is computed as explained in authentication key. The HMAC Hash is computed as explained in
Section 3. The resulting Hash is stored in the Authentication Data Section 3. The resulting Hash is stored in the Authentication Data
field prior to transmission. The authentication key MUST NOT be field prior to transmission. The authentication key MUST NOT be
carried in the packet. carried in the packet.
6.2. Receipt Using Cryptographic Authentication 6.2. Receipt Using Cryptographic Authentication
The receiving LSR applies acceptability criteria for received Hellos The receiving LSR applies acceptability criteria for received Hellos
using cryptographic authentication. If the Cryptographic using cryptographic authentication. If the Cryptographic
Authentication TLV is unknown to the receiving LSR, the received Authentication TLV is unknown to the receiving LSR, the received
packet MUST be discarded according to Section 3.5.1.2.2 of [RFC5036]. packet MUST be discarded according to Section 3.5.1.2.2 of [RFC5036].
The receiving router MUST determine whether to accept a Hello Message
from a particular source IP address as follows. First, if the router
has, for that source IP address, any LDP Hello authentication
information, such as a stored cryptographic sequence number or that
LDP Hello authentication is required, then the router MUST discard
any unauthenticated Hello packets. As specified later in this
section, a cryptographic sequence number is only stored for a source
IP address as a result of receiving a valid authenticated Hello.
The receiving LSR locates the LDP SA using the Security Association The receiving LSR locates the LDP SA using the Security Association
ID field carried in the message. If the SA is not found, or if the ID field carried in the message. If the SA is not found, or if the
SA is not valid for reception (i.e., current time < KeyStartAccept or SA is not valid for reception (i.e., current time < KeyStartAccept or
current time >= KeyStopAccept), LDP Hello message MUST be discarded, current time >= KeyStopAccept), LDP Hello message MUST be discarded,
and an error event SHOULD be logged. and an error event SHOULD be logged.
If the cryptographic sequence number in the LDP packet is less than If the cryptographic sequence number in the LDP Hello message is less
or equal to the last sequence number received from the same neighbor, than or equal to the last sequence number received from the same
the LDP message MUST be discarded, and an error event SHOULD be neighbor, the LDP Hello message MUST be discarded, and an error event
logged. SHOULD be logged.
Before the receiving LSR performs any processing, it needs to save Before the receiving LSR performs any processing, it needs to save
the values of the Authentication Data field. The receiving LSR then the values of the Authentication Data field. The receiving LSR then
replaces the contents of the Authentication Data field with AuthTag, replaces the contents of the Authentication Data field with AuthTag,
computes the Hash, using the authentication key specified by the computes the Hash, using the authentication key specified by the
received Security Association ID field, as explained in Section 3. received Security Association ID field, as explained in Section 3.
If the locally computed Hash is equal to the received value of the If the locally computed Hash is equal to the received value of the
Authentication Data field, the received packet is accepted for other Authentication Data field, the received packet is accepted for other
normal checks and processing as described in [RFC5036]. Otherwise, normal checks and processing as described in [RFC5036]. Otherwise,
if the locally computed Hash is not equal to the received value of if the locally computed Hash is not equal to the received value of
the Authentication Data field, the received packet MUST be discarded, the Authentication Data field, the received LDP Hello message MUST be
and an error event SHOULD be logged. The foresaid logging need to be discarded, and an error event SHOULD be logged. The foresaid logging
carefully rate limited, since while a LDP router is under attack of a need to be carefully rate limited, since while a LDP router is under
storm of spoofed hellos, the resource taking for logging could be attack of a storm of spoofed hellos, the resource taking for logging
overwelming. could be overwelming.
After the LDP Hello message has been successfully authenticated, After the LDP Hello message has been successfully authenticated,
implementations MUST store the 64-bit cryptographic sequence number implementations MUST store the 64-bit cryptographic sequence number
for the Hello message received from the neighbor. The saved for the LDP Hello message received from the neighbor. The saved
cryptographic sequence numbers will be used for replay checking for cryptographic sequence numbers will be used for replay checking for
subsequent packets received from the neighbor. subsequent packets received from the neighbor.
7. Security Considerations 7. Operational Considerations
Careful consideration must be given to when and how to enable and
disable authentication on LDP Hellos. On the one hand, it is
critical that an attack cannot cause the authentication to be
disabled. On the other hand, it is equally important that an
operator can change the hardware and/or software associated with a
neighbor's IP address and successfully bring up an LDP adjacency with
the desired level of authentication, which may be with different or
no authentication due to software restrictions.
LDP Hello authentication information (e.g. whether authentication is
enabled and what the last cryptographic sequence number is)
associated with an IP address is learned via a set of interfaces. If
an interface is administratively disabled, the LDP Hello
authentication information learned via that interface MAY be
forgotten. This enables an operator that is not specifically
manipulating LDP Hello authentication configurations to easily bring
up an LDP adjacency. An implementation of this standard SHOULD
provide a configuration mechanism by which the LDP Hello
authentication information associated with an IP address can be shown
and can be forgotten; configuration mechanisms are assumed to be
accessed via an authenticated channel.
8. Security Considerations
Section 1 of this document describes the security issues arising from Section 1 of this document describes the security issues arising from
the use of unauthenticated LDP Hello messages. In order to address the use of unauthenticated LDP Hello messages. In order to address
those issues, it is RECOMMENDED that all deployments use the those issues, it is RECOMMENDED that all deployments use the
Cryptographic Authentication TLV to authenticate the Hello messages. Cryptographic Authentication TLV to authenticate the Hello messages.
The quality of the security provided by the Cryptographic The quality of the security provided by the Cryptographic
Authentication TLV depends completely on the strength of the Authentication TLV depends completely on the strength of the
cryptographic algorithm in use, the strength of the key being used, cryptographic algorithm in use, the strength of the key being used,
and the correct implementation of the security mechanism in and the correct implementation of the security mechanism in
skipping to change at page 12, line 11 skipping to change at page 13, line 17
on the key are not feasible in their environments. In support of on the key are not feasible in their environments. In support of
these recommendations, management systems SHOULD support hexadecimal these recommendations, management systems SHOULD support hexadecimal
input of Authentication Keys. input of Authentication Keys.
The mechanism described herein is not perfect . However, this The mechanism described herein is not perfect . However, this
mechanism introduces a significant increase in the effort required mechanism introduces a significant increase in the effort required
for an adversary to successfully attack the LDP Hello protocol while for an adversary to successfully attack the LDP Hello protocol while
not causing undue implementation, deployment, or operational not causing undue implementation, deployment, or operational
complexity. complexity.
8. IANA Considerations 9. IANA Considerations
The IANA is requested to as assign a new TLV from the "Label The IANA is requested to as assign a new TLV from the "Label
Distribution Protocol (LDP) Parameters" registry, "TLV Type Name Distribution Protocol (LDP) Parameters" registry, "TLV Type Name
Space". Space".
Value Meaning Reference Value Meaning Reference
----- -------------------------------- ------------------------ ----- -------------------------------- ------------------------
TBD1 Cryptographic Authentication TLV this document (sect 2.3) TBD1 Cryptographic Authentication TLV this document (sect 2.3)
The IANA is also requested to as assign value from the The IANA is also requested to as assign value from the
skipping to change at page 12, line 35 skipping to change at page 13, line 41
Value Description Reference Value Description Reference
----- -------------------------------- ---------------------- ----- -------------------------------- ----------------------
TBD2 LDP Cryptographic Protocol ID this document (sect 4) TBD2 LDP Cryptographic Protocol ID this document (sect 4)
Note to the RFC Editor and IANA (to be removed before publication): Note to the RFC Editor and IANA (to be removed before publication):
The new value should be assigned from the range 0x400 - 0x4ff using The new value should be assigned from the range 0x400 - 0x4ff using
the first free value. the first free value.
9. Acknowledgements 10. Acknowledgements
We are indebted to Yaron Sheffer who helped us enormously in We are indebted to Yaron Sheffer who helped us enormously in
rewriting the draft to get rid of the redundant crypto mathematics rewriting the draft to get rid of the redundant crypto mathematics
that we had added here. that we had added here.
We would also like to thank Liu Xuehu for his work on background and We would also like to thank Liu Xuehu for his work on background and
motivation for LDP Hello authentication. And last but not the least, motivation for LDP Hello authentication. And last but not the least,
we would also thank Adrian Farrel, Eric Rosen, Sam Hartman, Stephen we would also thank Adrian Farrel, Eric Rosen, Sam Hartman, Stephen
Farrell, Eric Gray, Kamran Raza and Acee Lindem for their valuable Farrell, Eric Gray, Kamran Raza and Acee Lindem for their valuable
comments. comments.
10. References 11. References
10.1. Normative References
11.1. Normative References
[FIPS-180-3] [FIPS-180-3]
"Secure Hash Standard (SHS), FIPS PUB 180-3", October "Secure Hash Standard (SHS), FIPS PUB 180-3", October
2008. 2008.
[FIPS-198]
"The Keyed-Hash Message Authentication Code (HMAC), FIPS
PUB 198", March 2002.
[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, February Hashing for Message Authentication", RFC 2104, February
1997. 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.
[RFC5036] Andersson, L., Minei, I., and B. Thomas, "LDP
Specification", RFC 5036, October 2007.
11.2. Informative References
[RFC4822] Atkinson, R. and M. Fanto, "RIPv2 Cryptographic [RFC4822] Atkinson, R. and M. Fanto, "RIPv2 Cryptographic
Authentication", RFC 4822, February 2007. Authentication", RFC 4822, February 2007.
[RFC5036] Andersson, L., Minei, I., and B. Thomas, "LDP [RFC5082] Gill, V., Heasley, J., Meyer, D., Savola, P., and C.
Specification", RFC 5036, October 2007. Pignataro, "The Generalized TTL Security Mechanism
(GTSM)", RFC 5082, October 2007.
[RFC5310] Bhatia, M., Manral, V., Li, T., Atkinson, R., White, R., [RFC5310] Bhatia, M., Manral, V., Li, T., Atkinson, R., White, R.,
and M. Fanto, "IS-IS Generic Cryptographic and M. Fanto, "IS-IS Generic Cryptographic
Authentication", RFC 5310, February 2009. Authentication", RFC 5310, February 2009.
[RFC5709] Bhatia, M., Manral, V., Fanto, M., White, R., Barnes, M., [RFC5709] Bhatia, M., Manral, V., Fanto, M., White, R., Barnes, M.,
Li, T., and R. Atkinson, "OSPFv2 HMAC-SHA Cryptographic Li, T., and R. Atkinson, "OSPFv2 HMAC-SHA Cryptographic
Authentication", RFC 5709, October 2009. Authentication", RFC 5709, October 2009.
[RFC7166] Bhatia, M., Manral, V., and A. Lindem, "Supporting
Authentication Trailer for OSPFv3", RFC 7166, March 2014.
10.2. Informative References
[RFC5082] Gill, V., Heasley, J., Meyer, D., Savola, P., and C.
Pignataro, "The Generalized TTL Security Mechanism
(GTSM)", RFC 5082, October 2007.
[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.
[RFC6720] Pignataro, C. and R. Asati, "The Generalized TTL Security [RFC6720] Pignataro, C. and R. Asati, "The Generalized TTL Security
Mechanism (GTSM) for the Label Distribution Protocol Mechanism (GTSM) for the Label Distribution Protocol
(LDP)", RFC 6720, August 2012. (LDP)", RFC 6720, August 2012.
[RFC6952] Jethanandani, M., Patel, K., and L. Zheng, "Analysis of [RFC6952] Jethanandani, M., Patel, K., and L. Zheng, "Analysis of
BGP, LDP, PCEP, and MSDP Issues According to the Keying BGP, LDP, PCEP, and MSDP Issues According to the Keying
and Authentication for Routing Protocols (KARP) Design and Authentication for Routing Protocols (KARP) Design
Guide", RFC 6952, May 2013. Guide", RFC 6952, May 2013.
[RFC7166] Bhatia, M., Manral, V., and A. Lindem, "Supporting
Authentication Trailer for OSPFv3", RFC 7166, March 2014.
Authors' Addresses Authors' Addresses
Lianshu Zheng Lianshu Zheng
Huawei Technologies Huawei Technologies
China China
Email: vero.zheng@huawei.com Email: vero.zheng@huawei.com
Mach(Guoyi) Chen Mach(Guoyi) Chen
Huawei Technologies Huawei Technologies
China China
Email: mach.chen@huawei.com Email: mach.chen@huawei.com
Manav Bhatia Manav Bhatia
Alcatel-Lucent Ionos Networks
India India
Email: manavbhatia@gmail.com Email: manav@ionosnetworks.com
 End of changes. 34 change blocks. 
75 lines changed or deleted 108 lines changed or added

This html diff was produced by rfcdiff 1.41. The latest version is available from http://tools.ietf.org/tools/rfcdiff/