Internet DRAFT - draft-liu-nasr-requirements
draft-liu-nasr-requirements
Network Working Group C. Liu
Internet-Draft L. Iannone
Intended status: Informational Huawei
Expires: 4 September 2024 D. Lopez
A. Pastor
Telefonica
M. Chen
L. Su
China Mobile
3 March 2024
NASR Use Case and Requirements
draft-liu-nasr-requirements-01
Abstract
This document describes the use cases and requirements that guide the
specification of a Network Attestation for Secure Routing framework
(NASR).
About This Document
This note is to be removed before publishing as an RFC.
The latest revision of this draft can be found at
https://liuchunchi.github.io/draft-liu-nasr-requirements/draft-liu-
nasr-requirements.html. Status information for this document may be
found at https://datatracker.ietf.org/doc/draft-liu-nasr-
requirements/.
Source for this draft and an issue tracker can be found at
https://github.com/liuchunchi/draft-liu-nasr-requirements.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on 4 September 2024.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Note for NASR participants . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Backgrounds . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Definitions . . . . . . . . . . . . . . . . . . . . . . . . . 3
5. Use Cases . . . . . . . . . . . . . . . . . . . . . . . . . . 4
5.1. Use Case 1: Network Path Validation . . . . . . . . . . . 4
5.2. Use Case 2: Verifying Path Properties . . . . . . . . . . 5
5.3. Use Case 3: Sensitive Data Routing . . . . . . . . . . . 5
5.4. Use Case 4: Ingress Filtering . . . . . . . . . . . . . . 5
6. Requirements . . . . . . . . . . . . . . . . . . . . . . . . 6
6.1. Requirement 1: Proof-of-Transit (POT) Mechanisms . . . . 6
6.1.1. Per-hop POT header extensions . . . . . . . . . . . . 6
6.1.2. Out-of-band POT extensions . . . . . . . . . . . . . 7
6.2. Requirement 2: Attributes of a network element . . . . . 7
6.3. Requirement 3: Path Attestation Procedures . . . . . . . 8
7. Non-Requirements . . . . . . . . . . . . . . . . . . . . . . 8
7.1. Non-Requirements 1: Proof-of-Non-Transit (PONT)
Mechanisms . . . . . . . . . . . . . . . . . . . . . . . 8
7.2. Future Requirement 2: Packet Steering and Preventive
Mechanisms . . . . . . . . . . . . . . . . . . . . . . . 9
8. Commonly Asked Questions and Answers . . . . . . . . . . . . 9
8.1. Why not use static routing? . . . . . . . . . . . . . . . 9
8.2. Initially targeting for intra-domain or inter-domain
scenario? . . . . . . . . . . . . . . . . . . . . . . . . 9
8.3. Does tunneling solve the problem? . . . . . . . . . . . . 9
8.4. Does all nodes on the path need to compute the POT? . . . 9
9. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 9
10. Security Considerations . . . . . . . . . . . . . . . . . . . 10
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
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12. References . . . . . . . . . . . . . . . . . . . . . . . . . 10
12.1. Normative References . . . . . . . . . . . . . . . . . . 10
12.2. Informative References . . . . . . . . . . . . . . . . . 11
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12
1. Introduction
This document outlines the use cases and requirements that guide the
specification of a Network Attestation for Secure Routing framework
(NASR).
NASR is targeted to help attest a specific network path and verify if
actual forwarding result is compliant to the attested path and
attributes. The components of this network path can be any
combination of physical devices and links, and virtual links and
virtual network functions. The target network path can correspond to
a network overlay, or to an underlay supporting it, at any level in
the applicable overlay recursion hierarchy.
1.1. Note for NASR participants
This document collates and synthesizes discussion outcomes of NASR
mailing list and IETF 118 path validation side meeting.
It is created to help 1. Foster consensus among list members. 2.
Orient non-list members to NASR goals and current progress
This document may become a WG-draft but will stay as an informational
draft.
2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119], [RFC8174] when, and only when, they appear in all
capitals, as shown here.
3. Backgrounds
TBA
4. Definitions
We summarize the terms discussed in the list.
* NASR: Network Attestation For Secure Routing, a proposed framework
that mainly does the following:
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1. Attest to a network path
2. Verify actual forwarding path complies with the attested path
3. Prevent non-compliant forwarding (optional)
[Details to be added]
* Routing Security: [RFC4593], [RFC2828]
* Path Validation: [I-D.liu-path-validation-problem-statement]
* Secure Routing: [I-D.chen-secure-routing-use-cases-00]
* Proof-of-Transit: [I-D.ietf-sfc-proof-of-transit-08]
* Trustworthy Path Routing: [I-D.voit-rats-trustworthy-path-routing]
...
5. Use Cases
5.1. Use Case 1: Network Path Validation
Explicit routing protocols permit explicit control over the traffic
path, in order to meet certain performance, security or compliance
requirements. For example, operators can use SRv6 to orchestrate a
Service Function Chaining (SFC) path and provide packaged security
services or compliance services. For either of them, validating the
actual traffic path in the forwarding plane as an auditing measure is
needed for clients and/or authorities. NASR can help operator to
attest to an orchestrated path and provide verifiable forwarding
proofs to help clients/authorities audit the service.
SFC is used as an (possibly canon cal) example, therefor network
elements are not limited to Service Functions, and paths are not
limited to a SFC path. Other devices or network functions may
incorporate features (built-in security capabilities, roots of trust
and attestation mechanisms, etc.) suitable to support path
validation.
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5.2. Use Case 2: Verifying Path Properties
In use case 1, the orchestrated path is explicit and specific down to
each network element. Sometimes, clients do not need to know every
detail of the network path. Rather, clients will request the
verification of a certain property within the path, such as
trustworthiness, security level, geolocation, vendor characteristics,
transit provider, etc. from the operator. Using NASR, the operator
can orchestrate this path by selecting network elements and links
with the requested properties, attest to the path, and verifiably
prove to clients the path properties and that the traffic did follow
this path.
In both this and the previous case, the order of the elements in the
path may not be important, as the requests may be limited to a set of
attributes for the path nodes, or the guarantee that traffic
traversed a certain (set of) node(s).
5.3. Use Case 3: Sensitive Data Routing
Clients from specific industries such as finance or governments have
very low tolerance to data leakage. These clients require assurance
that their data only travels on top of their selected leased line,
MPLS VPN or SD-WAN path, and have (preferably real-time) visibility
evidence or proof. Some compliance requirements also prohibit
customer data escape a specific geolocation without permission. To
avoid data leakage and compliance risks, some clients are willing to
pay a premium for high data routing security guarantees. NASR can
detect such violations and make corrections promptly, therefore
supporting SLAs incorporating these guarantees.
Compared to the first and second use case, this use case also
requires some preventive measures before a wrongful forwarding
happens at the first place.
5.4. Use Case 4: Ingress Filtering
Ingress Filtering techniques help prevent source IP address spoofing
and denial-of-service (DoS) attacks [RFC8704][RFC5635]. It works by
validating the source IP address of a received packet by performing a
reverse path lookup in FIB table, all the way to the source. If the
path does not exist, the packet is dropped. NASR can be used to
regularly validate the path stored in the FIB table, and tell if it
continues to exist. Furthermore, when uRPF is not available and
source address cannot be trusted, NASR can offer a way to filter
malicious traffic based on the path used to carry out such an attack
[Yaar03]. The other usage is to check if a packet carries a valid
trail of transit proofs. If it does then the packet is verified.
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6. Requirements
Based on the main use-cases described in the previous section the
following requirements are identified.
6.1. Requirement 1: Proof-of-Transit (POT) Mechanisms
All use cases requested public verifiability of packet transit
history. Proof-of-Transit (POT) is a proof that a packet DID transit
certain network elements, and it can include a verification of the
order in which those elements where transited (Ordered POT, OPoO) or
not. A secure POT mechanism should verifiably reflect the identity
of the transited network elements and their relevant attributes, if
applicable:
* For basic POT, there is no further attribute than the identity of
the transited element and, optionally, its relative position/order
within the path. This is the goal of the POT mechanism defined in
[I-D.ietf-sfc-proof-of-transit-08].
* For extended POT, different attributes can be considered from a
list of relevant ones: trustworthiness measure, available security
capabilities, geolocation, vendor, etc. This needs the definition
of the relevant attributes of a network element, which is
discussed in Section 6.2
According to use case 2, the granularity of POT may also differ. POT
can be generated and recorded on a per-hop basis, or can be merged
into one collective summary at the path level.
The most appropriate POT mechanism for each scenarios may differ--
inter-domain or intra-domain, with or without a pre-attest, per-
packet or on-demand, privacy-preserving or not, etc.
6.1.1. Per-hop POT header extensions
POT could be either encapsulated and passed along the original path,
or sent out-of-band. It depends on the different operation modes:
who should verify the POT (other elements on the path, the end host,
or external security operation center (SOC)), timeliness of
verification, etc.
When the POT is passed along the path, it should be encapsulated in
hop-by-hop header extensions, such as IPv6 hop-by-hop options header,
In-situ OAM hop-by-hop option etc. Exact size and specifications of
data fields are subject to different POT mechanisms.
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6.1.2. Out-of-band POT extensions
For situations requiring real-time or near-real-time verification,
meaning some external security operation center (SOC) wishes to have
real-time visibility of the forwarding path, out-of-band methods are
needed to encapsulate and transmit POT. In this way, the SOC can
verify the POT of each packet in order to make sure the forwarding is
correct. For example, traffic monitoring protocols like IPFIX
[RFC7011] or ICMP [RFC792], specific management and control
protocols, etc. Similarly, exact size and specifications of data
fields are subject to different POT mechanisms.
6.2. Requirement 2: Attributes of a network element
The identity of a subject should be defined by the attributes (or
claims) it owns. Attribute-defined identity is a paradigm widely
accepted in SCIM [RFC7643], OAuth [RFC7519], SAML [SAML2], etc. POT
proof should reflect the identity and associated attributes, such as
element type, security level, security capability it has, remotely-
attested or not, vendor, deployed geolocation, current timestamp,
path it is on, hop index on the path etc.
Such attributes/claims/attestation results can reuse existing
specifications, for example [I-D.ietf-rats-eat],
[I-D.ietf-rats-ar4si] in RATS WG. Some existing claims that we can
reuse:
* hwmodel (Hardware Model)
* hwversion (Hardware Version)
* swname (Software Name )
* swversion (Software Version)
* location (location)
Some new claim extensions can be made:
elemtype
pathid
index
secfunctions
vendor
...
(subject to discussion, add, change)
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NASR could work closely with RATS on the standardization of above
attributes and means of proving them.
6.3. Requirement 3: Path Attestation Procedures
After a path is selected, it should be
1. Committed to prevent changes,
2. Publicized for common referencing and retrieval.
The stored path should contain this information: unique ID (within a
domain), all network elements on the path, and attributes of them.
(Schemas may vary depending on scenarios)
TBA
7. Non-Requirements
7.1. Non-Requirements 1: Proof-of-Non-Transit (PONT) Mechanisms
Proof-of-Non-Transit (PONT) is a proof that a packet did NOT transit
certain network elements. It is, essentially, the opposite to Req. 1
Proof-of-Transit. Certain potential user have expressed their
interest on PONT for compliance or security purposes.
First of all, PONT is a non-inclusion proof, and such non-existence
proof cannot be directly given. Second, under certain circumstances,
PONT can be _inferred_ from POT, especially when Ordered POT (OPOT)
is enforced. For example, assume devices are perfectly secure and
their behaviors completely compliant to expectations, then POT over
A-B-C indicates the packet did not transit X/Y/Z. To relax the
security assumptions, if the devices are remotely attested and such
claim is proved by POT, then the packet _should_ only transited these
trusted devices, assuming the RATS procedure is secure. The
reliability of such reasoning decreases as the security level of
device decreases.
NASR mailing list has agreed NOT to provide PONT mechanisms, but
could provide some informational measures and conditions that could
indicate PONT from POT results. For example, under xxx constraints
and circumstances, if traffic passed X AND Y (device or geolocation),
then it did NOT (or with a quantifiably low probability it did not)
pass Z.
Since this part is research-related, NASR will work with PANRG and
academia for counseling.
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7.2. Future Requirement 2: Packet Steering and Preventive Mechanisms
In the sensitive data routing use case, it is certainly necessary to
know and verify the transit path of a packet using POT mechanisms.
However, it might be too late to have the data already exposed to the
insecure devices and risk leakage. There should be packet steering
mechanisms or other preventive measures that help traffic stay in the
desired path. For example, doing an egress check before sending to
the next hop, preventing sending packet to a device with a non-
desirable attribute.
The mailing list and side meeting has received requests to this
requirement, it should fall in NASR interest, but also agreed this
may not be part of the initial scope of NASR-- it is a topic to be
included in further stages of NASR, in case of a rechartering.
8. Commonly Asked Questions and Answers
(From side meeting and mailing list feedbacks, to be updated)
8.1. Why not use static routing?
Static routing severely limits the scalability and flexibility for
performance optimizations and reconfigurations. Flexible
orchestration of paths will be prohibited. Also, even when static
routing is used, we still need proof of transit for compliance
checks.
8.2. Initially targeting for intra-domain or inter-domain scenario?
Limited domain with some trust assumptions and controls to devices
will be easy to start with. Then we can go do the interdomain.
8.3. Does tunneling solve the problem?
8.4. Does all nodes on the path need to compute the POT?
Whether the validation is strict or loose depends on the scenario.
For example, in SFC use cases, we are only interested in verifying
some important elements of interest processed the traffic.
9. Contributors
This document is made possible by NASR proponents, active mailing
list members and side meeting participants. Including but not
limited to: Andrew Alston, Nicola Rustignoli, Michael Richardson,
Mingxing Liu, Adnan Rashid and many others.
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Please create *Github issues* to comment, or raise a question.
Please create new commits and *Github Pull Requests* to propose new
contents.
10. Security Considerations
This document has no further security considerations.
11. IANA Considerations
This document has no IANA actions.
12. References
12.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/rfc/rfc2119>.
[RFC7011] Claise, B., Ed., Trammell, B., Ed., and P. Aitken,
"Specification of the IP Flow Information Export (IPFIX)
Protocol for the Exchange of Flow Information", STD 77,
RFC 7011, DOI 10.17487/RFC7011, September 2013,
<https://www.rfc-editor.org/rfc/rfc7011>.
[RFC7519] Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token
(JWT)", RFC 7519, DOI 10.17487/RFC7519, May 2015,
<https://www.rfc-editor.org/rfc/rfc7519>.
[RFC7643] Hunt, P., Ed., Grizzle, K., Wahlstroem, E., and C.
Mortimore, "System for Cross-domain Identity Management:
Core Schema", RFC 7643, DOI 10.17487/RFC7643, September
2015, <https://www.rfc-editor.org/rfc/rfc7643>.
[RFC792] Postel, J., "Internet Control Message Protocol", STD 5,
RFC 792, DOI 10.17487/RFC0792, September 1981,
<https://www.rfc-editor.org/rfc/rfc792>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/rfc/rfc8174>.
[RFC8704] Sriram, K., Montgomery, D., and J. Haas, "Enhanced
Feasible-Path Unicast Reverse Path Forwarding", BCP 84,
RFC 8704, DOI 10.17487/RFC8704, February 2020,
<https://www.rfc-editor.org/rfc/rfc8704>.
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12.2. Informative References
[I-D.chen-secure-routing-use-cases-00]
Chen, M. and L. Su, "The Use Cases for Secure Routing",
Work in Progress, Internet-Draft, draft-chen-secure-
routing-use-cases-00, 5 March 2023,
<https://datatracker.ietf.org/doc/html/draft-chen-secure-
routing-use-cases-00>.
[I-D.ietf-rats-ar4si]
Voit, E., Birkholz, H., Hardjono, T., Fossati, T., and V.
Scarlata, "Attestation Results for Secure Interactions",
Work in Progress, Internet-Draft, draft-ietf-rats-ar4si-
05, 30 August 2023,
<https://datatracker.ietf.org/doc/html/draft-ietf-rats-
ar4si-05>.
[I-D.ietf-rats-eat]
Lundblade, L., Mandyam, G., O'Donoghue, J., and C.
Wallace, "The Entity Attestation Token (EAT)", Work in
Progress, Internet-Draft, draft-ietf-rats-eat-25, 15
January 2024, <https://datatracker.ietf.org/doc/html/
draft-ietf-rats-eat-25>.
[I-D.ietf-sfc-proof-of-transit-08]
Brockners, F., Bhandari, S., Mizrahi, T., Dara, S., and S.
Youell, "Proof of Transit", Work in Progress, Internet-
Draft, draft-ietf-sfc-proof-of-transit-08, 1 November
2020, <https://datatracker.ietf.org/doc/html/draft-ietf-
sfc-proof-of-transit-08>.
[I-D.liu-path-validation-problem-statement]
Liu, P. C., Wu, Q., and L. Xia, "Path Validation Problem
Statement, History, Gap Analysis and Use Cases", Work in
Progress, Internet-Draft, draft-liu-path-validation-
problem-statement-00, 23 October 2023,
<https://datatracker.ietf.org/doc/html/draft-liu-path-
validation-problem-statement-00>.
[I-D.voit-rats-trustworthy-path-routing]
Voit, E., Gaddam, C. R., Fedorkow, G., Birkholz, H., and
M. Chen, "Trusted Path Routing", Work in Progress,
Internet-Draft, draft-voit-rats-trustworthy-path-routing-
09, 22 February 2024,
<https://datatracker.ietf.org/doc/html/draft-voit-rats-
trustworthy-path-routing-09>.
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[RFC2828] Shirey, R., "Internet Security Glossary", RFC 2828,
DOI 10.17487/RFC2828, May 2000,
<https://www.rfc-editor.org/rfc/rfc2828>.
[RFC4593] Barbir, A., Murphy, S., and Y. Yang, "Generic Threats to
Routing Protocols", RFC 4593, DOI 10.17487/RFC4593,
October 2006, <https://www.rfc-editor.org/rfc/rfc4593>.
[RFC5635] Kumari, W. and D. McPherson, "Remote Triggered Black Hole
Filtering with Unicast Reverse Path Forwarding (uRPF)",
RFC 5635, DOI 10.17487/RFC5635, August 2009,
<https://www.rfc-editor.org/rfc/rfc5635>.
[SAML2] "Assertions and Protocols for the OASIS Security Assertion
Markup Language (SAML) V2.0", March 2005,
<https://docs.oasis-open.org/security/saml/v2.0/saml-core-
2.0-os.pdf>.
[Yaar03] Yaar, A., Perrig, A., and D. Song, "Pi: a path
identification mechanism to defend against DDoS attacks",
IEEE Comput. Soc, Proceedings 19th International
Conference on Data Engineering (Cat. No.03CH37405),
DOI 10.1109/secpri.2003.1199330, May 2004,
<https://doi.org/10.1109/secpri.2003.1199330>.
Authors' Addresses
Chunchi Liu
Huawei
Email: liuchunchi@huawei.com
Luigi Iannone
Huawei
Email: luigi.iannone@huawei.com
Diego Lopez
Telefonica
Email: diego.r.lopez@telefonica.com
Antonio Pastor
Telefonica
Email: antonio.pastorperales@telefonica.com
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Meiling Chen
China Mobile
Email: chenmeiling@chinamobile.com
Li Su
China Mobile
Email: suli@chinamobile.com
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