DNS Scoped Data Through '_Underscore' Attribute Leaves
draft-crocker-dns-attrleaf-07
Revision differences
Document history
Date | Rev. | By | Action |
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2016-03-14
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07 | Tim Wicinski | Changed consensus to Yes from Unknown |
2016-03-14
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07 | Tim Wicinski | Intended Status changed to Best Current Practice from None |
2016-03-14
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07 | Tim Wicinski | IETF WG state changed to Adopted by a WG from Candidate for WG Adoption |
2015-12-02
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07 | Tim Wicinski | There is useful need for this to be documented, for better or for worse. |
2015-12-02
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07 | Tim Wicinski | IETF WG state changed to Candidate for WG Adoption |
2015-12-02
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07 | Tim Wicinski | Notification list changed to none |
2015-12-02
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07 | Tim Wicinski | Changed group to Domain Name System Operations (DNSOP) |
2015-12-02
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07 | Tim Wicinski | Changed stream to IETFgt; could, for example, support the differentiation of specific CAs or certificate profiles. Further path segments, for example, as … Changed stream to IETFgt; could, for example, support the differentiation of specific CAs or certificate profiles. Further path segments, for example, as specified in Lightweight CMP Profile [RFC9483], could indicate PKI management operations using an operationLabel <operation>. A valid full CMP URI can look like this: coap://www.example.com/.well-known/cmp coap://www.example.com/.well-known/cmp/<operation> coap://www.example.com/.well-known/cmp/p/<profileLabel> coap://www.example.com/.well-known/cmp/p/<profileLabel>/<operation> 2.2. Discovery of CMP RA/CA The EEs can be configured with enough information to form the CMP server URI. The minimum information that can be configured is the scheme, i.e., "coap:" or "coaps:", and the authority portion of the URI, e.g., "example.com:5683". If the port number is not specified in the authority, then the default port numbers MUST be assumed for the "coap:" and "coaps:" scheme URIs. The default port for "coap:" scheme URIs is 5683 and the default port for "coaps:" scheme URIs is 5684 [RFC7252]. Optionally, in the environments where a Local RA or CA is deployed, EEs can also use the CoAP service discovery mechanism [RFC7252] to discover the URI of the Local RA or CA. The CoAP CMP endpoints supporting service discovery MUST also support resource discovery in the Constrained RESTful Environments (CoRE) Link Format, as described in [RFC6690]. The link MUST include the 'ct' attribute defined in Section 7.2.1 of [RFC7252] with the value of "application/pkixcmp", as defined in the "CoAP Content-Formats" IANA registry. 2.3. CoAP Request Format The CMP PKIMessages MUST be DER encoded and sent as the body of the CoAP POST request. A CMP client MUST send each CoAP request marked as a Confirmable message [RFC7252]. If the CoAP request is successful, then the CMP RA or CA MUST return a Success 2.xx response code; otherwise, the CMP RA or CA MUST return an appropriate Client Error 4.xx or Server Error 5.xx response code. A CMP RA or CA may choose to send a piggybacked response [RFC7252] to the client, or it MAY send a separate response [RFC7252] in case it takes some time for the RA or CA to process the CMP transaction. When transferring CMP PKIMessage over CoAP, the content-format "application/pkixcmp" MUST be used. 2.4. CoAP Block-Wise Transfer Mode A CMP PKIMessage consists of a header, body, protection, and extraCerts structure, which may contain many optional and potentially large fields. Thus, a CMP message can be much larger than the Maximum Transmission Unit (MTU) of the outgoing interface of the device. The EEs and RAs or CAs MUST use the block-wise transfer mode [RFC7959] to transfer such large messages instead of relying on IP fragmentation. If a CoAP-to-HTTP proxy is in the path between EEs and an RA or EEs and a CA and if the server supports, then it MUST use the chunked transfer encoding [RFC9112] to send data over the HTTP transport. The proxy MUST try to reduce the number of packets sent by using an optimal chunk length for the HTTP transport. 2.5. Multicast CoAP CMP PKIMessages sent over CoAP MUST NOT use a Multicast destination address. 2.6. Announcement PKIMessage A CMP server may publish announcements that can be triggered by an event or periodically for the other PKI entities. Here is the list of CMP announcement messages prefixed by their respective ASN.1 identifier (see Section 5.1.2 of [RFC4210]): [15] CA Key Update Announcement [16] Certificate Announcement [17] Revocation Announcement [18] CRL Announcement An EE MAY use the CoAP Observe Option [RFC7641] to register itself to get any announcement messages from the RA or CA. The EE can send a GET request to the server's URI suffixed by "/ann". For example, a path to register for announcement messages may look like this: coap://www.example.com/.well-known/cmp/ann coap://www.example.com/.well-known/cmp/p/<profileLabel>/ann If the server supports CMP announcement messages, then it MUST send an appropriate Success 2.xx response code; otherwise, it MUST send an appropriate Client Error 4.xx or Server Error 5.xx response code. If for some reason the server cannot add the client to its list of observers for the announcements, it can omit the Observe Option [RFC7641] in the response to the client. Upon receiving a Success 2.xx response without the Observe Option [RFC7641], after some time, a client MAY try to register again for announcements from the CMP server. Since a server can remove the EE from the list of observers for announcement messages, an EE SHOULD periodically reregister itself for announcement messages. Alternatively, an EE MAY periodically poll for the current status of the CA via the "PKI Information Request" message; see Section 6.5 of [RFC4210]. If supported, EEs MAY also use "support messages" defined in Section 4.3 of Lightweight CMP Profile [RFC9483] to get information about the CA status. These mechanisms will help constrained devices that are acting as EEs to conserve resources by eliminating the need to create an endpoint for receiving notifications from the RA or CA. It will also simplify the implementation of a CoAP-to-HTTP proxy. 3. Proxy Support This section provides guidance on using a CoAP-to-HTTP proxy between EEs and RAs or CAs in order to avoid changes to the existing PKI implementation. Since the CMP payload is the same over CoAP and HTTP transfer mechanisms, a CoAP-to-HTTP cross-protocol proxy can be implemented based on Section 10 of [RFC7252]. The CoAP-to-HTTP proxy can either be located closer to the EEs or closer to the RA or CA. The proxy MAY support service discovery and resource discovery, as described in Section 2.2. The CoAP-to-HTTP proxy MUST function as a reverse proxy, only permitting connections to a limited set of preconfigured servers. It is out of scope of this document to specify how a reverse proxy can route CoAP client requests to one of the configured servers. Some recommended mechanisms are as follows: * Use the Uri-Path option to identify a server. * Use separate hostnames for each of the configured servers and then use the Uri-Host option for routing the CoAP requests. * Use separate hostnames for each of the configured servers and then use Server Name Indication [RFC8446] in case of the "coaps://" scheme for routing CoAP requests. 4. Security Considerations * If PKIProtection is used, the PKIHeader and PKIBody of the CMP are cryptographically protected against malicious modifications. As such, UDP can be used without compromising the security of the CMP. Security considerations for CoAP are defined in [RFC7252]. * The CMP does not provide confidentiality of the CMP payloads. If confidentiality is desired, CoAP over DTLS [RFC9147] SHOULD be used to provide confidentiality for the CMP payloads; although, it cannot conceal that the CMP is used within the DTLS layer. * Section 9.1 of [RFC7252] defines how to use DTLS [RFC9147] for securing CoAP. DTLS [RFC9147] associations SHOULD be kept alive and reused where possible to amortize on the additional overhead of DTLS on constrained devices. * An EE might not witness all of the announcement messages when using the CoAP Observe Option [RFC7641], since the Observe Option is a "best-effort" approach and the server might lose its state for subscribers to its announcement messages. The EEs may use an alternate method described in Section 2.6 to obtain time critical changes, such as Certificate Revocation List (CRL) [RFC5280] updates. * Implementations SHOULD use the available datagram size and avoid sending small datagrams containing partial CMP PKIMessage data in order to reduce memory usage for packet buffering. * A CoAP-to-HTTP proxy can also protect the PKI entities by handling UDP and CoAP messages. The proxy can mitigate attacks, like denial-of-service attacks, replay attacks, and resource-exhaustion attacks, by enforcing basic checks, like validating that the ASN.1 syntax is compliant to CMP messages and validating the PKIMessage protection before sending them to PKI entities. * Since the proxy may have access to the CMP-level metadata and control over the flow of CMP messages, proper role-based access control should be in place. The proxy can be deployed at the edge of the "end entities" network or in front of an RA and CA to protect them. However, the proxy may itself be vulnerable to resource-exhaustion attacks as it's required to buffer the CMP messages received over CoAP transport before sending it to the HTTP endpoint. This can be mitigated by using short timers for discarding the buffered messages and rate limiting clients based on the resource usage. 5. IANA Considerations IANA has registered "application/pkixcmp" (ID 259) in the "CoAP Content-Formats" registry <https://www.iana.org/assignments/core- parameters> to transfer CMP transactions over CoAP. Type name: application Subtype name: pkixcmp Reference: RFC 9482 [RFC4210] IANA has also registered a new path segment "ann" in the "CMP Well- Known URI Path Segments" registry <https://www.iana.org/assignments/ cmp> for the EEs to register themselves for the announcement messages. Path Segment: ann Description: The path to send a GET request with the CoAP Observe Option to register for CMP announcement messages. Reference: RFC 9482 IANA has added this document as a reference for the "cmp" entry in the "Well-Known URIs" registry <https://www.iana.org/assignments/ well-known-uris>. IANA has also added this document as a reference for the "p" entry in the "CMP Well-Known URI Path Segments" registry <https://www.iana.org/assignments/cmp/>. 6. References 6.1. 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/info/rfc2119>. [RFC4210] Adams, C., Farrell, S., Kause, T., and T. Mononen, "Internet X.509 Public Key Infrastructure Certificate Management Protocol (CMP)", RFC 4210, DOI 10.17487/RFC4210, September 2005, <https://www.rfc-editor.org/info/rfc4210>. [RFC6690] Shelby, Z., "Constrained RESTful Environments (CoRE) Link Format", RFC 6690, DOI 10.17487/RFC6690, August 2012, <https://www.rfc-editor.org/info/rfc6690>. [RFC6712] Kause, T. and M. Peylo, "Internet X.509 Public Key Infrastructure -- HTTP Transfer for the Certificate Management Protocol (CMP)", RFC 6712, DOI 10.17487/RFC6712, September 2012, <https://www.rfc-editor.org/info/rfc6712>. [RFC7252] Shelby, Z., Hartke, K., and C. Bormann, "The Constrained Application Protocol (CoAP)", RFC 7252, DOI 10.17487/RFC7252, June 2014, <https://www.rfc-editor.org/info/rfc7252>. [RFC7641] Hartke, K., "Observing Resources in the Constrained Application Protocol (CoAP)", RFC 7641, DOI 10.17487/RFC7641, September 2015, <https://www.rfc-editor.org/info/rfc7641>. [RFC7959] Bormann, C. and Z. Shelby, Ed., "Block-Wise Transfers in the Constrained Application Protocol (CoAP)", RFC 7959, DOI 10.17487/RFC7959, August 2016, <https://www.rfc-editor.org/info/rfc7959>. [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/info/rfc8174>. [RFC8615] Nottingham, M., "Well-Known Uniform Resource Identifiers (URIs)", RFC 8615, DOI 10.17487/RFC8615, May 2019, <https://www.rfc-editor.org/info/rfc8615>. [RFC9112] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke, Ed., "HTTP/1.1", STD 99, RFC 9112, DOI 10.17487/RFC9112, June 2022, <https://www.rfc-editor.org/info/rfc9112>. [RFC9147] Rescorla, E., Tschofenig, H., and N. Modadugu, "The Datagram Transport Layer Security (DTLS) Protocol Version 1.3", RFC 9147, DOI 10.17487/RFC9147, April 2022, <https://www.rfc-editor.org/info/rfc9147>. [RFC9480] Brockhaus, H., von Oheimb, D., and J. Gray, "Certificate Management Protocol (CMP) Updates", RFC 9480, DOI 10.17487/RFC9480, November 2023, <https://www.rfc-editor.org/info/rfc9480>. [RFC9483] Brockhaus, H., von Oheimb, D., and S. Fries, "Lightweight Certificate Management Protocol (CMP) Profile", RFC 9483, DOI 10.17487/RFC9483, November 2023, <https://www.rfc-editor.org/info/rfc9483>. 6.2. Informative References [RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S., Housley, R., and W. Polk, "Internet X.509 Public Key Infrastructure Certificate and Certificate Revocation List (CRL) Profile", RFC 5280, DOI 10.17487/RFC5280, May 2008, <https://www.rfc-editor.org/info/rfc5280>. [RFC8323] Bormann, C., Lemay, S., Tschofenig, H., Hartke, K., Silverajan, B., and B. Raymor, Ed., "CoAP (Constrained Application Protocol) over TCP, TLS, and WebSockets", RFC 8323, DOI 10.17487/RFC8323, February 2018, <https://www.rfc-editor.org/info/rfc8323>. [RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018, <https://www.rfc-editor.org/info/rfc8446>. Acknowledgements The authors would like to thank Hendrik Brockhaus, David von Oheimb, and Andreas Kretschmer for their guidance in writing the content of this document and providing valuable feedback. Authors' Addresses Mohit Sahni (editor) Palo Alto Networks 3000 Tannery Way Santa Clara, CA 95054 United States of America Email: msahni@paloaltonetworks.com Saurabh Tripathi (editor) Palo Alto Networks 3000 Tannery Way Santa Clara, CA 95054 United States of America Email: stripathi@paloaltonetworks.com |
2015-11-14
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07 | Dave Crocker | New version available: draft-crocker-dns-attrleaf-07.txt |
2011-10-13
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06 | (System) | New version available: draft-crocker-dns-attrleaf-06.txt |
2011-04-13
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05 | (System) | New version available: draft-crocker-dns-attrleaf-05.txt |
2011-03-30
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04 | (System) | New version available: draft-crocker-dns-attrleaf-04.txt |
2008-01-12
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06 | (System) | Document has expired |
2007-07-11
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03 | (System) | New version available: draft-crocker-dns-attrleaf-03.txt |
2006-10-25
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02 | (System) | New version available: draft-crocker-dns-attrleaf-02.txt |
2006-06-27
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01 | (System) | New version available: draft-crocker-dns-attrleaf-01.txt |
2006-06-21
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00 | (System) | New version available: draft-crocker-dns-attrleaf-00.txt |