Question:
The text below is a bit confusing as there are no details about how to to send replies and map responses to their requests in Section 7.1.1. This can be easily fixed by clarifying what Section 7.1.1 provides details on. But I was also wondering if there should be some more details on how to send replies and map responses to their requests somewhere?
Note: this will be in §9.3.2.1. after merge.
Is seems the concept of mapping requests/replies has been fully eliminated. So just removing this part of the example.
Thanks Philipp, LGTM.

The messageData object provides access to the bytes that were received for this Message, along with the length of the byte array. The messageContext is provided to enable retrieving metadata about <del> the message and referring to the message, e.g., to send replies and map responses to their requests.  See msg-ctx for details. </del> <ins> the message and referring to the message.  The messageContext object ist described in msg-ctx. </ins> See framing for handling Message framing in situations where the Protocol Stack only provides a byte-stream transport.


Question:
This adds SO_reuse commentry on the multicast UDP service. It seeks to
The implementation document should explain IGMP joining and SO_REUSEADDR for multicast
Text blob for thought or incorporation: In some uses, it is required to open multiple connections for the same address(es). This is used for some multicast applications. For example, one connection might be opened to listen to a multicast group, and later a separate one to send to the same group; two applications might independently listen to the same address(es) to send signals to and/or receive signals from a common multicast control bus. In these cases, the interface needs to explicitly enable re-use of the same set of addresses (equivalent to setting SO_REUSEADDR in the socket API).

is Any-source Multicast, and the path selection is based on the outbound route to the group supplied in the Local Endpoint. <ins> There are cases where it is required to open multiple connections for the same address(es).  For example, one Connection might be opened for a multicast group to for a multicast control bus, and another application later opens a separate Connection to the same group to send signals to and/or receive signals from the common bus.  In such cases, the interface needs to explicitly enable re-use of the same set of addresses (equivalent to setting SO_REUSEADDR in the socket API). </ins> UDP Multicast Receive Listeners will deliver new connections once they have received traffic from a new Remote Endpoint.


Question:
, , , , , .
In 8.1.1 the second sentence is convoluted. Is there a way to restate it without as many nots, nons, an different zeros?
Do you really mean "host" at "(endpoints) SHOULD represent the same host" in section 6, or do you mean something more like service, given that an endpoint may configured with a DNS name?
actually we mean service, good catch.
The "reformatted where necessary" part of the requirement in the last paragraph of 4.1 makes the MUST NOT almost impossible to conform to. I think I understand what the paragraph is trying to say, but the current formulation leaves the reader guessing. I think you are trying to say "Avoid using any of the terms listed as keywords in the protocol numbers registry as any part of a vendor or implementation-specific property name".
The first sentence-paragraph of section 4 is complex. Please break it apart.
has a comment that's too long for the text version
In the text version of the document, the last paragraph before 3.1.3 has some markup (~~~) that has leaked through.
As you can tell, I don't think the documents do what the first sentence of the API summary claims. This document would not lose anything if you deleted the sentence.
Agreed, we can lose this sentence.
Why? Removing this makes no sense to me.
For one, it's redundant - it only repeats what we already say earlier twice.
Ah, I see - so just this one instance..... then go ahead, we don't need to say something twice.

3. <del> The Transport Services API is the basic common abstract application programming interface to the Transport Services Architecture defined in the TAPS Architecture I-D.ietf-taps-arch. </del> An application primarily interacts with this API through two Objects: Preconnections and Connections.  A Preconnection object (pre- establishment) represents a set of properties and constraints on the


Question:
, , , , , .
In 8.1.1 the second sentence is convoluted. Is there a way to restate it without as many nots, nons, an different zeros?
Do you really mean "host" at "(endpoints) SHOULD represent the same host" in section 6, or do you mean something more like service, given that an endpoint may configured with a DNS name?
actually we mean service, good catch.
The "reformatted where necessary" part of the requirement in the last paragraph of 4.1 makes the MUST NOT almost impossible to conform to. I think I understand what the paragraph is trying to say, but the current formulation leaves the reader guessing. I think you are trying to say "Avoid using any of the terms listed as keywords in the protocol numbers registry as any part of a vendor or implementation-specific property name".
The first sentence-paragraph of section 4 is complex. Please break it apart.
has a comment that's too long for the text version
In the text version of the document, the last paragraph before 3.1.3 has some markup (~~~) that has leaked through.
As you can tell, I don't think the documents do what the first sentence of the API summary claims. This document would not lose anything if you deleted the sentence.
Agreed, we can lose this sentence.
Why? Removing this makes no sense to me.
For one, it's redundant - it only repeats what we already say earlier twice.
Ah, I see - so just this one instance..... then go ahead, we don't need to say something twice.

Preconnections are reusable after being used to initiate a Connection.  Hence, for example, after the Connections were closed, <del> the following would be correct: ~~~ //.. carry out adjustments to the Preconnection, if desire Connection := Preconnection.Initiate() ~~~ </del> <ins> the following would be correct: </ins> 3.1.3.


Question:
, , , , , .
In 8.1.1 the second sentence is convoluted. Is there a way to restate it without as many nots, nons, an different zeros?
Do you really mean "host" at "(endpoints) SHOULD represent the same host" in section 6, or do you mean something more like service, given that an endpoint may configured with a DNS name?
actually we mean service, good catch.
The "reformatted where necessary" part of the requirement in the last paragraph of 4.1 makes the MUST NOT almost impossible to conform to. I think I understand what the paragraph is trying to say, but the current formulation leaves the reader guessing. I think you are trying to say "Avoid using any of the terms listed as keywords in the protocol numbers registry as any part of a vendor or implementation-specific property name".
The first sentence-paragraph of section 4 is complex. Please break it apart.
has a comment that's too long for the text version
In the text version of the document, the last paragraph before 3.1.3 has some markup (~~~) that has leaked through.
As you can tell, I don't think the documents do what the first sentence of the API summary claims. This document would not lose anything if you deleted the sentence.
Agreed, we can lose this sentence.
Why? Removing this makes no sense to me.
For one, it's redundant - it only repeats what we already say earlier twice.
Ah, I see - so just this one instance..... then go ahead, we don't need to say something twice.

4. Each application using the Transport Services Interface declares its <del> preferences for how the transport service should operate using properties at each stage of the lifetime of a connection using Transport Properties, as defined in I-D.ietf-taps-arch. </del> <ins> preferences for how the transport service should operate.  This is done by using Transport Properties, as defined in I-D.ietf-taps-arch, at each stage of the lifetime of a connection. </ins> Transport Properties are divided into Selection, Connection, and Message Properties.  Selection Properties (see selection-props) can


Question:
, , , , , .
In 8.1.1 the second sentence is convoluted. Is there a way to restate it without as many nots, nons, an different zeros?
Do you really mean "host" at "(endpoints) SHOULD represent the same host" in section 6, or do you mean something more like service, given that an endpoint may configured with a DNS name?
actually we mean service, good catch.
The "reformatted where necessary" part of the requirement in the last paragraph of 4.1 makes the MUST NOT almost impossible to conform to. I think I understand what the paragraph is trying to say, but the current formulation leaves the reader guessing. I think you are trying to say "Avoid using any of the terms listed as keywords in the protocol numbers registry as any part of a vendor or implementation-specific property name".
The first sentence-paragraph of section 4 is complex. Please break it apart.
has a comment that's too long for the text version
In the text version of the document, the last paragraph before 3.1.3 has some markup (~~~) that has leaked through.
As you can tell, I don't think the documents do what the first sentence of the API summary claims. This document would not lose anything if you deleted the sentence.
Agreed, we can lose this sentence.
Why? Removing this makes no sense to me.
For one, it's redundant - it only repeats what we already say earlier twice.
Ah, I see - so just this one instance..... then go ahead, we don't need to say something twice.

Namespaces for each of the keywords provided in the IANA protocol numbers registry (see https://www.iana.org/assignments/protocol- <del> numbers/protocol-numbers.xhtml), reformatted where necessary to conform to an implementation's naming conventions, are reserved for Protocol Specific Properties and MUST NOT be used for vendor or implementation-specific properties. </del> <ins> numbers/protocol-numbers.xhtml) are reserved for Protocol Specific Properties and MUST NOT be used for vendor or implementation-specific properties.  Avoid using any of the terms listed as keywords in the protocol numbers registry as any part of a vendor- or implementation- specific property name. </ins> 4.2.


Question:
, , , , , .
In 8.1.1 the second sentence is convoluted. Is there a way to restate it without as many nots, nons, an different zeros?
Do you really mean "host" at "(endpoints) SHOULD represent the same host" in section 6, or do you mean something more like service, given that an endpoint may configured with a DNS name?
actually we mean service, good catch.
The "reformatted where necessary" part of the requirement in the last paragraph of 4.1 makes the MUST NOT almost impossible to conform to. I think I understand what the paragraph is trying to say, but the current formulation leaves the reader guessing. I think you are trying to say "Avoid using any of the terms listed as keywords in the protocol numbers registry as any part of a vendor or implementation-specific property name".
The first sentence-paragraph of section 4 is complex. Please break it apart.
has a comment that's too long for the text version
In the text version of the document, the last paragraph before 3.1.3 has some markup (~~~) that has leaked through.
As you can tell, I don't think the documents do what the first sentence of the API summary claims. This document would not lose anything if you deleted the sentence.
Agreed, we can lose this sentence.
Why? Removing this makes no sense to me.
For one, it's redundant - it only repeats what we already say earlier twice.
Ah, I see - so just this one instance..... then go ahead, we don't need to say something twice.

If more than one Remote Endpoint is specified on the Preconnection, then all the Remote Endpoints on the Preconnection SHOULD represent <del> the same host.  For example, the Remote Endpoints might represent </del> <ins> the same service.  For example, the Remote Endpoints might represent </ins> various network interfaces of a host, or a server reflexive address that can be used to reach a host, or a set of hosts that provide equivalent local balanced service.


Question:
, , , , , .
In 8.1.1 the second sentence is convoluted. Is there a way to restate it without as many nots, nons, an different zeros?
Do you really mean "host" at "(endpoints) SHOULD represent the same host" in section 6, or do you mean something more like service, given that an endpoint may configured with a DNS name?
actually we mean service, good catch.
The "reformatted where necessary" part of the requirement in the last paragraph of 4.1 makes the MUST NOT almost impossible to conform to. I think I understand what the paragraph is trying to say, but the current formulation leaves the reader guessing. I think you are trying to say "Avoid using any of the terms listed as keywords in the protocol numbers registry as any part of a vendor or implementation-specific property name".
The first sentence-paragraph of section 4 is complex. Please break it apart.
has a comment that's too long for the text version
In the text version of the document, the last paragraph before 3.1.3 has some markup (~~~) that has leaked through.
As you can tell, I don't think the documents do what the first sentence of the API summary claims. This document would not lose anything if you deleted the sentence.
Agreed, we can lose this sentence.
Why? Removing this makes no sense to me.
For one, it's redundant - it only repeats what we already say earlier twice.
Ah, I see - so just this one instance..... then go ahead, we don't need to say something twice.

Full Coverage This property specifies the minimum number of bytes in a received <del> message that need to be covered by a checksum.  A special value of 0 means that a received packet does not need to have a non-zero checksum field.  A receiving endpoint will not forward messages that have less coverage to the application.  The application is responsible for handling any corruption within the non-protected part of the message RFC8085. </del> <ins> message that need to be covered by a checksum.  A receiving endpoint will not forward messages that have less coverage to the application. The application is responsible for handling any corruption within the non-protected part of the message RFC8085.  A special value of 0 means that a received packet may also have a zero checksum field. </ins> 8.1.2.


Question:
In (Arch) section 3.3, you are talking about racing before you've described what it is. At the point where you note that racing should only happen over stacks with identical security properties, note when doing so might introduce privacy issues and what can be done about them.
Describe what you mean by caching and why you might want to isolate sessions earlier.

to a single address over a single interface.  They also present a single stream to the application.  Software layers built upon sockets often propagate this limitation of a single-address single-stream <del> model.  The Transport Services architecture is designed to handle multiple candidate endpoints, protocols, and paths; and support multipath and multistreaming protocols. </del> <ins> model.  The Transport Services architecture is designed: to handle multiple candidate endpoints, protocols, and paths; to support candidate protocol racing to select the most optimal stack in each situation; to support multipath and multistreaming protocols; to provide state caching and application control over it. </ins> Transport Services implementations are meant to be flexible at connection establishment time, considering many different options and <del> trying to select the most optimal combinations (gathering and racing).  This requires applications to provide higher-level endpoints than IP addresses, such as hostnames and URLs, which are used by a Transport Services implementation for resolution, path selection, and racing.  Transport services implementations can further implement fallback mechanisms if connection establishment of one protocol fails or performance is detected to be unsatisfactory. </del> <ins> trying to select the most optimal combinations by racing them and measuring the results (see gathering and racing).  This requires applications to provide higher-level endpoints than IP addresses, such as hostnames and URLs, which are used by a Transport Services implementation for resolution, path selection, and racing.  Transport Services implementations can further implement fallback mechanisms if connection establishment of one protocol fails or performance is detected to be unsatisfactory. Information used in connection establishment (e.g. cryptographic resumption tokens, information about usability of certain protocols on the path, results of racing in previous connections) are cached in the transport services implementation.  Applications have control over whether this information is used for a specific establishment, in order to allow tradeoffs between efficiency and linkability. </ins> Flexibility after connection establishment is also important. Transport protocols that can migrate between multiple network-layer


Question:
In (Arch) section 3.3, you are talking about racing before you've described what it is. At the point where you note that racing should only happen over stacks with identical security properties, note when doing so might introduce privacy issues and what can be done about them.
Describe what you mean by caching and why you might want to isolate sessions earlier.

system can race different security protocols, e.g., if the application explicitly specifies that it considers them equivalent. <ins> Whether information from previous racing attempts, or other information cached by the Transport Services implementation about past communications, is used during establishment is under application control.  This allows applications to make tradeoffs between efficiency (through racing) and privacy (via information that might leak from the cache toward an on-path observer).  Some applications have native concepts (e.g. "incognito mode") that align with this functionality. </ins> Applications need to ensure that they use security APIs appropriately.  In cases where applications use an interface to provide sensitive keying material, e.g., access to private keys or


Question:
Fix to Issue
We don’t mention layers in the text before: “A violation of any of the layers should cause” Is this better as: ” A violation that occurs at any of the policer layers should cause”
Fixed

application. In general, any protocol or path used for a connection must conform <del> to all three sources of constraints.  A violation of any of the layers should cause a protocol or path to be considered ineligible for use.  For an example of application preferences leading to constraints, an application may prohibit the use of metered network interfaces for a given Connection to avoid user cost.  Similarly, the system policy at a given time may prohibit the use of such a metered network interface from the application's process.  Lastly, the implementation itself may default to disallowing certain network interfaces unless explicitly requested by the application and allowed by the system. </del> <ins> to all three sources of constraints.  A violation that occurs at any of the policy layers should cause a protocol or path to be considered ineligible for use.  For an example of application preferences leading to constraints, an application may prohibit the use of metered network interfaces for a given Connection to avoid user cost. Similarly, the system policy at a given time may prohibit the use of such a metered network interface from the application's process. Lastly, the implementation itself may default to disallowing certain network interfaces unless explicitly requested by the application and allowed by the system. </ins> It is expected that the database of system policies and the method of looking up these policies will vary across various platforms.  An


Question:
During IETF 106 I solicited some feedback on the ACP IPsec/IKEv2 usage from Valery Smyslov; I've tried to digest that feedback into new text here. Some aspects are still subject to change. I also made a minor tweak to the DTLS section to bring it into parity with the IPsec one.
Merging first, then fixing.

certificate directly instead of relying on a referential mechanism such as communicating only a hash and/or URL for the certificate. <del> Any security association protocol MUST use PFS (such as profiles providing PFS). </del> <ins> Any security association protocol MUST provide Forward Secrecy (whether inherently or as part of a profile of the security association protocol). </ins> The degree of security required on every hop of an ACP network needs to be consistent across the network so that there is no designated


Question:
During IETF 106 I solicited some feedback on the ACP IPsec/IKEv2 usage from Valery Smyslov; I've tried to digest that feedback into new text here. Some aspects are still subject to change. I also made a minor tweak to the DTLS section to bring it into parity with the IPsec one.
Merging first, then fixing.

6.7.1. <del> An ACP node announces its ability to support IKEv2 as the ACP secure channel protocol in GRASP as "IKEv2". </del> <ins> An ACP node announces its ability to support IPsec, negotiated via IKEv2, as the ACP secure channel protocol in GRASP as the "IKEv2" method for the "AN_ACP" objective. </ins> 6.7.1.1. To run ACP via IPsec natively, no further IANA assignments/ definitions are required. <del> An ACP node that is supporting native IPsec MUST use IPsec security setup via IKEv2 for tunnel mode and IPsec/IKE signaling accordingly for IPv6 payload (e.g.: ESP next header of 41).  It MUST use local and peer link-local IPv6 addresses for encapsulation. Authentication MUST use the ACP domain certificates.  Certificate Encoding MUST support "PKCS #7 wrapped X.509 certificate" (0) (see IKEV2IANA for this and other IANA IKEv2 parameter names used in this text).  If certificate chains are used, all intermediate certificates up to, but not including the locally provisioned trust anchor certificate must be signaled. </del> <ins> The ACP usage of IPsec and IKEv2 mandates a narrow profile of the current standards-track usage guidance for IPsec RFC8221 and IKEv2 RFC8247.  This profile provides for stringent security properties and can exclude deprecated/legacy algorithms because there is no need for interoperability with legacy equipment for ACP channels.  Any such backward compatibility would lead only to increased attack surface and implementation complexity, for no benefit. An ACP node that is supporting native IPsec MUST use IPsec in tunnel mode, negotiated via IKEv2, and with IPv6 payload (e.g., ESP Next Header of 41).  It MUST use local and peer link-local IPv6 addresses for encapsulation.  Manual keying MUST NOT be used (independent of the security weaknesses of manual keying, it is incompatible with an autonomic platform). </ins> IPsec tunnel mode is required because the ACP will route/forward packets received from any other ACP node across the ACP secure


Question:
During IETF 106 I solicited some feedback on the ACP IPsec/IKEv2 usage from Valery Smyslov; I've tried to digest that feedback into new text here. Some aspects are still subject to change. I also made a minor tweak to the DTLS section to bring it into parity with the IPsec one.
Merging first, then fixing.

transport mode, it would only be possible to send packets originated by the ACP node itself. <del> IKEv2 authentication MUST use authentication method=1 ("RSA Digital Signature") for ACP certificates with RSA key and methods 9,10,11 for ACP certificates with ECC key according to the keys size/curve. A certificate payload with the ACP certificate MUST be included during IKEv2 authentication to support the ACP domain membership as described in certcheck, because it is using additional elements of the ACP certificates.  ACP peers are expected to have the same set of Trust Anchors (TA), so a certificate path MUST only be included in the signaled payload when the path contains intermediate certificates not in the TA set, such as sub-CAs (see acp-registrars). IPsec MUST support ESP with ENCR_AES_GCM_16 (RFC4106) due to its higher performance over ENCR_AES_CBC.  ACP MUST NOT use any NULL encryption option due to the confidentiality of ACP payload that may not be encrypted by itself (when carrying legacy management protocol traffics as well as hop-by-hop GRASP).  These requirements are based on RFC8221 but limited to the minimum necessary options because there is no need for interoperability with legacy equipment for ACP channels, instead any such backward compatibility would reduce the minimum security or performance required for ACP channels or increase the implementation complexity of the ACP. </del> <ins> ACP IPsec implementations MUST support ESP with ENCR_AES_GCM_16 (RFC4106) due to its higher performance over ENCR_AES_CBC.  ACP MUST NOT use any NULL encryption option due to the confidentiality of ACP payload that may not be encrypted by itself (when carrying legacy management protocol traffics as well as hop-by-hop GRASP).  When using AES encryption, 256-bit keys MUST be used.  AES-GCM is an AEAD cipher mode, so no ESP authentication algorithm requirement is needed. </ins> Once there are updates to RFC8221, these should accordingly be reflected in updates to these ACP requirements, for example if


Question:
During IETF 106 I solicited some feedback on the ACP IPsec/IKEv2 usage from Valery Smyslov; I've tried to digest that feedback into new text here. Some aspects are still subject to change. I also made a minor tweak to the DTLS section to bring it into parity with the IPsec one.
Merging first, then fixing.

long as they do not result in a reduction of security over the above MTI requirements.  For example, ESP compression MAY be used. <del> IKEv2 MUST follow RFC8247 as necessary to support the above listed IPsec requirements. </del> <ins> As for ESP (above), for IKEv2, the ENCR_AES_GCM_16 encryption algorithm (with 256-bit keys) MUST be supported.  The IKEv2 PRF_HMAC_SHA2_512 pseudorandom function MUST be supported. IKEv2 Diffie-Hellman key exchange group 19 (256-bit random ECP) MUST be supported (in addition to 2048-bit MODP).  ECC provides a similar security level to finite-field (MODP) key exchange with a shorter key length, so is generally preferred absent other considerations. IKEv2 authentication MUST use the ACP domain certificates.  The Certificate Encoding "PKCS #7 wrapped X.509 certificate" (1) MUST be supported (see IKEV2IANA for this and other IANA IKEv2 parameter names used in this text).  If certificate chains are used, all intermediate certificates up to, but not including the locally provisioned trust anchor certificate must be signaled. A certificate payload with the ACP certificate MUST be included during IKEv2 authentication to support the ACP domain membership check as described in certcheck, because it is using additional elements of the ACP certificates.  ACP peers are expected to have the same set of Trust Anchors (TA), so a certificate path MUST only be included in the signaled payload when the path contains intermediate certificates not in the TA set, such as sub-CAs (see acp-registrars). ACP nodes are identified by their ACP address, so the ID_IPv6_ADDR IKEv2 identification payload MUST be used and MUST convey the ACP address.  If the peer's ACP domain certificate includes an ACP address in the domain information, the address in the identification payload must match the address in the certificate (allowing for the presence of virtualization bits in the ACP addressing scheme used). IKEv2 authentication MUST use authentication method 14 ("Digital Signature") for ACP certificates; this authentication method can be used with both RSA and ECDSA certificates, as indicated by a PKIX- style OID. The Digital Signature hash SHA2-512 MUST be supported (in addition to SHA2-256). Once there are updates to RFC8247, these should accordingly be reflected in updates to these ACP requirements, for example if ENCR_AES_GCM_16 was to be superceeded in the future or the key- exchange group recommendations are changed. Additional requirements from RFC8247 MAY be used for ACP channels as long as they do not result in a reduction of security over the above MTI requirements. </ins> 6.7.1.2.


Question:
During IETF 106 I solicited some feedback on the ACP IPsec/IKEv2 usage from Valery Smyslov; I've tried to digest that feedback into new text here. Some aspects are still subject to change. I also made a minor tweak to the DTLS section to bring it into parity with the IPsec one.
Merging first, then fixing.

the first transport encryption supported in some classes of constrained devices. <ins> An ACP node announces its ability to support DTLS as the ACP secure channel protocol in GRASP as the "DTLS" method for the "AN_ACP" objective. </ins> To run ACP via UDP and DTLS v1.2 RFC6347 a locally assigned UDP port is used that is announced as a parameter in the GRASP AN_ACP objective to candidate neighbors.


Question:
Provides more context around the various elements of the model
Thanks a lot for your stab at Security Considerations! Also the I-D was in dire need for some expositional english text. Reads straight forward and comprehensive.

Abstract <del> This document defines a YANG RPC and a minimal datastore tree required to retrieve attestation evidence about integrity measurements from a composite device with one or more roots of trust for reporting.  Complementary measurement logs are also provided by the YANG RPC originating from one or more roots of trust of measurement.  The module defined requires at least one TPM 1.2 or TPM 2.0 and corresponding Trusted Software Stack included in the device components of the composite device the YANG server is running on. </del> <ins> This document defines a YANG RPC and a minimal datastore required to retrieve attestation evidence about integrity measurements from a device following the operational context defined in I-D.ietf-rats- tpm-based-network-device-attest.  Complementary measurement logs are also provided by the YANG RPC originating from one or more roots of trust of measurement.  The module defined requires at least one TPM 1.2 or TPM 2.0 and corresponding Trusted Software Stack included in the device components of the composite device the YANG server is running on. </ins> 1. This document is based on the terminology defined in the I-D.ietf- <del> rats-architecture and uses the interaction model and information elements defined in the I-D.birkholz-rats-reference-interaction-model document.  The currently supported hardware security modules (HWM) - sometimes also referred to as an embedded secure element (eSE) - is the Trusted Platform Module (TPM) version 1.2 and 2.0 specified by the Trusted Computing Group (TCG).  One ore more TPMs embedded in the components of a composite device - sometimes also referred to as an aggregate device - are required in order to use the YANG module defined in this document.  A TPM is used as a root of trust for reporting (RTR) in order to retrieve attestation evidence from a composite device (quote primitive operation).  Additionally, it is used as a root of trust for storage (RTS) in order to retain shielded secrets and store system measurements using a folding hash function (extend primitive operation). </del> <ins> rats-architecture and uses the operational context defined in I- D.ietf-rats-tpm-based-network-device-attest as well as the interaction model and information elements defined in I-D.birkholz- rats-reference-interaction-model.  The currently supported hardware security modules (HWM) are the Trusted Platform Module (TPM) TPM1.2 and TPM2.0 specified by the Trusted Computing Group (TCG).  One ore more TPMs embedded in the components of a composite device - sometimes also referred to as an aggregate device - are required in order to use the YANG module defined in this document.  A TPM is used as a root of trust for reporting (RTR) in order to retrieve attestation evidence from a composite device (quote primitive operation).  Additionally, it is used as a root of trust for storage (RTS) in order to retain shielded secrets and store system measurements using a folding hash function (extend primitive operation). </ins> 1.1.


Question:
Provides more context around the various elements of the model
Thanks a lot for your stab at Security Considerations! Also the I-D was in dire need for some expositional english text. Reads straight forward and comprehensive.

2.2.1. This YANG module imports modules from RFC6991, RFC8348, I-D.ietf- <del> netconf-crypto-types, ietf-asymmetric-algs.yang. </del> <ins> netconf-keystore, ietf-tcg-algs.yang. </ins> <del> 2.3. </del> <ins> 2.2.1.1. This module supports the following types of attestation event logs: <ima>, <bios>, and <netequip_boot>. 2.2.1.2. <tpm12-challenge-response-attestation> - Allows a Verifier to request a quote of PCRs from a TPM1.2 compliant cryptoprocessor.  When one or more <certificate-name> is not provided, all TPM1.2 compliant cryptoprocessors will respond. <tpm20-challenge-response-attestation> - Allows a Verifier to request a quote of PCRs from a TPM2.0 compliant cryptoprocessor.  When one or more <certificate-name> is not provided, all TPM2.0 compliant cryptoprocessors will respond. <log-retrieval> - Allows a Verifier to acquire the evidence which was extended into specific PCRs. 2.2.1.3. container <rats-support-structures> - This exists when there are more than one TPM for a particular Attester.  This allows each specific TPM to identify on which <compute-node> it belongs. container <tpms> - Provides configuration and operational details for each supported TPM, including the tpm-firmware-version, PCRs which may be quoted, certificates which are associated with that TPM, and the current operational status.  Of note is the certificates which are associated with that TPM.  As a certificate is associated with a single Attestation key, knowledge of the certificate allows a specific TPM to be identified. container <attester-supported-algos> - Identifies which TCG algorithms are available for use the Attesting platform.  This allows an operator to limit algorithms available for use by RPCs to just a desired set from the universe of all allowed by TCG. 2.2.1.4. 2.2.2. </ins> Cryptographic algorithm types were initially included within -v14 NETCONF's iana-crypto-types.yang.  Unfortunately all this content including the algorithms needed here failed to make the -v15 used <del> WGLC.  Therefore a modified version of this draft is included here. Perhaps someone will steward this list as a separate draft. </del> <ins> WGLC.  As a result this document has encoded the TCG Algorithm definitions of TCG-Algos, revision 1.32.  By including this full table as a separate YANG file within this document, it is possible for other YANG models to leverage the contents of this model. 2.2.2.1. There are two types of features supported <TPM12> and <TPM20>. Support for either of these features indicates that a cryptoprocessor supporting the corresponding type of TCG API is present on an Attester.  Most commonly, only one type of cryptoprocessor will be available on an Attester. 2.2.2.2. There are three types of identities in this model. The first are the cryptographic functions supportable by a TPM algorithm, these include: <asymmetric>, <symmetric>, <hash>, <signing>, <anonymous_signing>, <encryption_mode>, <method>, and <object_type>.  The definitions of each of these are in Table 2 of TCG-Algos. The second are API specifications for tpms: <tpm12> and <tpm2>. The third are specific algorithm types.  Each algorithm type defines what cryptographic functions may be supported, and on which type of API specification.  It is not required that an implementation of a specific TPM will support all algorithm types.  The contents of each specific algorithm mirrors what is in Table 3 of TCG-Algos. 2.2.2.3. Note that not all cryptographic functions are required for use by ietf-tpm-remote-attestation.yang.  However the full definition of Table 3 of TCG-Algos will allow use by additional YANG specifications. </ins> 3. This document will include requests to IANA: <del> To be defined yet. </del> <ins> To be defined yet.  But keeping up with changes to ietf-tcg-algs.yang will be necessary. </ins> 4. <del> There are always some. </del> <ins> The YANG module specified in this document defines a schema for data that is designed to be accessed via network management protocols such as NETCONF RFC6241 or RESTCONF RFC8040.  The lowest NETCONF layer is the secure transport layer, and the mandatory-to-implement secure transport is Secure Shell (SSH) RFC6242.  The lowest RESTCONF layer is HTTPS, and the mandatory-to-implement secure transport is TLS RFC5246. There are a number of data nodes defined in this YANG module that are writable/creatable/deletable (i.e., config true, which is the default).  These data nodes may be considered sensitive or vulnerable in some network environments.  Write operations (e.g., edit-config) to these data nodes without proper protection can have a negative effect on network operations.  These are the subtrees and data nodes and their sensitivity/vulnerability: Container: </rats-support-structures/attester-supported-algos> <tpm12-asymmetric-signing>, <tpm12-hash>, <tpm20-asymmetric- signing>, and <tpm20-hash> all could be populated with algorithms which are not supported by the underlying physical TPM installed by the equipment vendor. Container: </rats-support-structures/tpms> <tpm-name> - Although shown as 'rw', it is system generated <tpm20-pcr-bank> - It is possible to configure PCRs for extraction which are not being extended by system software.  This could unnecessarily use TPM resources. <certificates> - It is possible to provision a certificate which does not correspond to a Attestation Identity Key (AIK) within the TPM. RPC: <tpm12-challenge-response-attestation> - Need to verify that the certificate is for an active AIK. RPC: <tpm20-challenge-response-attestation> - Need to verify that the certificate is for an active AIK. RPC: <log-retrieval> - Pulling lots of logs can chew up system resources. </ins> 5. <ins> Changes from version 02 to version 03: moved to tcg-algs cleaned up model to eliminate sources of errors removed key establishment RPC added lots of XPATH which must all be scrubbed still Descriptive text added on model contents. </ins> Changes from version 01 to version 02: Extracted Crypto-types into a separate YANG file


Question: Not quite. It specifies secure bootstrapping of the individual nodes. It's RFC 8994 that bootstraps the ACP.

1. Bootstrapping Remote Secure Key Infrastructures BRSKI specifies <del> automated bootstrapping of an Autonomic Control Plane.  BRSKI Section 2.7 describes how a pledge "MAY contact a well-known URI of a cloud registrar if a local registrar cannot be discovered or if the pledge's target use cases do not include a local registrar". </del> <ins> automated network onboarding of devices, referred to as pledges, within an Autonomic Control Plane or other managed network infrastructure.  BRSKI Section 2.7 describes how a pledge "MAY contact a well-known URI of a cloud registrar if a local registrar cannot be discovered or if the pledge's target use cases do not include a local registrar". </ins> This document further specifies use of a BRSKI cloud registrar and clarifies operations that are not sufficiently specified in BRSKI.


Question: I find the "??" in the figure confusing. The Cloud Registrar and the MASA could just be shown as adjacent boxes; the explanation in the text is fine. That looks ugly as a single pseudo-sentence, and I'm not sure what it means. A more complete explanation would be good.

logically separate entities.  The two functions could of course be integrated into a single service. <del> TWO CHOICES: 1.  Cloud Registrar redirects to Owner Registrar 2. Cloud Registrar returns VOUCHER pinning Owner Register. </del> <ins> There are two different mechanisms for a cloud registrar to handle voucher requests: 1. the Cloud Registrar redirects the request to Owner Registrar for handling 2. the Cloud Registrar returns a voucher pinning the Owner Register and includes additional bootstrapping information embedded in the voucher Both mechanisms are described in detail later in this document. </ins> 2.1.


Question:
This replaces all mentions of capport (other than document slugs) with "captive portal". Note: this change includes the title of the document.
Joel Halpern writes, We should do this.
Or erase all mentions of 'capport'

<del> CAPPORT Architecture </del> <ins> Captive Portal Architecture </ins> draft-ietf-capport-architecture-08 Abstract <del> This document describes a CAPPORT architecture.  DHCP or Router Advertisements, an optional signaling protocol, and an HTTP API are used to provide the solution.  The role of Provisioning Domains (PvDs) is described. </del> <ins> This document describes a captive portal architecture.  DHCP or Router Advertisements, an optional signaling protocol, and an HTTP API are used to provide the solution.  The role of Provisioning Domains (PvDs) is described. </ins> 1.


Question:
This replaces all mentions of capport (other than document slugs) with "captive portal". Note: this change includes the title of the document.
Joel Halpern writes, We should do this.
Or erase all mentions of 'capport'

2.2.1. A standard for providing a portal URI using DHCP or Router <del> Advertisements is described in RFC7710bis.  The CAPPORT architecture expects this URI to indicate the API described in section_api. </del> <ins> Advertisements is described in RFC7710bis.  The captive portal architecture expects this URI to indicate the API described in section_api. </ins> 2.2.2.


Question:
Multiple reviewers objected to the way in which we captured interactions with headless/UI-less devices. Clarify the document's intent. Do this by removing language that indicated that we would eventually get around to adding the requirements, and specify explicitly that we are not handling devices without UIs.
Eric points out in his review: He suggests as a solution: I propose we do this. The first mention is in section one. We can say something along the lines of "A future document could provide a solution for devices without user interfaces. This document focuses on devices with user interfaces."
On page 4: Joel Halpern writes,
We might want to avoid relying on the captivity concept so heavily, but this is a good change nonetheless.

A side-benefit of the architecture described in this document is that devices without user interfaces are able to identify parameters of <del> captivity.  However, this document does not yet describe a mechanism for such devices to escape captivity. </del> <ins> captivity.  However, this document does not describe a mechanism for such devices to negotiate for unrestricted network access.  A future document could provide a solution to devices without user interfaces. This document focuses on devices with user interfaces. </ins> The architecture uses the following mechanisms:


Question:
Multiple reviewers objected to the way in which we captured interactions with headless/UI-less devices. Clarify the document's intent. Do this by removing language that indicated that we would eventually get around to adding the requirements, and specify explicitly that we are not handling devices without UIs.
Eric points out in his review: He suggests as a solution: I propose we do this. The first mention is in section one. We can say something along the lines of "A future document could provide a solution for devices without user interfaces. This document focuses on devices with user interfaces."
On page 4: Joel Halpern writes,
We might want to avoid relying on the captivity concept so heavily, but this is a good change nonetheless.

section_capport_enforcement, until site-specific requirements have been met. <del> At this time we consider only devices with web browsers, with web </del> <ins> This document only considers devices with web browsers, with web </ins> applications being the means of satisfying Captive Portal Conditions. <del> An example interactive User Equipment is a smart phone. </del> <ins> An example of such User Equipment is a smart phone. </ins> The User Equipment:


Question:
We only use UE in one section. Everywhere else we use User Equipment. Expand UE in that section so we are consistent with our use of it.
It was pointed out that we sometimes use UE rather than user equipment (e.g. section 3.5.). Let's be consistent, perhaps shortening all references to UE other than where it is defined.

A Captive Portal API needs to present information to clients that is unique to that client.  To do this, some systems use information from the context of a request, such as the source address, to identify the <del> UE. </del> <ins> User Equipment. </ins> Using information from context rather than information from the URI allows the same URI to be used for different clients.  However, it also means that the resource is unable to provide relevant <del> information if the UE makes a request using a different network path. This might happen when UE has multiple network interfaces.  It might also happen if the address of the API provided by DNS depends on where the query originates (as in split DNS RFC8499). </del> <ins> information if the User Equipment makes a request using a different network path.  This might happen when User Equipment has multiple network interfaces.  It might also happen if the address of the API provided by DNS depends on where the query originates (as in split DNS RFC8499). </ins> Accessing the API MAY depend on contextual information.  However, the <del> URIs provided in the API SHOULD be unique to the UE and not dependent on contextual information to function correctly. Though a URI might still correctly resolve when the UE makes the request from a different network, it is possible that some functions could be limited to when the UE makes requests using the captive network.  For example, payment options could be absent or a warning could be displayed to indicate the payment is not for the current connection. </del> <ins> URIs provided in the API SHOULD be unique to the User Equipment and not dependent on contextual information to function correctly. Though a URI might still correctly resolve when the User Equipment makes the request from a different network, it is possible that some functions could be limited to when the User Equipment makes requests using the captive network.  For example, payment options could be absent or a warning could be displayed to indicate the payment is not for the current connection. </ins> URIs could include some means of identifying the User Equipment in the URIs.  However, including unauthenticated User Equipment


Question:
The idea of a session is important, both because it is used in the API document, and because it helps to tie everything together. Define it in the terminology.
This is a first stab at defining the session. I suspect we may need to iterate on it once or twice. Let me know if you think it deserves its own section on top of the terminology.
Thanks for doing this! Here’s a suggested alternate way to explain this. Feel free to modify as desired. Captive Portal Session: Also referred to simply as the “session”, a Captive Portal Session is the association for a particular User Equipment that starts when it interacts with the Captive Portal and gains open access to the network, and ends when the User Equipment moves back into the original captive state. The Captive Network maintains the state of each active Session, and can limit Sessions based on a length of time or a number of bytes used. The Session is associated with a particular User Equipment using the User Equipment's identifier (see ).
Your phrasing is better. It manages to work in the session limits while keeping it about the same lenght. I've taken it almost verbatim. NAME Do you have any input on this topic?
From Ben's review of the API document, we should define "session" formally in the architecture. The architecture doc mentions it in passing once already. The API doc uses the term session much more.

Captive Portal Signaling Protocol: Also known as Signaling Protocol. The protocol for communicating Captive Portal Signals. <ins> Captive Portal Session: Also referred to simply as the "session", a Captive Portal Session is the association for a particular User Equipment that starts when it interacts with the Captive Portal and gains open access to the network, and ends when the User Equipment moves back into the original captive state.  The Captive Network maintains the state of each active Session, and can limit Sessions based on a length of time or a number of bytes used.  The Session is associated with a particular User Equipment using the User Equipment's identifier (see ue_identity). </ins> 2. 2.1.


Question:
The language of this section was hard for some of the reviewers to understand. Rephrase it to be more explicit and clear.
Yes. We should probably rephrase this. E.g. "The user makes an informed choice in deciding to visit and trust the Captive Portal URI. Since the network provides Captive Portal URI to the user equipment, thenetwork SHOULD do so securely so that the user's trust in the network can extend to their trust of the Captive Portal URI. E.g., the DHCPv6 AUTH option can sign this information."

Architecture RFC7556 provides some discussion on authenticating an operator. <del> Given that a user chooses to visit a Captive Portal URI, the URI location SHOULD be securely provided to the user's device.  E.g., the DHCPv6 AUTH option can sign this information. </del> <ins> The user makes an informed choice to visit and trust the Captive Portal URI.  Since the network provides Captive Portal URI to the user equipment, the network SHOULD do so securely so that the user's trust in the network can extend to their trust of the Captive Portal URI.  E.g., the DHCPv6 AUTH option can sign this information. </ins> If a user decides to incorrectly trust an attacking network, they might be convinced to visit an attacking web page and unwittingly


Question:
Attempting to fix issue . I attempted to reword the principles, adding more prose for the rationale. Also upgraded some SHOULD NOT to MUST NOT because it seems some people thought the SHOULD NOT says the existing approach is OK. These are just some ideas. I won't be offended if rejected.
I believe I addressed all comments. You'll probably want to review the complete diff again.
Benjamin writes in his review: Michael replied with this suggested text: This seems reasonable, as I mentioned in the reply. We should go with it, unless anyone has an objection. Also, attribute it to Michael Richardson.
S. Moonesamy writes
One approach I suggested in my reply to the feedback:
This is good. Thanks for sorting through this; it's important that this is right, and you have cleared it up a lot.Much clearer. Thanks!

This document describes an architecture for implementing captive portals while addressing most of the problems arising for current captive portal mechanisms.  The architecture is guided by these <del> principles: </del> <ins> requirements: </ins> A side-benefit of the architecture described in this document is that devices without user interfaces are able to identify parameters of


Question:
Attempting to fix issue . I attempted to reword the principles, adding more prose for the rationale. Also upgraded some SHOULD NOT to MUST NOT because it seems some people thought the SHOULD NOT says the existing approach is OK. These are just some ideas. I won't be offended if rejected.
I believe I addressed all comments. You'll probably want to review the complete diff again.
Benjamin writes in his review: Michael replied with this suggested text: This seems reasonable, as I mentioned in the reply. We should go with it, unless anyone has an objection. Also, attribute it to Michael Richardson.
S. Moonesamy writes
One approach I suggested in my reply to the feedback:
This is good. Thanks for sorting through this; it's important that this is right, and you have cleared it up a lot.Much clearer. Thanks!

The authors thank Benjamin Kaduk for providing the content related to TLS certificate validation of the API server. <ins> The authors thank Michael Richardson for providing wording requiring DNSSEC and TLS to operate without the user adding exceptions. </ins> The authors thank various individuals for their feedback on the mailing list and during the IETF98 hackathon: David Bird, Erik Kline, Alexis La Goulette, Alex Roscoe, Darshak Thakore, and Vincent van


Question:
One of the reviewers asked for more information about the attacker in section 7.3. This does so, describing what the attacker could achieve by compromising the security.
Benjamin writes, Without knowing the details of the particular solution, it's a bit hard to say for sure, but roughly I'd say it's someone who wants to interact with the API using the identity of the user. E.g. if we're using an 'unguessable' URI, an attacker snooping on the communication with the API could determine the URI, and use it.

The API MUST ensure the integrity of this information, as well as its confidentiality. <ins> An attacker with access to this information might be able to masquerade as a specific User Equipment when interacting with the API, which could then allow them to masquerade as that User Equipment when interacting with the User Portal.  This could give them the ability to determine whether the User Equipment has accessed the portal, or deny the User Equipment service by ending their session using mechanisms provided by the User Portal, or consume that User Equipment's quota.  An attacker with the ability to modify the information could deny service to the User Equipment, or cause them to appear as a different User Equipment. </ins> 7.4. If a Signaling Protocol is implemented, it may be possible for any


Question:
The working group has decided that we do not need to tackle specifying the signaling protocol. Rather than leaving the document with it partially specified, remove most of the text related to it. Keep some basic examples of constraints. This also removes the text which claimed that the document would specify rqeuirements for the protocol. It does not. Made a few related editorial changes.
As suggested by NAME : Do a pass through the document with this text in mind and make sure it makes sense. Clean up anything that may have depended on removed text.
Thanks for putting this together. This seems sufficient, and brief.

2.5. <del> User Equipment may send traffic to hosts blocked by the captive network prior to the Enforcement device granting it access.  The Enforcement Device rightly blocks or resets these requests.  However, in the absence of a signal from the Enforcement Device or interaction with the API server, the User Equipment can only guess at whether it is captive.  Consequently, allowing the Enforcement Device to explicitly signal to the User Equipment that the traffic is being blocked may improve the user's experience. An Enforcement Device may also want to notify the User Equipment of a pending expiry of its access to the external network, so providing the Enforcement Device the ability to preemptively signal may be desirable. A specific Captive Portal Signaling Protocol is out of scope for this document.  However, in order to ensure that future protocols fit into the architecture, requirements for a Captive Portal Signaling Protocol follow: The Captive Portal Signaling Protocol does not provide any means of indicating that the network prevents access to some destinations. The intent is to rely on the Captive Portal API and the web portal to which it points to communicate local network policies. The Captive Portal Enforcement function MAY send Captive Portal Signals when User Equipment that has not satisfied the Captive Portal Conditions attempts to send traffic to the network.  These signals MUST be rate-limited to a configurable rate. The signals MUST NOT be sent to the destinations/peers that the User Equipment is restricted from accessing.  The indications are only to be sent to the User Equipment. </del> <ins> When User Equipment first connects to a network, or when there are changes in status, the Enforcement Device could generate a signal toward the User Equipment.  This signal indicates that the User Equipment might need to contact the API Server to receive updated information.  For instance, this signal might be generated when the end of a session is imminent, or when network access was denied. An Enforcement Device MUST rate-limit any signal generated in response to these conditions.  See section_signal_risks for a discussion of risks related to a Captive Portal Signal. </ins> 2.6.


Question:
The working group has decided that we do not need to tackle specifying the signaling protocol. Rather than leaving the document with it partially specified, remove most of the text related to it. Keep some basic examples of constraints. This also removes the text which claimed that the document would specify rqeuirements for the protocol. It does not. Made a few related editorial changes.
As suggested by NAME : Do a pass through the document with this text in mind and make sure it makes sense. Clean up anything that may have depended on removed text.
Thanks for putting this together. This seems sufficient, and brief.

7.5. <del> The Signal could inform the User Equipment that it is being held captive.  There is no requirement that the User Equipment do something about this.  Devices MAY permit users to disable automatic reaction to captive-portal indications for privacy reasons.  However, there would be the trade-off that the user doesn't get notified when network access is restricted.  Hence, end-user devices MAY allow users to manually control captive portal interactions, possibly on the granularity of Provisioning Domains. </del> <ins> The Captive Portal Signal could inform the User Equipment that it is being held captive.  There is no requirement that the User Equipment do something about this.  Devices MAY permit users to disable automatic reaction to Captive Portal Signals indications for privacy reasons.  However, there would be the trade-off that the user doesn't get notified when network access is restricted.  Hence, end-user devices MAY allow users to manually control captive portal interactions, possibly on the granularity of Provisioning Domains. </ins>


Question:
We want to make TLS a requirement, not a suggestion, so I've chagned the wording around TLS to reflect this. I also added a section to the security section discussing the motivation behind the requirement.
Can you forward to the list please?

information, expiry time, method of providing credentials, security token for validating ICMP messages. <del> This document does not specify the details of the API. </del> <ins> The API MUST use TLS for privacy and server authentication.  The implementation of the API MUST ensure both privacy and integrity of any information provided by or required by it. </ins> <del> The CAPPORT API MUST support TLS for privacy and server authentication. </del> <ins> This document does not specify the details of the API. </ins> 2.4.


Question:
We want to make TLS a requirement, not a suggestion, so I've chagned the wording around TLS to reflect this. I also added a section to the security section discussing the motivation behind the requirement.
Can you forward to the list please?

5.2. The solution described here assumes that when the User Equipment <del> needs to trust the API server, server authentication will be utilized using TLS mechanisms. </del> <ins> needs to trust the API server, server authentication will be performed using TLS mechanisms. </ins> 5.3. <ins> The solution described here requires that the API be secured using TLS.  This is required to allow the user equipment and API server to exchange secrets which can be used to validate future interactions. The API must ensure the integrity of this information, as well as its confidentiality. 5.4. </ins> It is possible for any user on the Internet to send ICMP packets in an attempt to cause the receiving equipment to go to the captive portal.  This has been considered and addressed in the following


Question:
We want to make TLS a requirement, not a suggestion, so I've chagned the wording around TLS to reflect this. I also added a section to the security section discussing the motivation behind the requirement.
Can you forward to the list please?

Even when redirected, the User Equipment securely authenticates with API servers. <del> 5.4. </del> <ins> 5.5. </ins> The ICMP messaging informs the User Equipment that it is being held captive.  There is no requirement that the User Equipment do


Question: We need to discuss what information will be used to identify the UE from the perspective of the various components in the system. This updates the draft to discuss this concept, including desired properties of the identifier and some examples. This aims to address issue 5 (URL)

3. <ins> Multiple components in the architecture interact with both the User Equipment and each other.  Since the User Equipment is the focus of these interactions, the components must be able to both identify the user equipment from their interactions with it, and be able to agree on the identify of the user equipment when interacting with each other. The methods by which the components interact restrict the type of information that may be used as an identifying charactertics.  This section discusses the identifying charactersitics. 3.1. An Identifier is a chatacteristic of the User Equipment used by the components of a Captive Portal to uniquely determine which specific User Equipment is interacting with them.  An Identifier MAY be a field contained in packets sent by the User Equipment to the External Network.  Or, an Identifier MAY be an ephemeral property not contained in packets destined for the External Network, but instead correlated with such information through knowledge available to the different components. 3.2. The set of possible identifiers is quite large.  However, in order to be considered a good identifer, an identifier SHOULD meet the following criteria.  Note that the optimal identifier will likely change depending on the positino of the components in the network as well as the information available to them.  An identifier SHOULD: Uniquely Identify the User Equipment Be Hard to Spoof Be Visible to the API Be Visible to the Enforcement Device 3.2.1. In order to uniquely identify the User Equipment, at most one user equipment interacting with the other components of the Captive Portal MUST have a given value of the identifier. Over time, the user equipment identified by the value MAY change. Allowing the identified device to change over time ensures that the space of possible identifying vallues need not be overly large. Independent Captive Portals MAY use the same identifying value to identify different User Equipment.  Allowing indendent captive portals to reuse identifying values allows the identifier to be a property of the local network, expanding the space of possible identifiers. 3.2.2. A good identifier does not lend itself to being easily spoofed.  At no time should it be simple or straightforward for one User Equipment to pretend to be another User Equipment, regardless of whether both are active at the same time.  This property is particularly important when the user equipment is extended externally to devices such as billing systems, or where the identity of the User Equipment could imply liability. 3.2.3. Since the API will need to perform operations which rely on the identify of the user equipment, such as query whether it is captive, the API needs to be able to relate requests to the User Equipment making the request. 3.2.4. The Enforcement Device will decide on a per packet basis whether it should be permitted to communicate with the external network.  Since this decision depends on which User Equipment sent the packet, the Enforcement Device requires that it be able to map the packet to its concept of the User Equipment. 3.3. To evaluate whether an identifer is appropriate, one should consider every recommended property from the perspective of interactions among the components in the architecture.  When comparing identifiers, choose the one which best satifies all of the recommended properties. The architecture does not provide an exact measure of how well an identifier satisfies a given property; care should be taken in performing the evaluation. 3.4. This section provides some examples of identifiers, along with some evaluation of whether they are good identifiers.  The list of identifiers is not exhaustive.  Other identifiers may be used.  An important point to note is that whether the identifiers are good depends heavily on the capabilities of the components and where in the network the components exist. 3.4.1. The physical interface by which the User Equipment is attached to the network can be used to identify the User Equipment.  This identifier has the property of being extremely difficult to spoof: the User Equipment is unaware of the property; one User Equipment cannot manipulate its interactions to appear as though it is another. Further, if only a single User Equipment is attatched to a given physical interface, then the identifier will be unique.  If multiple User Equipment is attached to the network on the same physical interface, then this property is not appropriate. Another consideration related to uniqueness of the User Equipment is that if the attached User Equipment changes, both the API server and the Enforcement Device must invalidate their state related to the User Equipment. The Enforcement Device needs to be aware of the physical interface, which constrains the environment: it must either be part of the device providing physical access (e.g., implemented in firmware), or packets traversing the network must be extended to include information about the source physical interface (e.g.  a tunnel). The API server faces a similar problem, implying that it should co- exist with the Enforcement Device, or that the enforcement device should extend requests to it with the identifying information. 3.4.2. A natural identifier to consider is the IP address of the User Equipment.  At any given time, no device on the network can have the same IP address without causing the network to malfunction, so it is appropriate from the perspective of uniqueness. However, it may be possible to spoof the IP address, particularly for malicious reasons where proper functioning of the network is not necessary for the malicious actor.  Consequently, any solution using the IP address should proactively try to prevent spoofing of the IP address.  Similarily, if the mapping of IP address to User Equipment is changed, the components of the architecture must remove or update their mapping to prevent spoofing.  Demonstrations of return routeability, such as that required for TCP connection establishment, might be sufficient defense against spoofing, though this might not be sufficient in networks that use broadcast media (such as some wireless networks). Since the IP address may traverse multiple segments of the network, more flexibility is afforded to the Enforcement Device and the API server: they simply must exist on a segment of the network where the IP address is still unique.  However, consider that a NAT may be deployed between the User Equipment and the Enforcement Device.  In such cases, it is possible for the components to still uniquely identify the device if they are aware of the port mapping. In some situtations, the User Equipment may have multiple IP addresses, while still satisfying all of the recommended properties. This raises some challenges to the components of the network.  For example, if the user equipment tries to access the network with multiple IP addresses, should the enforcement device and API server treat each IP address as a unique User Equipment, or should it tie the multiple addresses together into one view of the subscriber?  An implementation MAY do either.  Attention should be paid to IPv6 and the fact that it is expected for a device to have multiple IPv6 addresses on a single link.  In such cases, idenfication could be performed by subnet, such as the /64 to which the IP belongs. 4. </ins> This section aims to improve understanding by describing a possible workflow of solutions adhering to the architecture. <del> 3.1. </del> <ins> 4.1. </ins> This section describes a possible work-flow when User Equipment initially joins a Captive Network.


Question: We need to discuss what information will be used to identify the UE from the perspective of the various components in the system. This updates the draft to discuss this concept, including desired properties of the identifier and some examples. This aims to address issue 5 (URL)

The User Equipment accesses the network until conditions Expire. <del> 3.2. </del> <ins> 4.2. </ins> This section describes a possible work-flow when conditions expire and the user visits the portal again (e.g., low quota, or time


Question: We need to discuss what information will be used to identify the UE from the perspective of the various components in the system. This updates the draft to discuss this concept, including desired properties of the identifier and some examples. This aims to address issue 5 (URL)

The User Equipment accesses the external network. <del> 4. </del> <ins> 5. </ins> This memo includes no request to IANA. <del> 5. </del> <ins> 6. </ins> <del> 5.1. </del> <ins> 6.1. </ins> When joining a network, some trust is placed in the network operator. This is usually considered to be a decision by a user on the basis of


Question: We need to discuss what information will be used to identify the UE from the perspective of the various components in the system. This updates the draft to discuss this concept, including desired properties of the identifier and some examples. This aims to address issue 5 (URL)

provide credentials to an attacker.  Browsers can authenticate servers but cannot detect cleverly misspelled domains, for example. <del> 5.2. </del> <ins> 6.2. </ins> The solution described here assumes that when the User Equipment needs to trust the API server, server authentication will be performed using TLS mechanisms. <del> 5.3. </del> <ins> 6.3. </ins> The solution described here requires that the API be secured using TLS.  This is required to allow the user equipment and API server to


Question: We need to discuss what information will be used to identify the UE from the perspective of the various components in the system. This updates the draft to discuss this concept, including desired properties of the identifier and some examples. This aims to address issue 5 (URL)

The API must ensure the integrity of this information, as well as its confidentiality. <del> 5.4. </del> <ins> 6.4. </ins> It is possible for any user on the Internet to send ICMP packets in an attempt to cause the receiving equipment to go to the captive


Question: We need to discuss what information will be used to identify the UE from the perspective of the various components in the system. This updates the draft to discuss this concept, including desired properties of the identifier and some examples. This aims to address issue 5 (URL)

Even when redirected, the User Equipment securely authenticates with API servers. <del> 5.5. </del> <ins> 6.5. </ins> The ICMP messaging informs the User Equipment that it is being held captive.  There is no requirement that the User Equipment do


Question:
URL CoAP over WebSockets The following now seems unrelated: Another possible configuration is to set up a CoAP forward proxy at the WebSocket endpoint. Depending on what transports are available Figure 12: CoAP Client (UDP client) accesses sleepy CoAP Server (WebSocket client) via a CoAP proxy (UDP server/WebSocket server) s/sleepy// (There is no mention of sleepiness here.) CoAP over WebSockets is intentionally very similar to CoAP over UDP. Therefore, instead of presenting CoAP over WebSockets as a new protocol, this document specifies it as a series of deltas from [RFC7252]. Probably best to delete that paragraph -- it is true not only for WS, but also for TCP. So why only here? 3.1. Opening Handshake Hmm, the title is confusing. WS also uses the same opening handshake as 2.3. The parts that relate to both TCP/TLS and WS/S need to be factored out. 3.2. Message Format The message format shown in Figure 14 is the same as the CoAP over TCP message format (see Section 2.4) with one restriction. The Length (Len) field MUST be set to zero because the WebSockets frame already contains the length. s/restriction/change/. The CoAP over TCP message format eliminates the Version field defined in CoAP over UDP. If CoAP version negotiation is required in the future, CoAP over WebSockets can address the requirement by the definition of a new subprotocol identifier that is negotiated during the opening handshake. This paragraph is a bit weird. Maybe: As with CoAP over TCP, the message format for CoAP over Websockets eliminates the Version field defined in CoAP over UDP. If CoAP Empty messages (Code 0.00) MUST be ignored by the recipient (see also Section 4.4). Why are we saying this here and not in Section 2? Factor out. 3.3. Message Transmission Similar as with CoAP over TCP, Retransmission and deduplication of messages is provided by the WebSocket protocol. CoAP over WebSockets therefore does not make a distinction between Confirmable or Non-Confirmable messages, and does not provide Acknowledgement or Reset messages. 3.4. Connection Health There is no way to retransmit a request without creating a new one. Re-registering interest in a resource is permitted, but entirely unnecessary. (See the discussion we already had.) [Brian] - The reference is
Closing the Connection Does this mean, only the client must cancel the requests? Or should the server do this also? Then a clarfication may be useful.
The original - URL - was specific to Observe: ~ All updates to Observe are now captured in a single place - Appendix A. This specific case is in URL At this point, I think that Closing the Connection could simply be deleted because there are no specific changes required.
Let's say a client has sent one or more requests to a server but hasn't received any response yet, and/or is observing a resource at a server. If the client or the server closes the connection or if the connection goes down unexpectedly, then the client will never receive the responses or any further notifications. The client has to reconnect and send new requests. Neither the client nor the server needs to send anything to cancel active requests before closing the connection; when a connection closes, all active requests are canceled automatically. The client should signal that to the code waiting for the responses, e.g., by throwing an exception. The server should abort processing the requests or at least discard the responses once the requests have been processed. The server also should remove the client from the lists of observers (at latest when it tries to send the next notification and it notices that the connection is down).
URL General - It's not clear "how" mandatory the use of the CSM is. Clause 2.3 on TCP/TLS indicates that the CSM message must be sent at the start of the connection. Clause 3.1 on Websockets makes no mention of CSM messages. Clause 4.3 indicates that the CSM MUST be sent at the start of the connection also and makes no distinction between TCP/TLS and Websockets. Clause 2.3 also indicates that the connection must be aborted if the CSM is missing or invalid as the first message on the connection. Given the discussion about address changes does more information need to be provided what start of connection means?
In the , the intent of this statement is unclear: There is no way to retransmit a request without creating a new one. Re-registering interest in a resource is permitted, but entirely unnecessary.
Response from Klaus Hartke: In general, CoAP clients are not allowed to use a token while it is still in use. RFC 7641 defines an exception: a client is allowed to confirm its interest in receiving notifications for a resource by sending a request identical to the original registration request, including the token that is already in use. The above paragraph just says that this is also the case for CoAP over TCP/TLS/WebSockets, but points out that sending a Ping (which checks the health of the connection and hence of all active observations) is better than confirming the interest for all active observations individually. Response from Carsten: Yes, the text is much easier to understand in that context — in the old draft, it was clear that this talks about reregistering interest. So in the new text, we probably need to prefix a sentence like For use with UDP, RFC 7641 discusses ways to re-register interest in a resource to deal with the case that the server providing this resource might have lost the information about this interest. In CoAP over TCP, the framework of the current connection provides fate-sharing between the health of the connection and the health of the expression of interest.
After further review, I think that this note belongs in Appendix A with the other updates/guidance for Observe on reliable transports. Connection Health should limit its discussion to WebSocket specific changes - in this case, the use of the CoAP Ping Signaling message instead of WebSocket Ping/Pong.

2.2. <del> Both the client and the server MUST send a Capabilities and Settings message (CSM see csm) as its first message on the connection.  This message establishes the initial settings and capabilities for the endpoint such as maximum message size or support for block-wise transfers.  The absence of options in the CSM indicates that base values are assumed. To avoid unnecessary latency, a client MAY send additional messages without waiting to receive the server CSM; however, it is important to note that the server CSM might advertise capabilities that impact how a client is expected to communicate with the server.  For example, the server CSM could advertise a Max-Message-Size option (see max-message-size) that is smaller than the base value (1152). Clients and servers MUST treat a missing or invalid CSM as a connection error and abort the connection (see sec-abort). 2.3. </del> The CoAP message format defined in RFC7252, as shown in CoAP-Header, relies on the datagram transport (UDP, or DTLS over UDP) for keeping the individual messages separate and for providing length


Question:
URL CoAP over WebSockets The following now seems unrelated: Another possible configuration is to set up a CoAP forward proxy at the WebSocket endpoint. Depending on what transports are available Figure 12: CoAP Client (UDP client) accesses sleepy CoAP Server (WebSocket client) via a CoAP proxy (UDP server/WebSocket server) s/sleepy// (There is no mention of sleepiness here.) CoAP over WebSockets is intentionally very similar to CoAP over UDP. Therefore, instead of presenting CoAP over WebSockets as a new protocol, this document specifies it as a series of deltas from [RFC7252]. Probably best to delete that paragraph -- it is true not only for WS, but also for TCP. So why only here? 3.1. Opening Handshake Hmm, the title is confusing. WS also uses the same opening handshake as 2.3. The parts that relate to both TCP/TLS and WS/S need to be factored out. 3.2. Message Format The message format shown in Figure 14 is the same as the CoAP over TCP message format (see Section 2.4) with one restriction. The Length (Len) field MUST be set to zero because the WebSockets frame already contains the length. s/restriction/change/. The CoAP over TCP message format eliminates the Version field defined in CoAP over UDP. If CoAP version negotiation is required in the future, CoAP over WebSockets can address the requirement by the definition of a new subprotocol identifier that is negotiated during the opening handshake. This paragraph is a bit weird. Maybe: As with CoAP over TCP, the message format for CoAP over Websockets eliminates the Version field defined in CoAP over UDP. If CoAP Empty messages (Code 0.00) MUST be ignored by the recipient (see also Section 4.4). Why are we saying this here and not in Section 2? Factor out. 3.3. Message Transmission Similar as with CoAP over TCP, Retransmission and deduplication of messages is provided by the WebSocket protocol. CoAP over WebSockets therefore does not make a distinction between Confirmable or Non-Confirmable messages, and does not provide Acknowledgement or Reset messages. 3.4. Connection Health There is no way to retransmit a request without creating a new one. Re-registering interest in a resource is permitted, but entirely unnecessary. (See the discussion we already had.) [Brian] - The reference is
Closing the Connection Does this mean, only the client must cancel the requests? Or should the server do this also? Then a clarfication may be useful.
The original - URL - was specific to Observe: ~ All updates to Observe are now captured in a single place - Appendix A. This specific case is in URL At this point, I think that Closing the Connection could simply be deleted because there are no specific changes required.
Let's say a client has sent one or more requests to a server but hasn't received any response yet, and/or is observing a resource at a server. If the client or the server closes the connection or if the connection goes down unexpectedly, then the client will never receive the responses or any further notifications. The client has to reconnect and send new requests. Neither the client nor the server needs to send anything to cancel active requests before closing the connection; when a connection closes, all active requests are canceled automatically. The client should signal that to the code waiting for the responses, e.g., by throwing an exception. The server should abort processing the requests or at least discard the responses once the requests have been processed. The server also should remove the client from the lists of observers (at latest when it tries to send the next notification and it notices that the connection is down).
URL General - It's not clear "how" mandatory the use of the CSM is. Clause 2.3 on TCP/TLS indicates that the CSM message must be sent at the start of the connection. Clause 3.1 on Websockets makes no mention of CSM messages. Clause 4.3 indicates that the CSM MUST be sent at the start of the connection also and makes no distinction between TCP/TLS and Websockets. Clause 2.3 also indicates that the connection must be aborted if the CSM is missing or invalid as the first message on the connection. Given the discussion about address changes does more information need to be provided what start of connection means?
In the , the intent of this statement is unclear: There is no way to retransmit a request without creating a new one. Re-registering interest in a resource is permitted, but entirely unnecessary.
Response from Klaus Hartke: In general, CoAP clients are not allowed to use a token while it is still in use. RFC 7641 defines an exception: a client is allowed to confirm its interest in receiving notifications for a resource by sending a request identical to the original registration request, including the token that is already in use. The above paragraph just says that this is also the case for CoAP over TCP/TLS/WebSockets, but points out that sending a Ping (which checks the health of the connection and hence of all active observations) is better than confirming the interest for all active observations individually. Response from Carsten: Yes, the text is much easier to understand in that context — in the old draft, it was clear that this talks about reregistering interest. So in the new text, we probably need to prefix a sentence like For use with UDP, RFC 7641 discusses ways to re-register interest in a resource to deal with the case that the server providing this resource might have lost the information about this interest. In CoAP over TCP, the framework of the current connection provides fate-sharing between the health of the connection and the health of the expression of interest.
After further review, I think that this note belongs in Appendix A with the other updates/guidance for Observe on reliable transports. Connection Health should limit its discussion to WebSocket specific changes - in this case, the use of the CoAP Ping Signaling message instead of WebSocket Ping/Pong.

The semantics of the other CoAP header fields are left unchanged. <del> 2.4. </del> <ins> 2.3. Once a connection is established, both the client and the server MUST send a Capabilities and Settings message (CSM see csm) as its first message on the connection.  This message establishes the initial settings and capabilities for the endpoint such as maximum message size or support for block-wise transfers.  The absence of options in the CSM indicates that base values are assumed. To avoid unnecessary latency, a client MAY send additional messages without waiting to receive the server CSM; however, it is important to note that the server CSM might advertise capabilities that impact how a client is expected to communicate with the server.  For example, the server CSM could advertise a Max-Message-Size option (see max-message-size) that is smaller than the base value (1152). Clients and servers MUST treat a missing or invalid CSM as a connection error and abort the connection (see sec-abort). </ins> CoAP requests and responses are exchanged asynchronously over the TCP/TLS connection.  A CoAP client can send multiple requests without


Question:
URL CoAP over WebSockets The following now seems unrelated: Another possible configuration is to set up a CoAP forward proxy at the WebSocket endpoint. Depending on what transports are available Figure 12: CoAP Client (UDP client) accesses sleepy CoAP Server (WebSocket client) via a CoAP proxy (UDP server/WebSocket server) s/sleepy// (There is no mention of sleepiness here.) CoAP over WebSockets is intentionally very similar to CoAP over UDP. Therefore, instead of presenting CoAP over WebSockets as a new protocol, this document specifies it as a series of deltas from [RFC7252]. Probably best to delete that paragraph -- it is true not only for WS, but also for TCP. So why only here? 3.1. Opening Handshake Hmm, the title is confusing. WS also uses the same opening handshake as 2.3. The parts that relate to both TCP/TLS and WS/S need to be factored out. 3.2. Message Format The message format shown in Figure 14 is the same as the CoAP over TCP message format (see Section 2.4) with one restriction. The Length (Len) field MUST be set to zero because the WebSockets frame already contains the length. s/restriction/change/. The CoAP over TCP message format eliminates the Version field defined in CoAP over UDP. If CoAP version negotiation is required in the future, CoAP over WebSockets can address the requirement by the definition of a new subprotocol identifier that is negotiated during the opening handshake. This paragraph is a bit weird. Maybe: As with CoAP over TCP, the message format for CoAP over Websockets eliminates the Version field defined in CoAP over UDP. If CoAP Empty messages (Code 0.00) MUST be ignored by the recipient (see also Section 4.4). Why are we saying this here and not in Section 2? Factor out. 3.3. Message Transmission Similar as with CoAP over TCP, Retransmission and deduplication of messages is provided by the WebSocket protocol. CoAP over WebSockets therefore does not make a distinction between Confirmable or Non-Confirmable messages, and does not provide Acknowledgement or Reset messages. 3.4. Connection Health There is no way to retransmit a request without creating a new one. Re-registering interest in a resource is permitted, but entirely unnecessary. (See the discussion we already had.) [Brian] - The reference is
Closing the Connection Does this mean, only the client must cancel the requests? Or should the server do this also? Then a clarfication may be useful.
The original - URL - was specific to Observe: ~ All updates to Observe are now captured in a single place - Appendix A. This specific case is in URL At this point, I think that Closing the Connection could simply be deleted because there are no specific changes required.
Let's say a client has sent one or more requests to a server but hasn't received any response yet, and/or is observing a resource at a server. If the client or the server closes the connection or if the connection goes down unexpectedly, then the client will never receive the responses or any further notifications. The client has to reconnect and send new requests. Neither the client nor the server needs to send anything to cancel active requests before closing the connection; when a connection closes, all active requests are canceled automatically. The client should signal that to the code waiting for the responses, e.g., by throwing an exception. The server should abort processing the requests or at least discard the responses once the requests have been processed. The server also should remove the client from the lists of observers (at latest when it tries to send the next notification and it notices that the connection is down).
URL General - It's not clear "how" mandatory the use of the CSM is. Clause 2.3 on TCP/TLS indicates that the CSM message must be sent at the start of the connection. Clause 3.1 on Websockets makes no mention of CSM messages. Clause 4.3 indicates that the CSM MUST be sent at the start of the connection also and makes no distinction between TCP/TLS and Websockets. Clause 2.3 also indicates that the connection must be aborted if the CSM is missing or invalid as the first message on the connection. Given the discussion about address changes does more information need to be provided what start of connection means?
In the , the intent of this statement is unclear: There is no way to retransmit a request without creating a new one. Re-registering interest in a resource is permitted, but entirely unnecessary.
Response from Klaus Hartke: In general, CoAP clients are not allowed to use a token while it is still in use. RFC 7641 defines an exception: a client is allowed to confirm its interest in receiving notifications for a resource by sending a request identical to the original registration request, including the token that is already in use. The above paragraph just says that this is also the case for CoAP over TCP/TLS/WebSockets, but points out that sending a Ping (which checks the health of the connection and hence of all active observations) is better than confirming the interest for all active observations individually. Response from Carsten: Yes, the text is much easier to understand in that context — in the old draft, it was clear that this talks about reregistering interest. So in the new text, we probably need to prefix a sentence like For use with UDP, RFC 7641 discusses ways to re-register interest in a resource to deal with the case that the server providing this resource might have lost the information about this interest. In CoAP over TCP, the framework of the current connection provides fate-sharing between the health of the connection and the health of the expression of interest.
After further review, I think that this note belongs in Appendix A with the other updates/guidance for Observe on reliable transports. Connection Health should limit its discussion to WebSocket specific changes - in this case, the use of the CoAP Ping Signaling message instead of WebSocket Ping/Pong.

Retransmission and deduplication of messages is provided by the TCP/ TLS protocol. <ins> 2.4. Empty messages (Code 0.00) can always be sent and MUST be ignored by the recipient.  This provides a basic keep-alive function that can refresh NAT bindings. If a client does not receive any response for some time after sending a CoAP request (or, similarly, when a client observes a resource and it does not receive any notification for some time), it can send a CoAP Ping Signaling message (sec-ping) to test the connection and verify that the server is responsive. </ins> 3. <ins> CoAP over WebSockets is intentionally similar to CoAP over TCP; therefore, this section only specifies the differences between the transports. </ins> CoAP over WebSockets can be used in a number of configurations.  The most basic configuration is a CoAP client retrieving or updating a <del> CoAP resource located at a CoAP server that exposes a WebSocket </del> <ins> CoAP resource located on a CoAP server that exposes a WebSocket </ins> endpoint (arch-1).  The CoAP client acts as the WebSocket client, establishes a WebSocket connection, and sends a CoAP request, to which the CoAP server returns a CoAP response.  The WebSocket