Robots Exclusion Protocol
draft-koster-rep-12

[Ballot comment]
Thanks for working on this specification. I have skimmed through the document due to shortage of my time and haven't notices any transport protocol related issues.

[Ballot comment]
Thanks for the draft.

In writing this comment I'm going to state up front that what's in here is normally pretty far from my field of expertise - so please excuse any confusion or inaccuracies - happy to be corrected.

In section 2.1:

Crawlers MUST find the group that matches the product token exactly,
  and then obey the rules of the group.

To me this seems to conflict with:

The matching of the product token MUST be case-insensitive.

I was also a little confused here - since I noticed in 2.2 it states:

product-token = identifier / "*"

This would seem to imply a wildcard - if I'm reading this correctly, which also seems to not correlate with an exact match.

[Ballot comment]
# GEN AD review of draft-koster-rep-09

CC @larseggert

## Nits

All comments below are about very minor potential issues that you may choose to
address in some way - or ignore - as you see fit. Some were flagged by
automated tools (via https://github.com/larseggert/ietf-reviewtool), so there
will likely be some false positives. There is no need to let me know what you
did with these suggestions.

### Outdated references

Reference `[RFC2616]` to `RFC2616`, which was obsoleted by `RFC7235`,
`RFC7234`, `RFC7233`, `RFC7232`, `RFC7231`, and `RFC7230` (this may be on
purpose).

### Grammar/style

#### Section 2.2.1, paragraph 5
```
he URI. The matching SHOULD be case sensitive. The most specific match found
                              ^^^^^^^^^^^^^^
```
This word is normally spelled with a hyphen.

#### Section 2.2.1, paragraph 7
```
and disallow rule is equivalent, the allow SHOULD be used. If no match is f
                                  ^^^^^^^^^
```
After "the", the verb "allow" doesn't fit. Is "allow" spelled correctly? If
"allow" is the first word in a compound adjective, use a hyphen between the two
words. Using the verb "allow" as a noun may be non-standard.

## Notes

This review is in the ["IETF Comments" Markdown format][ICMF], You can use the
[`ietf-comments` tool][ICT] to automatically convert this review into
individual GitHub issues. Review generated by the [`ietf-reviewtool`][IRT].

[ICMF]: https://github.com/mnot/ietf-comments/blob/main/format.md
[ICT]: https://github.com/mnot/ietf-comments
[IRT]: https://github.com/larseggert/ietf-reviewtool

[Ballot comment]
IESG Note: The shepherd writeup claims Informational status, but consensus during the first Last Call was to move it to Proposed Standard, hence the discrepancy.

[Ballot comment]
Thank you for the work on this document.

Many thanks to Todd Herr for his ART ART review: https://mailarchive.ietf.org/arch/msg/art/oaAMYwH7lWH4Xty01nSh1qSu7XU/.

I wonder if the reference to RFC 2616 should not be replaced with RFC 9111, or is there a reason to keep the old obsoleted reference?

Francesca

[Ballot comment]
Thanks for doing this work, it is good to have it formally specified in an RFC.

My only comment:

    This document specifies and extends the "Robots Exclusion Protocol"

It would be nice if it said what the extending part is, as those parts might be less supported in the wild as these are presumably new and not widely supported yet.

[Ballot comment]
# Éric Vyncke, INT AD, review of # Éric Vyncke, INT AD, review of draft-koster-rep-09
CC @evyncke

Thank you for the work put into this document. As a webmaster for some minor websites, this robots.txt is simple but efficient.

Please find below some non-blocking COMMENT points (but replies would be appreciated even if only for my own education).

Special thanks to Ted Hardie for the shepherd's detailed write-up even if I had liked to have the justification of the intended status.

I hope that this helps to improve the document,

Regards,

-éric

## COMMENTS

### Section 1.1

As always, I personally find weird when an informational document uses BCP14 normative language; but the IESG has agreed on this use of BCP14. So, let it be ;-)

### Section 2.3

Suggest to remove the "http" example.

### Section 2.3.1.2

In `The server may respond to a robots.txt fetch request` should this be a `MAY`(to contradict my previous comment on the use of BCP14)

### Section 2.5

I must admit that this is the first time that I read "kibibyte"... Please use normal units or add a reference, e.g., https://simple.wikipedia.org/wiki/Kibibyte (BTW, thank you, I have learned a new word!)

The sentence is rather hard to parse, could it be replaced by "Crawlers MUST be able to parse at least 500 KiB)" ?

## Notes

This review is in the ["IETF Comments" Markdown format][ICMF], You can use the
[`ietf-comments` tool][ICT] to automatically convert this review into
individual GitHub issues.

[ICMF]: https://github.com/mnot/ietf-comments/blob/main/format.md
[ICT]: https://github.com/mnot/ietf-comments

[Ballot comment]
Thank you for this work which formally standardizes long standing Internet practice.

** I recommend an editorial pass to consistently use client, crawlers or robots.

** Is robots.txt practically used beyond the HTTPS, HTTP and FTP schemes?  If not, it might be worth writing an applicability statement around these limited protocols, suggesting but not committing to broader use, and then be much more specific in Section 2.3 about error handling.

** Section 1.
  This document specifies the rules
  originally defined by the "Robots Exclusion Protocol" [ROBOTSTXT]
  that crawlers are expected to obey when accessing URIs.

“… expected to obey when accessing URIs” seems too strong.  Maybe “… are requested to honor.”  There is no enforcement mechanism or even requirement that a crawler even check for robots.txt.

** Section 2.2.2.
Crawlers SHOULD allow the following special characters.

-- The subject of the normative language seems reversed.  Isn’t this really (roughly) “the robots.txt file supports the following additional grammar”?  It is in the ABNF.

-- In a sense, the crawler is free to ignore anything the robots.txt says.  Why is providing flexibility with a SHOULD any different than the rest of the content?

** Section 2.2.4.  I’m not familiar with the operational practices that add additional “protocols” into robots.txt.  How would a ‘sitemap’ file be added to robots.txt?  Sitemaps is an XML blob.  It would make for a non-conforming robot.txt and an invalid XML. 

** Section 2.3.1.3 and 2.3.1.4.  These sections map neatly to HTTP error codes.  This protocol is scoped as being generic.  What is the expected behavior if a protocol doesn’t distinguish between unavailable and unreachable?

** Section 2.3.1.3 and 2.3.1.4.  Could equivalent error semantics be described for FTP.

** Section 2.3.1.4.

  For
  other undefined status codes, the crawler MUST assume the robots.txt
  is unreachable.

Are those other HTTP code, or is this sentence a reference to other protocols?

** Section 2.3.1.4

  If the robots.txt is undefined for a reasonably long period of time
  (for example, 30 days), clients MAY assume the robots.txt is
  Unavailable

What does this persistent “unavailability” suggest about the crawler’s behavior.  Since this is a “MAY”, does it continue to assume “complete disallow” or follow Section 2.3.1.3 behavior of “complete allow”?

** Section 2.3.1.5.

(a)  Crawlers SHOULD try to parse each line of the robots.txt file.

(b)  Crawlers MUST use the parseable rules.

I appreciate that there is context from the Section header, but as written these appear conditional.  Since (a) is a SHOULD, then (b) won’t always be true since I can choose not to parse certain lines.  Is there a reason why (a) can’t be a MUST?

** Section 3.  Recommend acknowledging the obvious that this protocol is for crawlers willing to following directives in the file.  Also, paths, not URIs, are in the file.

OLD
  The Robots Exclusion Protocol is not a substitute for more valid
  content security measures.  Listing URIs in the robots.txt file
  exposes the URI publicly and thus makes the URIs discoverable.

NEW
The Robots Exclusion Protocol provides no access control and is advisory in nature to conforming crawlers. Non-compliant crawlers can avoid accessing the robots.txt file or ignore directives in it.  Listing paths in the robots.txt file exposes them publicly and thus makes the discoverable.

[Ballot comment]
Hi,

Thanks for this document, it looks like a useful update and it was a pretty easy read.  I just have a few comments/clarifications for the authors to consider that may improve this document:

1.
  Crawlers MUST find the group that matches the product token exactly,
  and then obey the rules of the group.

  The matching of the product token MUST be case-insensitive

For me, matching exactly and also being case-insensitive seem to slightly contradict each other.  Would the text be more clear if these were combined into a single sentence?

2.
  The most specific match is the match that has the most octets.

Should the document specify that the match is from the root of the path?  Otherwise it implies that any substring match of the path may be acceptable.

3. For the examples:

Would it be helpful to include a line that has no space between the allow: and the match (e.g., allow:/foobar)?

4.
  Disallow: /*.gif$

Would this also be allowed without the initial '/' character?  Is this worth clarifying/specifying?

Thanks,
Rob

(BEGIN IANA COMMENTS)

IESG/Authors/WG Chairs:

The IANA Functions Operator has reviewed draft-koster-rep-08, which is currently in Last Call, and has the following comments:

We understand that this document doesn't require any registry actions.

While it's often helpful for a document's IANA Considerations section to remain in place upon publication even if there are no actions, if the authors strongly prefer to remove it, we do not object.

If this assessment is not accurate, please respond as soon as possible.

For definitions of IANA review states, please see:

https://datatracker.ietf.org/help/state/draft/iana-review

Thank you,

Michelle Thangtamsatid
IANA Services Specialist

(END IANA COMMENTS)

The following Last Call announcement was sent out (ends 2022-06-02):

From: The IESG
To: IETF-Announce
CC: Ted Hardie , draft-koster-rep@ietf.org, superuser@gmail.com, ted.ietf@gmail.com
Reply-To: last-call@ietf.org
Sender:
Subject: Last Call:  (Robots Exclusion Protocol) to Proposed Standard


The IESG has received a request from an individual submitter to consider the
following document: - 'Robots Exclusion Protocol'
  as Proposed Standard

The IESG plans to make a decision in the next few weeks, and solicits final
comments on this action. Please send substantive comments to the
last-call@ietf.org mailing lists by 2022-06-02. Exceptionally, comments may
be sent to iesg@ietf.org instead. In either case, please retain the beginning
of the Subject line to allow automated sorting.

Abstract


  This document specifies and extends the "Robots Exclusion Protocol"
  method originally defined by Martijn Koster in 1996 for service
  owners to control how content served by their services may be
  accessed, if at all, by automatic clients known as crawlers.




The file can be obtained via
https://datatracker.ietf.org/doc/draft-koster-rep/



No IPR declarations have been submitted directly on this I-D.


The document contains these normative downward references.
See RFC 3967 for additional information:
    rfc1945: Hypertext Transfer Protocol -- HTTP/1.0 (Informational - Internet Engineering Task Force (IETF))

(Via drafts-lastcall-comment@iana.org): IESG/Authors/WG Chairs:

The IANA Functions Operator has reviewed draft-koster-rep-06, which is currently in Last Call, and has the following comments:

We understand that this document doesn't require any registry actions.

While it's often helpful for a document's IANA Considerations section to remain in place upon publication even if there are no actions, if the authors strongly prefer to remove it, we do not object.

If this assessment is not accurate, please respond as soon as possible.

Thank you,

Michelle Thangtamsatid
IANA Services Specialist

The following Last Call announcement was sent out (ends 2022-04-07):

From: The IESG
To: IETF-Announce
CC: Ted Hardie , draft-koster-rep@ietf.org, superuser@gmail.com, ted.ietf@gmail.com
Reply-To: last-call@ietf.org
Sender:
Subject: Last Call:  (Robots Exclusion Protocol) to Informational RFC


The IESG has received a request from an individual submitter to consider the
following document: - 'Robots Exclusion Protocol'
  as Informational RFC

The IESG plans to make a decision in the next few weeks, and solicits final
comments on this action. Please send substantive comments to the
last-call@ietf.org mailing lists by 2022-04-07. Exceptionally, comments may
be sent to iesg@ietf.org instead. In either case, please retain the beginning
of the Subject line to allow automated sorting.

Abstract


  This document specifies and extends the "Robots Exclusion Protocol"
  method originally defined by Martijn Koster in 1996 for service
  owners to control how content served by their services may be
  accessed, if at all, by automatic clients known as crawlers.




The file can be obtained via
https://datatracker.ietf.org/doc/draft-koster-rep/



No IPR declarations have been submitted directly on this I-D.

As required by RFC 4858, this is the current template for the Document
Shepherd Write-Up. Changes are expected over time.

This version is dated 1 November 2019.

(1) What type of RFC is being requested (BCP, Proposed Standard, Internet Standard, Informational, Experimental, or Historic)? Why is this the proper type of RFC? Is this type of RFC indicated in the title page header?

This is informational, and this is correctly noted on the title page.


(2) The IESG approval announcement includes a Document Announcement Write-Up. Please provide such a Document Announcement Write-Up. Recent examples can be found in the "Action" announcements for approved documents. The approval announcement contains the following sections:

Technical Summary:

This document specifies and extends the "Robots Exclusion
  Protocol"  method originally defined by
  Martijn Koster in 1996 for service owners to control how content
  served by their services may be accessed, if at all, by automatic
  clients known as crawlers.


Working Group Summary:

This was not a working group document, though it was discussed by DISPATCH.

Document Quality:

The specified mechanism is very widely implemented and deployed; is the corner of crawler behavior management.

Personnel:

Ted Hardie is the Document Shepherd? Murray Kucherawy is the Responsible Area Director?

(3) Briefly describe the review of this document that was performed by the Document Shepherd. If this version of the document is not ready for publication, please explain why the document is being forwarded to the IESG.

This document was reviewed by the document shepherd and changes in the ABNF and certain descriptions requested; those have been made, and the shepherd now believes this is ready for publication.

(4) Does the document Shepherd have any concerns about the depth or breadth of the reviews that have been performed?

No.

(5) Do portions of the document need review from a particular or from broader perspective, e.g., security, operational complexity, AAA, DNS, DHCP, XML, or internationalization? If so, describe the review that took place.

No specialist reviews were requested.  Note that the security considerations, specifically disclaims the use of robots.txt as a security mechanism.  While this is not generally the approach taken for security considerations, it does highlight the principal concern:  that the specification of crawler behavior might provide privacy properties or guarantees it does not.

(6) Describe any specific concerns or issues that the Document Shepherd has with this document that the Responsible Area Director and/or the IESG should be aware of? For example, perhaps he or she is uncomfortable with certain parts of the document, or has concerns whether there really is a need for it. In any event, if the WG has discussed those issues and has indicated that it still wishes to advance the document, detail those concerns here.

I have no discomfort with this document.

(7) Has each author confirmed that any and all appropriate IPR disclosures required for full conformance with the provisions of BCP 78 and BCP 79 have already been filed. If not, explain why?

Yes, they have.

(8) Has an IPR disclosure been filed that references this document? If so, summarize any WG discussion and conclusion regarding the IPR disclosures.

No.

(9) How solid is the WG consensus behind this document? Does it represent the strong concurrence of a few individuals, with others being silent, or does the WG as a whole understand and agree with it?

This is not relevant, as this is not a WG document.

(10) Has anyone threatened an appeal or otherwise indicated extreme discontent? If so, please summarise the areas of conflict in separate email messages to the Responsible Area Director. (It should be in a separate email because this questionnaire is publicly available.)

No.

(11) Identify any ID nits the Document Shepherd has found in this document. (See http://www.ietf.org/tools/idnits/ and the Internet-Drafts Checklist). Boilerplate checks are not enough; this check needs to be thorough.

ID nits notes that some elements might benefit from and .  The shepherd did not advice this because the relevant parts of the document are ABNF.

(12) Describe how the document meets any required formal review criteria, such as the MIB Doctor, YANG Doctor, media type, and URI type reviews.

These were not required.

(13) Have all references within this document been identified as either normative or informative?

Yes.

(14) Are there normative references to documents that are not ready for advancement or are otherwise in an unclear state? If such normative references exist, what is the plan for their completion?

No.

(15) Are there downward normative references references (see RFC 3967)? If so, list these downward references to support the Area Director in the Last Call procedure.

No.

(16) Will publication of this document change the status of any existing RFCs? Are those RFCs listed on the title page header, listed in the abstract, and discussed in the introduction? If the RFCs are not listed in the Abstract and Introduction, explain why, and point to the part of the document where the relationship of this document to the other RFCs is discussed. If this information is not in the document, explain why the WG considers it unnecessary.

No.

(17) Describe the Document Shepherd's review of the IANA considerations section, especially with regard to its consistency with the body of the document. Confirm that all protocol extensions that the document makes are associated with the appropriate reservations in IANA registries. Confirm that any referenced IANA registries have been clearly identified. Confirm that newly created IANA registries include a detailed specification of the initial contents for the registry, that allocations procedures for future registrations are defined, and a reasonable name for the new registry has been suggested (see RFC 8126).

The document has no actions for IANA.

(18) List any new IANA registries that require Expert Review for future allocations. Provide any public guidance that the IESG would find useful in selecting the IANA Experts for these new registries.

See above.

(19) Describe reviews and automated checks performed by the Document Shepherd to validate sections of the document written in a formal language, such as XML code, BNF rules, MIB definitions, YANG modules, etc.

The ABNF was checked using Bill Fenner's ABNF checker and passed.

(20) If the document contains a YANG module, has the module been checked with any of the recommended validation tools (https://trac.ietf.org/trac/ops/wiki/yang-review-tools) for syntax and formatting validation? If there are any resulting errors or warnings, what is the justification for not fixing them at this time? Does the YANG module comply with the Network Management Datastore Architecture (NMDA) as specified in RFC8342?

There is no YANG module in this document.

As required by RFC 4858, this is the current template for the Document
Shepherd Write-Up. Changes are expected over time.

This version is dated 1 November 2019.

(1) What type of RFC is being requested (BCP, Proposed Standard, Internet Standard, Informational, Experimental, or Historic)? Why is this the proper type of RFC? Is this type of RFC indicated in the title page header?

This is informational, and this is correctly noted on the title page.


(2) The IESG approval announcement includes a Document Announcement Write-Up. Please provide such a Document Announcement Write-Up. Recent examples can be found in the "Action" announcements for approved documents. The approval announcement contains the following sections:

Technical Summary:

This document specifies and extends the "Robots Exclusion
  Protocol"  method originally defined by
  Martijn Koster in 1996 for service owners to control how content
  served by their services may be accessed, if at all, by automatic
  clients known as crawlers.


Working Group Summary:

This was not a working group document, though it was discussed by DISPATCH.

Document Quality:

The specified mechanism is very widely implemented and deployed; is the corner of crawler behavior management.

Personnel:

Ted Hardie is the Document Shepherd? Murray Kucherawy is the Responsible Area Director?

(3) Briefly describe the review of this document that was performed by the Document Shepherd. If this version of the document is not ready for publication, please explain why the document is being forwarded to the IESG.

This document was reviewed by the document shepherd and changes in the ABNF and certain descriptions requested; those have been made, and the shepherd now believes this is ready for publication.

(4) Does the document Shepherd have any concerns about the depth or breadth of the reviews that have been performed?

No.

(5) Do portions of the document need review from a particular or from broader perspective, e.g., security, operational complexity, AAA, DNS, DHCP, XML, or internationalization? If so, describe the review that took place.

No specialist reviews were requested.  Note that the security considerations, specifically disclaims the use of robots.txt as a security mechanism.  While this is not generally the approach taken for security considerations, it does highlight the principal concern:  that the specification of crawler behavior might provide privacy properties or guarantees it does not.

(6) Describe any specific concerns or issues that the Document Shepherd has with this document that the Responsible Area Director and/or the IESG should be aware of? For example, perhaps he or she is uncomfortable with certain parts of the document, or has concerns whether there really is a need for it. In any event, if the WG has discussed those issues and has indicated that it still wishes to advance the document, detail those concerns here.

I have no discomfort with this document.

(7) Has each author confirmed that any and all appropriate IPR disclosures required for full conformance with the provisions of BCP 78 and BCP 79 have already been filed. If not, explain why?

Yes, they have.

(8) Has an IPR disclosure been filed that references this document? If so, summarize any WG discussion and conclusion regarding the IPR disclosures.

No.

(9) How solid is the WG consensus behind this document? Does it represent the strong concurrence of a few individuals, with others being silent, or does the WG as a whole understand and agree with it?

This is not relevant, as this is not a WG document.

(10) Has anyone threatened an appeal or otherwise indicated extreme discontent? If so, please summarise the areas of conflict in separate email messages to the Responsible Area Director. (It should be in a separate email because this questionnaire is publicly available.)

No.

(11) Identify any ID nits the Document Shepherd has found in this document. (See http://www.ietf.org/tools/idnits/ and the Internet-Drafts Checklist). Boilerplate checks are not enough; this check needs to be thorough.

ID nits notes that some elements might benefit from and .  The shepherd did not advice this because the relevant parts of the document are ABNF.

(12) Describe how the document meets any required formal review criteria, such as the MIB Doctor, YANG Doctor, media type, and URI type reviews.

These were not required.

(13) Have all references within this document been identified as either normative or informative?

Yes.

(14) Are there normative references to documents that are not ready for advancement or are otherwise in an unclear state? If such normative references exist, what is the plan for their completion?

No.

(15) Are there downward normative references references (see RFC 3967)? If so, list these downward references to support the Area Director in the Last Call procedure.

No.

(16) Will publication of this document change the status of any existing RFCs? Are those RFCs listed on the title page header, listed in the abstract, and discussed in the introduction? If the RFCs are not listed in the Abstract and Introduction, explain why, and point to the part of the document where the relationship of this document to the other RFCs is discussed. If this information is not in the document, explain why the WG considers it unnecessary.

No.

(17) Describe the Document Shepherd's review of the IANA considerations section, especially with regard to its consistency with the body of the document. Confirm that all protocol extensions that the document makes are associated with the appropriate reservations in IANA registries. Confirm that any referenced IANA registries have been clearly identified. Confirm that newly created IANA registries include a detailed specification of the initial contents for the registry, that allocations procedures for future registrations are defined, and a reasonable name for the new registry has been suggested (see RFC 8126).

The document has no actions for IANA.

(18) List any new IANA registries that require Expert Review for future allocations. Provide any public guidance that the IESG would find useful in selecting the IANA Experts for these new registries.

See above.

(19) Describe reviews and automated checks performed by the Document Shepherd to validate sections of the document written in a formal language, such as XML code, BNF rules, MIB definitions, YANG modules, etc.

The ABNF was checked using Bill Fenner's ABNF checker and passed.

(20) If the document contains a YANG module, has the module been checked with any of the recommended validation tools (https://trac.ietf.org/trac/ops/wiki/yang-review-tools) for syntax and formatting validation? If there are any resulting errors or warnings, what is the justification for not fixing them at this time? Does the YANG module comply with the Network Management Datastore Architecture (NMDA) as specified in RFC8342?

There is no YANG module in this document.