Subject: [tcpm] [Technical Errata Reported] RFC5961 (5068)

From: RFC Errata System <[email-masked]>
Date: Wed, 12 Jul 2017 10:03:07 -0700 (PDT)

The following errata report has been submitted for RFC5961,
"Improving TCP's Robustness to Blind In-Window Attacks".

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You may review the report below and at:
http://www.rfc-editor.org/errata/eid5068

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Type: Technical
Reported by: Wesley Eddy <[email-masked]>

Section: 3.2

Original Text
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   [RFC0793] currently requires handling of a segment with the RST bit
   when in a synchronized state to be processed as follows:
...
   Instead, implementations SHOULD implement the following steps in
   place of those specified in [RFC0793] (as listed above).

Corrected Text
--------------
   [RFC0793] currently requires handling of a segment with the RST bit
   when in a synchronized state to be processed as follows:
...
   Instead, when in either a synchronized state or SYN-RECEIVED,
   implementations SHOULD implement the following steps in place of
   those specified in [RFC0793] (as listed above, for the synchronized
   states).  Note that transition from SYN-RECEIVED to either LISTEN or
   CLOSED and user signaling is still subject to whether the connection
   was originated by a passive OPEN (as described in RFC 793).

Notes
-----
The text in section 3.2 begins by stating a change from RFC 793 for RST bit handling "when in a synchronized state" (which means all states except for LISTEN, SYN-SENT, and SYN-RECEIVED).  Later in the section, the same change is described more loosely and text states that it's applicable "In all states except SYN-SENT", and separate behavior is provided for SYN-SENT, but the earlier text leaves uncertainty if the former is supposed to apply to SYN-RECEIVED as well, since the earlier text in the section section begins by discussing only "synchronized" states.

Since the check is totally valid for SYN-RECEIVED, and the behavior in steps 1, 2, and 3 are valid for SYN-RECEIVED, it seems appropriate to make sure this is clarified in the earlier text.

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RFC5961 (draft-ietf-tcpm-tcpsecure-13)
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Title               : Improving TCP's Robustness to Blind In-Window Attacks
Publication Date    : August 2010
Author(s)           : A. Ramaiah, R. Stewart, M. Dalal
Category            : PROPOSED STANDARD
Source              : TCP Maintenance and Minor Extensions
Area                : Transport
Stream              : IETF
Verifying Party     : IESG