Subject: [AVTCORE] [Technical Errata Reported] RFC5764 (3913)

From: RFC Errata System <[email-masked]>
Date: Thu, 6 Mar 2014 01:53:36 -0800 (PST)

The following errata report has been submitted for RFC5764,
"Datagram Transport Layer Security (DTLS) Extension to Establish Keys for the Secure Real-time Transport Protocol (SRTP)".

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You may review the report below and at:
http://www.rfc-editor.org/errata_search.php?rfc=5764&eid=3913

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Type: Technical
Reported by: Martin Thomson <[email-masked]>

Section: 5.1.2

Original Text
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Arriving packets may be of types RTP, DTLS, or STUN [RFC5389].
...
                   |       B < 2   -+--> forward to STUN
...
If the value of this byte is 0 or 1, then the packet is STUN.

Corrected Text
--------------
Arriving packets may be of types RTP, DTLS, or STUN [RFC5389].  
STUN messages with methods identifiers of 1280 or higher cannot 
be demultiplexed.
...
                   |       B < 20  -+--> forward to STUN
...
If the value of this byte is less than 20, then the packet is STUN.

Notes
-----
This is a tricky one.  We can't distinguish all STUN message types, because - at least in theory - new message types >= 1280 can be added to STUN, which could collide with DTLS.

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RFC5764 (draft-ietf-avt-dtls-srtp-07)
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Title               : Datagram Transport Layer Security (DTLS) Extension to Establish Keys for the Secure Real-time Transport Protocol (SRTP)
Publication Date    : May 2010
Author(s)           : D. McGrew, E. Rescorla
Category            : PROPOSED STANDARD
Source              : Audio/Video Transport
Area                : Real-time Applications and Infrastructure
Stream              : IETF
Verifying Party     : IESG