Re: [tsvwg] sanity checking DTLS ICMP errors

Yoshifumi Nishida <nishida@sfc.wide.ad.jp> Thu, 22 January 2015 08:35 UTC

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Date: Thu, 22 Jan 2015 00:34:54 -0800
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From: Yoshifumi Nishida <nishida@sfc.wide.ad.jp>
To: Michael Tuexen <Michael.Tuexen@lurchi.franken.de>
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Cc: tsvwg <tsvwg@ietf.org>, Dan Wing <dwing@cisco.com>
Subject: Re: [tsvwg] sanity checking DTLS ICMP errors
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On Mon, Jan 19, 2015 at 2:36 PM, Michael Tuexen <
Michael.Tuexen@lurchi.franken.de> wrote:

> > On 19 Jan 2015, at 20:43, 🔓Dan Wing <dwing@cisco.com> wrote:
> >
> > To reduce the attack surface, TCP implementations have been validating
> ICMP error messages to be in-window (RFC5927).
> >
> > On a thread over on RTCWEB with Michael Tüxen, it seems DTLS-encrypted
> packets might benefit from a similar validation.
> Just to add some information:
> Dan was asking why we couldn't just process incoming ICMP packets
> indicating that a packet
> sent was too big by SCTP when running over DTLS. My point was that we
> can't the validation
> of the verification tag as we do normally for SCTP. That is why we use
> PMTUD as described
> in RFC4821 for
> http://tools.ietf.org/html/draft-ietf-tsvwg-sctp-dtls-encaps-08


Sorry if I miss something..
I'm just curious after reading the following texts.

 Incoming ICMP or ICMPv6 messages can't be processed by the SCTP
   layer, since there is no way to identify the corresponding
   association.


If the socket used for UDP encap is connected and if only one SCTP
association over DTLS is mapped to the socket, is it still impossible for
SCTP layer to know if it receives ICMP errors?

Thanks,
--
Yoshi