Re: [tcpm] comments on draft-ietf-tcpm-icmp-attacks-05

Fernando Gont <fernando@gont.com.ar> Thu, 11 June 2009 08:30 UTC

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Date: Thu, 11 Jun 2009 05:30:11 -0300
From: Fernando Gont <fernando@gont.com.ar>
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Cc: "tcpm@ietf.org" <tcpm@ietf.org>, Fernando Gont <fernando.gont@gmail.com>
Subject: Re: [tcpm] comments on draft-ietf-tcpm-icmp-attacks-05
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Hello, Wes,

Comments in-line....

> As both a WG-participant and co-chair, I think that the
> Appendix A explanations of which ICMPs need to be paid
> attention to because some of them say things that I'm
> not sure are totally supported by prior RFCs.  

Any specific issues?


> For
> instance, I'm not certain that setting the DF bit is
> only possible for hosts that support PMTUD ... is there
> a reference for that?  

What's the reason for setting the DF flag for IP packets carrying TCP
segments if you don't implement PMTUD?

Actually, if you don't implement PMTUD, "frag needed" becomes a hard
error. So setting the DF flag would be sort of dumb, as in the event one
of your segments needs to be fragmented, you'd received an ICMP "frag
needed" message, which would reset your connection.



> Further, it discusses ambiguity
> in 1122, that we should be clarifying in the main text
> rather than an appendix, I think ... what does the rest
> of the WG think?

The appendix was at some point part of the main text. I moved the text
into an appendix probably on request of somebody, but not because I
thought the text should be there. So I have no problem moving the
entirre appendix (or part of it) back into the main part of the document.

Thanks!

Kind regards,
-- 
Fernando Gont
e-mail: fernando@gont.com.ar || fgont@acm.org
PGP Fingerprint: 7809 84F5 322E 45C7 F1C9 3945 96EE A9EF D076 FFF1