Re: [tcpm] TCP-AO and ICMP attacks (was Re: comments on draft-ietf-tcpm-icmp-attacks-05)

Fernando Gont <fernando@gont.com.ar> Wed, 17 June 2009 01:00 UTC

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Cc: "tcpm@ietf.org" <tcpm@ietf.org>, Fernando Gont <fernando.gont@gmail.com>
Subject: Re: [tcpm] TCP-AO and ICMP attacks (was Re: comments on draft-ietf-tcpm-icmp-attacks-05)
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Joe,

> I think we both agree that the text on ICMP handling should be moved out
> of the security considerations section and put it its own section.

Agreed.


> You prefer defaults, and are recommending ICMP handling similar to that
> in documents the WG has decided not to recommend for TCP not running AO.

Yes. Note that virtually all real implementations already do this for
connections that do not use TCP-AO. Nobody is going to change this for
non-TCP-AO, or even less abort TCP-AO connections in response to ICMP
error messages.



> I want to leave TCP-AO's handling of ICMPs the same as IPsec's - up to
> the user.

Just making my point clear: I think leaving unspecified what to do with
ICMP errore messages would be a bad decision. It might end up with
implementations honoring these error messages, which would mean that
TCP-AO would be (by default) useless for protecting TCP against
ICMP-based reset attacks.

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