Re: [tcpm] WG Last Call for ICMP Attacks

Fernando Gont <fernando@gont.com.ar> Wed, 09 September 2009 20:51 UTC

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Date: Wed, 09 Sep 2009 17:51:33 -0300
From: Fernando Gont <fernando@gont.com.ar>
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To: Joe Touch <touch@ISI.EDU>
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Cc: "Smith, Donald" <Donald.Smith@qwest.com>, Carlos Pignataro <cpignata@cisco.com>, 'tcpm Extensions WG' <tcpm@ietf.org>, 'David Borman' <david.borman@windriver.com>
Subject: Re: [tcpm] WG Last Call for ICMP Attacks
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Joe Touch wrote:

> Routers sometimes get locked up doing various things. Their control
> planes often operate completely independently of the data plane, and
> have priorities that can starve various routines that aren't required to
> be timely. Errors that get hit with that could end up on the wire
> seconds, minutes - *any* time later.
> 
> And they'd be *compliant* with FC1812.

OT, but probably useful for the sake of theoretical discussion: There's
no requirement in the TCP/IP specs that the TTL of packets get
decremented according to the properties of the link on which the packets
will be forwarded. This means that in theory you could forward a packet
on a link that has a delay of 5 minutes (or, say, over quite a few links
that have a delay of one minute, or whatever), and then any assumptions
about "Maximum Segment Lifetime" are invalid (you'd need something like
Delta-t).

And these scenarios would still be compliant with RFC 791, RFC793,
RFC1222, RFC 1812, and others.

Nevertheless, your comment will be addressed in the icmp attacks I-D.

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