Subject: #1047 Path field delimiters - feed behaviour? (fwd)

From: Harald Tveit Alvestrand <[email-masked]>
Date: Wed, 29 Jun 2005 13:56:05 +0200

I haven't seen an answer to this question - would anyone else like to 
answer?

                   Harald

---------- Forwarded Message ----------
Date: fredag, juni 24, 2005 09:04:27 +0200
From: Harald Tveit Alvestrand <[email-masked]>
To: John Stanley <[email-masked]>, [email-masked]
Cc:
Subject: #1047 Path field delimiters - feed behaviour?

Attempting to return to the problem at hand, rather than the discussion on
how to discuss these things - John, can you educate me a little bit about
USENET feeds?

--On 23. juni 2005 17:05 -0700 John Stanley <[email-masked]> wrote:

> It would seem to be unwise to use it in IPV6 addresses as well, since
> ::FFFF:129.144.52.38 and ::FFFF:129.145.23.23 are clearly two different
> addresses but the same failure that would make the dead:beef admin an
> idiot would make both of these people idiots. (I.e., non-conforming
> servers would match the "path-identity" of FFFF for both systems and
> feeds  would be disrupted.)

If, in a message arriving at the old system "here", there is a Path: header
that says

Path: there!::FFFF:129.144.52.38!not-for-mail

and "here" does not know about any system named "FFFF", will any change in
handling happen?

Conversely, if a message arrives with a Path: header that says

Path: there!::FFFF:129.144.52.38!::FFFF:129.145.23.23!not-for-mail

will the two occurences of "FFFF" in the Path: cause anything bad to happen?

Or is there some third circumstance that I haven't guessed at yet that will
cause something bad to happen?

I'd like to understand what you mean when you say "feeds will be
disrupted".....

                   Harald

---------- End Forwarded Message ----------

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From: Henry Spencer <[email-masked]>
Date: Wed, 29 Jun 2005 09:30:38 -0400 (EDT)

On Wed, 29 Jun 2005, Harald Tveit Alvestrand wrote:
> If, in a message arriving at the old system "here", there is...

Nope.  The Path header affects article propagation only to neighbors whose
names are mentioned in it.  If "FFFF" isn't known to be the name of a
neighbor, no effect. 

> will the two occurences of "FFFF" in the Path: cause anything bad to happen?

Not in the implementations I'm familiar with, and probably not in any
implementation.

                                                          Henry Spencer
                                                       [email-masked]

---

From: Bruce Lilly <[email-masked]>
Date: Wed, 29 Jun 2005 11:13:33 -0400

> I haven't seen an answer to this question - would anyone else like to 
[...]
> and "here" does not know about any system named "FFFF", will any change in

Change relative to what?  Does "here" "know" about a system "named"
"129.144.52.38?   The root of the issue is that colon always has been
and remains today a delimiter.

> will the two occurences of "FFFF" in the Path: cause anything bad to happen?

Not that I know of.  Some statistics gathering scripts might interpret
that as a loop of some sort.  No problem for propagation. (assuming of
course that the conditions for the previous question still apply)
 
> cause something bad to happen?

Yes,

Path: there!FEDC:BA98:7654:3210:FEDC:BA98:7654:3210!foo

(example IPv6 address literal from RFC 3513 section 2)  Will cause the article
not to be propagated to any sites "known" to "here" "named" "FEDC", "BA98",
"7654", and/or "3210" (a less repetitive IPv6 example would of course provide
more opportunity for damage).

The RFC 3513 example and description of the problem has been previously
described in http://www.imc.org/ietf-usefor/2004/Jul/0192.html
which was part of a discussion also referenced in recent discussion.

An example of a highly problematic IPv6 literal incorporating observations
made by Frank and Russ would be DEAD:BEEF:FEE:BEE:CAFE:ABBE:ED:BE.

---

From: Seth Breidbart <[email-masked]>
Date: Wed, 29 Jun 2005 11:52:45 -0400 (EDT)

> Not in the implementations I'm familiar with, and probably not in any

Almost certainly not.  One April 1, admins from The Hierarchy That
Shall Not Be Named all decided to add one bogus entry to their Path
entries to force it to first in the propagation statistics.  It
typically showed up several times in every article, with no observable
effects.

Seth

---

From: Frank Ellermann <[email-masked]>
Date: Wed, 29 Jun 2005 19:59:18 +0200

Seth Breidbart wrote:
 
> One April 1, admins from The Hierarchy That Shall Not Be
> Named all decided to add one bogus entry to their Path

Curious, what hierarchy might that be, something starting
with "f" or ending with "2" ?

> It typically showed up several times in every article,
> with no observable effects.

For a _bogus_ path entry I'd expect no effect, but for a
_real_ path entry it could be interesting.  Bye, Frank