kirvin
Subject: Cancel Messages: Frequently Asked Questions, Part 3/3 (v1.1)
Supersedes: <4i2722$kek@vixen.cso.uiuc.edu>
Date: 25 Mar 1996 18:18:09 GMT
Summary: This is a list of Frequently Asked Question about cancel messages
. on Usenet.  It mainly discusses how cancels work, who issues 
. them, their history, and what to do about them.  It is more of
. a general purpose FAQ than anything else; it's not required 
. reading anywhere, just more of a reference.

Posting-Frequency: monthly
Last-modified: 1996/03/18
Version: 1.1
URL: http://www.uiuc.edu/ph/www/tskirvin/cancel.html

Cancel Messages 
Frequently Asked Questions
Part 3/3

This document contains information about cancel messages on Usenet, such
as who is allowed to use them, how they operate, what to do if your
message is cancelled, and the like.  It does not contain detailed 
instructions on how to cancel a third party's posts.  It is not intended 
to be a fully technical document; its audience is the average Usenet user, 
up to a mid-level administrator.

This document is not meant to be a comprehensive explanation of Usenet
protocols, or of Usenet itself, but a basic knowledge of these concepts
is assumed.  Please refer to news.announce.newusers, RFC1036, and/or
RFC1036bis if you wish to learn them.

Disclaimers: The information contained within is potentially hazardous;
applying it without the permission of your news administrator may cause
the revocation of your account, civil action against you, and even the
possibility of criminal lawsuits.  The author of this document is in no 
way liable for misuse of the information contained within, nor is he in
any way responsible for damages related to the use or accuracy of the
information.  Proceed at your own risk.


Table of Contents..> = In other parts of the FAQ
=================
>I. What are cancel messages?
>II. How do cancels work?
>III. So your post was cancelled...
>IV. What does it take to cancel messages?
>V. That idiot forge-cancelled my posts!
>VI. What moral issues are involved with cancel messages?
VII. What's going to happen to cancels in the future?
   A. What are authenticated cancels?
   B. Are there any other Usenet methods to delete messages?
   C. Why are some people turning off cancels altogether?
   D. What is NoCeM?
VIII. What about these other things?
   A. What is Lazarus?
   B. What is Dave the Resurrector?
   C. What was the Judges-L mailing list?
   D. What is the UDP?

Changes
To Do
Contributors
Pointers


VII. What's going to happen to cancels in the future?
=====================================================
 A. What are authenticated cancels?

.Usenet was not built with security in mind.  The fact that it's
relatively simple to forge a cancel proves this.  

.As time goes on, though, the need for security is becoming more
and more obvious.  One way of making this security would be to change
the software to only accept authenticated cancels, or cancels that
verify the identity of the original author before deleting the post.

.There have been many methods proposed to accomplish this; at
this point, none are in wide use.  If anyone would like to write some
software to accomplish this, please do so, and discuss it on n.a.n-a.m;
the CancelMoose has a few suggestions for authenticated cancels on his 
web page at http://www.cm.org.


 B. Are there any other Usenet methods to delete messages?

.Of course.  

  1.  How does the Supersedes: header work?

.The Supersedes: header replaces an old message with a new one.
For instance, to replace the message <4b6uce$ou7@vixen.cso.uiuc.edu>, you
would want to add the header:

Supersedes: <4b6uce$ou7@vixen.cso.uiuc.edu>

.The use of Supersedes: is otherwise basically the same as a
cancel message, and they should basically be treated as the same.

  2.  How does the Expires: header work?

.By adding the Expires: header to your post, you can make your
message be deleted from most systems at a certain time.  For instance,
if you want your message to expire at 7:50:06 (PST) on 2/11/96, add the
following header:

Expires: Sun, 11 Feb 1996 19:50:06 PST

.Your message should expire by this date.  It may also expire
early, depending on the storing system's expiry times.

  3.  What is the Also-Control: header?

.The Also-Control: header acts just like a standard Control:
header, except that the post is also filed in whatever groups it was
posted to, as opposed to being filed in control.  Otherwise, the two are
interchangeable.


 C. Why are some people turning off cancels altogether?

.In the mean time, there are few options to avoid forged cancels.
One option, advocated by a very few (but also very vocal) people, is to
not accept cancels at all.  If you want to do so, you're welcome to, but
it probably isn't the best option.  


 D. What is NoCeM?

.NoCeM, pronounced "No See-Umm", is a piece of software written
by the CancelMoose (moose@cm.org) to possibly replace cancels.  Instead of
actually deleting the post, this software automatically marks as "read"
any articles that somebody else thought were inappropriate.  It is being
hailed as a replacement for cancels, and is slowly picking up support.

.For more information, check http://www.cm.org.



VIII. What about these other things?
====================================
 A. What is Lazarus?

.Lazarus is a program written for use on alt.religion.scientology
by Homer Wilson Smith (homer@light.lightlink.com).  It monitors control 
and posts a message to a.r.s whenever it finds a message relating to the 
group.  The basic effect of this is that all cancels are *very* visible.  

.For more information on why this was necessary, refer to Ron
Newman's "The Church of Scientology vs the Net" page, at http://www.
cybercom.net/~rnewman/scientology/home.html.


 B. What is Dave the Resurrector?

.After a particularly obnoxious run of cancels from ixc.net,
Chris Lewis decided that it was time to write a program to repost stuff
that was cancelled on news.admin.net-abuse.misc.  The Resurrector, named
Dave, was the result.  The practical effect of this is that cancels to 
news.admin.net-abuse.misc are not effective unless Chris says so.  

.The name was suggested by Tim Skirvin (*wave*) for reasons only
he knows; Chris accepted the name in honor of Dave Hayes, of
news.admin.* fame (see the net.legends FAQ for details).


 C. What was the Judges-L mailing list?

.A while back, a guy named David Stodolsky decided that he was
going to be in charge of cancels on Usenet.  He set up a mailing list to
this effect, Judges-L, and expected to start up.

.The rest of the world didn't exactly want him to be Emperor of 
Usenet.

.After a short flamewar, an early FAQ on Cancel Messages was
written as a result of the Judges-L list; while technically accurate, it
had little influence on the creation of this FAQ.  In the mean time, the
Judges-L list was dissolved; David Stodolsky is rarely seen on Usenet
anymore.


 D. What is the UDP?

.UDP stands for the "Usenet Death Penalty",  the final weapon 
against those that attempt to abuse Usenet.  It is never entered into
lightly.

.Originally, the UDP referred to auto-cancellation of all
messages from a certain site as a final solution to too much abuse.  As
Usenet terms tend to change over time, the meaning mutated into meaning
to refer to the aliasing out of a certain site by many major sites, thus
"shunning" them off of Usenet.  

.In recent times, both definitions have been used at the same
time.  The original version, however, is currently more commonly
accepted.


Changes
=======
v1.0  -> v1.01.Updated the style slightly
..Clarified the meanings of EMP and ECP
..Added a section in I, "Where can I find cancel messages?"
..Added some newsreaders' cancel buttons
v1.01 -> v1.1.Updated the addresses to have the HTML version
..Got some information about CNews
..Got approval for posting to news.answers
..Fixed a few errors here and there

To Do
=====
.This is, of course, not entirely finished.  I still have a few
things to do with it, and some things that I need to figure out before I
can write anything more; this what will hopefully be in future versions.

  Fill in the technical sections in general, especially with other 
    software.


Contributors
============
.In creating this FAQ, I discovered one important thing: it's a
*lot* of work.  These are the people that have helped me out in doing
it, with suggestions, moral support, or whatever.

.Thank you all.  I couldn't have done this without you.  Literally.
And, if I missed anyone, don't hesitate to speak up...

Johann Beda...j-beda@uiuc.edu
CancelMoose...moose@cm.org
Ian Collier...imc@comlab.ox.ac.uk
Peter Da Silva...peter@bonkers.taronga.com
Richard Depew...red@redpoll.mrfs.oh.us
Frans P. de Vries..fpv@xymph.iaf.nl
Ernie Diaz...trebor@slip.net
Arnould Engelfriet..galactus@stack.urc.tue.nl
J.D. Falk...jdfalk@cybernothing.org
Follower of the Clawed Albino.edmcdo01@terra.spd.louisville.edu
The Gentleman...gentlman@alinc.com
Dave Hayes...dave@jetcafe.org
Jim Hill...jthill@netcom.com
Jonathan Kamens...jik@mit.edu
Tom Lewis...thomas.lewis@me.gatech.edu
Chris Lewis ...clewis@ferret.ocunix.on.ca
Charles H. Lindsey..chl@clw.cs.man.ac.uk
Guy Macon...guymacon@deltanet.com
John Milburn...jem@xpat.com
Bernhard Muenzer..mue@gsf.de
Ron Newman...rnewman@cybercom.net
Matthew Paden...mpaden@emory.edu
Joshua Putnam...josh@wolfenet.com
John Rickard...jrr@atml.co.uk
Wolfgang Schelongowski..ws@xivic.ruhr.de
Keith Thompson...kst@thomsoft.com
Jason Untulis...untulis@netcom.com
Matthew P Wiener..weemba@sagi.wistar.upenn.edu
Michael Wise...mjwise@unixg.ubc.ca
Dick Yuknavech...rey@mindspring.com


Pointers
========
.For more information on cancel messages, or for information on
related issues, try checking some of the following pages:

Related FAQs
------------
news.admin.net-abuse FAQ .
  http://www.cybernothing.org/faq/net-abuse-faq.html
Advertising on Usenet FAQ.
  http://www.danger.com/advo.html
The Spam Tracking FAQ (draft).
  http://ddi.digital.net/~gandalf/spamfaq.html

Utilities
---------
GFilter, a filter patch for INN   
  http://www.backplane.com/news/
Adcomplain shell script..
  http://www.rdrop.com/~billmc/adcomplain

RFCs
----
RFC 1036 -- Usenet Guidelines
  http://www.cis.ohio-state.edu/htbin/rfc/rfc1036
RFC 1855 -- Netiquette Guidelines
  http://www.cis.ohio-state.edu/htbin/rfc/rfc1855
RFC 1036bis (temporary).
  http://arh0062.urh.uiuc.edu/rfc1036b

Newsgroups
----------
news.announce.newusers..
news.answers
news.admin.net-abuse.announce
news.admin.net-abuse.misc
news.admin.misc
news.groups

Additional/Other
----------------
The Jargon File...
  http://www.ctrl-c.liu.se/~ingvar/jargon/
net.legends FAQ
  http://arh0062.urh.uiuc.edu/legends.html



--
Copyright 1996, Tim Skirvin.  All rights reserved.  
http://www.uiuc.edu/ph/www/tskirvin/cancel.html
