perl-nocem - A NoCeM-on-spool implementation for INN 2.x
NoCeM, which is pronounced No See Em, is a protocol enabling
authenticated third-parties to issue notices which can be used to
cancel unwanted articles (like spam and articles in moderated
newsgroups which were not approved by their moderators). It can also
be used by readers as a third-party killfile. It is intended to
eventually replace the protocol for third-party cancel messages.
perl-nocem processes third-party, PGP-signed article cancellation
notices. It is possible not to honour all NoCeM notices but only those
which are sent by people whom you trust (that is to say if you trust
the PGP key they use to sign their NoCeM notices). Indeed, it is up to
you to decide whether you wish to honour their notices, depending on
the criteria they use.
Processing NoCeM notices is easy to set up:
1. Import the keys of the NoCeM issuers you trust in order to check
the authenticity of their notices. You can do:
gpg --no-default-keyring --primary-keyring=/etc/news/pgp/ncmring.gpg \
--no-options --allow-non-selfsigned-uid --no-permission-warning \
--batch --import <key-file>
where <pathetc> is the value of the pathetc parameter set in
inn.conf and <key-file> the file containing the key(s) to import.
The keyring must be located in <pathetc>/pgp/ncmring.gpg; you only
have to create the directory <pathetc>/pgp before using gpg (it
will automatically generate the ncmring.gpg file). For old PGP-
generated keys, you may have to use --allow-non-selfsigned-uid if
they are not properly self-signed, but anyone creating a key really
should self-sign the key. Current PGP implementations do this
The keys of NoCeM issuers can be found in the web site of The NoCeM
You can even download there a unique file which contains all the
2. Create a nocem.ctl config file in pathetc indicating the NoCeM
issuers and notices you want to follow. This permission file
contains lines like:
This will remove all articles for which the issuer (first part of
the line, before the colon ":") has issued NoCeM notices
corresponding to the criteria specified after the colon.
You will also find information about that on the web site of The
3. Add to the newsfeeds file an entry like this one in order to feed
perl-nocem the NoCeM notices posted to alt.nocem.misc and
with the correct path to perl-nocem, located in <pathbin>. Then,
reload the newsfeeds file ("ctlinnd reload newsfeeds 'NoCeM channel
Note that you should at least carry news.lists.filters on your news
server (or other newsgroups where NoCeM notices are sent) if you
wish to process them.
4. Everything should now work. However, do not hesitate to manually
test perl-nocem with a NoCeM notice, using:
grephistory '<Message-ID>' | perl-nocem
Indeed, perl-nocem expects tokens on its standard input, and
grephistory can easily give it the token of a known article, thanks
to its Message-ID.
When you have verified that everything works, you can eventually turn
off regular spam cancels, if you want, not processing any longer
cancels containing "cyberspam" in the Path: header (see the
refusecybercancels parameter in inn.conf).
The Perl script itself used to process NoCeM notices.
The configuration file which specifies the NoCeM notices to be
The keyring which contains the public keys of trusted NoCeM
The Subject: header is not checked for the @@NCM string and there is no
check for the presence of the References: header.
The Newsgroups: pseudo header is not checked, but this can be done in
The Hierarchies: header is ignored.
Copyright 2000 by Miquel van Smoorenburg <email@example.com>.
Copyright 2001 by Marco d’Itri <firstname.lastname@example.org>.
$Id: perl-nocem.in 8539 2009-06-28 10:01:24Z iulius $
gpgv(1), grephistory(1), inn.conf(5), newsfeeds(5), pgp(1).