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Microbrew MicroSieve

This product has begun the End of Life(EOL) process. Please see the EOL Notice for more information.

Latest is: 0.7.0 Beta
Latest Stable is: 0.4.0

Please refer to the support page for instructions on installation and further project information.


Microbrew MicroSieve is designed to be a high speed spam filter for USENET news. After using some other filter programs written in Perl, it was clear that there needed to be a faster way to filter spam for today's high-bandwidth news systems (greater than 200GB/day), and thus MicroSieve was born. As with all Microbrew products, this software is released under the GNU General Public License.

Platform Availability

MicroSieve has been tested and is known to work on the following platforms:

  • Solaris 7 (SPARC) running Cyclone News Server.
  • Solaris 7 (SPARC) running Typhoon News Reader.
  • Linux 2.4.x (i386) running Cyclone News Server.


Given the large amount of spam riding around in major USENET news systems, a spam filter has to be very fast and remain effective. MicroSieve has easily achieved 5000 articles per minute while only imposing a 2% - 10% CPU load on a Sun Ultra Enterprise 2 (one 300MHz CPU) while checking for all of the following:

  • Large Articles - Rejects articles above a user definable size.
  • Spambots - Removes any articles sent by popular spambots.
  • Binaries in Non-binary groups - Only allows binaries to be posted to binary groups, keeping non-binary groups free of clutter.
  • Path Header Auto-accept - Allows you to set up auto-accept keyed on the path header so that you don't have to keep filtering articles you already filtered on another server.
  • Path Header Auto-Blackhole - Allows you to set up and auto-reject based on path-header to block out problem sites.
  • Duplicate Article History Checking - Allows filtering of duplicate articles based on a custom data-dependent hashing algorithm.
  • Maximum Cross Post Limit - Sets a limit on the number of newsgroups that an article can be posted to. This is effective since articles that span many newsgroups tend to be junk anyway.
  • User Supplied Filters - Allows the administrators of news systems to supply their own filters without having to delve into the code of MicroSieve.


The MicroSieve project evolved out of Jeremy Nixon's Cleanfeed project and implements a useful subset of its functionality. Although MicroSieve uses many of the same rules that Cleanfeed employs, it shares no actual code with the Cleanfeed project.

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