The Jargon File (version 4.4.7, 29 Dec 2003):

bogon filter
 /boh'gon fil'tr/, n.

    Any device, software or hardware, that limits or suppresses the flow and/or
    emission of bogons. ?Engineering hacked a bogon filter between the Cray and
    the VAXen, and now we're getting fewer dropped packets.? See also bogosity
    , bogus.


The Free On-line Dictionary of Computing (30 December 2018):

bogon filter

   /boh'gon fil'tr/ Any device, software or hardware, that limits
   or suppresses the flow and/or emission of bogons.
   "Engineering hacked a bogon filter between the Cray and the
   VAXen, and now we're getting fewer dropped packets."  See
   also bogosity.