I've noticed that a significant percentage of the matches I'm receiving are from RFC-1918 space(private addresses) which I am of course not able to reach.

I've got filtering set up in Gnucleus 1.5.2.0 which I would have thought would block all of this cruft, but apparently not as the matches are happening and attempting to download them results in my firewall dropping the packets on the floor (which means they're getting past Gnucleus.)

Any ideas why this might be happening? It's pointless for most people to receive matches from private address space...