Wikimedia Bugzilla is closed!

[I did not analyse the feasibility of this feature, nor I state that there isn't
a better solution, to which I am open to hear]

Blocking some idiots are tough: they're using large netblocks, which isn't
really possible to ban without alienating lots of nice people. 

It would be nice to have the possibility to "mark" netblocks, which could be
listed as "show only marked" in Recentchanges, or to show them in red (or
whatever emphasizing is active in the skin) in Recent changes / Watchlists. It
would make it easier to see and follow known anon vandals without having to
resort to banning a large subnet.

I would show these marked nets when a new user is created from them, but
probably not the general non-anon edits (this is probably to be discussed, it
may or may not prove useful and/or insecure). So sockpuppet creation could be
followed more easily.