It's IRC terminology: http://en.wikipedia.org/wiki/IRCd#K-line

A K-Line is a ban of an client (or multiple clients) from an irc network:

http://en.wikipedia.org/wiki/K-line_(IRC)#K-line

I was just musing that the only word in this headline recognizable to someone outside this small subset of the tech world is "all", and yet it makes perfect sense if you know all the words.

Happened to me. Incomprehension is the reason I clicked the link.

kline (K-line) basically [K]ills a network or IP block, forbidding them from connecting to the IRC server. (I think the term stems from the config files for the original ircd, circa 1988)

Just to clarify: most servers haven't K:lined the blocks, but D:lined them (even though the efnet.org article says 'klines'). K:line = kill line, D:line = deny line. The difference is where the check happens, after the client has had a chance to identify and a identd response is received or not, or at the TCP level on remote IP address alone (D:Line).

D:Lines are less resource intensive obviously. Not much difference for the client though :)

kline is short for "kill line" and refers to lines in configuration files for IRC daemons (IRCd), i.e. IP ban.

The short answer is that they've banned all users connecting from those IP blocks,.

Various *-lines for IRC: http://en.wikipedia.org/wiki/IRCd#Configuration

It is an IRC term for a "kill line". If your host tuple (nickname, username and hostname) somehow matches the kill line, your connection to the server will be closed with a message on why it was closed.