Certain groups that have gone out of their way to cause me trouble receive instant bans upon attempting to connect to the server, if he seriously wants to play here, he must remove himself from the group and I'll unban him.
I didn't put measures in place against SA just because of that last guy, but because a lot of them came onto the server and did the same, and then to top it off, a bunch of our previous bans issued for various reasons just also happened to be SA members.
Oh, and let's not forget one of them cleverly trying to guess my password for my forum account.