I'm also curious since it looks like there is no activity at all.
I also own a beta server since quite some time, without the authentication servers griefers are just a plague without any viable solution for it, there is no way to ban someone from a server other than a ton of server-side duct-tape solutions involving tracking IPs, quering known vpn lists and etc.
It's a well known problem in the "old" minecraft community and it'd be nice to finally see a solution for it.
https://bugs.mojang.com/browse/WEB-1995
Is not related _at all_ I don't know why it's on the list of potential duplicates.