Ok so I am just going to throw this out there. If you have a server or computer of any type on the Internet guess what you are going to experience every day? Brute force attacks. There is no way to entirely avoid them other than using non-standard ports, restricting access to your services via IP / firewall etc..
Now this is something you just gotta live with. Its going to happen. If you have your servers properly secured then you dont really have anything to worry about. One of the things I personally have done to mitigate these issues is created a distributed block list for IP's attacking my servers.
One server receives the attack, blocks the IP address, submits it to a central database, and the other servers pull down the list and block the malicious IP. Additionally all the other servers can also submit data to the central database. I have it configured to only block / save unique IP's but thats one solution I have implemented. If this is a big concern for you then you should look into options to secure your servers in a similar fashion.
Side note: No the code is not open source at this time, however it may be soon.
Malicious IP list is available here if you want it: