How to cut down on ssh attacks

[Robert Moskowitz]

I just installed logwatch on my mailserver.

the server has been running for a couple weeks, so it is 'known'. Ran a 
test of logwatch daily and the sshd authentication failures lists

575 lines, each with multiple attempts!

In one day!

ufw does specify 'limit' port 22:

22/tcp                     LIMIT       Anywhere
22/tcp (v6)                LIMIT       Anywhere (v6)

anything else I can do to slow this nonsense down?

I tried my regular of moving sshd to another port, but MiaB has ssh so 
embedded in its functionality that I gave up running through all the 
changes in it I need on moving sshd.  Don't ask my opinion on this 
dependency, but MiaB is otherwise worth the pain....