Server logs on my internet facing servers indicate people brute force attack ssh by guessing passwords. This happens about an average of one person (or host) per day who tries for several hours and then they wander off to (presumably) try another target.
I realise there are things that can defend against this (ie. IP access control, moving ssh to a non-standard port number, root login disallowed etc.) and that, statistically, they will not guess a password correctly anytime soon. I'm not interested in discussion of these techniques (though others may be).
However, I think, psychologically, it can be a bit unpleasant knowing that people are attacking your servers. Do you guys worry about this? Even when knowing the probability of a successful guess is negligible?