Dictionary attack indeed. I started having serious problems with dictionary attacks on a Mandrake server I was running. To echo the above, I highly recommend using public key authentication. It is much more secure. Just type "openssh key authentication" in google and you’ll get plenty of information. It is pretty easy to do if you basically know your way around Linux.
Also, you should take advantage of AllowUsers in /etc/ssh/sshd_config. Only allow the users you want, that way nobody can get in through some strange user account you didn’t even know about that has a weak password or no password at all. Type "man sshd_config" for more information.
After I started using these two things, attacks on my ssh server basically stopped or were completely ineffective.