Cutting down on ssh breakin attempts

[Kyle Jensen]

Hi,

I run a webmail server for a small company, which
is (of course) running FreeBSD 5-stable.  I get about
50-100 failed loging attempts via ssh on a daily basis.

Occasionally, these show up in my daily security digest
with messages like:

reverse mapping checking getaddrinfo for h169-210-68-8.a
dcast.com.tw failed - POSSIBLE BREAKIN ATTEMPT!

But mostly it's stuff like

Illegal user postgres from 210.68.8.169

What's the best way to cut down on these attempts?
I thought about adding a blacklist to my pf.conf rules
for the pf firewall.

Any thoughts would be greatly appreciated!
Kyle