> What do I have to do to trigger it? Just fail a bunch of SSH logins in a row?
Yes, that's what I do. If you have SSH login via password disabled (you should) then just temporarily move your private key(s) out of your ~/.ssh directory and try logging in a few times. "ssh user@machine && ssh user@machine && ssh user@machine" will do it if you have a ban set for three failed attempts. If it's working, your target machine should no longer respond at all, and connections will time out. If it's a web server the site should be unreachable with your web browser until after the bantime passes.
Ack, I figured it out. The ban does get triggered, but it doesn't succeed because iptables doesn't work on my system -- some module isn't properly compiled for the kernel. Thanks for helping me figure this out!
Yes, that's what I do. If you have SSH login via password disabled (you should) then just temporarily move your private key(s) out of your ~/.ssh directory and try logging in a few times. "ssh user@machine && ssh user@machine && ssh user@machine" will do it if you have a ban set for three failed attempts. If it's working, your target machine should no longer respond at all, and connections will time out. If it's a web server the site should be unreachable with your web browser until after the bantime passes.