>> I've since recently put my board back on port 23... and I now recall 
 >> why I took it off of it. I keep getting all of these connections from 
 >> hackers, I take it. Anyone know of a way to filter these bad 
 >> connections?

 >> I've tried Janis' iptables suggestion, but it isn't working.

Have a look at fail2ban www.fail2ban.org  claims to be a "poor man's ids".

I installed it from the yum repos on CentOS7 & configured it for 3 attempts.
If you fail to login for 3 attempts you are banned for 15 minutes. All activity
is logged. Luckily I was smart enough to setup several local accounts 
so when I forget the admin password I was still able to reset the timer for
that
acount via sudo...

I like it lots!

 

--- Msged/LNX 6.1.2