petard.sh
You know how every once in a while you get some moron trolling for unsecured accounts over SSH and your logs get spammed with “invalid user” for every single username in their dictionary?
I finally figured out what to do about it. They tend to have their own SSH port open. So as soon as anyone tries to log in with an invalid username, I just NAT all further connection attempts back to them. tail -f + a few lines of shell = Ahhhhhhh. Mine is an evil laugh.