So I’ve been playing a lot with iptables again at work. I’ve worked out a couple different rules for trying to limit how many hack attempts actually get through to the box, and one of the steps I took was to craft up two rules to limit the time that someone can connect to the box via ssh. I typed it all in and got the following error message.
iptables v1.4.2: Unknown arg `(null)’
Try `iptables -h’ or ‘iptables –help’ for more information.