Even if we secure our computer systems from remote intrusions, hackers will never stop at testing your defenses. Whilst having a sufficiently secure system may be sufficient, the fact that these hackers are continuously attempting to breach your defense will affect the way your computer system performs and also eat up on precious network resources.
Take for instance a brute force attack on an open SSH port. Whilst this may be secure, the traffic generated by attempting to break your password several times per minute will eventually take its toll. So how do you limit this? Well, it is a good thing that iptables can be configured to limit the frequency of such attacks. I highly recommend that you do this – will save you some precious bandwidth as well.