Fedora Security :: Block Some Ip Address That Are Attacking Server?

I want to block some ip address that are attacking my server and making my ssh port busy. On searching the google, I found

Code:
iptables -A INPUT -s ip_address -j DROP

I will add this rule in iptables. My questions are:
1) do I have to do

Code:
chkconfig iptables on

so that it load the iptables at boot. I am wondering why do I need this because iptables is already modified and it loads the iptables at boot time if firewall is enabled.

2) When we add the above rule, which file is modified? Another way, where are this rules stored? It is not in /etc/sysconfig/iptables and /etc/sysconfig/iptables_config.