Configure firewall to block certain IP addresses

Hi,

I really have no idea how the iptables/bastille firewall works and want to add some rules to block certain IP addresses from accessing any services on any of my servers (including ones that don't run ISPConfig3).

What is the preferred method for doing this with ISPConfig3 running on Ubuntu 9.10?

What about servers NOT running ISPConfig3 and runnign Ubuntu 9.10?

Thanks and sorry for the simplistic question, but I really want to start small to figure out how to use these tools.

Danté

ps. output of iptables -L:

Code:

sudo iptables -L
Chain INPUT (policy ACCEPT)
target     prot opt source               destination         
fail2ban-ssh  tcp  --  anywhere             anywhere            multiport dports ssh 

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination         

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination         

Chain fail2ban-ssh (1 references)
target     prot opt source               destination         
RETURN     all  --  anywhere             anywhere

 

a basic iptables primer:

http://bodhizazen.net/Tutorials/iptables/

 

http://www.howtoforge.com/forums/showpost.php?p=38142&postcount=4