Hi, I would like to get some inputs on how to configure iptables. I have referred to CentOS wiki http://wiki.centos.org/HowTos/Network/IPTables and it has been very helpful. I have configured iptables with the help of this tutorial, but I haven't understood few things about default firewall config. - What does 'RH-Firewall-1-INPUT' chain means? This also seems to be a predefined chain, although not mentioned in wiki. - The wiki page approach is to flush existing rules and then add required rules to iptables. Is it possible to add/append required rules without flushing existing set of rules? Not sure, but I think this is where 'RH-Firewall-1-INPUT' chain comes into picture (user defined rules). Any explanation or resource link on this would be really helpful. Thanks, CS.