If you need iptables up and running, you need to add some rules to get ports opened in networker server. In recent versions of Networker Security Guide are not given this rules (I don't know why, honestly). But you can see "Networker 7.5 Firewall and TCP configurations" to consider rules given there.
We don't use iptables, We delegate security to external Firewall. So, we disable iptables. I am not expert in CentOS, but for RHEL you can disable with "service iptables stop" and then use "chkconfig iptables off" to prevent iptables go up when reboot server.
Hope it helps.
Perfect ledugarte Thanks lot for your help.. This works..
I fixed temporarily with "iptables -F", I heard after reboot again it will block. From your statement, I can prevent this even after reboot also.