CentOS defaults only 22 ports to use a different port, you need to add yourself, saidonline, long time did, and here is what successful bloggers own test methods:
Add port: #/sbin/iptables-I INPUT-p TCP–dport port-j ACCEPT
Save settings: #/etc/rc.d/init.d/iptables save
See if successfully added: #/etc/init.d/iptables status | grep tcp