To change the CentOS default SSH port to 8223:
vi /etc/ssh/sshd_config
Make the following change:
#Port 22
to
Port 8223
Restart SSH:
service sshd restart
Add an exception to the firewall:
#/sbin/iptables -I INPUT -p tcp –dport 8223 -j ACCEPT
#/etc/rc.d/init.d/iptables save
#service iptables restart