Poking a hole in the CentOS firewall
With CentOS 5.2 (as ever), use the following to enable a listening tcp port (in this case 8000) to be accessed through the firewall.
sudo /sbin/iptables -A INPUT -p tcp –dport 8000 -j ACCEPT
sudo /sbin/service iptables save
sudo /sbin/iptables -F