CentOS, by default, turns IPTables on and enforces a pretty strict security policy with SELinux. If you're trying to get at the port from another computer, the default IPTables setup drops all incoming connections except SSH. If you aren't worried about security, you can simply run
sudo service iptables stop
to turn off IPTables completely.
The other thing that could be holding you up, on CentOs, is SELinux. This acts as a second layer of security on processes and the file system and prevents some servers from having permission to serve files by default, since they don't have access to the directory to serve files from. You have a couple options here.
1) Turn off SELinux by changing the setting in
/etc/selinux/config as seen below:
SELINUX=disabled in /etc/selinux/config
2) More preferable, use
audit2allow to check if SELinux blocks your server, and if so, generate a new security policy to allow the server. See this CentOS Wiki entry as well as this blog entry.
Finally, if you're running on a VM, make sure your VM has network access and permissions to use the underlying hardware's NIC setup.