Have you tried opening a port? CentOS comes with most ports closed by default.
Try this:
CentOS7
$ sudo firewall-cmd --zone=public --add-port=38000/tcp --permanent
$ sudo firewall-cmd --reload
CentOS6
$ sudo iptables -I INPUT -p tcp -m tcp --dport 38000 -j ACCEPT
$ sudo service iptables save
Source:
How to open a port RHEL/CentOS
Mike