I have found the best solution for me.
I use the redirect rules in iptables of my cloud Ubuntu14.04.
The comand below will redirect port 80 to port 3000. Use your NodeBB at port 3000
sudo iptables -t nat -A PREROUTING -i eth0 -p tcp --dport 80 -j REDIRECT --to-port 3000
The comand above will works up to next reboot. It means that you have to add the following string to
** /etc/rc.local file **
iptables -t nat -A PREROUTING -i eth0 -p tcp --dport 80 -j REDIRECT --to-port 3000
Important
Check if your network interface use the name eth0. Perhaps you have to use other network interface (for example eth1... etc)