32.4 Port Forwarding
If the Ubuntu system hosting the web server sits on a network protected by a firewall (either another computer running a firewall, or a router or wireless base station containing built-in firewall protection) you will need to configure the firewall to forward port 80 and/or port 443 to your web server system. The mechanism for performing this differs between firewalls and devices so check your documentation to find out how to configure port forwarding.