Configure port forwarding rules on your router via the UPnP protocol.
Forward the external TCP port 80 to port 8080 on a local machine
upnpc -a 192.168.0.1 8080 80 tcp
Delete any port redirection for external TCP port 80
upnpc -d 80 tcp
Get information about UPnP devices on your network
upnpc -s
List existing redirections
upnpc -l