i have a machine running apache web server in my LAN with address
192.168.0.236 using port 8080 for http.
my ISP give me a static IP address: xx.xx.xx.xx .
how do i configure my router so that i can access my web server with the public address that i have.
i want just the theory and the principe of that because i know that each router have it's commands and config tools.
Note : i have a SMC router.
You will need to use NAPT / PAT / Port Forwarding / Port Mapping / Port Redirection (same technology, different names) to forward connections destined to a specific port of your public router interface to a specific port of a host inside your network. The theory is not much more than that, you just configure the router to make the port mapping, that is to send each packet it receives from the internet to the internal computer, editing some of the IP header information as appropriate for the redirection to work. You can find detailed info on this at the Firewalls > Network Address Translation section of this site.