what happens internally in a router when lan is configured?

You have an broadband connection with one static ip it is configured in dlink router the lan is 192.168.1.0 and now you wanted to make a hosting in one of your systems in lan how to do that?

• Answer:

  You have to use port forwarding. By "hosting" you mean probably running a web server. A www (http) server listens to incoming connections on a TCP port number 80. Therefore you must configure on your router a port forward, which will open port 80 on the router and forward all traffic to port 80 on your "hosting" computer. It will act as sort of an "extension", a peephole through which the world will see this specific service on your computer, which is otherwise hidden behind a "fence" (router). This is done by specifying: - which machine's port is to be forwarded (computer's IP address on the LAN) - which port on that machine will be forwarded - on which port of the router it will be forwarded - what type of protocol will be used (TCP, UDP or both). Sometimes a router won't allow both, then the forwarding must be done twice, once for TCP and second time for UDP. For a webserver TCP is enough. If you want to serve other services, like FTP or whatever, you must forward the ports used by this service. For example, for FTP it will be ports 20 & 21, for SSH - 22, for ECHO (ping response) - port 8, for secure http - port 443 etc. Search the internet for a "list of known TCP/IP ports" to find out more.