Router firewall port forwarding question.

[wonder mike]

I have a certain serial server device that communicates on port 4660. I open port udp & tcp port 4660 and forward them to the Serial Server's ip, communication works fine. What I want to know is when the client software from a remote location wants to access the Serial Server thru the router, does the client send a port request for port 4660 then the router routes it to the correct ip, or does it broadcast a request thru out the lan and waits for a repsonse from the correct device? I've always thought if your server is running on a specific port the client software must make a request to the router at the same port.


Cheers

 

[gaidin123]

With port mapping you have the option of forwarding any port on your router to any port on any IP on your internal network.

Let's assume that you are running 10 web servers on 10 internal machines, all running on port 80, you would set up something like ports 8000-8009 on your router to be forwarded to:
router_ip:8000 -> internal_ip1:80
router_ip:8001 -> internal_ip2:80
etc.

It's kind of convenient since now you won't have to custom configure each webserver/similar service running behind your router to use specific ports, it can all be set up on your firewall/router.

In your case since you only have one server running that likes port 4660 you might as well just open up port 4660 on your firewall and point it to your Serial Server. But nothing's stopping you from opening something like port 80 on your router and forwarding it to port 4660 on your internal Serial Server (except maybe the desire to not get probed constantly on port 80 ).

Gaidin

Edit: When a remote client makes a request on port 4660, your router will simply forward that request on to your internal Serial Server. It will not get broadcast on your local LAN to see which machine responds. That would be a very bad thing...