Port Forwarding

Posted on 2005-04-12
Last Modified: 2010-04-10

1) Network consisits of 1 laptop and 2 pcs. 1 pc acts as an internet gateway with Internet Connection Sharing enabled and sharing internet across the network to the other laptop and PC. I have all that working.

2) I have this MMORPG(Massively Mutliplayer Online RolePlayer game) which i am trying to use on the 2 clients (not the gateway) simultaneaously. In discussion with the game community in order to do so I ave to change the local port of the game client on the client machines which I have done fine.

3) when i try to log on both clients at the same time (even using different local ports) one of them is never able to log on.

4) The problem as I can see it is that the 2 clients may be using 2 different local ports, but that they might still be going out the one port on the gateway, meaning one will never be able to login with the other one already logged in. Assuming my diagnosis is correct is there any way to allow the 2 clients programs to go out 2 different ports on the gateway machine, through port forwarding or what not.

All systems are using windows Xp.

Any help would be greatly appreciated.
Question by:enigma_b17
    LVL 24

    Expert Comment

    Interesting... I think I may see what the issue is...

    1.  Your router needs to be set up with two port-forward rules.  It should forward traffic received on port x to client a, and traffic received on port y to client b.  To save confusion, it should forward the traffic to the same port on the client (e.g. traffic coming in on port 1765 on the router is forwarded to port 1765 on client a).

    2. client a needs to be set up to use port x, client b to use port y.  I presume you can change the settings of the game as to which port it uses?  If not, that is your problem!

    This should do it.  It is the incoming port that is important, as this is how the router (and the game community) can distinguish your two machines (because they will both have the same public IP address - that of the router).

    Author Comment

    ok dont ave a router, my gateway pc has the internet connection in it, and simply shares it across the network, so I cant actually do port forwarding that i  Know, sorry if i didnt make that clearer. Is there, i dunno, software or somed that will allow me to forward ports on the gateway machine?
    LVL 24

    Accepted Solution

    So you are using Internet Connection Sharing?

    You can configure this to port forward:

    1. Double-click Network Connections in Control Panel.
    2. Right-click the Internet connection (which is also the connection where ICS is enabled), and then click Properties.
    3. On the Advanced tab, click Settings.
    4. Click Add.
    5. Fill in the Service Settings form as follows:
    • Description of Service: Game Client 1
    • Name or IP: IP address of client 1
    • Protocol: TCP
    • External Port number for this service: 1234
    • Internal Port number for this service: 1234
    6. Click OK to complete the configuration.
    7. Add the service for client 2 (same details, only difference being the port number)
    8. OK out of the setup.

    Now all you need to do is set each of the game clients to use the ports you have just configured.

    LVL 24

    Expert Comment

    lol, you were quite clear in your original post incidentally, I just didn't read it properly.  Sorry!
    LVL 4

    Expert Comment

    Check with game operators if they allow to login from one IP address as for them you are trying to establish 2 connections from one machine.

    Author Comment

    worked like a charm....thanks purple :)

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