David Calkins on Thu, 2 May 2002 05:20:28 +0200


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Re: [PLUG] port forwarding question



> Are you using port forwarding though?  Do you use "ipmasqadm portfw" to
> setup the port forwarding?

I don't know.

Can you please explain this to me. There are 3 machines behind my network
connection all connected to internet through my box. I may be confused on
how I do this.

Fred

I have a similar setup, with 2 machines using the Linux box to get at the internet. This works when the machines inside the network make connections to machines on the internet (web browsing, email, etc). What happens is that a LAN box tries to connect to an outside machine. The linux box then makes the connection for you and takes care of sending any responses back to the LAN box.


The problem is that some applications operate on the principle where the client makes a connection with the server, but then the server sends a stream of UDP packets back to the client on a seperate port (multiplayer games for example). In this situation the initial client to server connection works great. But, when the server starts sending UDP packets back to the "client" (really the linux firewall box), they never get back to the LAN box.

The solution is to simply have the Linux box forward all UDP traffic on certain known ports back to one of the LAN boxes.

I'm still trying to figure out how to do this, but it should solve the problem if I can get it working.



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