Re: [PLUG] port forwarding question

[David Calkins <dcalk@bellatlantic.net>]

> > 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.



______________________________________________________________________
Philadelphia Linux Users Group       -      http://www.phillylinux.org
Announcements-http://lists.phillylinux.org/mail/listinfo/plug-announce
General Discussion  -  http://lists.phillylinux.org/mail/listinfo/plug