Port Forwarding with 2.2 kernel

Port Forwarding with 2.2 kernel

[Steve Holmes]

I want to run Speak Freely on a machine inside my local area network.
Thus I need to forward the packets through my IP masqueraded network host
which is currently running a 2.2.20 kernel with ipchains.  The basic
firewall stuff is making sense now but a couple of the related HOWTOs
don't say much about port forwarding whereby trafic is forwarded on
through the firewall to another box inside my subnet.  They touch quite
briefly about having to add other patches to the kernel and all that.

My question, is there anyone on this list doing this sort of thing
already? If so, I would be most interested in any firewall scripts you
might be using.

Thanks for the help.

Re: Port Forwarding with 2.2 kernel

[Geoff Shang]

Hi:

I've never forwarded speak freely, but the below worked for me when using
buddy phone on a windows box behind my linux machine, so it should work
just as well for speak freely.

I use the ipmasqadm program to do port forwarding.  This requires a few
things to be compiled into the kernel, namely the port forwarding stuff.  I
think the ipmasqadm docs mention this.  Don't confuse ipmasqadm with
ipfwadm, the program that was the equivalent to ipchains in the 2.0.x
kernels.

I suggest a command like so:

ipmasqadm portfw -a -P udp -L <external IP> 2074 -R <internal IP> 2074

Where external IP is your regular IP address that your firewall box has,
and your internal IP is the machine on the inside where you want speak
freely packets to go.  You will need UDP ports 2074 and 4074 to be
forwarded.  On the rare occasions where I've had to use speak freely behind
a firewall, I found performance much better if I only forwarded these and
not 2075, 4075, 2076 and 4076 as well, but your milage may vary so try that
too.

Geoff.