Re: IPTables - Unix script and Smoothwall

> From: Richard Nason <[email protected]>
> Reply-To: <[email protected]>
> Date: Sun, 31 Oct 2004 16:30:08 -0000
> To: _Gpl List <[email protected]>
> Subject: RE: [gpl] IPTables - Unix script and Smoothwall
> 
> Hello David,
> 
> ::  -----Original Message-----
> ::  From: [email protected]
> ::  [mailto:[email protected]]On Behalf Of David Wilson
> ::  Sent: 31 October 2004 01:12
> ::  To: [email protected]
> ::  Subject: [gpl] IPTables - Unix script and Smoothwall
> ::
> ::
> ::  [Resending this. No response first time and I'm not sure it got out...]
> 
> Yes, it got out, this is the third time we've seen it.

Woops, please accept my apologies for this. I did think it was unusual not
to get a reply from the list and that perhaps I had made an error on the
mailing.

> I suspect that you didn't get any replies because this isn't
> really a Smoothwall issue. I'm not a gamer so I don't know
> what you plan to host behind this. Perhaps some more details
> about you goals would be useful.

I'm basically trying to resolve an issue with the Blizzard game StarCraft
when it's played with a local server (in this case PvPGN). The issue comes
about when there are multiple players on the internal LAN and just one
player connected via the Internet. Game responses degrade immediately and
the game plays at an unacceptably slow speed.

I suspect that packets from the internet are unable to find the host they
are destined for.

"someone" has it working and used the script with the IPTABLES configuration
to resolve the issue along with a minor modification to the game config
itself.

Basically each player on the internal LAN is allocated a specific port
number. Thus now I know that 192.168.10.200 will play on port 16200

What I don't understand is what the script is trying to do when it executes:
   iptables -t nat -A PREROUTING -p udp -d $EXT_IP --dport $PORT_II -j DNAT
--to-destination $HOST:$PORT_II
   iptables -t nat -A POSTROUTING -p udp -s $HOST --sport $PORT_II -j SNAT
--to-source $EXT_IP:$PORT_II

I have successfully run the script on smoothwall, however it appears to have
had no effect. I confess that I do not understand "iptables" and I have no
idea what is being done with the "PREROUTING" and "POSTROUTING" as when I
dump the iptables in smoothwall these ?sections? Are more or less empty??


> Not really a glowing commendation but Smoothwall deals with
> wicked things...:-)   If you run this on your Smoothie you
> may well break it. (see above!)

:-)  It didn't break it AND I was able to re-run the script with the "stop"
parameter to undo what I'd done.


My apologies again for multiple mailing to the list.



- David
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