Re: redirection trouble

[MartÃn <martin@xxxxxxxxxxxxxxxxxxxxxx>]

Ok, I think I got it... but does not work. I see the traffic being 
redirected, but the conection gets lost, I got this in the snuiffer:

02:02:51.640513 192.168.2.1 > 192.168.2.5: icmp: 192.168.2.1 udp port 10000 
unrachable [tos 0x40]

Any Idea?




En Tue, 4 Nov 2003 11:20:42 +0800, Edmund Turner <eturner@xxxxxxxxxxxxx> 
escribiÃ:

> Martin, Alistairs explanation and solution is correct.
> In short 192.168.2.5 will only see traffic thru and fro 192.168.2.1
> @port 10000. Put a packet analyser or a sniffer on 192.168.2.5 to
> confirm.
> In Iptables if you do a prerouting as such :
>
> #This will redirect all packets to 192.168.2.1 dport 10000 to
> 200.24.24.200:10000
>
> iptables -t nat -I PREROUTING -i eth1 -d 192.168.2.1 -p udp --dport
> > 10000 -j DNAT --to 200.45.45.200:10000
>
> You donât have to worry about the packets coming in back from
> 200.24.24.200. They will be tracked and sent back to 192.168.2.5 as
> source IP of 192.168.2.1. Im not sure which module is responsible for
> this, but I think its done by the ip_conntrack module. Maybe someone can
> enlighten us on this?
>
>
> Regards
> edmund
>
> > -----Original Message-----
> From: netfilter-admin@xxxxxxxxxxxxxxxxxxx
> [mailto:netfilter-admin@xxxxxxxxxxxxxxxxxxx] On Behalf Of MartÃn
> Sent: Tuesday, November 04, 2003 10:37 AM
> To: alistair@xxxxxxxxxx
> Cc: netfilter@xxxxxxxxxxxxxxxxxxx
> Subject: Re: redirection trouble
>
> En Mon, 3 Nov 2003 21:21:09 -0500, Alistair Tonner <Alistair@xxxxxxxxxx>
>
> escribiÃ:
>
> > On November 3, 2003 08:53 pm, MartÃn wrote:
> > > This is the situation:
> > >
> > >
> > >
> > > Internal LAN machine (192.168.2.5)
> > >
> > >
> > >
> > > (eth1 192.168.2.1) NAT LINUX ( eth0 192.168.1.10 > adsl ppp0 IP
> dinamic)
> > > Server 200.45.45.200 (service at port 10000)
> > >
> > >
> > >
> > > This is what I intend to do:
> > > For particular reasons, I need that a soft at 192.168.2.5 comunicate 
> > > with a
> > > server with a service at port 10000 (UDP), but this canÂt be done 
> > > through
> > > normal NAT. So i want to establish a link between both (server and
> > > 192.168.2.5) manually useing the NAT LINUX
> > > So, 192.168.2.5 comunicates to 192.168.2.1 port 10000, the NAT LINUX
> > > redirect this traffic to the server 200.45.45.200 port 10000. The
> server
> > > will respond to the NAT LINUX who will redirect this traffic to 
> > > 192.168.2.5
> > > (port 10000 also)
> > > I try to do all this in this way:
> > >
> > >
> > > iptables -t nat -I PREROUTING 1 -i eth1 -d 192.168.2.1 -p udp --dport
>
> > > 10000
> > > -j DNAT --to 200.45.45.200
> > >
> > > iptables -t nat -I POSTROUTING 1 -o eth0 -p udp --dport 10000 -j SNAT



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