Re: Transparent gateway

[Jason Opperisano <opie@817west.com>]

On Thu, 2004-11-18 at 08:56, Mattia Martinello wrote:
> > why?
> 
> Beacuse I want to call from my LAN the server using its public IP address.

which has nothing to do with SNAT-ing your internal LAN.

> > because you told it to...
> 
> Can't I solve this problem?
> 
> > don't NAT traffic from your LAN to your DMZ.  if clients inside the LAN
> > are requesting the public IP of the DMZ server and not it's actual DMZ
> > IP, you'll need something along the lines of:
> 
> See above... I always want to call the server using its public IP address.

you need a DNAT rule that translates requests from your internal LAN to
the public IP of DMZ server to the DMZ IP of DMZ server.

> > other than that--you haven't provided near enough information to answer
> > your questions (hint:  post your rules [1])
> 
> This is my simple script:
> 
> 
> #!/bin/sh
> 
> modprobe iptable_nat
> echo 1 > /proc/sys/net/ipv4/ip_forward
> echo 0 > /proc/sys/net/ipv4/conf/all/rp_filter
> 
> iptables -F INPUT
> iptables -F OUTPUT
> iptables -F FORWARD
> iptables -t nat -F POSTROUTING
> iptables -t nat -F PREROUTING
> iptables -t nat -F OUTPUT
> 
> iptables -P INPUT ACCEPT
> iptables -P OUTPUT ACCEPT
> iptables -P FORWARD ACCEPT
> iptables -t nat -P POSTROUTING ACCEPT
> iptables -t nat -P PREROUTING ACCEPT
> iptables -t nat -P OUTPUT ACCEPT
> 
> iptables -t nat -A POSTROUTING -s 192.168.1.0/255.255.255.0 -o ppp0 -j 
> MASQUERADE
> iptables -t nat -A POSTROUTING -s 192.168.1.0/255.255.255.0 -o eth0 -j 
> MASQUERADE
> iptables -t nat -A POSTROUTING -s 192.168.1.0/255.255.255.0 -o eth2 -j 
> MASQUERADE
> iptables -t nat -A POSTROUTING -s 192.168.2.0/255.255.255.0 -o ppp0 -j 
> MASQUERADE
> 
> iptables -t nat -A PREROUTING -s 0.0.0.0/0 -d $EXTERNAL_IP -j DNAT --to 
> 192.168.2.99

assuming ppp0 is your external interface--delete both "-o ethX" MASQ
rules.  your are excessively NAT-ing for no good reason.  the DNAT rule
you have will translate requests from the internal LAN to $EXTERNAL_IP
to 192.168.2.99 for you.

> So all trafic to the external server IP seems to come from 
> 192.168.2.254. How I can avoid this?

-j

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