iptables /nat and route

iptables /nat and route

[Klaus Wacker]

Hi, it seems it is a simple task, but can't get it going.
I want have a couple of private machines accessing a public one  (and other way around) through a router/gateway
At the moment I do not care about ports (one to one is enough for me), just try to get a ping through in both directions including a change of source and destination ip
The default gateways address of the public machine I did set to OUTIP  respectively INIP for internal machine. 
Here is my setup:

echo #rc.my.iptables

####network######
#given IP (not yet DHCP)
PUP_IP="192.168.10.99"

#internal devices (might be a range)
NET_IP1="192.168.9.1"

####router#######
OUT_INFC="eth0"
IN_INFC="eth2"
INIP="192.168.9.200"
OUTIP="192.168.10.200"


### iptables #####
##for incoming from puplic ###
iptables -t nat   -A PREROUTING -i $IN_INFC -s $PUP_IP -d $INIP -j DNAT --to $NET_IP1
iptables -t filter -A FORWARD -s $PUP_IP -d $NET_IP1 -j ACCEPT

###return way ### 
iptables -t nat   -A POSTROUTING -d $PUP_IP -s $NET_IP1 -j SNAT  --to $INIP
#(have tried without next line)
iptables -t filter -A FORWARD -s $NET_IP1 -d $PUP_IP -j ACCEPT


## keep things going, (have tried without)###
iptables -A FORWARD -i eth0  -o eth2  -m state --state RELATED,ESTABLISHED -j ACCEPT
iptables -A FORWARD -i eth2  -o eth0  -m state --state RELATED,ESTABLISHED -j ACCEPT
 

It does not work in any direction. I am wondering it may have something to do with my route settings:


Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
default         192.168.10.1    255.255.255.0   UG    0      0        0 eth0
default         192.168.9.1     255.255.255.0   UG    0      0        0 eth2
192.168.10.0    *               255.255.255.0   U     0      0        0 eth0
192.168.9.0     *               255.255.255.0   U     0      0        0 eth2
default         127.0.0.0       0.0.0.0         UG    0      0        0 lo
 

Cheers
Klaus


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