Help with NAT

[mlist@rrbsystems.ch]

Hello 

As you can see I use the iptables utility for accountiong. 

We have two privat networks (172.16.10.0 and 172.16.133.0) wich are connected 
to the firewall. In the network 172.16.133.0 are some web-, mail- and ftp 
servers. From the outside (internet) they have be accessable via a public IP. 
That means that the web server 172.16.133.58 should have a public IP 
1.2.133.58 for example. I tried this with:

$IPTABLES -t nat -A POSTROUTING -s 172.16.133.58 -o $EXT -j SNAT --to-source 
1.2.133.58

but it dosen't work.

Can somebody help me and complete my firewall script.

Thanks a lot for your help

Damian

#!/bin/bash
# Firewall script
#==============================================================================
# Variablen
#==============================================================================

modprobe ip_tables
modprobe ip_conntrack

IPTABLES=/usr/sbin/iptables

PUBLIC_NET=1.2.133.0/24
PRIVAT_NET=172.16.0.0/16

#==============================================================================
# Grundkonfiguration
#==============================================================================

echo "1" > /proc/sys/net/ipv4/ip_forward
echo "1" > /proc/sys/net/ipv4/ip_dynaddr
echo "1" > /proc/sys/net/ipv4/tcp_syncookies
echo "1" > /proc/sys/net/ipv4/icmp_echo_ignore_broadcasts
echo "1" > /proc/sys/net/ipv4/icmp_ignore_bogus_error_responses

#==============================================================================
# Default Policy und flush
#==============================================================================

$IPTABLES -P INPUT ACCEPT
$IPTABLES -P FORWARD ACCEPT
$IPTABLES -P OUTPUT ACCEPT

$IPTABLES -F
$IPTABLES -t nat -F
$IPTABLES -X

#==============================================================================
# Accounting
#==============================================================================

$IPTABLES -A FORWARD -s 172.16.10.40
$IPTABLES -A FORWARD -d 172.16.10.40
$IPTABLES -A FORWARD -s 172.16.133.58
$IPTABLES -A FORWARD -d 172.16.133.58

#==============================================================================
# ausgehende Pakete bei bereits aufgebauter Verbindung
#==============================================================================

$IPTABLES -A OUTPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
$IPTABLES -A FORWARD -i $INT -o $EXT -m state --state ESTABLISHED,RELATED -j 
ACCEPT

#==============================================================================
# eingehende Pakete zu einer bestehenden Verbindung
#==============================================================================

$IPTABLES -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
$IPTABLES -A FORWARD -i $EXT -o $INT -m state --state ESTABLISHED,RELATED -j 
ACCEPT
$IPTABLES -t nat -A POSTROUTING -s 172.16.133.58 -o $EXT -j SNAT --to-source 
193.193.133.58eeds 
#==============================================================================
# Source NAT
#==============================================================================

$IPTABLES -t nat -A POSTROUTING -s 172.16.133.58 -o $EXT -j SNAT --to-source 
193.193.133.58

#==============================================================================
# Masquerading
#==============================================================================

$IPTABLES -t nat -A POSTROUTING -s $PRIVAT_NET -o $EXT -j MASQUERADE