настройка NAT

помогите с настройками ната
это файл конфигурации, но часть которая отвечаетза нат не работает

*filter
:FORWARD ACCEPT [0:0]
:INPUT ACCEPT [0:0]
:RH-Firewall-1-INPUT - [0:0]
:OUTPUT ACCEPT [0:0]
-A INPUT -j RH-Firewall-1-INPUT
-A FORWARD -j RH-Firewall-1-INPUT
-A RH-Firewall-1-INPUT -i lo -j ACCEPT
-A RH-Firewall-1-INPUT -p icmp --icmp-type any -j ACCEPT
-A RH-Firewall-1-INPUT -p 50 -j ACCEPT
-A RH-Firewall-1-INPUT -p 51 -j ACCEPT
-A RH-Firewall-1-INPUT -p udp -m udp -i eth1 --dport 631 -j ACCEPT
-A RH-Firewall-1-INPUT -p tcp -m tcp -i eth1 --dport 631 -j ACCEPT
-A RH-Firewall-1-INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
-A RH-Firewall-1-INPUT -p udp -m udp -i eth1 -m state --dport 123 --state NEW -j ACCEPT
-A RH-Firewall-1-INPUT -p tcp -m tcp -i eth1 -m state --dport 123 --state NEW -j ACCEPT
-A RH-Firewall-1-INPUT -p tcp -m tcp -m state -i eth1 --dport 21 --state NEW -j ACCEPT
-A RH-Firewall-1-INPUT -p tcp -m tcp -i eth1 --dport 22 -j ACCEPT
-A RH-Firewall-1-INPUT -p udp -m state -m udp -i eth1 --dport 137 --state NEW -j ACCEPT
-A RH-Firewall-1-INPUT -p udp -m state -m udp -i eth1 --dport 138 --state NEW -j ACCEPT
-A RH-Firewall-1-INPUT -p tcp -m state -m tcp -i eth1 --dport 139 --state NEW -j ACCEPT
-A RH-Firewall-1-INPUT -p tcp -m state -m tcp -i eth1 --dport 445 --state NEW -j ACCEPT
-A RH-Firewall-1-INPUT -p tcp -m state -m tcp -i eth1 --dport 80 --state NEW -j ACCEPT
-A RH-Firewall-1-INPUT -p tcp -m state -m tcp -i eth1 --dport 443 --state NEW -j ACCEPT
-A RH-Firewall-1-INPUT -p tcp -m state -m tcp -i eth1 --dport 25 --state NEW -j ACCEPT
-A RH-Firewall-1-INPUT -p tcp -m state -m tcp -i eth1 --dport 10000 --state NEW -j ACCEPT
-A RH-Firewall-1-INPUT -p tcp -m state -m tcp -i eth1 --dport 110 --state NEW -j ACCEPT
-A RH-Firewall-1-INPUT -p tcp -m state -m tcp -i eth1 --dport 3128 --state NEW -j ACCEPT
-A RH-Firewall-1-INPUT -p tcp -m state -m tcp -i eth1 --dport 888 --state NEW -j ACCEPT
-A RH-Firewall-1-INPUT -p tcp -m state -m tcp -i eth1 --dport 143 --state NEW -j ACCEPT
-A RH-Firewall-1-INPUT -p tcp -m state -m tcp -i eth1 --dport 53 --state NEW -j ACCEPT
-A RH-Firewall-1-INPUT -p tcp -m state -m tcp -i eth1 --dport 5222 --state NEW -j ACCEPT
-A RH-Firewall-1-INPUT -p tcp -m state -m tcp -i eth1 --dport 5223 --state NEW -j ACCEPT
-A RH-Firewall-1-INPUT -p tcp -m state -m tcp -i eth1 --dport 5269 --state NEW -j ACCEPT
-A RH-Firewall-1-INPUT -p udp -m state -m udp -i eth1 --state NEW -j ACCEPT
-A RH-Firewall-1-INPUT -j REJECT --reject-with icmp-host-prohibited
COMMIT
*mangle
:FORWARD ACCEPT [0:0]
:INPUT ACCEPT [0:0]
:PREROUTING ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
:POSTROUTING ACCEPT [0:0]
-A PREROUTING -i eth0
-A FORWARD -p tcp -o ppp+ --tcp-flags SYN,RST SYN -j TCPMSS --set-mss 1250
COMMIT
*nat
:OUTPUT ACCEPT [0:0]
:PREROUTING ACCEPT [0:0]
:POSTROUTING ACCEPT [0:0]
-A POSTROUTING -s 192.168.0.0/24 -o eth1 -j SNAT --to-source 192.168.xxx.xxx
COMMIT

eth1 смотрит в локальную сетку
eth0 в сетку провайдера
нужно что бы с любого компьютера в лок. сети можно было заходить в сеть провайдера, а от провайдера лок. сеть должна быть спрятана