Error : Invalid Argument

[João Carlos Garcia]

Hi, 

I´m trying to configure iptables rules, but ...
I´m testing the rules in a separeted environment, but the final topology will be the following
ADSL -- [ LINUX ] -- LOCAL NETWORK

The script look like this

    #!/bin/sh
    INTIF=eth0
    EXTIF=eth1
    INTIP=192.168.0.3
    EXTIP=172.16.0.3

    echo 1 > /proc/sys/net/ipv4/conf/eth0/proxy_arp
    echo 1 > /proc/sys/net/ipv4/conf/eth1/proxy_arp
    echo 1 > /proc/sys/net/ipv4/ip_forward
    for f in /proc/sys/net/ipv4/conf/*/rp_filter; 
    do 
    echo 1 > $f; 
    done

    iptables -F INPUT
    iptables -F OUTPUT
    iptables -F FORWARD
    iptables -A INPUT -j DROP
    iptables -A FORWARD -j DROP
    iptables -A OUTPUT -j DROP
    ...

    iptables -t nat -A POSTROUTING -s 192.168.0.0/24 -o $EXTIF -j SNAT --to-source $EXTIP

When the script run the last rule ( NAT ), occurs an error : iptables invalid argument.
I want that the iptables change the source IP address ( 192.168 ) to his ip address ( 172.16.0.3 ) to all connection to Internet

Could anyone help me ?
Thanks in advanced
João Carlos


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