# enable forwarding
echo "1" > /proc/sys/net/ipv4/ip_forward

# load netfilter modules
modprobe ip_tables
modprobe nf_conntrack
modprobe nf_conntrack_ftp
modprobe nf_conntrack_ipv4

# flush all
iptables -F
iptables -F -t nat

# masq. all going out of eth0
iptables -A POSTROUTING -t nat -o eth0 -j MASQUERADE