iptables -t nat -F
nic #
 iptables -F
nic #
 iptables -t nat -L
Chain PREROUTING (policy ACCEPT)
target     prot opt source               destination         
Chain INPUT (policy ACCEPT)
target     prot opt source               destination         
Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination         
Chain POSTROUTING (policy ACCEPT)
target     prot opt source               destination         
nic #
 # NAT
nic #
 #iptables -t nat -A POSTROUTING -s 192.1.3.0/24 -p udp --sport 4500 -j SNAT --to-source 192.1.2.254:32768-33000
nic #
 #iptables -t nat -A POSTROUTING -s 192.1.3.0/24 -p udp --sport 500 -j SNAT --to-source 192.1.2.254:33001-33100
nic #
 #iptables -t nat -A POSTROUTING --source 192.1.3.0/24 --destination 0.0.0.0/0 -j SNAT --to-source 192.1.2.254
nic #
 #iptables -I FORWARD 1 --proto 50 -j DROP
nic #
 echo done
done

