Many users use the modem in their homes. This modem automatically does NAT. I have told you the meaning of the NAT before the last post. Today I will talk about NAT-T(Nat traversal). Sometimes I need open the tunnel to somewhere behind the NAT. Generally, IPSEC works IP to IP. So, we must define from real-IP to real-IP to establish the IPSEC tunnel. If we don't have enough real-IP for defining or may need different, that time we use the NAT-T feature on our device. You can lo