Fortunately, NAT has another trick up its sleeve in the form of Port Address Translation.
Now NAT is fine if you only need to translate one public IP to private IP address (1 to 1 mapping) or vice versa but what if you have multiple devices on your LAN? You would need one public IP address for each of the devices you needed to access the internet. Well not without help but that’s another topic. This added layer of complexity does offer you a benefit your first layer of security as nobody outside of your network can access it. The fact we have to use NAT to overcome the limitations described above when connecting to the internet creates two separate networks, your LAN, which is private and the internet, which is public. Public, those which can be routed across the internet IPv4 addresses are broken into 2 types, termedĪ. Translates public IP addresses to private ones and vice versa. To overcome this limitation of IPv4 two mechanism’s are employedġ. Due to the way IPv4 works there are simply not enough of these addresses available for every one or device in the world to have a unique IP address. Needing a unique IP address causes a problem.
You could think of this like a postman delivering mail on your street, if there are two houses numbered 12 then which does he deliver mail addressed for number 12 too, probably the first number 12 they get to. IP addresses have to be unique on a network if they are duplicated then data may not be delivered to its intended recipient. This is an overview not an in depth discussion of IPv4 networking