Private IPv4 addresses

As defined by RFC 1918, there are three classes of private IPv4 address that are allocated for private use only. This means within a private network such as LAN. The benefit of using the private address space (RFC 1918) is that the classes are not unique to any particular organization or group. They can be used within an organization or a private network. However, on the internet, the public IPv4 address is unique to a device. This means that if a device is directly connected to the internet with a private IPv4 address, there will be no network connectivity to devices on the internet. Most ISPs usually have a filter to prevent any private addresses (RFC 1918) from entering their network.

The private address space is divided into three classes: