All IPv4 IP addresses can be divided into two main groups: global, or public, or external – this group can also be called ‘WAN addresses’ – those that are used on the Internet, and private, local or internal addresses – those that are used on the local area network (LAN).
There are also special-use addresses, intended for technical purposes, such as protocol functions, etc. Typically, they are not exposed to the user at all.
Public IP address
These are global public addresses used on the Internet. A public IP address is an IP address used to access the Internet. Public (global) IP addresses are routed over the Internet, unlike private addresses.
The presence of a public IP address on your router or computer will allow you to organize your own server (VPN, FTP, WEB, etc.), remote access to your computer, video surveillance cameras and access them from anywhere on the network global.
With a public IP address, you can configure any home server to publish it to the Internet: Web (HTTP), VPN (PPTP/IPSec/OpenVPN), media (audio/video), FTP, NAS network drive, game server , etc.
Note: All servers and websites on the Internet use public IP addresses (eg google.com – 22.214.171.124, Google DNS server – 126.96.36.199).
All public IP addresses on the Internet are unique to their host or server and cannot be duplicated for assignment.
For home users, the provider can only provide one or more public IP addresses (as a rule, it is a paid service).
The NAT-enabled IPv4 router allows home network devices to use one and the same public IP address that the system obtained from a provider on the device’s WAN interface for connecting to the Internet. It is this external public IP address that can be used to access the home network computer from the Internet as well, but for that you need to configure port forwarding on your router.
Due to the limited number of public IP addresses and the increasing number of Internet users, ISPs are now increasingly being forced to use private IP addresses assigned to subscribers.