The RFC 1918 IP private addresses, also known as non-routable IP addresses, are a set of IP address ranges that have been reserved for private network use. These addresses are not allowed to be used on the public Internet. The reason for this restriction is to prevent conflicts and routing issues that could arise if these private addresses were to be used publicly.
The private IP address ranges defined in RFC 1918 are as follows:
– 10.0.0.0 to 10.255.255.255 (10.0.0.0/8)
– 172.16.0.0 to 172.31.255.255 (172.16.0.0/12)
– 192.168.0.0 to 192.168.255.255 (192.168.0.0/16)
These address ranges have been specifically reserved for use within private networks, such as home or office networks. They are not globally unique and can be reused in multiple private networks without causing conflicts.
When a device on a private network wants to communicate with a device on the public Internet, a process called network address translation (NAT) is used. NAT allows multiple devices on a private network to share a single public IP address when communicating with the Internet. This allows private networks to have thousands of devices using private IP addresses, while only requiring a single public IP address.
If a device on a private network were to use a private IP address on the public Internet, it would not be able to communicate with other devices on the Internet. This is because routers on the Internet are configured to drop packets with private IP addresses, as they are not routable. In other words, routers will not forward packets with private IP addresses to other networks.
For example, if a device on a private network with the IP address 192.168.1.10 tries to access a website on the Internet, it will send the request to its default gateway (usually a router). The router will then perform NAT and replace the source IP address with its own public IP address before forwarding the packet to the Internet. The response from the website will be sent back to the router, which will then reverse the NAT process and forward the response to the original device on the private network.
Using private IP addresses on the public Internet is generally considered a security risk. It can expose the internal network topology and potentially allow unauthorized access to private resources. It is therefore important to ensure that private IP addresses are not leaked onto the public Internet.
The RFC 1918 IP private addresses are not allowed on the Internet to prevent conflicts and routing issues. These addresses are reserved for use within private networks and are not globally routable. Network address translation (NAT) is used to allow devices on private networks to communicate with the public Internet. Using private IP addresses on the public Internet can pose security risks and should be avoided.
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