Information, Computer and Network Security Terms Glossary and Dictionary

Private IP Address

Private IP addresses, also often called RFC1918 addresses, are the IP addresses set aside by IANA according to IETF RFC 1918 for private use by companies and organizations in their private network. Private IP Addresses cannot be used to connect directly to the Internet because they are non-routable. On the other hand, the public IP addresses are typically owned, either by very large corporations or by ISPs for public to use for routing across any public network such as the Internet. When a user contracts for service from an ISP, the user is allocated to some number of legitimate IP Addresses out of that ISPs pool of public IP addresses. IANA has set aside three address ranges for use by private or non-Internet connected networks. This is referred to as Private Address Space with the reserved address blocks as: 10.0.0.0 to 10.255.255.255 (10/8 prefix) 172.16.0.0 to 172.31.255.255 (172.16/12 prefix) 192.168.0.0 to 192.168.255.255 (192.168/16 prefix).

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Private IP Address