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Tim Fisher has more than 30 years' of professional technology experience. He's been writing about tech for more than two decades and serves as the VP and General Manager of Lifewire.

How do I make my IP address private?

How can I tell what device is associated with a private IP address?

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A private IP address is an IP address that's reserved for internal use behind a router or other Network Address Translation (NAT) device, apart from the public. These are in contrast to public IP addresses , which are public and can't be used within a home or business network. Sometimes a private address is also referred to as a local IP address.

The Internet Assigned Numbers Authority (IANA) reserves the following IP address blocks for use as private IP addresses:

The first set allows for over 16 million addresses, the second for over 1 million, and over 65,000 for the last range.

Another range of private IP addresses is 169.254.0.0 to 169.254.255.255, but those are for Automatic Private IP Addressing (APIPA) use only.

In 2012, the IANA allocated 4 million addresses of 100.64.0.0/10 for use in carrier-grade NAT environments.

Instead of having devices inside a home or business network each use a public IP address, of which there's a limited supply, private IP addresses provide an entirely separate set of addresses that allow access on a network but without taking up a public IP address space.

For example, most routers in homes and businesses across the globe have the IP address of 192.168.1.1 , and assign 192.168.1.2 , 192.168.1.3 , ... to the various devices that connect to it (using DHCP ).

It doesn't matter how many routers use the 192.168.1.1 address, or how many dozens or hundreds of devices inside that network share IP addresses with users of other networks because they aren't communicating with each other directly. Instead, the devices in a network use the router to translate requests through the public IP address, which can communicate with other public IP addresses and eventually to other local networks.

The hardware within a specific network that's using a private IP address can communicate with all the other hardware within the confines of that network but require a router to communicate with devices outside the network, after which the public IP address is used for the communication.

For example, before landing on this page, your device (such as a computer or phone), which uses a private IP address, requested this page through a router, which has a public IP address. Once the request was made and Lifewire responded to deliver the page, it was downloaded to your device through a public IP address before reaching your router, after which it was handed off to your private/local address to reach your device.

All the devices (laptops, desktops, phones, tablets, and others) that are contained within private networks around the world can use a private IP address with virtually no limitation, which can't be said for public IP addresses.

Private IP addresses also provide a way for devices that don't need a connection to the internet, such as file servers and printers, to communicate with the other devices on a network without being directly exposed to the public.

Another set of IP addresses that are restricted even further are called reserved IP addresses. These are similar to private IP addresses in the sense that they can't be used to communicate on the internet, but they're even more restrictive than that.

The most famous reserved IP is 127.0.0.1 . This address is called the loopback address and is used to test the network adapter or integrated chip. No traffic addressed to 127.0.0.1 is sent over the local network or public internet.

Technically, the entire range from 127.0.0.0 to 127.255.255.255 is reserved for loopback purposes, but you'll almost never see anything but 127.0.0.1 used in the real world.

Addresses in the range from 0.0.0.0 to 0.255.255.255 are also reserved but don't do anything at all. If you're even able to assign a device an IP address in this range, it will not function properly no matter where on the network it's installed.

Knowing your private IP address is only helpful in specific, and for most people rare, situations.

If you want to connect one computer to another on your network, for example, a mapped network drive , you can do so through its local IP address. You can also use a local IP address with remote desktop software to control a computer from afar. A private IP address is also needed to direct a specific network port from a router to a particular computer on the same network, a process called port forwarding .

The easiest way to find your private IP address in Windows is to use Command Prompt with the ipconfig command .

If you're not sure what your router or other default gateway's private IP address is, see How to Find Your Default Gateway IP Address . You can also find your public IP address , but it works a little differently.

When a device such as a router is plugged in, it receives a public IP address from an ISP . It's the devices that connect to the router that are given private addresses.

Private IP addresses can't communicate directly with a public IP address. This means if a device that has a private IP address is connected directly to the internet, and therefore becomes non-routable, the device will have no network connection until the address is translated into a working address through a NAT, or until the requests it sends are sent through a device that does have a valid public IP address.

All traffic from the internet can interact with a router. This is true for everything from regular HTTP traffic to FTP and RDP. However, because private IP addresses are hidden behind a router, the router must know which IP address it should forward information to if you want an FTP server to be set up on a home network. For this to work properly for private IP addresses, port forwarding must be set up.

Forwarding one or more ports to a specific private IP address involves logging into the router to access its settings, and then choosing which ports to forward and to where they should go.

You can use a virtual private network (VPN) service to hide your IP address. VPNs mask your actual IP address by assigning a virtual location and encrypting your personal information. Another way to hide your IP address when browsing online is to use a web proxy to create an anonymous IP address.
One option is to look up the IP addresses of all the devices connected to your network . You can usually find the addresses in the device settings. If you need to find IP addresses of network hardware in Windows, use the tracert command.

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From Wikipedia, the free encyclopedia

^ Classful addressing is obsolete and has not been used in the Internet since the implementation of Classless Inter-Domain Routing (CIDR), starting in 1993. For example, while 10.0.0.0 / 8 was a single class A network, it is common for organizations to divide it into smaller / 16 or / 24 networks. Contrary to a common misconception, a / 16 subnet of a class A network is not referred to as a class B network. Likewise, a / 24 subnet of a class A or B network is not referred to as a class C network. The class is determined by the first three bits of the prefix. [3]

^ The first and last / 24 subranges of the subnet (addresses 169.254.0.0 through 169.254.0.255 and 169.254.255.0 through 169.254.255.255 ) are reserved for future use by RFC 3927

^ Jump up to: a b Y. Rekhter; B. Moskowitz; D. Karrenberg; G. J. de Groot; E. Lear (February 1996). Address Allocation for Private Internets . Network Working Group IETF . doi : 10.17487/RFC1918 . BCP 5. RFC 1918 .

^ Jump up to: a b R. Hinden; B. Haberman (October 2005). Unique Local IPv6 Unicast Addresses . Network Working Group IETF . doi : 10.17487/RFC4193 . RFC 4193 .

^ Forouzan, Behrouz (2013). Data Communications and Networking . New York: McGraw Hill. pp. 530–31. ISBN 978-0-07-337622-6 .

^ Jump up to: a b J. Weil; V. Kuarsingh; C. Donley; C. Liljenstolpe; M. Azinger (April 2012). Reserved IPv4 Prefix for Shared Address Space . IETF . p. 8. doi : 10.17487/RFC6598 . ISSN 2070-1721 . BCP 153. RFC 6598 .

^ C. Huitema; B. Carpenter (September 2004). Deprecating Site Local Addresses . Network Working Group. doi : 10.17487/RFC3879 . RFC 3879 .

^ R. Hinden; S. Deering (February 2006). IP Version 6 Addressing Architecture . Network Working Group, IETF . doi : 10.17487/RFC4291 . RFC 4291 . Updated by RFC 5952, RFC 6052, RFC 7136, RFC 7346, RFC 7371, RFC 8064.

^ S. Thomson; T. Narten; T. Jinmei (September 2007). IPv6 Stateless Address Autoconfiguration . Network Working Group, IETF . doi : 10.17487/RFC4862 . RFC 4862 . Updated by RFC 7527.

In Internet networking , a private network is a computer network that uses a private address space of IP addresses . These addresses are commonly used for local area networks (LANs) in residential, office, and enterprise environments. Both the IPv4 and the IPv6 specifications define private IP address ranges. [1] [2]

Private network addresses are not allocated to any specific organization. Anyone may use these addresses without approval from regional or local Internet registries . Private IP address spaces were originally defined to assist in delaying IPv4 address exhaustion . IP packets originating from or addressed to a private IP address cannot be routed through the public Internet .

The Internet Engineering Task Force (IETF) has directed the Internet Assigned Numbers Authority (IANA) to reserve the following IPv4 address ranges for private networks: [1] : 4

In practice, it is common to subdivide these ranges into smaller subnets.

In April 2012, IANA allocated the block 100.64.0.0/10 (100.64.0.0 to 100.127.255.255, netmask 255.192.0.0) for use in carrier-grade NAT scenarios. [4]

This address block should not be used on private networks or on the public Internet. The size of the address block (2 22 , approximately 4 million addresses) was selected to be large enough to uniquely number all customer access devices for all of a single operator's points of presence in a large metropolitan area such as Tokyo . [4]

The concept of private networks has been extended in the next generation of the Internet Protocol , IPv6 , and special address blocks are reserved.

The address block fc00:: / 7 is reserved by IANA for Unique Local Addresses (ULA). [2] They are unicast addresses, but contain a 40-bit random number in the routing prefix to prevent collisions when two private networks are interconnected. Despite being inherently local in usage, the IPv6 address scope of unique local addresses is global.

The first block defined is fd00:: / 8 , designed for /48 routing blocks, in which users can create multiple subnets, as needed.

A former standard proposed the use of site-local addresses in the fec0:: / 10 block, but because of scalability concerns and poor definition of what constitutes a site , its use has been deprecated since September 2004. [5]

Another type of private networking uses the link-local address range. The validity of link-local addresses is limited to a single link; e.g. to all computers connected to a switch , or to one wireless network . Hosts on different sides of a network bridge are also on the same link, whereas hosts on different sides of a network router are on different links.

In IPv4, link-local addresses are codified in RFC 6890 and RFC 3927. Their utility is in zero-configuration networking when Dynamic Host Configuration Protocol (DHCP) services are not available and manual configuration by a network administrator is not desirable. The block 169.254.0.0 / 16 was allocated for this purpose. If a host on an IEEE 802 ( Ethernet ) network cannot obtain a network address via DHCP, an address from 169.254.1.0 to 169.254.254.255 [Note 2] may be assigned pseudorandomly . The standard prescribes that address collisions must be handled gracefully.

In IPv6, the block fe80:: / 10 is reserved for IP address autoconfiguration. [6]
The implementation of these link-local addresses is mandatory, as various functions of the IPv6 protocol depend on them. [7]

Private addresses are commonly used in residential IPv4 networks. Most Internet service providers (ISPs) allocate only a single publicly routable IPv4 address to each residential customer, but many homes have more than one computer , smartphone , or other Internet-connected device. In this situation, a network address translator (NAT/PAT) gateway is usually used to provide Internet connectivity to multiple hosts.

Private addresses are also commonly used in corporate networks which, for security reasons, are not connected directly to the Internet. Often a proxy, SOCKS gateway, or similar devices are used to provide restricted Internet access to network-internal users. 24-bit block private addresses are also commonly used in the North Korean Kwangmyong network .

In both cases, private addresses are often seen as enhancing network security for the internal network, since use of private addresses internally makes it difficult for an Internet (external) host to initiate a connection to an internal system.

It is common for packets originating in private address spaces to be misrouted onto the Internet. Private networks often do not properly configure DNS services for addresses used internally and attempt reverse DNS lookups for these addresses, causing extra traffic to the Internet root nameservers . The AS112 project attempted to mitigate this load by providing special blackhole anycast nameservers for private address ranges which only return negative result codes ( not found ) for these queries.

Organizational edge routers are usually configured to drop ingress IP traffic for these networks, which can occur either by misconfiguration, or from malicious traffic using a spoofed source address. Less commonly, ISP edge routers drop such egress traffic from customers, which reduces the impact to the Internet of such misconfigured or malicious hosts on the customer's network.

Since the private IPv4 address space is relatively small, many private IPv4 networks unavoidably use the same address ranges. This can create a problem when merging such networks, as some addresses may be duplicated for multiple devices. In this case, networks or hosts must be renumbered, often a time-consuming task, or a network address translator must be placed between the networks to translate or masquerade one of the address ranges.

IPv6 defines unique local addresses in RFC 4193, providing a very large private address space from which each organization can randomly or pseudo-randomly allocate a 40-bit prefix, each of which allows 65536 organizational subnets. With space for about one trillion (10 12 ) prefixes, it is unlikely that two network prefixes in use by different organizations are the same, provided each of them was selected randomly, as specified in the standard. When two such private IPv6 networks are connected or merged, the risk of an address conflict is therefore virtually absent.

Despite official warnings, historically some organizations have used other parts of the reserved IP addresses for their internal networks. [ citation needed ]

fdxx:xxxx:xxxx:yyyy:zzzz:zzzz:zzzz:zzzz

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An MIT graduate who brings years of technical experience to articles on SEO, computers, and wireless networking.

Chris Selph is a CompTIA-certified technology and vocational IT teacher. He also serves as network & server administrator and performs computer maintenance and repair for numerous clients.

Lifewire is part of the Dotdash Meredith publishing family.

We've updated our Privacy Policy, which will go in to effect on September 1, 2022. Review our Privacy Policy

Get tech's top stories in 30 seconds:

IP addresses in Internet Protocol (IP) version 4 (IPv4) range from 0.0.0.0 up to 255.255.255.255. The IP address 0.0.0.0 has several special meanings on computer networks. However, it can not be used as a general-purpose device address.

This IP address is structured like a regular one (it has four places for numbers). However, it's a placeholder address or one that's used to describe that there isn't a normal address assigned—neither public nor private . For example, instead of putting no IP address into the network area of a program, 0.0.0.0 can be used to mean anything from accept all IP addresses or block all IP addresses to the default route.

It's easy to confuse 0.0.0.0 and 127.0.0.1 . An address with four zeros has several defined uses (as described below), while 127.0.0.1 has one specific purpose of allowing a device to send messages to itself.

The 0.0.0.0 IP address is sometimes called a wildcard address, unspecified address, or INADDR_ANY.

In short, 0.0.0.0 is a non-routable address that describes an invalid or unknown target. However, it means something different depending on whether it's seen on a client device like a computer or on a server machine.

PCs and other client devices normally show an address of 0.0.0.0 when not connected to a TCP/IP network. A device might give itself this address by default whenever it is offline.

It might also be automatically assigned by DHCP in the case of address assignment failures. When set with this address, a device cannot communicate with any other devices on that network.

0.0.0.0 can also theoretically be set as a device's subnet mask rather than its IP address. However, a subnet mask with this value has no practical purpose. Both the IP address and network mask are typically assigned 0.0.0.0 on a client.

Depending on the way it's used, firewall or router software might use 0.0.0.0 to indicate that every IP address should be blocked (or allowed).

Some devices, particularly network servers , possess more than one network interface. TCP/IP software applications use 0.0.0.0 as a programming technique to monitor network traffic across all the IP addresses currently assigned to the interfaces on that multi-homed device.

While connected computers do not use this address, messages carried over IP sometimes include 0.0.0.0 inside the protocol header when the source of the message is unknown.

If a computer is properly configured for TCP/IP networking but shows 0.0.0.0 for an address, try the following to troubleshoot this problem and obtain a valid address:

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