IANA reserved address

Source: Internet
Author: User
Tags reserved port number

The IANA refers to (Internet assigned Numbers authority), the Internet number distribution authority. Responsible for IP address assignment planning and port definition for TCP/UDP public services. The Internet proxy member authority (IANA) is the governing body of IP addresses, domain names, and many other parameters used in the Internet. The day-to-day responsibilities of IP addresses, members of autonomous systems, and many top-level and two-level domain assignments are assumed by the Internet Registry (IR) and regional registries.

The port number can be divided into three ranges: known ports, registered ports, and dynamic and/or private ports.

"Known ports" are ports from 0 to 1023.

The "register Port" is a port from 1024 to 49151.

"Dynamic and/or private ports" are ports from 49152 to 65535. In theory, these ports should not be assigned to services.

Known ports are assigned by the IANA and can only be used by systems (or root) processes or programs executed by privileged users in most systems. The port used in TCP [RFC793] is used to name the logical connection end of a long-term conversation. To provide services to unknown callers, the system defines a service contact port.

The contact port is sometimes referred to as a "known port." To maximize these ports, UDP [RFC768] uses the same port assignment. The assigned port uses only a small number of available port numbers. For many years, the assigned port has been in the range of 0-255. Recently, the range of allocated ports managed by the IANA has expanded to 0-1023.

Register Port number

The "register Port" is listed by the IANA and can be used by ordinary user processes or programs executed by ordinary users on most systems. The port used in TCP [RFC793] is used to name the logical connection end of a long-term conversation. To provide services to unknown callers, the system defines a service contact port.

The IANA registers the use of these ports and provides convenience to the community. To maximize these ports, UDP [RFC768] uses the same port assignment. The "Register port" range is 1024-49151.

Within the range of IP addresses, the routing address IANA (internetassignednumbersauthority) retains part of the address as a private IP address space and is used exclusively for internal LAN use, which are listed below:

Class IP address range network number

A (equivalent to 1 IP addresses of type a)

b (equivalent to 16 consecutive B-Class IP addresses)

C (equivalent to 256 consecutive C-Class IP addresses)

These addresses are not assigned by the Internet, so they are never routed on the internet, and although they are not directly connected to the Internet, they can still be used to communicate with the Internet, and we can use the appropriate address classes as needed, Boldly use these addresses as public IP addresses in an internal LAN. On the Internet, these addresses are also available for devices that do not need to communicate with the Internet, such as printers, managed hubs, and so on to conserve IP address resources.

Special IP address (reserved IP address) Introduction

Just as each of us has an ID number, every computer in the network (or, more specifically, the network interface of each device) has an IP address to mark itself. We may all know that these addresses are made up of four bytes, dotted decimal notation and their a,b,c classification, however, in the total number of Chiceae available IP addresses, do you know some of the following common special meaning addresses? Let's take a look at it:


Strictly speaking, is no longer a real IP address. It represents such a collection: all unknown host and destination networks. The "unclear" here means that there are no specific entries in the local routing table indicating how to get there. For this machine, it is a "shelter", all do not know "three without" personnel, are sent in. If you set a default gateway in your network settings, the Windows system automatically generates a default route with a destination address of


Restrict broadcast addresses. For this computer, this address refers to all hosts within the network segment (the same broadcast domain). If translated into human language, it should be like this: "Everyone in this room has noticed!" This address cannot be forwarded by the router.


The native address, used primarily for testing. In Chinese it means "myself". In the Windows system, this address has an alias "Localhost". Addressing such an address is not able to send it to the network interface. Unless there is an error, there should never be a packet with the destination address "" on the transport media.


multicast address, notice the difference between it and the broadcast. This is the address from to refers to all hosts, refers to all routers. Such addresses are used for a number of specific programs and multimedia programs. If your host has a IRDP (Internet Routing Discovery protocol, using multicast functionality), you should have a route in your host routing table.

Five, 169.254.x.x

If your host uses DHCP to automatically obtain an IP address, then when your DHCP server fails, or the response time is too long to exceed a system-specified time, the wingdows system assigns you such an address. If you find that your host IP address is a sort of address, it's unfortunate that your network is not functioning properly.

Six, 10.x.x.x, 172.16. X. x~172.31. X. X, 192.168. X. X

Private addresses, which are used in a large number of enterprise internal networks. Some broadband routers also tend to use as the default address. Private networks may use arbitrary IP addresses because they are not interconnected with the outside. Such an address is reserved for use in order to avoid the confusion of addresses when accessing public networks later. Private networks that use private addresses, when connected to the Internet, use address translation (NAT) to translate private addresses into public legitimate addresses. This type of address is not present on the Internet.

For a host on a network, it can receive three kinds of legitimate destination network address: Native IP address, broadcast address and multicast address.

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