Overview

MAC address is also called physical address, hardware address or link address, which is written inside the hardware when it is produced by the network equipment manufacturer. Both the IP address and the MAC address are expressed in binary in the computer, the IP address is 32 bits, and the MAC address is 48 bits. The length of the MAC address is 48 bits (6 bytes), usually expressed as 12 hexadecimal numbers, and each 2 hexadecimal numbers are separated by colons, such as: 08:00:20:0A:8C: 6D is a MAC address, where the first 6 hexadecimal numbers 08:00:20 represent the network hardware manufacturer’s number, which is assigned by the IEEE Institute of Electrical and Electronics Engineers, and the last 3 hexadecimal numbers 0A:8C:6D represent The serial number of a network product (such as a network card) manufactured by this manufacturer. As long as you don't change your MAC address, then your MAC address is unique in the world.

Bits 0-23 are allocated by the manufacturer. Bits 24-47 are called organizationally unique identifiers that identify LAN (local area network) nodes. The 40th bit is the multicast address flag. The physical address of the network card is usually It is the EPROM (a flash memory chip that can usually be erased and written by a program) burned into the network card by the network card manufacturer. It stores the addresses of the computer that actually sends the data and the host that receives the data when transmitting data.

To put it vividly, the MAC address is just like the ID number on our ID card, which is unique in the world.

Manufacturers that produce network cards, routers, WIFI wireless products, and Bluetooth products need to apply for the IEEE OUI code for the product, that is, the manufacturer code of the MAC address. After the manufacturer obtains this code, add a 24-bit (bite) manufacturer's self-edited device number to form the MAC address of the device.