MAC Addresses
What is a MAC Address?⌗
A media access control (MAC) address is a unique identification number assigned to every network interface controller (NIC).
MAC addresses are assigned by the device manufacturer and are burned-in to the NIC.
MAC Addresses are also called
- Burned-in address: as the address is burned into the Read-only Memory (ROM) of the NIC,
- Physical address: The MAC address is the unique hardware address of every NIC,
- Hardware address
- Ethernet hardware address
Structure of MAC Address⌗
A MAC address is a 48-bit address. It has 6 groups of 2 hexadecimal digits.
The 6 octets are separated by colons (:), hyphens (-), or left without a separator.
Organizationally Unique Identifier⌗
The first 3 octets of a MAC address represent the manufacturer of the NIC.
The OUI are assigned by the IEEE Registration Authority.
For example,
OUI | Organization |
---|---|
AC:ED:5C | Intel Corporate |
CC:46:D6 | Cisco Systems, Inc |
F8:8F:CA | Google, Inc. |
C4:2A:D0 | Apple, Inc. |
Manufacturers usually have multiple OUIs. The full list of OUIs is here.
Some virtualisation softwares have their own OUIs, such as VMware (00:50:56
), QEMU (52:54:00
), etc.
Network Interface Controller⌗
The NIC is the hardware component that connects a device to the network, such an adapter or card.
The last 3 octets of the MAC address identify the NIC.