MAC Address
It is the Physical Addressing System for a device operating on Layer 2
These addresses are tied to the NIC of the device and they cannot be (physically) changed
No two NICs anywhere in the world have the same MAC address
EUI-48
MAC Addresses are generally made of 48 bits
They are represented using 12 hexadecimal characters
Each hexadecimal character is 4 bits (nibble) long i.e. 4 * 12 = 48 bits
First 6 characters (24-bits) are called OUI (Organizational Unique Identifier)
It is unique to each manufacturer (Vender Code)
Last 6 characters (24-bits) are assigned sequentially and are unique for each card
EUI-64
Some newer devices support MAC addresses that are made of 64 bits
24-bits are used to identify the manufacturer
And the last 40-bits are used to uniquely identify the device
There are used for IPv6 addressing
EUI-48 (MAC) is used to generate the longer EUI-64 interface ID
FF:FE is added in between the MAC address to make it compatible with IPv6
Different MAC Address Notations
08:00:27:EC:10:60 (Linux/ MAC)
08-00-27-EC-10-60 (Windows)
0800.27EC.1060 (Cisco)
MAC Address: Used to Identify a device (Who)
IP Address: Used to locate a device (Where)
ARP (Address Resolution Protocol) is used to find the MAC Address of other devices
Command: getmac /FO list /V
Types of MAC Address
Unicast
Unique address that is used by each device
Multicast
Send the packet to a group of devices that are on the network
0: Unicast Address
1: Multicast AddressWe can differentiate between unicast and multicast addresses by look at the LSB of the first byte
Broadcast
FF-FF-FF-FF-FF-FF
Send the packet to all the devices on the network