In the world of hacking and specially Networking, you will often come across this term “MAC Address”. It is used in various hacks, but the majority doesn’t even knows what it is. So What exactly is it? What does it do? How it is used? Is it related to IP address?
The Media Access Control (MAC) address is a binary number used to uniquely identify computer network adapters. These numbers (sometimes called “hardware addresses”) are physically burned into the network hardware during the manufacturing process, or stored in firmware, and designed to not be modified. Some refer to them as “Ethernet addresses” for historical reasons, but most popular types of networks utilize MAC addressing including Ethernet, WiFi and Bluetooth.
Format of a MAC Address:
The leftmost 6 digits (24 bits) called “prefix” are associated with the adapter manufacturer. Each vendor registers and obtains MAC prefixes as assigned by the IEEE (Institute of Electrical and Electronics Engineers). Vendors often possess many prefix numbers associated with their different products. For example, the prefixes:
00:13:10, 00:25:9C and 68:7F:74 (plus many others) all belong to Linksys (Cisco Systems).
The rightmost digits of a MAC address represent an identification number for the specific device. Among all devices manufactured with the same vendor prefix, each is given their own unique 24-bit number. Note that hardware from different vendors may happen to share the same device portion of the address.
64-bit MAC Addresses:
While traditional MAC addresses are all 48 bits in length, a few types of networks require 64-bit addresses instead. “ZigBee” wireless home automation and other similar networks based on “IEEE 802.15.4”, for example, require 64-bit MAC addresses to be configured on their hardware devices. TCP/IP networks based on IPv6 also implement a different approach to communicating with MAC addresses compared to mainstream IPv4. Instead of 64-bit hardware addresses. (TECHNICAL: IPv6 automatically translates 48-bit MAC address to a 64-bit address by inserting a fixed (hardcoded) 16-bit value in between the vendor prefix and the device identifier. IPv6 calls these numbers “identifiers” to distinguish them from true 64-bit hardware addresses.)
For example, a 48-bit MAC address-
00:25:96:12:34:56 might appear on an IPv6 network as say for example, in either of these two forms:
(They simply add in the remaining 16 bits containing known characters at a known position so it can be easily converted back and forth, if needed to. In above case, “FFFE” fills up the requirement.)
MAC vs. IP Address Relationship
TCP/IP networks use both MAC addresses and IP addresses but for separate purposes. A MAC address remains fixed to the device’s hardware while the IP address for that same device can be changed depending on its TCP/IP network configuration and ISP. Media Access Control operates at one Layer of the OSI model (Open Systems Interconnection) while Internet Protocol operates at another Layer, meaning they each do their own tasks without interfering with each other. This allows MAC addressing to support other kinds of networks besides TCP/IP.
IP networks manage the conversion between IP and MAC addresses using Address Resolution Protocol (ARP). Basically, ARP defines a set of rules according to which IP and MAC addresses can be related. So, all in all MAC addresses are simply a unique number assigned to a Network adapter. They help identifying the specific device to which a specific packet of information must reach in order to create a successful connection to exchange data. You need an address to send a mail, right? That is just what MAC addresses brings to the table.