Month: May 2025

What is a MAC Address?

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A MAC address (Media Access Control address) is a unique identifier assigned to a network interface controller (NIC) for use as a network address in communications within a network segment. MAC addresses are primarily used for network technologies that operate in the data link layer (Layer 2) of the OSI model, such as Ethernet and Wi-Fi.

Format of a MAC Address

A MAC address is typically a 48-bit number (although some newer types use 64-bit) and is usually displayed as six groups of two hexadecimal digits, separated by colons (:), hyphens (-), or no separator. For example:

mathematica
00:1A:2B:3C:4D:5E
00-1A-2B-3C-4D-5E
001A.2B3C.4D5E

Types of MAC Addresses

  1. Unicast – Identifies a single network device.

  2. Multicast – Identifies a group of devices.

  3. Broadcast – Sent to all devices on the network (FF:FF:FF:FF:FF:FF).

Structure

A standard 48-bit MAC address includes:

  • OUI (Organizationally Unique Identifier) – The first 24 bits (first 3 bytes), assigned by IEEE, identify the manufacturer.

  • NIC Specific – The last 24 bits are uniquely assigned by the manufacturer.

For example:

makefile
00:14:22:01:23:45

  • 00:14:22 is the OUI (e.g., Dell Inc.)

  • 01:23:45 is the unique identifier for the device.

Purpose of a MAC Address

  • Device Identification: Helps uniquely identify hardware on a local network.

  • Network Communication: Used by switches and routers to forward data to the correct destination.

  • Security Filtering: Network administrators can allow or block access using MAC address filtering.

  • Tracking: MAC addresses can be used to track devices within networks (e.g., Wi-Fi).

MAC Address vs IP Address

Feature MAC Address IP Address
Layer Data Link (Layer 2) Network (Layer 3)
Scope Local network Global/Internet
Permanence Permanent (burned into NIC) Can change (dynamic/static)
Format 48-bit hexadecimal 32-bit (IPv4) or 128-bit (IPv6)

Can a MAC Address Be Changed?

Yes, although it’s usually hardcoded into the device hardware, MAC spoofing is possible using software to temporarily change it. This can be useful for:

  • Privacy protection

  • Network testing

  • Bypassing MAC filters

How to Find Your MAC Address

On Windows:

  1. Open Command Prompt

  2. Type ipconfig /all

  3. Look for “Physical Address”

On macOS/Linux:

  1. Open Terminal

  2. Type ifconfig or ip link

  3. Look for “ether” or “HWaddr”