Endereço MAC

Structure and Assignment

A MAC (Media Access Control) address is a 48-bit identifier burned into a network interface controller (NIC) at manufacture. It is written as six pairs of hexadecimal digits separated by colons or hyphens, for example 00:1A:2B:3C:4D:5E. The first three octets form the Organizationally Unique Identifier (OUI), assigned by the IEEE to the manufacturer — you can identify who made a device from its OUI. The final three octets are the device-specific serial number chosen by the manufacturer.

How MAC Addresses Are Used

MAC addresses operate at Layer 2 (the data link layer) and are used for communication within a single Subnet MaskA 32-bit number (e.g., 255.255.255.0) that divides an IP address into network and host portions. It determines which part of the address identifies the network and which part identifies individual devices. segment. When a device sends data across a local network, the frame header contains both a source and destination MAC address. ARPAddress Resolution Protocol. A Layer 2 protocol that maps an IP address to a physical MAC address on a local network. When a device needs to communicate with another on the same subnet, ARP discovers the target's hardware address. resolves IPv4Internet Protocol version 4. The fourth revision of IP using 32-bit addresses (e.g., 192.168.1.1), providing approximately 4.3 billion unique addresses. Still the most widely used internet protocol despite address exhaustion. addresses to MAC addresses so that frames reach the correct device on the same broadcast domain. Unlike Public IP AddressA globally unique IP address assigned by an ISP that is routable on the public internet. Every device directly accessible from the internet must have a public IP address. or Private IP AddressAn IP address from reserved ranges (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16) used within local networks. Private addresses are not routable on the public internet and require NAT for external communication. addresses, MAC addresses are not routed across the internet — RouterA network device that forwards data packets between different networks by examining destination IP addresses and consulting its routing table. Routers operate at Layer 3 (Network) of the OSI model. devices strip and rewrite Layer 2 headers at every HopOne segment of a network path between a source and destination, representing the passage of a packet through a single router or intermediate device. The total number of hops affects latency and is visible via traceroute..

MAC Randomization and Privacy

Modern operating systems use MAC address randomization for Wi-FiA family of wireless networking protocols based on the IEEE 802.11 standards, enabling devices to connect to a local network without cables. Wi-Fi 6 (802.11ax) and Wi-Fi 7 (802.11be) are the latest generations. probe requests to prevent tracking by passive scanners. iOS, Android, and Windows 10+ generate a random MAC when scanning for networks and may use a per-network randomized address after association. Network administrators managing device policies via MAC-based access control lists should be aware that randomization can break such policies unless the device is configured to use a stable MAC for known SSIDService Set Identifier. The human-readable name of a Wi-Fi network that access points broadcast so nearby devices can discover and connect to it. SSIDs can be hidden to reduce casual visibility. connections.