MAC Address Formatter
Result
00:1A:2B:3C:4D:5E
How it works
MAC addresses (Media Access Control addresses) are 48-bit hardware identifiers assigned to network interface cards. They are formatted as 6 pairs of hexadecimal octets, but different systems use different separator conventions: colons (Linux, macOS: 00:1A:2B:3C:4D:5E), hyphens (Windows: 00-1A-2B-3C-4D-5E), dots in groups of four (Cisco IOS: 001a.2b3c.4d5e), and no separators (00:1A:2B:3C:4D:5E as 001A2B3C4D5E). This tool normalizes between these formats.
**MAC address structure** First 3 bytes (24 bits): OUI (Organizationally Unique Identifier) — assigned to the hardware manufacturer by the IEEE. 00:50:56 = VMware. 00:0C:29 = VMware (workstation). 08:00:27 = VirtualBox. Bit 0 of first byte: 0 = unicast, 1 = multicast. Bit 1 of first byte: 0 = globally unique (OUI-assigned), 1 = locally administered (random or manually assigned).
**Randomized MAC addresses** Modern mobile OSes (iOS 14+, Android 10+, Windows 10+) randomize MAC addresses per network SSID to prevent tracking across access points. Randomized MACs have the locally administered bit set (bit 1 of first byte = 1) and change periodically. This makes MAC-based device identification and DHCP reservation unreliable for mobile devices.
**ARP and L2 switching** MAC addresses operate at Layer 2 (Data Link). Ethernet switches build MAC address tables (CAM tables) mapping MAC to port, forwarding frames only to the correct port. ARP (IPv4) and NDP (IPv6) resolve IP addresses to MAC addresses within a subnet. MAC addresses are local to a subnet — routers do not forward L2 frames.
Frequently Asked Questions
- Linux/macOS: ip link show or ifconfig. Look for 'ether xx:xx:xx:xx:xx:xx'. Windows: ipconfig /all — look for 'Physical Address'. Alternative (Windows): Get-NetAdapter | Select Name, MacAddress in PowerShell. Android: Settings → About Phone → Status → Wi-Fi MAC Address (note: modern Android shows a randomized MAC). iOS: Settings → Wi-Fi → (i) next to connected network → shows the current MAC (may be randomized per SSID since iOS 14).
- iOS 14+, Android 10+, and Windows 10+ randomize the MAC address per network SSID to prevent cross-network tracking. The locally administered bit (bit 1 of byte 1) is set to 1 in randomized MACs. The random MAC changes periodically (iOS every few weeks, Android configurable). This breaks MAC-based network management: DHCP reservations (assigning a specific IP to a device by MAC) fail because the MAC changes. MAC address filtering on Wi-Fi access points becomes ineffective. Network admission control and device inventory systems need to use 802.1X authentication instead.
- The MAC address in a transmitted frame is set by software, not hardware — despite being called a 'hardware address.' On Linux: ip link set dev eth0 address 00:11:22:33:44:55. On macOS: sudo ifconfig en0 ether 00:11:22:33:44:55. On Windows: change through Device Manager → adapter properties → Network Address. MAC spoofing is used for: testing MAC-based access controls, privacy (same purpose as OS-level MAC randomization), and connecting to networks with MAC filtering (in authorized penetration testing). Network equipment detects and may block MAC spoofing through port security features (sticky MAC, 802.1X).
- OUI (Organizationally Unique Identifier) is the first 3 bytes (24 bits) of a MAC address, assigned by the IEEE to hardware manufacturers. The IEEE maintains the public OUI registry at standards.ieee.org/products-programs/regauth. Tools: macvendors.com, Wireshark's built-in OUI lookup (Help → About → Folders → Personal configuration → manuf file), and CLI tools like nmap --script broadcast-arp. Virtualization platforms have well-known OUIs: 00:50:56/00:0C:29 = VMware, 08:00:27 = VirtualBox, 00:16:3E = Xen, 52:54:00 = QEMU/KVM.