MAC Address Tool

MAC Address Formats

MAC addresses are 48-bit hardware identifiers, but every operating system, vendor, and tool seems to format them differently. Linux and most Unix systems use colon-separated pairs (00:1A:2B:3C:4D:5E). Windows uses dash-separated pairs (00-1A-2B-3C-4D-5E). Cisco IOS uses dotted triplets (001A.2B3C.4D5E). Some logs and databases store them as bare hex (001A2B3C4D5E). Joining inventory data across systems requires normalizing all of these into a single canonical form.

OUI Vendor Lookup

The first three bytes of a MAC address are the Organizationally Unique Identifier (OUI), assigned by IEEE to a specific vendor. Looking up the OUI tells you which company manufactured the network interface — useful for identifying unknown devices on a network, auditing inventory, and detecting rogue hardware. This tool includes a curated OUI lookup for common vendors.

Locally-Administered and Multicast Bits

Two bits in the first byte have special meaning. The locally-administered bit (LAA) indicates the address was assigned by software, not burned in by the manufacturer — common with virtual machines and randomized addresses on mobile devices. The multicast bit indicates a group address rather than a single device. This tool decodes both flags so you can quickly tell physical hardware from virtual or randomized addresses. For related networking tools, see the Subnet Calculator, IP Address Converter, and DNS Lookup. Need help building network asset reporting or device inventory automation? Get in touch.