OUI Lookup
OUI Lookup (MAC Vendor)
Identify the manufacturer of a MAC address
Formats: 00:1A:2B:3C:4D:5E or 001A2B3C4D5E
Popular examples
What is OUI?
OUI (Organizationally Unique Identifier) is a 24-bit code assigned by the IEEE Registration Authority to network equipment manufacturers. The first 6 characters (3 octets) of a MAC address identify the manufacturer.
OUIs are represented in hexadecimal notation with hyphens (e.g. 00-1A-2B) or
colons (00:1A:2B). The IEEE maintains a public registry of all assigned OUIs,
which can be queried to determine which manufacturer produced a specific network device.
MAC addresses are formed by concatenating the 24-bit OUI with a 24-bit extension identifier
assigned by the manufacturer, resulting in EUI-48 identifiers (also known as MAC-48). For
more modern applications like IPv6, EUI-64 identifiers are used, which expand the address by
inserting the bytes FF-FE in the middle.
Common Use Cases
- Network administration: Identify device manufacturers on a corporate network for inventory and auditing
- Security: Detect unauthorized or suspicious devices by analyzing MAC addresses in network traffic
- Troubleshooting: Determine the source of connectivity issues by identifying the manufacturer of a switch or router
- Access control: Implement MAC whitelists or blacklists by manufacturer on enterprise WiFi networks
- Digital forensics: Trace the origin of devices involved in security incidents