The Institute of Electrical and Electronics Engineers (IEEE) collects and maintains a database of Organizationally Unique Identifiers (OUI). Each identifier is a 24-bit number that uniquely identifies vendors, manufactures, and other organizations. MAC addresses are generated by prefixing this 24-bit number to ensure that all devices manufactured have unique MAC addresses.

An updated set of OUI data can be obtained from IEEE at http://standards-oui.ieee.org/oui.txt. This file is typically located at /usr/share/misc on most Linux systems. A sanitized list can also be obtained from https://linuxnet.ca/ieee/oui/