Package mactracker provides IEEE OUI lookups for MAC addresses. The package ships with an embedded database of IEEE OUI/CID/IAB/OUI-28/OUI-36 registrations, supplemented by tables for virtual-machine and other private prefixes. The simplest entry point is Lookup, which accepts any common MAC notation: When you already have the address as a byte slice (e.g. from a packet capture), use LookupBytes to avoid an unnecessary string round-trip: ParseMAC converts a string in any common format to an OuiHardwareAddr: Lookup returns a [OUiBlock] with a [Virtual] flag for known virtual-machine prefixes,and you can also check against the virtual table directly with LookupVirtual, LookupVirtual checks a MAC address against a table of hypervisor and cloud-provider prefixes: LookupOUI searches only the primary IEEE registration table: LookupOverride searches only the override table for unofficial and private registrations: MaskFromCIDR creates a byte-level mask useful for custom prefix matching: