Convert a 48-bit MAC address into its modified EUI-64 interface identifier and the resulting IPv6 address.
Modified EUI-64 splits the MAC in half, inserts ff:fe in the middle and flips the universal/local bit so that a globally unique MAC produces an identifier marked as universally administered. This is the identifier SLAAC generates by default, so being able to derive it by hand is how you predict an address before a host boots and how you recognise one in a log.
EUI-64
ff:fe is inserted between the OUI and the device identifier, and bit 7 of the first octet (the universal/local bit) is inverted.
ff:fe is inserted between the OUI and the device identifier, and bit 7 of the first octet (the universal/local bit) is inverted. Modified EUI-64 splits the MAC in half, inserts ff:fe in the middle and flips the universal/local bit so that a globally unique MAC produces an identifier marked as universally administered.
This is the identifier SLAAC generates by default, so being able to derive it by hand is how you predict an address before a host boots and how you recognise one in a log.
This calculator takes 2 inputs: MAC address, Network prefix (first four groups). The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.