EUI-64 IPv6 Address Generator
Turn a MAC address into its modified EUI-64 interface identifier, the fe80:: link-local address and the SLAAC address inside a /64 prefix.
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Input
Generate an IPv6 address from a MAC (EUI-64)
Output
fe80::21a:2bff:fe3c:4d5e
Interface identifier
21a:2bff:fe3c:4d5e
02 1a 2b ff fe 3c 4d 5e
Link-local
fe80::21a:2bff:fe3c:4d5e
SLAAC address in the prefix
2001:db8:1:2:21a:2bff:fe3c:4d5e
Modified EUI-64 (RFC 4291) puts ff:fe in the middle of the MAC and flips bit 1 of the first byte. Because the MAC is visible in the address, RFC 8981 privacy addresses and RFC 7217 stable-opaque addresses are the default on current Windows, macOS, Android and most Linux distributions; EUI-64 addresses still show up on routers, servers and embedded devices.
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About this tool
Method, assumptions, practical next steps, and limits.
Where you still see it
Routers, servers with static configuration, network equipment and embedded devices often use EUI-64 addresses, and link-local addresses on many systems still follow it. Recognising the ff:fe in the middle of an address tells you the MAC behind it, which is useful when matching neighbour tables to switch ports. See RFC 4291 appendix A.
Why desktops stopped
An address that embeds the MAC follows a laptop from network to network. RFC 8981 temporary addresses and RFC 7217 stable but opaque identifiers replaced EUI-64 for global addresses on current Windows, macOS, iOS, Android and most Linux distributions.