MAC ↔ IPv6 / EUI-64

MAC ↔ IPv6 / EUI-64

Local Processing

Derive EUI-64 and IPv6 link-local addresses from a MAC, or recover the MAC from an IPv6 address.

How It Works & Processing Standards

Derive EUI-64 and IPv6 link-local addresses from a MAC, or recover the MAC from an IPv6 address.

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Current Limits

  • Maximum input length: 100,000 characters

IPv6 autoconfiguration inserts ff:fe into the middle of the MAC and flips the 7th bit (modified EUI-64) to form the address suffix. Choose MAC → link-local, MAC → EUI-64 or IPv6 → MAC under "Task".

What You Can Do

MAC → link-local
Builds the fe80:: link-local address.
MAC → EUI-64
Shows the 64-bit interface identifier.
IPv6 → MAC
Recovers the MAC from an EUI-64-based IPv6 address.

How to Use MAC ↔ IPv6 / EUI-64

  1. 1
    Choose a taskPick the direction.
  2. 2
    Enter an addressPaste a MAC or IPv6 address.
  3. 3
    CopyCopy the converted address.

Examples

MAC → link-local
Input: 00:1A:2B:3C:4D:5E
Result: fe80::21a:2bff:fe3c:4d5e
MAC → EUI-64
Input: 00:1A:2B:3C:4D:5E
Result: 02:1a:2b:ff:fe:3c:4d:5e
IPv6 → MAC
Input: fe80::21a:2bff:fe3c:4d5e
Result: 00:1a:2b:3c:4d:5e

Common Use Cases

  • Finding which device an fe80:: address in a neighbour table belongs to
  • Checking EUI-64 exercises for networking courses

Frequently Asked Questions (FAQ)

Why does 00 become 02?

Modified EUI-64 flips the U/L bit (the 7th bit) of the first byte, so 00 (0000 0000) becomes 02 (0000 0010).

Can every IPv6 address be turned back into a MAC?

No. Modern operating systems often use random identifiers for privacy. Only addresses with ff:fe in the middle can be reversed.

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