Random MAC address generator
Random MAC addresses for virtual machines, containers and network test fixtures. The locally administered bit is set so they never clash with real hardware.
Press generate to fill this table.
Reading the first byte
A MAC address is 48 bits. In the first byte, bit 0 selects unicast (0) or multicast (1), and bit 1 selects a globally unique, manufacturer-assigned address (0) or a locally administered one (1). Phones that randomise their Wi-Fi MAC for privacy, as iOS and Android do by default, set that locally administered bit too.
Questions people ask
What is a locally administered MAC address?
The second-least-significant bit of the first byte (the U/L bit) marks an address as locally administered rather than assigned by a manufacturer under an IEEE OUI. Setting it guarantees your random MAC can’t clash with real hardware. Such addresses have 2, 6, A or E as the second hex digit.
Why is the multicast bit cleared?
The least-significant bit of the first byte marks a multicast address. Network interfaces need unicast addresses, so the generator always clears it.
Which separator should I use?
Colons (00:1a:2b:…) are standard on Linux and macOS, hyphens on Windows, and Cisco IOS uses dotted groups of four (001a.2b3c.4d5e).