MAC Address Generator

Random MAC addresses are needed for virtual machines, containers, test networks and lab equipment. This generator creates up to 1,000 unique addresses at a time in the format your tool expects — colon, hyphen, Cisco dotted or plain — and sets the two special bits correctly: unicast or multicast, and locally administered so a random address can never collide with one a manufacturer assigned. Hypervisor prefixes for VMware, VirtualBox, Hyper-V, QEMU/KVM and Xen are built in.

How to use this tool

1. Choose how many addresses you need.
2. Pick the output format and letter case.
3. Keep "locally administered" and "unicast" for normal devices, or choose a hypervisor or custom prefix.
4. Copy the list.

Formula

first byte: bit 0 (I/G) = 0 unicast, 1 multicast · bit 1 (U/L) = 0 universally administered (OUI), 1 locally administered

A MAC address is 6 bytes. The first three form the OUI that the IEEE assigns to a manufacturer. A locally administered unicast address therefore starts with a byte whose second hex digit is 2, 6, A or E. With a prefix, only the remaining bytes are random.

Example

A random locally administered unicast address might be 6A:1F:C3:09:7B:E2 — 0x6A in binary is 0110 1010, so bit 0 is 0 (unicast) and bit 1 is 1 (locally administered). With the VMware prefix every address starts with 00:50:56, VMware's OUI, and only the last three bytes vary. In Cisco format the first example is written 6a1f.c309.7be2.