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Random MAC address generator

The MAC address generator produces a random 48-bit address with the locally administered bit set and the multicast bit clear, so it is a valid unicast address that cannot clash with a vendor-assigned one. Developers use it for virtual machine NICs, network simulators, DHCP test pools and packet fixtures. Pick the notation your tool expects: AA:BB:CC:DD:EE:FF, AA-BB-CC-DD-EE-FF, Cisco's aabb.ccdd.eeff or plain AABBCCDDEEFF. The second hex digit of the first octet is always 2, 6, A or E.

Open MAC Address Gen in the app Browse all tools

How to use MAC Address Gen

  1. Open MAC Address Gen in the Toolbox101 app; an address is already in the Output box.
  2. Pick the Format your tool expects: colons, hyphens, dots (Cisco style) or no separators.
  3. Click Generate New to draw another address.
  4. Click Copy and paste the address into your VM definition, simulator config or test data file.

Worked example

MAC Address Gen gives a different result every time, so yours will differ. This is one run:

Output

DE:23:73:E0:69:33

Frequently asked questions

What do the locally administered and unicast bits mean?

The two lowest bits of the first octet carry flags. The locally administered bit is set, which marks the address as chosen locally rather than assigned by a manufacturer, and the multicast bit is clear, so it is an ordinary unicast address. That is why the first octet always ends in 2, 6, A or E.

What formats can the generator output?

Four spellings of the same 48-bit address: colons (4A:2B:3C:0D:1E:5F), hyphens (4A-2B-3C-0D-1E-5F), Cisco dotted lowercase (4a2b.3c0d.1e5f) and plain (4A2B3C0D1E5F). Choose with the Format list; the notation changes, the address does not.

Can I use a generated address with a virtual machine?

Yes. Hypervisors such as libvirt and VirtualBox accept a plain hex MAC in the VM definition, and a locally administered address is the right kind for virtual NICs. For long-lived VMs many hypervisors can assign addresses themselves, which avoids collisions across machines you manage.

Are generated MAC addresses guaranteed to be unique?

No. Each draw is independent over 46 random bits, so two outputs could in theory collide. For a handful of test fixtures the risk is negligible; for fleets, let your tooling assign addresses.

Use MAC Address Gen now

Open MAC Address Gen in the app

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