Random MAC Address Generator
Generate random MAC addresses with correct unicast/multicast and locally administered bits, an optional vendor OUI prefix and colon, hyphen or Cisco format.
1 to 5 bytes in hex, e.g. 00:1A:2B. The rest is random.
The two lowest bits of the first byte are set as chosen: bit 0 = multicast, bit 1 = locally administered. Locally administered unicast addresses (second digit 2, 6, A or E) never clash with real hardware.
What is MAC Address Generator?
Generate random 48-bit MAC (EUI-48) addresses for virtual machines, containers, network labs and tests. By default the addresses are locally administered unicast, so they can never clash with a manufacturer-assigned address. You can also keep a vendor prefix (OUI) and choose colon, hyphen, Cisco dot or no-separator formatting.
How to use MAC Address Generator
- Set How many addresses and the output Format.
- Keep Locally administered ticked (recommended), and leave Multicast unticked for device addresses.
- Optionally enter a Vendor prefix / OUI such as
00:1A:2B; only the remaining bytes are random. - Click Regenerate for new addresses and copy or download them.
Example
How many 3, Colons, Locally administered
2a:78:3b:41:ae:64 ea:6f:53:fc:13:5c a6:a1:3d:92:20:8c
The second hex digit of every address is 2, 6, A or E: locally administered unicast. Random — yours will differ.
When to use MAC Address Generator
Use it to assign MAC addresses to VMs (KVM, VirtualBox, Proxmox), Docker macvlan networks, test fixtures or network simulations. Do not use a real vendor's OUI on a network where it could collide with physical devices, and do not use it to impersonate other devices.
How MAC Address Generator works
Six random bytes are drawn with crypto.getRandomValues. In the first byte, bit 0 (I/G) is set for multicast or cleared for unicast and bit 1 (U/L) is set for locally administered or cleared for universally administered addresses. That is why locally administered unicast addresses always have 2, 6, A or E as the second hex digit (e.g. x2:…). With a vendor prefix, its bytes are copied unchanged and only the rest is random.
Common Use Cases
- Assigning static MACs to virtual machines or containers
- Creating test data for network inventory or DHCP software
- Building lab topologies in GNS3 or EVE-NG
- Generating sample addresses in Cisco xxxx.xxxx.xxxx format
FAQs
What is a locally administered MAC address?
One whose U/L bit (bit 1 of the first byte) is set. Manufacturers never use these, so they are safe for virtual and test devices.
What is the multicast bit?
Bit 0 of the first byte. If it is 1 the address identifies a group of receivers, so network cards must use unicast (0) addresses.
Will a vendor prefix make the MAC look like that brand?
Yes, tools that look up OUIs will show that vendor. Use it only in isolated test environments.