๐ง MAC Address Generator
* Generated addresses are locally-administered (the LAA bit is set), distinguishing them from real vendor-assigned addresses.
Generate a batch of random MAC addresses for network equipment testing or dummy data. Choose the separator (colon or hyphen) and letter case. Generated addresses are locally-administered (the bit that marks a randomly-generated address is set).
How to use
- Enter the separator character and how many addresses to generate.
- Click "Generate" to see a list of random MAC addresses.
- Use the "Copy" buttons to copy an individual address or all of them.
How the calculation works
A MAC address is a 48-bit (six-byte) number that identifies network hardware, normally written as pairs of hex digits such as "3C:5A:B4:12:9F:0E". Manufacturers put an Organisationally Unique Identifier (OUI) assigned by the IEEE in the first three bytes, so addresses are unique worldwide. The two lowest bits of the first byte have special meanings. The lowest (the I/G bit) is 1 for multicast (a group of recipients) and 0 for unicast (a single device). The next bit up (the U/L bit) set to 1 marks a locally administered address โ one assigned by an administrator or software rather than the manufacturer. This tool generates six bytes from a cryptographically secure random source (crypto.getRandomValues), then clears the lowest bit of the first byte and sets the U/L bit. Every address it produces is therefore a unicast, locally administered address, distinguishable from real manufacturer-assigned ones.
Worked example
Suppose the random first byte is 0x3C (binary 00111100) Clearing the lowest bit (already 0) and setting the second-lowest gives 00111110 = 0x3E. Example: 3E:5A:B4:12:9F:0E For a locally administered unicast address, the second hex digit of the first byte is always 2, 6, A or E. The "randomised MAC addresses" phones use on Wi-Fi work the same way.
Things to be aware of
- Locally administered addresses can still collide by chance. Check for duplicates if you use them on the same network.
- Addresses imitating a particular manufacturer's OUI are not generated.
- Changing a device's MAC address can affect network authentication such as MAC address filtering.
- Intended for testing and dummy data.
FAQ
Could a generated MAC address collide with a real device's address?
The "locally administered" bit is set, distinguishing these from globally-assigned vendor MAC addresses. That said, this doesn't guarantee absolutely no collisions are possible.
Can I generate a MAC address for a specific vendor (OUI)?
No โ this tool doesn't mimic any specific vendor's OUI; it only generates random locally-administered addresses.
Can I configure real network equipment with these?
These are intended for testing and dummy data. Follow your network's policies before configuring real devices.