Generate MAC addresses for testing and convert them between colon, hyphen, Cisco dotted and separator-free notation
Paste addresses you already have and they are rewritten line by line into the notation selected above. Mixed separators are fine; each line is read as 12 hex digits.
A MAC address is 48 bits, that is six bytes. The first three bytes are the OUI that IEEE assigns to a manufacturer; the remaining three are assigned by that manufacturer per device. In a value such as 00:1A:2B the left three groups are the OUI. Entering up to three groups in the prefix field fixes them and fills the rest at random.
The lowest bit of the first byte (0x01) is the I/G bit: 1 means multicast, 0 means unicast. The next bit (0x02) is the U/L bit: 1 means locally administered, 0 means a globally assigned IEEE address. With the locally administered option enabled, generation sets 0x02 and clears 0x01, producing a locally administered unicast address.
Six fully random bytes can land inside a real vendor OUI. A value printed in a document or screenshot then appears to name hardware you never touched. Locally administered addresses are defined not to overlap the assigned ranges, so that confusion cannot happen. It is the same reasoning behind using 192.0.2.0/24 for documentation IP addresses.
| Notation | Example | Where you see it |
|---|---|---|
| Colons | 00:1a:2b:3c:4d:5e | Linux ip / ifconfig, macOS |
| Hyphens | 00-1A-2B-3C-4D-5E | Windows ipconfig /all |
| Dotted groups of four | 001a.2b3c.4d5e | Cisco show commands |
| No separator | 001a2b3c4d5e | Config files, logs, CSV |
All four carry the same 48-bit value and differ only in separators and letter case. Some devices and tools accept just one form, so convert to whatever the destination expects.
Use locally administered addresses. When the second-lowest bit of the first byte (value 0x02) is set, the address is defined as locally administered and never overlaps the OUI ranges IEEE assigns to vendors. Such values cannot collide with a real device, so they are suited to documentation, testing and dummy data.
It depends on where you paste it. Colons (00:1a:2b:3c:4d:5e) are usual on Linux and macOS, hyphens (00-1A-2B-3C-4D-5E) on Windows, and dotted groups of four (001a.2b3c.4d5e) on Cisco equipment. All of them carry the same 48-bit value; only the notation differs.
It is the Organizationally Unique Identifier that IEEE assigns to a manufacturer. The remaining three bytes are assigned by that manufacturer per device. Fixing a known OUI produces vendor-like values, but those can collide with real hardware, so prefer a locally administered address for testing.