What is a regular expression for a MAC Address?

In this format:

3D:F2:C9:A6:B3:4F

or:

3D-F2-C9-A6-B3-4F

The standard (IEEE 802) format for printing MAC-48 addresses in human-friendly form is six groups of two hexadecimal digits, separated by hyphens - or colons :.

So:

^([0-9A-Fa-f]{2}[:-]){5}([0-9A-Fa-f]{2})$

A little hard on the eyes, but this:

/^(?:[[:xdigit:]]{2}([-:]))(?:[[:xdigit:]]{2}\1){4}[[:xdigit:]]{2}$/

will enforce either all colons or all dashes for your MAC notation.

(A simpler regex approach might permit A1:B2-C3:D4-E5:F6, for example, which the above rejects.)

This regex matches pretty much every mac format including Cisco format such as 0102-0304-abcd

^([[:xdigit:]]{2}[:.-]?){5}[[:xdigit:]]{2}$

Example strings which it matches:

01:02:03:04:ab:cd
01-02-03-04-ab-cd
01.02.03.04.ab.cd
0102-0304-abcd
01020304abcd

Mixed format will be matched also!

delimiter: ":","-","."

double or single: 00 = 0, 0f = f

/^([0-9a-f]{1,2}[\.:-]){5}([0-9a-f]{1,2})$/i

or

/^([0-9a-F]{1,2}[\.:-]){5}([0-9a-F]{1,2})$/

exm: 00:27:0e:2a:b9:aa, 00-27-0E-2A-B9-AA, 0.27.e.2a.b9.aa ...